ARTICLE | doi:10.20944/preprints202103.0522.v1
Subject: Biology, Anatomy & Morphology Keywords: Commensal bacteria; Neisseria; antimicrobial resistance; multidrug resistance
Online: 22 March 2021 (11:37:13 CET)
Pathogenic Neisseria gonorrhoeae causes the sexually-transmitted infection gonorrhea. N. gonorrhoeae has evolved high levels of antimicrobial resistance (AR) leading to therapeutic failures even in dual-therapy treatment with azithromycin and ceftriaxone. AR mechanisms can be acquired by genetic transfer from closely related species, such as naturally-competent commensal Neisseria species. At present, little is known about the antimicrobial resistance profiles of commensal Neisseria. Here, we characterized the phenotypic resistance profile of four commensal Neisseria species (N. lactamica, N. cinerea, N. mucosa, and N. elongata) against 10 commonly used antibiotics, and compared their profiles to 4 N. gonorrhoeae strains, using disk diffusion and minimal inhibitory concentration assays. Overall, we observed that 3 of the 4 commensals were more resistant to several antibiotics than pathogenic N. gonorrhoeae strains. Next, we compared the penicillin-binding-protein 2 (PBP2) sequences between commensal and N. gonorrhoeae strains. We found mutations in PBP2 known to confer resistance in N. gonorrhoeae also present in commensal Neisseria sequences. Our results suggest that commensal Neisseria have unexplored antibiotic resistance gene pools that may be exchanged with pathogenic N. gonorrhoeae, possibly impairing drug development and clinical treatment.
ARTICLE | doi:10.20944/preprints202207.0086.v1
Subject: Biology, Agricultural Sciences & Agronomy Keywords: antimicrobial multidrug resistance; foodborne pathogens; food safety
Online: 6 July 2022 (04:32:25 CEST)
Due to nutritional benefits and perceived humane ways of treating the animals, the demand for antibiotic-free pastured poultry chicken has continued to be on a steady rise. However, despite non-usage of antibiotics in pastured poultry broiler production, antibiotic resistance (AR) is reported in zoonotic poultry pathogens. However, actors that drive multidrug resistance (MDR) in pastured poultry are not known. In this study, we used machine learning and deep learning approaches to predict farm management practices, and physicochemical properties of feces and soil that drive MDR in zoonotic poultry pathogens. Antibiotic use in agroecosystems is known to contribute to resistance. Evaluation of the development of resistance in environments that are free of antibiotics such as the all-natural antibiotic-free, pastured poultry production systems described here is critical to understand the background AR. We analyzed 1,635 preharvest (feces and soil) samples collected from forty-two pastured poultry flocks and eleven farms in the Southeastern United States. CDC National Antimicrobial Resistance Monitoring System guidelines were used to determine antimicrobial/multidrug resistance profiles of Salmonella, Listeria and Campylobacter. A combination of two traditional machine learning (RandomForest and XGBoost) and three deep learning (Multi-layer Perceptron, Generative Adversarial Network, and Auto-Encoder) approaches, identified critical farm/environmental variables that drive multidrug resistance in poultry pathogens, in broiler production systems that represents background resistance. This study enumerates management practices that contribute to AR and recommendations to potentially mitigate multidrug resistance and prevalence of Salmonella and Listeria in pastured poultry.
ARTICLE | doi:10.20944/preprints202102.0132.v1
Subject: Medicine & Pharmacology, Ophthalmology Keywords: multidrug resistance protein 4; ATP-binding cassette (ABC) transporters; aging; retina; mouse; electroretinogram
Online: 4 February 2021 (10:58:06 CET)
Multidrug resistance protein 4 (MRP4) is an energy-dependent membrane transporter that is responsible for cellular efflux of a broad range of xenobiotics and physiological substrates. In this trial, we aimed to investigate the co-effects of aging and MRP4 deficiency using gene expression microarray and morphological and electrophysiological analyses of the mouse retina. Mrp4-knockout (null) mice and wild-type (WT) mice were reared in the same condition to 8–12 wk (young) or 45–55 wk (aged). Microarray analysis identified 186 differently expressed genes from the retinas of aged Mrp4-null mice as compared to that from aged WT mice, and subsequence gene ontology and KEGG pathway analyses showed that differently expressed genes were related to lens, eye development, vision, and transcellular barrier function that are involved in metabolic pathways or viral infection pathways. No significant change in thickness was observed for each retinal layer among young/aged WT mice and young/aged Mrp4-null mice. Moreover, immunohistochemical analyses of retinal cell type did not exhibit an overt change in the cellular morphology or distribution among the 4 age/genotype groups, and the electroretinogram responses showed no significant differences in the amplitude or the latency between aged WT mice and aged Mrp4-null mice. Aging would be an insufficient stress to cause some damage to the retina in the presence of MRP4 deficiency.
ARTICLE | doi:10.20944/preprints202103.0024.v1
Subject: Life Sciences, Biochemistry Keywords: Methicillin-resistant Staphylococcus aureus; Multidrug resistance; mecA gene; Frozen chicken meat; Bangladesh
Online: 1 March 2021 (13:56:33 CET)
Infections by methicillin-resistant Staphylococcus aureus (MRSA) are continuously expanding within the community. Chicken meat is usually contaminated by MRSA, and this contaminated chicken meat is an important source of foodborne infections in humans. In this study, a cross-sectional supershop survey was conducted to determine the prevalence and antimicrobial resistance pattern of MRSA in 113 domestic frozen chicken meat samples purchased from nine branded supershops available in five divisional megacities of Bangladesh. The study also focused on the determination of methicillin resistance gene in MRSA isolates. S. aureus was identified by standard culture-based and molecular methods, and subjected to antimicrobial susceptibility testing. MRSA was screened by cefoxitin disk diffusion test. Methicillin resistance gene was identified by PCR. Of samples, 54.9% were positive for S. aureus, and, of these, 37.1% isolates were identified as MRSA. All the isolates were multidrug resistant (MDR): 52.2% were resistant to 6−8 antimicrobial classes, and 47.8% isolates to 9−12 classes. Three (3.2%) isolates of S. aureus were possible extensively drug resistant. The highest rates of resistance were observed against cefoxitin (100%), followed by nalidixic acid, ampicillin and oxacillin (97.7%), colistin (91.3%), amoxicillin-clavulanic acid and amoxicillin (87%), penicillin-G and cloxacillin (82.6%), oxytetracycline (78.3%) and cefixime (73.9%). Screening of methicillin resistance gene revealed that 43.5% isolates of MRSA were positive for mecA gene. The high prevalence of MDR MRSA in frozen chicken meat samples in this study emphasizes the need for better sanitary education of food handlers in hygienic practices focusing on their potential role as reservoirs and spreaders of MRSA.
ARTICLE | doi:10.20944/preprints202011.0454.v1
Subject: Life Sciences, Biochemistry Keywords: Enteroaggregative E. coli; infant diarrhea; genetic diversity; severity; multidrug-resistance E. coli; Bolivia
Online: 17 November 2020 (14:10:29 CET)
Enteroaggregative Escherichia coli (EAEC) is an emerging pathogen frequently associated with acute diarrhea in children and travelers to endemic regions. EAEC was found the most prevalent bacterial diarrheal pathogen from hospitalized Bolivian children less than five years of age with acute diarrhea from 2007 to 2010. Here, we further characterized the epidemiology of EAEC infection, virulence genes, and antimicrobial susceptibility of EAEC isolated from 414 diarrheal and 74 non-diarrheal cases. EAEC isolates were collected and subjected to a PCR-based virulence gene screening of seven virulence genes and a phenotypic resistance test to nine different antimicrobials. Our results showed that atypical EAEC (a-EAEC, AggR-negative) was significantly associated with diarrhea (OR, 1.62, 95% CI, 1.25 to 2.09, P < 0.001) in contrast to typical EAEC (t-EAEC, AggR-positive). EAEC infection was most prevalent among children between 7 - 12 months of age. The number of cases exhibited a biannual cycle with a major peak during the transition from warm to cold season (April – June). Both typical and a-EAEC infections were graded as equally severe; however, t-EAEC harbored more virulence genes. aap, irp2, and pic were the most prevalent genes. Surprisingly, we detected 60% and 52.6% of multidrug resistance (MDR) EAEC among diarrheal and non-diarrheal cases. Resistance to ampicillin, sulfonamides, and tetracyclines was most common, being the corresponding antibiotics, the ones that are frequently used in Bolivia. Our work is the first study that provides comprehensive information on the high heterogenicity of virulence genes in t-EAEC and a- EAEC and the large prevalence of MDR EAEC in Bolivia.
ARTICLE | doi:10.20944/preprints201808.0036.v1
Subject: Life Sciences, Microbiology Keywords: ESKAPE-bacteria; persistence; resistance; Intrinsic/Acquired/ Multidrug (MDR) and Pan – Resistance; genetic background; experimental evolution; collateral sensitivity; agrocin
Online: 2 August 2018 (06:29:07 CEST)
The challenge posed by multi-drug resistance (MDR) of pathogenic organisms, spectacularly manifested in the 6 “ESKAPE” bacterium (two Gram-positive, four Gram-negative) species, should invoke new comprehensive strategies, and needs cooperation of scientists with medical, veterinary and natural science background. This review is aimed at informing newcomers, coming from the field of biology and genetics, about problems related to rapidly emerging, new multi-drug resistant, pathogenic, bacteria. Unlike persistence, the antibiotic resistance is inherited. A functioning “resistance gene” makes a susceptible organism resistant to a given antibiotic, encoding for polypeptides capable of acting either as decomposing enzymes, or acting as trans-membrane pumps, or membrane structure components capable of modifying the permeability implementing a «by pass» mechanism enabling the antibiotic molecule to reach its cellular target(s). A functioning “sensitivity gene” encode for a polypeptide, capable (directly or indirectly) of transferring toxic molecules into target cells, or of metabolizing non-transferable to transferable, or non-toxic molecules to toxic derivatives. A gene of a normal function could act as a “sensitivity” gene in the presence of antibiotics of chemical structures similar to the natural substrate of the gene product, (enzyme or binding/ trans-membrane protein). The Agrocin 84 story is a good example. Multi-drug resistance is a phenotypic consequence of the sequential accumulation of mutations, and/or up-take of plasmids or genomic islands carrying resistance genes from the environment via horizontal gene transfer, mediated by conjugative plasmid or bacteriophage carrying mobile genetic elements. Both multi-drug resistance and collateral sensitivity are evolutionary products. Some revealed evolutionary process and their Lamarckian and Darwinian interpretations are discussed. Toolkits of comparative full-genome sequencing, genomics, experimental evolution and population genetics may provide perspectives for overcoming the invincibility of multi-drug panresistance. The status of some recently emerging pathogenic bacterium species with zoonic features and of veterinary background is also discussed.
ARTICLE | doi:10.20944/preprints202209.0326.v1
Subject: Medicine & Pharmacology, Other Keywords: multidrug resistance organism; sepsis; adequate empirical antibiotics; source of infection; APACHE II; ICU length stay; predictors; risk factors; mortality
Online: 21 September 2022 (10:45:23 CEST)
Background: Multi-drug resistance organisms (MDRO) often cause increased morbidity, mortality, and length of stays (LOS). However, there is uncertainty whether the infection of MDRO increase the morbidity, mortality, and ICU-LOS. Objective: This study performed to determine the prevalence of MDRO in ICU, site of infection and the association of MDRO or site of infection with mortality. Secondary outcome was determined by ascertaining the association of MDRO or site of infection with (ICU-LOS). Methods: A retrospective cohort study was performed with adult sepsis patients in ICU. Univariate and multivariate (MVA) logistic regression with cox regression modeling were performed to compute the association of MDRO on ICU-mortality. MVA modelling was performed for ICU-LOS predictors. Results: Out of 228 patients, the isolated MDRO was 97 (42.5%) of which 78% were gram-negative bacteria. The mortality rate among those with MDRO was 85 (37.3%). The hospital acquired infection (HAI) was significantly predictor for ICU-LOS in univariate linear regression (R² = 0.034, P=0.005). In MVA linear regression, both Enterococcus faecalis infection and acinetobacter baumannii (AC) -MDRO were predictors for ICU-LOS with (R² = 0.478, P<0.05). In the univariate cox regression, only the infection with AC- MDRO was a risk factor for ICU-mortality with [ HR =1.802 (95% CI: 1.2 – 2.706; P = 0.005)]. Conclusions: Identifying risk factors for MDRO highlight the appropriate administration of empirical antibiotics and effectively control of source of infection which would reduce mortality and ICU-LOS. The usage of broad- spectrum antibiotics should be limited for those having substantial risk factors to acquire MDRO.
REVIEW | doi:10.20944/preprints202111.0358.v1
Subject: Life Sciences, Microbiology Keywords: multidrug-resistant (MDR); Nanotechnology; Antimicrobial
Online: 19 November 2021 (14:31:33 CET)
The global spread of multidrug-resistant (MDR) microbial infections is currently one of the most severe risks to global public health, with 10 million fatalities expected by 2050 unless action is taken. Nanotechnology has revolutionized science and medicine. The reliance on nanotechnology is growing. Nanoparticles have distinct properties that improve biological, chemical, and physical properties studied for various uses. A significant area of attention in the synthesis of nanoscale modulators is the utilization of crude formulations, retro-synthesized, and pure chemicals, mainly from herbal sources, with fewer adverse effects. Green chemistry has devised a tangential technique for synthesizing metals and metal oxides to produce nanoparticles. Plant extracts (leaves, stems, and shoots) and microorganisms (bacteria, fungus, and yeast) are used as reducing intermediates to make nanoparticles. Studies in microbiology have shown that nanoparticles kill bacteria, fungi, viruses, and protozoa. These green nanoparticles contain antibacterial, antifungal, and anti-inflammatory effects. Most nanoparticles have high antibacterial properties, indicating they may be used to combat diseases and biological contaminants. These nanoparticles have antibacterial action against pathogenic microorganisms that cause serious illnesses, including multidrug-resistant pathogens. The current research will pave the way for future applications and improved methods for producing nanoparticles, paving the way for an innovative route in nano-life sciences with widespread recognition.
REVIEW | doi:10.20944/preprints202209.0037.v1
Subject: Biology, Animal Sciences & Zoology Keywords: Multidrug-resistant Acinetobacter baumannii; Phage therapy
Online: 2 September 2022 (09:51:24 CEST)
Acinetobacter baumannii is a multidrug-resistant and invasive pathogen associated with the etiopathology of both an increasing number of nosocomial infections and of relevance to poultry production systems. Multidrug-resistant Acinetobacter baumannii has been reported in connection to severe challenges to clinical treatment, mostly due to an increase rate of resistance to carbapenems. Amid the possible strategies aiming to reduce the insurgence of antimicrobial resistance, phage therapy has gained particular importance for the treatment of bacterial infections. This review summarises the different phage-therapy approaches currently in use for multiple-drug resistant Acinetobacter baumannii, including single phage therapy, phage cocktails, phage -antibiotic combination therapy, phage coding Acinetobacter baumannii and the novel phage enzyme treatment. Although phage therapy represents a potential treatment solution for multidrug-resistant Acinetobacter baumannii, further research is needed to unravel some unanswered questions especially in regard to its in vivo applications, before possible routine clinical use.
ARTICLE | doi:10.20944/preprints202010.0116.v1
Subject: Life Sciences, Biochemistry Keywords: antibiotic conjugates; ciprofloxacin; multidrug resistance bacteria; triphenylphosphonium
Online: 6 October 2020 (10:16:11 CEST)
Multidrug resistant (MDR) bacteria have become a severe problem for public health. Developing new antibiotics for MDR bacteria is difficult, from inception to the clinically approved stage. Here, we have used a new approach; we have modified the antibiotic, ciprofloxacin (CFX), with triphenylphosphonium (TPP, PPh3) moiety via ester- (CFX-ester-PPh3) and amide-coupling (CFX-ester-PPh3), to target bacterial membranes. In this study, we have evaluated the antibacterial activities of CFX and its derivatives against 16 species of bacteria, including MDR bacteria, using minimum inhibitory concentration (MIC) assay, morphological monitoring, and expression of resistance-related genes. TPP-conjugated CFX, CFX-ester-PPh3 and CFX-amide-PPh3 showed significantly improved antibacterial activity against Gram-positive bacteria, Staphylococcus aureus, including MDR S. aureus (MRSA) strains. The MRSA ST5 5016 strain showed high antibacterial activity, with an MIC values of 11.12 µg/mL for CFX-ester-PPh3 and 2.78 µg/mL for CFX-amide-PPh3. The CFX derivatives inhibited biofilm formation in MRSA by more than 74.9% of CFX-amide-PPh3. In the sub-MIC, CFX derivates induced significant morphological changes in MRSA, including irregular deformation and membrane disruption, accompanied by a decrease in the level of resistance-related gene expression. With these promising results, this method is very likely to combat MDR bacteria, through a simple TPP moiety modification of known antibiotics, which can be readily prepared at clinical sites.
REVIEW | doi:10.20944/preprints202108.0218.v1
Subject: Life Sciences, Biotechnology Keywords: cancer; nanoparticles; chemotherapy; cellular targeting; multidrug resistance; cryosurgery; scale-up
Online: 10 August 2021 (09:44:24 CEST)
Cancer is one of the leading causes of death and morbidity with a complex pathophysiology. Traditional cancer therapies include chemotherapy, radiation therapy, targeted therapy, and immunotherapy. However, limitations such as lack of specificity, cytotoxicity, and multi-drug resistance pose a substantial challenge for favorable cancer treatment. The advent of nanotechnology has revolutionized the arena of cancer diagnosis and treatment. Nanoparticles (1-100nm) can be used in the treatment of cancer owing to their specific advantages such as biocompatibility, reduced toxicity, more excellent stability, enhanced permeability and retention effect, and precise targeting. Nanoparticles are classified into several main categories. The nanoparticle drug delivery system is particular and utilizes tumor and tumor environment characteristics. Nanoparticles not only solve the limitations of conventional cancer treatment but also overcome multidrug resistance. Additionally, as new multidrug resistance mechanisms are unraveled and studied, nanoparticles are being investigated more vigorously. Various therapeutic implications of nano-formulations have created brand new perspectives for cancer treatment. However, a majority of the research is limited to in vivo and in vitro studies, and the number of nano-drugs that are approved has not much amplified over the years. In this review, we discuss numerous types of nanoparticles, targeting mechanisms along with approved nanotherapeutics for oncological implications in cancer treatment. Further, we also summarize the current perspective, advantages, and challenges in clinical translation.
ARTICLE | doi:10.20944/preprints201802.0142.v1
Subject: Chemistry, Medicinal Chemistry Keywords: reactive selenium species; arylmethyl selenocyanate; cellular thiolstat; antimicrobial; anticancer; ESKAPE; multidrug resistance
Online: 22 February 2018 (11:34:22 CET)
Selenocyanates form an interesting class of organic selenium compounds as they serve as multifunctional agents (being the precursors of seleninic acids and diselenides in synthetic chemistry and as antimicrobial and cytotoxic agent in biology) and, due to their similarity with better known thiocyanates promise high biological activity. Yet whilst selenocyanates are common in synthetic chemistry, they are rarely considered in pharmaceutical design. Arylmethyl selenocyanates (1-13) have been synthesized and an insight into their structural properties using X-ray crystallography has been obtained. The compounds subsequently have been evaluated for their potential antimicrobial, nematicidal and cytotoxic activity. ADMET properties in vitro, using mutagenicity (AMES) and permeability (PAMPA) tests, have been determined. The compounds exhibit pronounced activity against various strains of bacteria (both Gram-positive and Gram-negative) and yeasts. Among them, benzylselenocyanate (1) represents the most active anti-ESKAPE agent, with potent antibacterial activity, especially against multidrug resistant MRSA strains (HEMSA 5). Our results demonstrate that the arylmethyl selenocyantes are not only non-mutagenic but also possess moderate cytotoxic activity against cancer cells.
ARTICLE | doi:10.20944/preprints201812.0362.v1
Subject: Keywords: Antibiotic resistance, efflux pump inhibitors, Escherichia coli, efflux pumps, multidrug resistance, Staphylococcus aureus
Online: 31 December 2018 (09:55:32 CET)
Bacterial antibiotic resistance has become a major global health concern. One of the main reasons for the development of multi-drug resistance properties in bacteria is due to the bacterial efflux pump systems. They are important transport proteins, mainly involved in the removal of toxic substrates like antibiotics from inner cell environment. These pumps are responsible for the intrinsic ability of bacteria to get resistant to the antibiotic. Various types of efflux pumps are present in the Gram-positive and Gram-negative bacteria. Plant-derived products like Capsaicin, Olympicin A, and Indirubicin were found to be inhibitors of an efflux pump in Staphylococcus aureus similarly Ursolic acid derivatives; Daidzein and Lanatoside C were plant-derived inhibitors of an efflux pump in Escherichia coli. In this review detail information have been provided about efflux pump inhibitors that have been found to be effective in the Gram-positive bacteria and Gram-negative bacteria. The aim of this review is to focus on the role of plant-derived compounds as effective efflux pumps inhibitors with reference to mainly Staphylococcus aureus and Escherichia coli.
ARTICLE | doi:10.20944/preprints201809.0077.v1
Subject: Life Sciences, Microbiology Keywords: Garlic, Antibiotics, Lomé, Uropathogenic bacteria, Urinary Tract Infection, Multidrug resistance and alternative therapy.
Online: 5 September 2018 (01:35:46 CEST)
The urinary tract infection (UTI) is the most common bacterial infection, especially in women. The increased incidence of UTIs, at the last decades have paralleled with the growing emergence of antibiotic resistance. The aim is to evaluate aqueous garlic extract (AGE) susceptibility against multidrug-resistant (MDR) bacteria isolated in urine of women. The investigation of antibacterial propriety and time kill effect of AGE was performed by the well method, microdilution method and spectrophotometer assay. Antibiotics susceptibility assay revealed that the nine MDR bacteria had high resistance against Amoxicillin/ clavulanic acid (100%) and Erythromycin (100%), Cefotaxime (83.33%) and Ceftazidime (83.33%). AGE exhibited potent antibacterial activity against the nine MDR bacteria tested. In Gram-negative bacteria, the inhibition diameters ranged from 20 ± 3 to 32 ± 4 mm, with Minimum Inhibitory Concentrations (MICs) ranging from 10% to 12.5% (w/v) and Minimum Bactericidal Concentration (MBCs) was 12.5 % (w/v). Gram-positive bacteria exhibited diameters ranging from 38 ± 2 to 45 ± 1 mm; MIC and MBC values ranged from 05 to 10 % (w/v) and were found more susceptible than Gram-negative bacteria. To conclude, this investigation shown that AGE have high potential antibacterial to use as an alternative to treat women UTIs.
ARTICLE | doi:10.20944/preprints201703.0017.v1
Subject: Materials Science, Nanotechnology Keywords: green synthesis; silver nanoparticles; trimethylchitosan nitrate; catalytic activity; antibacterial activity; multidrug-resistant Acinetobacter baumannii
Online: 2 March 2017 (08:49:35 CET)
We report a facile route for the green synthesis of trimethylchitosan nitrate-capped silver nanoparticles (TMCN-AgNPs) with positive surface charge. In this synthesis, silver nitrate, glucose, and trimethyl chitosan nitrate (TMCN) were used as silver precursor, reducing agent, and stabilizer, respectively. The reaction was carried out in a stirred basic aqueous medium at room temperature without the use of energy-consuming or expensive equipment. We investigated the effects of the concentrations of NaOH, glucose, and TMCN on the particle size, zeta potential, and formation yield. The AgNPs were characterized by UV-visible spectroscopy, photon correlation spectroscopy, laser Doppler anemometry, transmission electron microscopy, X-ray diffraction, and X-ray photoelectron spectroscopy. The catalytic activity of the TMCN-AgNPs was studied by the reduction of 4-nitrophenol using NaBH4 as a reducing agent. We evaluated the antibacterial effects of the TMCN-AgNPs on Acinetobacter baumannii, Escherichia coli, Pseudomonas aeruginosa, and Staphylococcus aureus using the broth microdilution method. The results showed that both gram-positive and gram-negative bacteria were killed by the TMCN-AgNPs at very low concentration (< 6.13 μg/mL). Moreover, the TMCN-AgNPs also showed high antibacterial activity against clinically isolated multidrug-resistant A. baumannii strains, and the minimum inhibitory concentration (MIC) was ≤ 12.25 μg/mL.
ARTICLE | doi:10.20944/preprints202104.0456.v1
Subject: Life Sciences, Biochemistry Keywords: ethidium; tetraphenylphosphonium; multidrug resistance; outer membrane permeability; efflux inhibitor; phenylalanyl-arginyl-β-naphtylamide, Polymyxin B
Online: 18 April 2021 (10:14:56 CEST)
Bacterial resistance to antibiotics due to an increased efficiency of the efflux is a serious problem in clinics of infectious diseases. Knowledge of the factors affecting the activity of efflux pumps would help to find the solution. For this, fast and trustful methods for the efflux analysis are needed. Here we analyzed how the assay conditions affect the accumulation of efflux indicators ethidium (Et+) and tetraphenylphosphonium in Salmonella enterica ser. Typhimurium cells. An inhibitor phenyl-alanyl-arginyl-β-naphtylamide was applied to evaluate the input of RND family pumps into the total efflux. In parallel to spectrofluorimetric analysis, we used an electrochemical assessment of Et+ concentration. Results of our experiments indicated that Et+ fluorescence increases immediately after the penetration of this indicator into the cells. However, when cells bind a high amount of Et+, intensity of the fluorescence reaches the saturation level and stops reacting to the accumulated amount of this indicator. For this reason, electrochemical measurements provide more trustful information about the efficiency of efflux when cells accumulate high amounts of Et+. Measure-ments of Et+ interaction with the purified DNA demonstrated that affinity of this lipophilic cation to DNA depends on the medium composition. The capacity of DNA to bind Et+ considerably de-creases in presence of Mg2+, Polymyxin B or when DNA is incubated in high ionic strength media.
ARTICLE | doi:10.20944/preprints202011.0065.v1
Subject: Life Sciences, Biochemistry Keywords: Carbapenem resistant Enterobacteriaceae (CRE); E.coli; Antimicrobial Resistance; Multidrug resistance; Phylogenetic diversity; chicken; food animals; Antimicrobials
Online: 2 November 2020 (17:14:31 CET)
Carbapenem resistant Enterobacteriaceae (CRE) has been public health risk in several countries and recent reports indicate the emergence of CRE in food animals. This study was conducted to investigate the occurrence, resistance patterns, and phylogenetic diversity of CRE E.coli from chicken. Routine bacteriology, PCR detection of E.coli species, multiplex PCR to detect carbapenemase encoding genes and phylogeny of CRE E. coli were conducted. The results show that 24.36 % (19/78) were identified as CRE based on the phenotypic identifications of which 17 were positive for the tested carabanemase genes. The majority, 57.99% (11/19) of the isolates harbored multiple carbapenemase genes. Four isolates harbored all blaNDM blaOXA, blaIMP, five and two different isolates harbored blaNDM and blaOXA, and blaOXA and blaIMP respectively. The Meropenem, Imipenem and Ertapenem MIC values for the isolates ranged from 2g/mL to ≥256g/mL. Phylogenetic grouping showed that the CRE E.coli isolates belonged to five different groups; groups A, B1, C, D and unknown. The detection of carbapenem resistant E.coli in this study shows that CRE is has become an emerging problem in farm animals, particularly, in poultry farms. This also implies the potential public health risks posed by CRE from chicken to the consumers.
REVIEW | doi:10.20944/preprints201809.0236.v1
Subject: Life Sciences, Biophysics Keywords: molecular dynamics simulation; rare event; string method; multiscale enhanced sampling; weighted ensemble; multidrug transporter; Onsager-Machlup action
Online: 13 September 2018 (12:01:39 CEST)
To understand functions of biomolecules such as proteins, not only structures but their conformational change and kinetics are important to be characterized but its atomistic details are hard to obtain both experimentally and computationally. We review our recent computational studies using novel enhanced sampling techniques for conformational sampling of biomolecules and calculations of their kinetics. For efficiently characterizing the free energy landscape of a biomolecule, we introduce the multiscale enhanced sampling method, which uses a combined system of atomistic and coarse-grained models. Based on the idea of Hamiltonian replica exchange, we can recover the statistical properties of the atomistic model without any biases. We next introduce the string method as a path search method to calculate the minimum free energy pathways along a multidimensional curve in high dimensional space. Finally we introduce novel methods to calculate kinetics of biomolecules based on the ideas of path sampling: One is the Onsager-Machlup action method, and the other is the weighted ensemble method. Some applications of above methods to biomolecular systems are also discussed and illustrated.
REVIEW | doi:10.20944/preprints202007.0375.v1
Subject: Medicine & Pharmacology, Other Keywords: bacterial infection; non-healing wounds; antimicrobial resistance; multidrug resistance; antimicrobial peptides (AMPs); AMP conjugates; AMP carriers and delivery systems
Online: 17 July 2020 (09:26:21 CEST)
Bacterial infections occur when wound healing fails to reach the final stage of healing, usually hindered by the presence of different pathogens. Different topical antimicrobial agents are used to inhibit bacterial growth due to antibiotic failure in reaching the infected site accompanied very often by an increased drug resistance and other side effects. In this review, we focus on antimicrobial peptides (AMPs), especially those with a high potential of efficacy against multidrug-resistant and biofilm-forming bacteria and fungi present in wound infections. Currently, different AMPs undergo preclinical and clinical phase to combat infection-related diseases. AMP dendrimers (AMPDs) have been mentioned as potent microbial agents. Various AMP delivery strategies, such as polymers, scaffolds, films and wound dressings, organic and inorganic nanoparticles, to combat infection and modulate the healing rate have been discussed as well. New technologies such as CRISPR-Cas are taken into consideration as potential future tools for AMP delivery in skin therapy.
ARTICLE | doi:10.20944/preprints202108.0329.v1
Subject: Materials Science, Surfaces, Coatings & Films Keywords: face shield; facial protective equipment; SARS-CoV-2; phi 6; MRSA; MRSE; polyethylene terephthalate; benzalkonium chloride; COVID-19; multidrug-resistant bacteria
Online: 16 August 2021 (11:38:49 CEST)
Transparent materials used for facial protection equipment provide protection against microbial infections caused by viruses and bacteria, including multidrug-resistant strains. However, transparent materials used for this type of application are made of materials that do not possess antimicrobial activity. They just avoid direct contact between the person and the biological agent. Therefore, healthy people can get infected through contact of the contaminated material surfaces and this equipment constitute an increasing source of infectious biological waste. Furthermore, infected people can transmit microbial infections easily because the protective equipment do not inactivate the microbial load generated while breathing, sneezing, or coughing. In this regard, the goal of this work consisted of fabricating a transparent face shield with intrinsic antimicrobial activity that could provide extra-protection against infectious agents and reduce the generation of infectious waste. Thus, a single-use transparent antimicrobial face shield composed of polyethylene terephthalate and an antimicrobial coating of benzalkonium chloride has been developed for the next generation of facial protective equipment. The antimicrobial coating was analyzed by atomic force microscopy and field emission scanning electron microscopy with elemental analysis. This is the first facial transparent protective material capable of inactivating enveloped viruses such as SARS-CoV-2 in less than one minute of contact, and the methicillin-resistant Staphylococcus aureus and Staphylococcus epidermidis. Bacterial infections contribute to severe pneumonia associated with the SARS-CoV-2 infection, and their resistance to antibiotics is increasing. Our extra protective broad-spectrum antimicrobial composite material could also be applied for the fabrication of other facial protective tools such as such as goggles, helmets, plastic masks and space separation screens used for counters or vehicles. This low-cost technology would be very useful to combat the current COVID-19 pandemic and protect health care workers from multidrug-resistant infections in developed and underdeveloped countries.