ARTICLE | doi:10.20944/preprints202208.0143.v1
Subject: Biology And Life Sciences, Immunology And Microbiology Keywords: non-typhoidal Salmonella; ERIC-PCR typing; WGS; virulence-related genes; SPIs; Salmonella virulence plasmids; prophages
Online: 8 August 2022 (10:07:34 CEST)
In this work, we analysed human isolates of nontyphoidal Salmonella enterica subsp. enterica (NTS), which were collected from salmonellosis cases in Armenia from 1996 to 2019. This disease became a leading food-borne bacterial infection in the region, with the younger age groups especially affected. The isolates were characterised by serotyping, Enterobacterial Repetitive Intergenic Consensus (ERIC-PCR) typing, and whole genome sequencing (WGS). The main serotypes were S. Typhimurium, S. Enteritidis, and S. Arizonae. ERIC-PCR indicated a high degree of clonality among S. Typhimurium strains, which were also multidrug-resistant and produced extended spectrum beta-lactamases. During the study period, the frequency of S. Typhimurium and S. Arizonae isolations were decreasing, but with the increase of S. Enteritidis and other NTS. A total of 42 NTS isolates were subjected to WGS and explored for virulence-related traits and the corresponding genetic elements. Some virulence and genetic factors were shared by all NTS serotypes, while the main differences were attributed to the serotype-specific diversity of virulence genes, SPIs, virulence plasmids, and phages. The results indicated the variability and dynamics in the epidemiology of salmonellosis and a high virulence potential of human NTS isolates circulating in the region.
ARTICLE | doi:10.20944/preprints202310.2099.v1
Subject: Medicine And Pharmacology, Veterinary Medicine Keywords: Oral vaccine; Salmonella delivery; porcine circovirus type 2; PCV2d
Online: 31 October 2023 (14:35:37 CET)
Oral vaccines are highly envisaged for veterinary applications due to their convenience and ability to induce protective mucosal immunity as the first line of defense. The present investigation harnessed live-attenuated Salmonella Typhimurium to orally deliver novel expression vector systems containing the Cap and Rep genes from porcine circovirus type 2 (PCV2), a significant swine pathogen. The antigen expression by the vaccine candidates JOL2885 and JOL2886, comprising eukaryotic pJHL204 and pro-eukaryotic expression pJHL270 plasmids respectively, was confirmed by western blot and IFA. We evaluated their immunogenicity and protective efficacy through oral vaccination in a mouse model. This approach elicited both mucosal and systemic immunity against PCV2d. Oral administration of the candidates induced PCV2-specific sIgA, serum IgG antibodies, and neutralizing antibodies, resulting in reduced viral loads in the livers and lungs of PCV2d-challenged mice. T-lymphocyte proliferation and flow-cytometry assays confirmed enhanced cellular immune responses after oral inoculation. The synchronized elicitation of both Th1 and Th2 responses was also confirmed by enhanced expression of TNF-α, IFN-γ, IL-4, MHC-I, and MHC-II. Our findings highlight the effectiveness and safety of the constructs with an engineered-attenuated S. Typhimurium, suggesting its potential application as an oral PCV2 vaccine candidate.
ARTICLE | doi:10.20944/preprints202307.2137.v1
Subject: Medicine And Pharmacology, Complementary And Alternative Medicine Keywords: grape seed extract; Vitis vinifera L.; anti-virulence factors; LPS; bacterial biofilm; Salmonella Typhimurium; Escherichia coli; Galleria mellonella; Caco-2.
Online: 1 August 2023 (11:13:42 CEST)
Biofilm formation and lipopolysaccharide (LPS) are implicated in the pathogenesis of gastrointestinal (GI) diseases caused by Gram-negative such as Escherichia coli and Salmonella enterica serovar Typhimurium. Grape seeds, wine industry by-products, have antioxidant, antimicrobial, and anti-inflammatory activities. In the present study, the protective effect of procyanidin-rich grape seed extract (prGSE), from unfermented pomace of Vitis vinifera cv Bellone, on bacterial LPS-induced oxidative stress and epithelial barrier integrity damages has been studied in a model of Caco-2 cells. The in vitro activity of prGSE against formation of biofilm of S. Typhimurium and E. coli, has been investigated. In vivo, prGSE activity using infected Galleria mellonella larvae has been evaluated. The results showed that the prGSE, if administered with LPS, can significantly reduce the LPS-induced permeability alteration. Moreover, the ability of the extract to prevent Reactive Oxygen Species (ROS) production induced by LPS treatment of Caco-2 cells has been demonstrated. prGSE inhibited the biofilm formation of E. coli and S. Typhimurium. In in vivo activity, increased survival of infected G. mellonella larvae after treatment with prGSE has been demonstrated. In conclusion, grape seed extracts could be used in the reduction of GI damage caused by bacterial endotoxin and biofilm of Gram-negative bacteria.
ARTICLE | doi:10.20944/preprints202111.0176.v1
Subject: Biology And Life Sciences, Immunology And Microbiology Keywords: whole genome sequencing; antibiotic resistance; Salmonella Enteritidis; Salmonella Typhimurium; Salmonella Bovismorbificans; colistin resistance; mcr-1; mcr-9
Online: 9 November 2021 (13:46:05 CET)
Polymyxin resistance, determined by mcr genes located on plasmid DNA, currently pose a high epidemiological threat. Non-typhoid Salmonella (NTS) are one of the key pathogens causing diarrheal diseases. Here, we report the isolation and whole genome sequencing of multidrug colistin-resistant/susceptible isolates of non-typhoid Salmonella enterica serovars carries mcr genes. Non-typhoid strains of Salmonella enterica subsp. enterica were isolated during microbiological monitoring of the environment, food, and diarrheal disease patients between 2018 and 2020 in Russia (n=586). mcr-1 genes were detected using a previously developed qPCR assay and whole genome sequencing of mcr positive isolates was performed by both short-read (Illumina) and long-read (Oxford Nanopore) approaches. Three colistin-resistant isolates including two isolates of S. Enteritidis and one isolate of S. Bovismorbificans carried the mcr-1.1 gene located on IncX4 and IncI2 conjugative plasmids, respectively. The phenotypically colistin-susceptible isolate of S. Typhimurium carried a mcr-9 gene on plasmid IncHI2. In conclusion, we present the first three cases of mcr gene carrying NTS isolates detected in Russia with both outbreak and sporadic epidemiological background.
ARTICLE | doi:10.20944/preprints202309.0774.v1
Subject: Biology And Life Sciences, Immunology And Microbiology Keywords: Salmonella Typhimurium; biofilm; disinfectant
Online: 13 September 2023 (02:36:24 CEST)
Biofilms are complex communities of microorganisms that adhere to surfaces and develop a protective matrix. The colonization of devices in the food and health care industries by microbial biofilms poses numerous risks. Existing antimicrobial agents often fail to penetrate the biofilm matrix, allowing the pathogen to grow and persist. The objective of this study was to evaluate the impact of MADIO PRO+ multipurpose disinfectant on Salmonella Typhimurium biofilm using crystal violet assay and FTIR spectroscopy. Results demonstrated that MADIO PRO+ multipurpose disinfectant significantly (p<0.05) inhibited biomass of S. Typhimurium biofilm and altered the structure of S. Typhimurium biofilm. In conclusion, MADIO PRO+ multipurpose disinfectant offers an advantage in biofilm control strategy. This discovery could help the food and health care industries to plan better microbial intervention strategies.
ARTICLE | doi:10.20944/preprints202203.0367.v1
Subject: Biology And Life Sciences, Immunology And Microbiology Keywords: Salmonella; Novel Antibacterial Agents; Cannabinoids
Online: 28 March 2022 (14:30:09 CEST)
Products derived from Cannabis sativa have gained increased interest and popularity. As these products become common amongst the public, the heath and potential therapeutic values associated with hemp have become a premier focus of research. While the psychoactive and medicinal properties of Cannabis products have been extensively highlighted in literature, the antibacterial properties of CBD have not been explored in depth. This research serves to examine the antibacterial potential of CBD against Salmonella newington and Salmonella typhimurium. In this study we observed bacterial response to CBD exposure through biological assays, bacterial kinetics, and fluorescence microscopy. Additionally, comparative studies between CBD and ampicillin were conducted against Salmonella typhimurium and Salmonella newington to determine comparative efficacy. Furthermore, we observed potential resistance development of our Salmonella spp. against CBD treatment.
ARTICLE | doi:10.20944/preprints202211.0030.v1
Subject: Biology And Life Sciences, Immunology And Microbiology Keywords: PCR; Salmonella Typhi; Widal Test; BHI
Online: 1 November 2022 (12:43:58 CET)
Salmonella is a foodborne pathogen associated with localized outbreaks that potentially pose a huge risk to the public health in some countries such as Africa and India, especially in the regions lacking health care measures. The focus of the present study is the molecular detection method of salmonella. The study was conducted to identify Salmonella strains by PCR targeting flagellin specific gene from suspected patient’s clinical blood samples. Serologically, Widal test results showed that all serum samples except one patient (ID 7) were positive for O antigen. The serum of three patients (ID 4, 5 and 10) were found to be positive for H and O antigens while one patient (ID 9) showed agglutination for antigen H. The PCR approach used in this study was successful for fast and precise detection of clinically related Salmonella Typhi. Seven samples out of 10 were positive for Salmonella Typhi as fragments of 458-497bp were observed on the gel-agarose 0.8% corresponds to flagellin gene of S. Typhi. Relatively, smaller amplicons of 366-343bp were observed utilizing nested PCR as well, which seems more sensitive than the conventional PCR. Therefore, we recommend the PCR approach performed in this study to be used as a fast, cost-effective, and time-consuming tool for diagnostic purposes of Salmonella.
ARTICLE | doi:10.20944/preprints202110.0308.v1
Subject: Biology And Life Sciences, Immunology And Microbiology Keywords: Salmonella newington; ɛ34 phage; Lipopolysaccharides; Antibacterial
Online: 21 October 2021 (12:47:13 CEST)
Salmonella can cause acute and chronic infections in humans. Salmonella species are known to cause food poisoning and other diseases in developing countries. Their role in the pathogenesis of these diseases has received increased international attention. Despite numerous advances in sanitation, they still can infect humans and cause outbreaks in developed countries. For example, Salmonella causes about 1.2 million illnesses in the US each year with over 450 deaths. Additionally, Salmonella outbreaks cause significant losses to chicken producers globally. The Salmonella species is also prone to acquiring resistance to various classes of antibiotics. Hence, the need for a paradigm shift from antibiotics to bacteriophages to manage, control and treat bacterial infections. The ɛ34 phage belongs to Podoviruses and categorized into the P22-like phages. The P22-like phages include ɛ34, ES18, P22, ST104, and ST64T. In this work, we investigated the antibacterial property of ɛ34 phage tailspike protein against Salmonella newington (S. newington). We demonstrate here that, the phage’s tailspike protein enzymatic property as a LPS hydrolase synergizes with Vero Cell culture supernatant in killing S. newington. Using decellularized cartilage scaffold as an ex vivo tissue model, the ɛ34 TSP protected the scaffold from S. newington biofilm formation. Computational analysis of the ɛ34 TSP interaction with membrane proteins of S. newington demonstrated a higher probability (0.7318) of binding to ompA of S. newington, and when docked to ompA extracellular component, it produced a high free energy of -11.3kcal/mol. We also demonstrate the resistance/sensitivity of the tailspike to the digestive enzyme trypsin. The data obtained in this work indicates that the trypsin resistant tailspike protein of Ɛ34 phage can be formulated as a novel antibacterial agent against S. newington.
ARTICLE | doi:10.20944/preprints202006.0252.v1
Subject: Medicine And Pharmacology, Epidemiology And Infectious Diseases Keywords: Salmonella typhi; control; Widal test; incidence
Online: 21 June 2020 (10:23:15 CEST)
Typhoid fever is a communicable disease transmitted by the bacteria Salmonella typhi, related to serotype paratyphi A, B and C. The disease is of a significant health concern in most developing countries especially Cameroon. Objectives: The study aimed at determining the prevalence and associated risk factors of typhoid fever in children ( 0-18 years) attending the “Deo Gratias” hospital in Douala. Method: A hospital base cross sectional study from August to September 2018 was carried out in patients’ age 0-18 years suffering from typhoid fever at the Deo gratias Catholic hospital. Widal slide agglutination test was the diagnostic test used. Positive tested patients were administered questionnaires to evaluate the level of knowledge, attitude and practice toward the disease, as well as their self-management abilities. Data obtained from respondents was analysed by descriptive statistics. One-way ANOVA and means comparison using Tukey’s test (α = 0.05) was performed to check whether the population of respondents differed significantly across risk factor practices. Results were finally presented on bar charts, tables and pie chart. Results: Typhoid fever was more prevalent in females (52.3%) than in males (47.7%), with a high proportion in the ages 5-9 years (38.6%). A significant difference was observed in population of respondents across risk factor practices. Conclusion: Water quality have a great impact on the burden of typhoid fever among children. The identification of risk factors associated to the disease is of great importance in the development of rational control strategies of the disease.
ARTICLE | doi:10.20944/preprints202311.1291.v1
Subject: Biology And Life Sciences, Animal Science, Veterinary Science And Zoology Keywords: Antibiotic resistance; Dessie; Kombolcha; Prevalence; Salmonella species
Online: 21 November 2023 (10:45:42 CET)
Bacteria are the major pathogens affecting food safety and foods of animal origin are main vehicles of human illness since food animals are the main reservoirs for many food-borne pathogens. Moreover, emergence and spread of multidrug-resistant food-borne bacterial pathogens become a significant public health concern globally. A cross-sectional study was conducted from October 2019 to July 2021 to estimate the prevalence, identify associated factors, and determine antibiotic resistance pattern of Salmonella species from foods of bovine origin in Dessie and Kombolcha towns. A total of 384 samples were collected. Simple and systematic random sampling techniques were employed for sampling milking cows and carcasses among cattle slaughtered at abattoirs, respectively. Samples from milk tanks, milk products, and beef were also selected randomly. Salmonella species were isolated and identified according to recommended standard bacteriological protocols. All the detected Salmonella species isolates were screened for in vitro antimicrobial susceptibility using agar disc diffusion method against 12 antimicrobial disks. The collected raw data were analyzed using descriptive and inferential analysis techniques. The overall prevalence rate of Salmonella species was 7.0%. The highest prevalence rate of Salmonella species (16.7%) was obtained from milk tank samples but not detected in milk products. Multidrug resistance to three and more than three drugs was observed among all isolated Salmonella species. All Salmonella species isolates (100.0%) were found to be resistant to Erythromycin, Tetracycline, and Vancomycin. The majority of the isolates (96.3%) were also resistant to Doxycycline and Polymyxin B. On the other hand, all isolates (100.0%) were sensitive to Gentamicin and Ciprofloxacin. The detection of multidrug-resistant Salmonella species showed that foods of bovine origin produced in the study sites were not safe for consumption. Hence, preventive measures are required to reduce bacterial contamination, concurrently to improve the wholesomeness and safety of foods of bovine origin.
COMMUNICATION | doi:10.20944/preprints202306.1663.v1
Subject: Biology And Life Sciences, Food Science And Technology Keywords: Salmonella spp; food safety; food official control
Online: 23 June 2023 (11:12:38 CEST)
Salmonella is the second most frequent bacterial pathogen involved in human gastrointestinal outbreaks in the European Union; it can enter the food production chain from animal or environmental sources or from asymptomatic food operators. European food legislation has established microbiological criteria to ensure consumer protection. Salmonella is listed under both process hygiene criteria and food safety criteria. Each Member State designates an agency to organize or perform controls and other official activities. This paper describes the official control plans performed by competent authorities in northern Italy in the three-year period 2019-2021. A total of 4413 food samples were delivered to the IZS Food Safety laboratories for Salmonella detection and 36 (0.8 %) tested positive. Salmonella was most frequently detected in poultry meat samples (25/36 positive samples) followed by other meat products and pork products. The official controls for the protection of consumer health apply the EU’s from farm-to-fork approach: the samples were collected during production (food production plants) and on the market and from collective catering (restaurants, cafeterias, canteens). This manuscript will provide information about the presence of Sal-monella in foodstuffs and can help competent authorities to set control plans based on a risk assessment.
ARTICLE | doi:10.20944/preprints202111.0248.v1
Subject: Biology And Life Sciences, Virology Keywords: Bacteriophage therapy; antimicrobial resistance; Salmonella; antibiotic synergy
Online: 15 November 2021 (10:44:07 CET)
The prevalence of multidrug resistant bacterial diseases is a major global health risk. Multidrug resistant bacterial diseases are prevalent, and the need for novel methods of treatment is essential to the preservation of public health. Annually foodborne pathogens cause 1.35 million infections and 26,500 hospitalizations in the United States alone. Foodborne pathogens such as Salmonella spp. are a major threat to public health. Bacteriophages offer a unique method for the treatment of these multidrug resistant bacteria. We studied the infection dynamics of a potential mono-phage therapy of Salmonella typhimurium under various pathophysiological conditions. Furthermore, we determined the resistance dynamics of Salmonella typhimurium against P22 phage treatment. We also determined synergy with antibiotics such as ampicillin and kanamycin. This research helps to further define and show the versatility of bacteriophages as potential novel treatment methods.
ARTICLE | doi:10.20944/preprints202105.0069.v1
Subject: Biology And Life Sciences, Biochemistry And Molecular Biology Keywords: Antimicrobial Resistance; Biosecurity; Egg; Nigeria; Poultry; Salmonella
Online: 5 May 2021 (15:04:41 CEST)
Salmonella remains one of the notable food-borne bacterial pathogens. It is associated with poultry and poultry products including eggs. This study investigated Salmonella distribution in eggshell and content, their antimicrobial resistance pattern, and the possible risk factors driving contamination in Ogun State, Nigeria. A total of 500 eggs (5 eggs pooled into one sample) were collected and culturally examined for the presence of Salmonella serovars. Isolates were further characterized biochemically using Microbact 20E (Oxoid) and Antimicrobial susceptibility determined by the Kirby-Bauer disk diffusion method. A total of 14 Salmonella isolates spread across 10 serovars were recovered from the 100 pooled egg samples; 10 (10%) from the market and 4 (4%) farms, 13(13%) eggshell, and 1(1%) egg content. All tested serovars were susceptible to ampicillin, chloramphenicol, florfenicol, and kanamycin. Resistance was mostly observed in sulfamethoxazole 8 (80%), followed by ciprofloxacin 5 (50%) and tetracycline 3 (30%). Sales of eggs in the market appears to be a strong factor encouraging contamination in addition to poor biosecurity and unhygienic handling of eggs on the farm.
ARTICLE | doi:10.20944/preprints201907.0169.v1
Subject: Biology And Life Sciences, Immunology And Microbiology Keywords: polyvalent bacteriophage FP01, Escherichia coli, Salmonella, genome
Online: 12 July 2019 (13:07:09 CEST)
Recently the polyvalent bacteriophage FP01, isolated from wastewater in Valparaiso, Chile, was described to have lytic activity across species against Escherichia coli and Salmonella enterica serovars. Due to it polyvalent nature the bacteriophage FP01 could have potential application in food and agri-industry. Also, fundamental aspects of polyvalent bacteriophage biology are not well known. In this study we sequenced and describe the complete genome of the polyvalent phage FP01 (MH745368) using the nanopore technology. The bacteriophage FP01 genome has a 44,900 bp, double-stranded DNA with an average G+C content of 49.41% and 90 coding sequences (CDSs). We found that the phage FP01 critically depends on host factors for replication and transcription. Also, it has a critical lysogenic repressor pseudogene. Phylogenetic analyses indicated that the phage FP01 is closely related to phages lambda and P22. These results suggest that the phage FP01 could be a lytic variant of a lysogenic phage or acquired genes from lysogenic phages during host infection.
ARTICLE | doi:10.20944/preprints202012.0679.v1
Subject: Biology And Life Sciences, Biochemistry And Molecular Biology Keywords: Antimicrobial resistance; Salmonella species; E.coli; Broiler chickens; Malaysia
Online: 28 December 2020 (10:49:17 CET)
Abstract:Salmonella species (spp) and Escherichia coli (E. coli) are the most common infectious pathogens in poultry. Antimicrobials were given either for the treatment or growth promoters that can increase the possibility of emergence of bacterial resistance towards antimicrobials. The aim of this study was to determine the prevalence of antimicrobial resistant (AMR) Salmonella spp and E. coli isolated from a sample of broiler farms in East Coast Malaysia from 2018-2019. A total of 384 cloacal swabs were collected from broilers farms in Kelantan, Terengganu, and Pahang. The bacteria were isolated and confirmed by bacteriological and serological methods. Following that, confirmed isolates were subjected to antimicrobial susceptibility test. Salmonella spp and E. coli were recovered from the cloacal swabs samples with the overall prevalence of 6.5% and 51.8% respectively. In Kelantan, Terengganu and Pahang, the prevalence of Salmonella spp were 7%, 6.5% and 5.8% respectively, while the prevalence for E. coli were 50%, 48.3% and 58% respectively. Salmonella spp and E. coli displayed resistance towards the following antimicrobials: erythromycin (100% for both pathogens), chloramphenicol (76.2%, 84.5%), tetracycline (62%, 94.6%), ampicillin (47.7%, 87%), sulfamethoxazole/trimethoprim (42.9%, 83.3%), ciprofloxacin (4.8%, 23.8%), nalidixic acid (9.6%, 60.7%), streptomycin (19%,66%), and kanamycin (28.6%,57%), cephalotin (0%, 11%), gentamicin (0%, 20.2%) respectively. No resistance were recorded towards colistin for both pathogens. Multidrug resistance (MDR) was recorded in 82% of Salmonella spp and 100% of E. coli. These findings demonstrate the high prevalence of MDR Salmonella spp. and E. coli in broiler farms in East coast Malaysia. This could be attributed to the excessive use of antimicrobial agents by the poultry farm owners. Enhanced control measures and a strong monitoring system should be urgently implemented to reduce the emergence of antimicrobial resistance that is harmful to public health.
REVIEW | doi:10.20944/preprints202310.0950.v2
Subject: Biology And Life Sciences, Animal Science, Veterinary Science And Zoology Keywords: probiotics in poultry; Salmonella infections; antibiotic resistance; poultry health
Online: 9 November 2023 (02:28:48 CET)
Salmonella infection is one of major challenges to the poultry industry because of its pressing effects on health of poultry, food safety and human well-being that later may devastate economic losses to the poultry sector. The paper reviews public health implications and the use of antibiotics together with the risk of drug resistance. In recent years, the usage of probiotics in poultry industry has been growing to mitigate an increasing pressure to adopt sustainable farming practices. The mechanisms which probiotics may control Salmonella and important criteria for selecting effective probiotics in poultry are reported. Various studies highlighting the additional benefits of probiotics in poultry production in addition to Salmonella controls are also included. While probiotics offer promise in enhancing poultry health, challenges and limitations in their utilization must also be carefully considered.
ARTICLE | doi:10.20944/preprints202209.0143.v1
Subject: Biology And Life Sciences, Immunology And Microbiology Keywords: Salmonella; novel antibacterial agents; cannabidiol; co-therapy; bacterial genetics
Online: 12 September 2022 (09:55:22 CEST)
New generation antibiotics are needed to combat the development of resistance to antimicrobials. One of the most promising new classes of antibiotics is cannabidiol (CBD). It is a non-toxic and low-resistance chemical that can be used to treat bacterial infections. The antibacterial activity of Cannabis sativa L. byproducts, specifically CBD, has been of growing interest in the field of novel therapeutics. As research continues to define and characterize the antibacterial activity that CBD possesses against a wide variety of bacterial species it is important to examine potential interaction between CBD and common therapeutics such as broad-spectrum antibiotics. Here, we show that CBD-antibiotic co-therapy can effectively fight S. typhimurium via membrane integrity disruption. This research serves to examine the potential synergy between CBD and three broad-spectrum antibiotics for potential antibiotic-CBD co-therapy. In this study, we reveal that Salmonella typhimurium (S. typhimurium) growth is inhibited at very low dosages of CBD-antibiotic. This interesting finding demonstrates that CBD and CBD-antibiotic co-therapies are viable novel alternatives to combating Salmonella typhimurium.
ARTICLE | doi:10.20944/preprints201811.0445.v1
Subject: Biology And Life Sciences, Immunology And Microbiology Keywords: Contamination, Escherichia coli, fecal coliforms, Nakawa, Salmonella, Staphylococcus aureus
Online: 19 November 2018 (10:19:56 CET)
This study evaluated the microbial safety of vended boiled, pasteurized and UHT milk sold in Nakawa, Kampala-Uganda. 15 milk samples were analyzed; 2 samples had Salmonella, 5 had S. aureus with a count of 1.66 0.02 log10CFU/ml. E. coli was detected in 8 samples with 1.0 0.02 to 3.0 0.01log10CFU/ml count. A high load of 3.0 CFU/ml was obtained in 3 samples with E. coli. Four E. coli positive samples had a contamination load of 2.0 0.015log10 CFU/ml of which one was pasteurized milk. Only a pasteurized milk showed a low E. coli load at 1.0 0.02log10 CFU/ml. All UHT milk had no microbial contamination. Both boiled and pasteurized milk had Salmonella, S. aureus and E. coli in levels above the set threshold limits. Milk consumers in Nakawa stand a potential public health risk of food poisoning reflected by presence of Salmonella, S. aureus and E. coli in some milk sold in the area.
REVIEW | doi:10.20944/preprints202311.0732.v1
Subject: Biology And Life Sciences, Immunology And Microbiology Keywords: Salmonella Typhi; Typhoid Fever; Fimbriae; Vaccine; Antibacterial Agent; Drug Target
Online: 13 November 2023 (10:04:43 CET)
Despite recent public health and hygiene advancements, enteric fever, commonly referred to as typhoid fever, remains a common disease in developing nations. The common mode of infection is contaminated water or food. Additionally, person-to-person transmission through poor hygiene and sewage contamination of water supplies has been blamed for most outbreaks. The exact burden of typhoid has yet to be discovered because of the lack of surveillance systems in many developing nations. This makes it difficult to estimate the number of cases. Recent studies have shown that the actual number of cases of typhoid has been estimated to be around 21.6 million annually. The mortality studies suggest that the incidence of typhoid is highest in children under five years old. Typhoid fever and paratyphoid fever have been demonstrated to be life-threatening illnesses. Salmonella serotype Typhi (S. Typhi) is the causative organism of typhoid fever whereas Salmonella serotype Paratyphi is the causative organism for paratyphoid fever. The S. Typhi bacterium is known to be resistant to various drugs. There is a dire need to develop new drugs to treat and overcome the current drug-resistant S. Typhi. The identification of new targets marks the beginning of the process of developing new anti-S. Typhi drugs. The S. Typhic genome sequencing and recent cutting-edge molecular biology tools have led to the discovery of numerous new inhibitors and targets. The goal of this review is to identify the most critical targets in the S. Typhi that are targeted by drugs. It also highlights the various promising vaccines on the market or are still in preclinical studies. A detailed understanding of the targets could help researchers develop safer and more efficient antibacterial agents against S. Typhi.Additionally, the advancement of molecular techniques and the knowledge of the Salmonella pathogenesis pathways have opened better avenues to develop effective antibiotics and vaccines against this pathogen. This review also sought to identify and summarize critical structures of this pathogen that play significant roles in the maturation, development, and pathogenesis of S. Typhi. The endpoint of this work is to provide valuable information on potential therapeutic targets of S. Typhi for drug and vaccine developers.
ARTICLE | doi:10.20944/preprints202310.0630.v1
Subject: Public Health And Healthcare, Public, Environmental And Occupational Health Keywords: Enterobacteriaceae; Camels; Cattle; Sheep; Slaughterhouses; Butcher Shops; Salmonella; Al-Ahsa
Online: 10 October 2023 (12:21:52 CEST)
Enterobacteriaceae can contaminate meat during various stages of processing, including slaughter, evisceration, and butchering, causing foodborne illnesses. The purpose of the study was to investigate the prevalence of Enterobacteriaceae associated with carcasses obtained from slaughterhouses and raw cut meat collected from butcher shops. A total of 120 samples of camels and cattle were identified using biochemistry and PCR testing. Total viable count (TVC) was range from 4.91 to 5.37 Log10 CFU/g in slaughterhouses and butcher shops. E. coli was predominating with 84 (70%) among all samples, where the camels had the highest with 100% and sheep the lowest with 30%. Salmonella spp. was confirmed in 40% of camel samples, 47.5% of cattle samples, and 32.5% in sheep samples. Twenty-five Enterobacteriaceae genera were confirmed using PCR. Where sheep’s samples had the highest occurrence of Enterobacteriaceae with 15 different genera followed by camels and cattle samples with 14 different genera. The prevalence of Enterobacteriaceae among camel, cattle, and sheep carcasses raises significant concerns regarding food safety. Adherence to good hygiene practices throughout animal slaughtering is crucial to minimize the risk of infection and transmission and ensure food safety.
ARTICLE | doi:10.20944/preprints202002.0383.v1
Subject: Medicine And Pharmacology, Medicine And Pharmacology Keywords: Salmonella; antibiotic resistance; immunoinformatic; epitope; molecular docking; molecular dynamics simulation
Online: 26 February 2020 (01:56:41 CET)
Salmonella, especially invasive non-typhoidal Salmonella (iNTS) are responsible for developing various invasive diseases, and possess higher mortality rate, due to their higher antibiotic resistance profile than the other bacteria. Therefore, the present study was concerned to develop epitope based peptide vaccine against iNTS species as a successive and substitute protective measures. The study considered comprehensive Immunoinformatic approaches, followed by molecular docking and molecular dynamics simulation to predict the efficient vaccine candidate T cell and B cell epitopes, based on the outer membrane proteins. The study identified two best epitopes YGIFAITAL and KVLYGIFAI from total iNTS outer membrane proteins, which showed higher immunity, non-allergenicity, non-toxicity and also showed higher conservancy and population coverage values. Both epitopes showed higher binding affinity and stability towards HLA-C* 03:03. The MM-PBSA binding free energy showed the YGIFAITAL epitope binds more tightly with both MHC-I and MHC-II molecules. The total contact, H-bond analysis and RMSF results also validate the efficiency of these epitopes as vaccine candidate. The projected B cell epitopes AAPVQVGEAAGS, TGGGDGSNT and TGGGDGSNTGTTTT showed higher antigenicity. Overall, the study concluded that these epitopes can be considered as the potential vaccine candidate to make a successive vaccine against iNTS species. However, this result further needs to be validate by wet lab research to make successive vaccine with these projected epitopes.
ARTICLE | doi:10.20944/preprints202305.0138.v1
Subject: Biology And Life Sciences, Food Science And Technology Keywords: Edible coating; Salmonella; Listeria; Pistacia vera; essential oil; chicken breast; resin
Online: 3 May 2023 (10:49:51 CEST)
Antimicrobial edible coatings could eliminate pathogen contamination risk on the surface of meat and poultry products during storage. In this study, the edible coating (EC) based on wheat gluten, Pistacia vera L. tree resin (PVR), and essential oil (EO) of PVR were applied on chicken breast fillets (CBF) by dipping method to prevent the growth of Salmonella Typhimurium and Listeria monocytogenes. The samples were packed in foam trays wrapped with low-density polyethylene stretch film and stored at 8°C for 12 days to observe antimicrobial effects and sensory properties. The total bacteria count (TBC), L. monocytogenes, and S. Typhimurium were reported during the storage. All samples coated with EC containing 0.5, 1, 1.5, and 2% v/v EO (ECEO) decreased microbial growth significantly compared to control samples. The growth of TBC, L. monocytogenes, and S. Typhimurium was suppressed by 4.6, 3.2, and 1.6 logs, respectively, at the end of 12 days on the samples coated by ECEO (2%) compared to uncoated controls (p<0.05). Coating with ECEO (2%) also preserved appearance, smell, and general acceptance parameters better than uncoated raw chicken (p<0.05) on the 5th day of storage. In grilled chicken samples, ECEO (2%) did not significantly change the sensory properties of appearance, smell, and texture but had increased taste and general acceptance scores (p>0.05). So, ECEO (2%) can be a feasible and reliable alternative to preserve chicken breast fillets without affecting their sensory properties adversely during the shelf life.
ARTICLE | doi:10.20944/preprints202207.0338.v1
Subject: Medicine And Pharmacology, Veterinary Medicine Keywords: Non-typhoidal Salmonella; poultry; risk factor; Nigeria; fowl typhoid; pullorum disease
Online: 22 July 2022 (13:12:50 CEST)
Salmonellosis is a bacterial zoonosis with array of health conditions. Non-typhoidal salmonellosis (NTS) have a discrete adaptation to certain animals; in poultry, pullorum and fowl typhoid are its primary disease manifestations. The diseases are prevalent in the Nigerian poultry and have been well studied in Nigeria, but less so in the north central Nigeria (NCN). Using field sampling, laboratory methods and semi structured questionnaire in 1000 poultry farms from NCN, we explore the incidence and risk factors for the persistence of NTS infection in poultry. Approximately 41.6% of the farms have experienced NTS but only 6.3% have current infection with NTS. Farm experience of NTS moderately predicted awareness of salmonellosis. Increasing stock in smallholder farms, self-mixing of concentrate on the farm, usage of stream water, pen odour, non-adherence and partial adherence of farms to recommended poultry vaccination against pullorum and fowl typhoid, and lack of and non-adherence to biosecurity were identified risk factors that increased the odds of NTS infection in poultry. Antibiotic use practice may have reduced the isolation rate of NTS, yet NTS continues to challenge poultry farms in Nigeria. Identified risk practices must be mitigated intentionally and biosecurity and hygiene must improve to reduce the burden of NTS.
ARTICLE | doi:10.20944/preprints202201.0181.v1
Subject: Biology And Life Sciences, Immunology And Microbiology Keywords: One Health Strategies; Antimicrobial Resistance; Salmonella isolates; Poultry Farms, Turkey Poults
Online: 12 January 2022 (18:12:21 CET)
Antimicrobial resistance (AMR) is an increasing hazard to human and animal health that necessitates an international response. Surveillance methods in high-income nations aided in the development of measures to combat AMR in animals. Demand for meat is increasing in countries making it critical to implement anti-AMR initiatives. Surveillance of AMR, on the other hand, is at best in its infancy, and the current evidence base for informing policymakers is geographically disparate. All of the isolates had high rates of AMR to medicines that are critical/highly important in human and animal medicine. A higher incidence of AMR was found in poultry farms. Our findings show that AMR, including MDR, is common in coli, Salmonella spp., commonly found in poultry. The study promotes the development of national policies, programs, and additional research based on a "One Health" approach that helps humans and animals, as well as the environment.
Subject: Biology And Life Sciences, Agricultural Science And Agronomy Keywords: Salmonella enterica; food safety; genome; theory; single nucleotide polymorphisms; recombination; serotype
Online: 31 August 2021 (12:47:33 CEST)
Adenine and thymine homopolymer strings of at least 8 nucleotides (AT 8+mers) were characterized in Salmonella entericasubspecies I. The motif differed between cother taxonomic classes but not between Salmonella enterica serovars. The motif in plasmids was associated with serovar. Approximately 12.3% of the S. enterica motif loci had mutations. Mutability of AT 8+mers suggests that genomes undergo frequent repair to maintain optimal gene content, and that the motif facilitates self-recognition; in addition, serovar diversity is associated with plasmid content. A theory that genome regeneration accounts for both persistence of predominant Salmonella serovars and serovar diversity provides a new framework for investigating root causes of foodborne illness.
ARTICLE | doi:10.20944/preprints201912.0373.v1
Subject: Biology And Life Sciences, Biochemistry And Molecular Biology Keywords: bacterial flagellar motility; flagellin; Salmonella; FljB; FliC; electron cryomicroscopy; viscosity; infection
Online: 29 December 2019 (07:47:57 CET)
The bacterial flagellum is a motility organelle, consisting of a long helical filament as a propeller and a rotary motor that drives rapid filament rotation to produce thrust. Salmonella enterica serovar Typhimurium has two genes of flagellin, fljB and fliC, for flagellar filament formation and autonomously switches their expression at a frequency of 10-3–10-4 per cell per generation. We report here differences in their structures and motility functions under high viscosity conditions. A Salmonella strain expressing FljB showed a higher motility than the one expressing FliC under high viscousity. To examine the reasons for this motility difference, we carried out structural analyses of the FljB filament by electron cryomicroscopy and found that the structure is nearly identical to that of the FliC filament except for the position and orientation of the outermost domain D3 of flagellin. The density of domain D3 was much lower in FljB than FliC, suggesting that domain D3 of FljB is more flexible and mobile than that of FliC. These differences suggest that domain D3 plays an important role not only in changing antigenicity of the filament but also in optimizing motility function of the filament as a propeller under different conditions.
ARTICLE | doi:10.20944/preprints201904.0055.v1
Subject: Biology And Life Sciences, Immunology And Microbiology Keywords: biofilm; carboxyfluorescein diacetate; Listeria monocytogenes; Salmonella; E. coli O157:H7; microplate assay
Online: 4 April 2019 (12:45:18 CEST)
Biofilms enable the persistence of pathogens in food processing environments. In order to inactivate these microorganisms, sanitizing agents are needed that are effective against pathogens entrapped in biofilms which are more difficult to inactivate than planktonic cells that are displaced and found on equipment surfaces. We examined conditions to develop, analyze, and enumerate robust biofilms of 3 different foodborne pathogens assisted by fluorescence adherence assay and enzymatic detachment. We compared 3 different isomeric forms of fluorescent substrates that are readily taken up by bacterial cells based on carboxy-fluorescein diacetate (5-CFDA, 5,6-CFDA, 5,6-CFDA,SE). Biofilm-forming strains of L. monocytogenes, E.coli O157:H7, and Salmonella serovars were detected using the chosen substrate in a microplate fluorescence assay define previously for use with Listeria. Adherence levels were determined by differences in relative fluorescence units (RFU). Multiple hydrolytic enzymes were examined for each representative pathogen for the most suitable enzyme for detachment and enumeration to confirm data obtained by fluorescence assay. Cultures were grown overnight in microplates, incubated, washed and replenished with fresh sterile growth medium; this cycle was repeated 7 times before used as ‘biofilms’. All treatments were performed in triplicate and compared by one-way analysis of variance (ANOVA) to determine significant differences (p < 0.05). Analysis of 7-day biofilms by SEM indicated possible extracellular polysaccharide involvement with Salmonella and E. coli.
ARTICLE | doi:10.20944/preprints202304.0425.v1
Subject: Biology And Life Sciences, Horticulture Keywords: Enteric pathogens; hydroponic; nutrient solution; Salmonella; Listeria mono-cytogenes; Listeria innocua; lettuce; temperature
Online: 17 April 2023 (07:54:47 CEST)
This study aimed to determine the persistence of Salmonella Javiana, Listeria monocytogenes, and Listeria innocua in hydroponic nutrient solution (NS) at 15, 25, 30, and 37°C over a 21-day period to mimic time from seedling to mature lettuce. Bacteria were inoculated in modified Hoagland's NS at 106 CFU/ml and maintained at 15, 25, 30, and 37°C. Samples were collected at various time points and quantified. Data were analyzed using a mixed effect model to compare mean log CFU/ml obtained from each sampling point for all three bacteria at four different temperatures. Least mean squares were calculated to compare mean log CFU/ml. Tukey-Kramer honest significant difference test was used to compare mean values. At all temperatures, S. Javiana persisted in NS throughout the 21-day study period, compared to L. innocua and L. monocytogenes where persistence was limited to d 5 to d 14 and d 1 to d 14, respectively. Similarly, decimal reduction values (D-values) of S. Javiana indicated longer persistence in nutrient solution than L. innocua and L. monocytogenes at most temperatures. For instance, at 15°C and 25°C D-values for S. Javiana were estimated at 82 and 26 d, respectively, compared to D-values of 3.6 and ~3 d for L. monocytogenes. Data indicate that temperature has minimal effect on S. Javiana and thus may pose a greater risk during hydroponic production of leafy greens due to longer survival in NS when compared to Listeria spp. This study furthers the understanding of potential food safety risks associated with hydroponic systems and may aid in developing management strategies to reduce foodborne outbreaks, fresh produce recalls, and economic losses.
REVIEW | doi:10.20944/preprints202207.0365.v1
Subject: Biology And Life Sciences, Immunology And Microbiology Keywords: Salmonella; Campylobacter; poultry; review; vaccines; processing; farm-to-fork; broilers; meat birds; production
Online: 25 July 2022 (09:24:22 CEST)
Enteropathogens, namely Salmonella and Campylobacter, are a concern in global public health and have been attributed in numerous risk assessments to a poultry source. During the last decade a large body of research addressing this problem has been published. The literature reviewed contains review articles on certain aspects of poultry production chain, however in the past decade there hasn’t been a review on the through production chain, farm to fork, production of poultry. This review, a pool of 514 articles were selected for relevance via a systematic screening process (from >7500 original search articles). These studies identified a diversity of management and intervention strategies for the elimination or reduction of enteropathogens in poultry production. Many studies were laboratory or limited field trials with implementation in true commercial operations being problematic. Entities considering using commercial anti-enteropathogen products and interventions are advised to perform an internal validation and fit for purpose trial as Salmonella and Campylobacter serovars and biovars may have regional diversity. Future research should focus on non-chemical application within the processing plant and how synergistic through chain intervention may contribute to reducing the overall carcass burden of enteropathogen, coupled with increased consumer education on safe handling and cooking of poultry.
ARTICLE | doi:10.20944/preprints202009.0707.v1
Subject: Biology And Life Sciences, Biochemistry And Molecular Biology Keywords: antimicrobial alternatives; fermented defatted ‘alperujo’; intestinal health; olive oil by-products; Salmonella Typhimurium.
Online: 29 September 2020 (10:47:47 CEST)
Salmonella spp. contaminates egg and poultry meat leading to foodborne infections in humans. The emergence of antimicrobial-resistant strains limit the use of antimicrobials. We aimed to determine the effects of the food supplement, fermented defatted ‘alperujo’, a modified olive-oil by-product, on Salmonella Typhimurium colonisation in broilers. One hundred and twenty 1-day-old broilers were divided into four experimental groups: 2 control groups and 2 treated groups, and challenged with S. Typhimurium at day 7 or 21. On days 7, 14, 21, 28, 35 and 42 of life, duodenum and caecum tissue samples were collected for histopathological and histomorphometric studies. Additionally, cecum content was collected for Salmonella spp. detection by culture and qPCR, and for metagenomic analysis. Our results showed a significant reduction of Salmonella spp. in the cecum of 42-day-old broilers, suggesting that fermented defatted ‘alperujo’ stimulates Salmonella Typhimurium clearance in that cecum and may contribute to diminishing the risk of carcass contamination at the time of slaughter. Additionally, the improvement of the mucosal integrity suggests that enhancing intestinal health helps to limit Salmonella spp. colonisation in the host, mitigating production losses. These results could provide evidence that FDA would contribute to prophylactic and therapeutic measures to reduce salmonellosis prevalence in poultry farms.
ARTICLE | doi:10.20944/preprints201702.0006.v1
Subject: Biology And Life Sciences, Immunology And Microbiology Keywords: Deformed cloacal region; Danio rerio; Live-Cell imaging; Salmonella infection; Immune response; Cloacitis
Online: 3 February 2017 (04:18:59 CET)
Pathogenic Salmonella strains have a set of virulence factors allowing them to generate systemic infections and damage in a variety of hosts. Among these factors, bacterial proteins secreted by specialized systems are used to penetrate the host’s intestinal mucosa, through the invasion and destruction of specialized epithelial M cells in the intestine. On the other hand, numerous studies have demonstrated that humans, as well as experimental animal hosts, respond to Salmonella infection by activating both innate and adaptive immune responses. Here, through live cell imaging of S. Typhimurium infection of zebrafish larvae, we showed that besides the intestinal colonization, a deformed cloacae region and a concomitant accumulation of S. Typhimurium cells was observed upon bacterial infection. The swelling led to a persistent inflammation of infected larvae, although the infection was non-lethal. The in vivo inflammation process was confirmed by the co-localization of GFP-tagged S. Typhimurium with mCherry-tagged neutrophils at 72 hours post exposition. Our live-cell analyses suggest that Salmonella Typhimurium induce cloacitis-like symptoms in zebrafish larvae. Typhimurium induce cloacitis-like symptoms in zebrafish larvae.
ARTICLE | doi:10.20944/preprints202309.0727.v1
Subject: Biology And Life Sciences, Virology Keywords: Salmonella virus; viral genome-packaging motor; small terminase; large terminase; Bacteriophage P22; electron microscopy
Online: 12 September 2023 (04:43:44 CEST)
Concatemeric viral DNA is packaged into Bacteriophage P22 procapsids via a headful packaging mechanism mediated by a molecular machine consisting of small (gp3) and large (gp2) terminase subunits. Although a negative stain reconstruction exists for the terminase holoenzyme, it is not clear how this complex binds dodecameric portal protein located at a 5-fold mismatch vertex. Herein, we describe new assemblies for the holoenzyme. Both native mass spectrometry and transmission electron microscopy reveal that the P22 terminase complex adopts three main assemblies, which include a nonameric S-terminase bound to two L-terminase 1(gp3)9:2(gp2), two nonameric S-terminase bound to five L-terminase 2(gp3)9:5(gp2), and three nonameric S-terminase bound to seven L-terminase 3(gp3)9:7(gp2). Native agarose gel electrophoresis shows that the terminase complex interacts with procapsid with mild crosslinking. These results herein illustrate the P22 terminase complex can adopt a variety of confirmations and assembly states.
ARTICLE | doi:10.20944/preprints202106.0638.v1
Subject: Biology And Life Sciences, Biochemistry And Molecular Biology Keywords: pancreatic ductal adenocarcinoma; targeted therapies; therapeutic resistance; tumor microenvironment; desmoplasia; collagen; collagenase; attenuated Salmonella typhimurium
Online: 28 June 2021 (10:36:31 CEST)
Therapeutic resistance in pancreatic ductal adenocarcinoma (PDAC) can be attributed, in part, to a dense extracellular matrix containing excessive collagen deposition. Here, we describe a novel Salmonella typhimurium (ST) vector expressing the bacterial collagenase Streptomyces omiyaensis trypsin (SOT), a serine protease known to hydrolyze collagens I and IV, which are predominantly found in PDAC. Utilizing aggressive models of PDAC, we show that ST-SOT selectively degrades intratumoral collagen leading to enhancement of immune checkpoint blockade (ICB) therapy in tumor-bearing mice. Ultimately, we found that ST-SOT treatment significantly modifies the intratumoral immune landscape to generate a microenvironment more conducive to ICB.
ARTICLE | doi:10.20944/preprints201911.0063.v2
Subject: Biology And Life Sciences, Immunology And Microbiology Keywords: contamination; pathogens; bacteria; escherichia coli; staphylococcus aureus; hygiene; shigella; salmonella; milk processing; foodborne infection; cfu
Online: 13 November 2019 (10:37:25 CET)
Pasteurized milks are still causing food borne illness. Milk contamination can occur at any stage from its way from cow to our tables. Usually milk is pure and sterile when produced in udder of a healthy cow. Like humans, cow are reservoirs of bacteria which are harmless to humans and some cows can harbour few bacteria that are harmful to humans even though they are not harmful to the cow. Milk can be contaminated during or after milking. Also, cow feeds can be contaminated with mycotoxins such as aflatoxins produced by the fungi, Aspergillus flavus. Four types of aflatoxins are known which are; aflatoxin B1, B2, G1, G2. Cows comsuming feeds contaminated with aflatoxin B1 leads to secretion in the milk of aflatoxin M1 and M2 causing aflatoxicosis. Microbial contamination of milk and dairy products is a universal problem and foodborne infections accounting for 20 million cases annually in the world have been identified as an important public health and economic problem in developed as well as developing nations. The main objective of this study was to determine milk microbial quality in Kicukiro district. The specific objectives are to identify bacteria pathogens in milk collected in Kicukiro district, to compare milk quality among sectors of Kicukiro district, to compare milk processed by industries and home-processed milk. The methodology employed in this research was cross-sectional and experimental as the study began with collection of raw data and went through laboratory analysis from July–August, 2018. The findings showed that 59.56% of the milk fell within Grade I – Grade III (< 200,000 ≤ 2,000,000 cfu/ml) and 40.42 % of the milk samples were not within the acceptable limit of total count quality as per COMESA and EAS, non-lactobacilli and fungi were present in most samples as examined through microscope and no Staphylococcus aureus was present in any sample as examined by catalase and coagulase tests.
Subject: Biology And Life Sciences, Immunology And Microbiology Keywords: essential oil; Mentha pulegium; Mentha suaveolens; Listeria monocytogenes; Salmonella enterica; antioxidant; sub-lethally injured bacteria
Online: 5 May 2019 (12:05:03 CEST)
The essential oils (EOs) obtained from aromatic plants are rich in natural compounds with interesting biological effects. The aim of this study was to evaluate the chemical composition of EOs of Mentha pulegium (MP-EO) and Mentha suaveolens (MS-EO) collected from Morocco, and their antioxidant properties and antibacterial activity against Salmonella enterica and Listeria monocytogenes. The EOs were extracted by hydro-distillation, while the chemical compositions were determined by GC-MS. The antioxidant activity was evaluated by DPPH and FRAP assay. Antibacterial activity was tested with disc diffusion assay; determination of minimum inhibitory concentration, minimum bactericidal concentration and the evaluation of sub-lethally injured cell were also performed. The results of chemical composition showed the presence of compounds not still reported in EOs obtained from these plants. MS-EO was characterized by the best antioxidant and antibacterial activity vs S. enterica and L. monocytogenes respect to MP-EO. The EOs tested in this study were rich in compounds with interesting activities and they could be applied in the medical fields, as well as in food industries as natural preservatives against tested food borne pathogens.
ARTICLE | doi:10.20944/preprints202311.1652.v1
Subject: Biology And Life Sciences, Biology And Biotechnology Keywords: Food safety; Fresh fruits and vegetables; E. coli; Vibrio spp; Salmonella spp; metagenomic
Online: 27 November 2023 (11:11:22 CET)
This study aimed to assess the microbiological quality of set of fruits and vegetables sold on stalls in the streets and open markets of Dakar, the capital city of Senegal. Samples purchased in seven sites were analyzed to isolate E. coli, Salmonella spp. and Vibrio spp. Some primary samples with a positive microbiological culture were subjected to DNA extraction and subsequent metagenomic analysis. A total of 240 fresh fruit and vegetable samples were collected including lettuce (n=40), tomatoes (n=40), mango slices (n=40), onion slices (n=40), mint leaves (n=40), strawberries and grapes (respectively n=20). Of these samples, 50.83% (122/240) and 60.41% (145/240) was contaminated with Escherichia coli and Vibrio spp. respectively, while Salmonella was not isolated in any product. Levels of contamination with both E. coli (1.3 103 to 6 106 CFU/g) and Vibrio spp. (4.55 102 to 8.73 106 CFU/g) were significantly above the thresholds acceptable for human consumption. The most contaminated samples were lettuce with a prevalence of 98% (39/40) for E. coli and for Vibrio spp. followed by mint leaves with 100% (40/40) and 93% (37/40) of the samples containing for E. coli and Vibrio spp. respectively. Out of 46 samples sequenced, metagenomic analysis revealed high contamination rates for E. coli, Vibrio spp. and Salmonella spp. with 100%, 67.39% and 93.47% of prevalence respectively. On the other hand, the alpha diversity analysis shows a high bacterial diversity in lettuce and mint leaf samples while beta diversity analysis highlighted the presence of two major clusters. Our results stress the need of a surveillance system that extends this investigation to a national scale while increasing the number of sampling sites and products analyzed.
ARTICLE | doi:10.20944/preprints202310.0754.v1
Subject: Biology And Life Sciences, Food Science And Technology Keywords: Salvia officinalis essential oil; beef tenderloin (musculus psoas major); sous-vide; Salmonella enterica; antimicrobial effect; novel application; active substance
Online: 12 October 2023 (04:59:25 CEST)
Sous-vide is a process in which food is vacuum-sealed and prepared in a water bath, heated to a precise temperature, and circulated in a sous-vide machine. This cooking technique is increasingly common in homes and catering establishments due to its simplicity and affordability. However, manufacturers' and chefs' recommendations for low-temperature and long-term sous-vide cooking in media raise food safety concerns, particularly when preparing beef tenderloin. In this study, Salmonella enterica was found to be inactivated by heat and sage essential oil (EO) in beef tenderloin from musculus psoas major that had undergone sous-vide processing. To determine whether heat treatment was likely to increase the sous-vide efficiency, S. enterica and sage EO were mixed. After being vacuum-packed and injected with S. enterica, the samples were cooked sous-vide for the prescribed time at 50, 55, 60, or 65 °C. On days 1, 3, and 6, the amounts of S. enterica, total bacteria, and coliform bacteria were measured in both groups of sous vide beef tenderloin. Mass spectrometry was used to identify bacterial strains on various days and categories. Each day that was measured, the test group exposed to a temperature of 50 °C for 5 minutes had a higher number of all microbiota. The most isolated microorganisms from the control and treated groups were Pseudomonas fragi, and in the treated group also S. enterica. It has been shown that adding sage essence oil (EO) in combination with the sous-vide gastronomic method leads to the stabilization and safety of beef tenderloin.