ARTICLE | doi:10.20944/preprints201911.0063.v2
Subject: Life Sciences, 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.
ARTICLE | doi:10.20944/preprints201808.0466.v1
Subject: Life Sciences, Microbiology Keywords: antibiotic; diarrhea; prevalence, shigella; shigellosis
Online: 27 August 2018 (15:08:52 CEST)
Infectious diarrhoea such as shigellosis causes considerable morbidity and mortality, especially in infants, immune-compromised individuals and those living with HIV/AIDS. It is endemic in developing countries and in Sub-Saharan Africa, including South Africa, where diarrhoeal disease remains a leading cause of morbidity and mortality. This study was undertaken to establish incidences of Shigella, its serotype and resistant pattern of isolates from human faeces from residence of Johannesburg, South Africa. All stools received between January to April from the private healthcare system were cultured on Xylose Lysine Deoxycholate and MacConkey Agar and Shigella was confirmed by standard biochemical reactions and a serological method. An antimicrobial sensitivity test was used. A total of 11 009 samples from patients between 22 days to 94 years old yielded 110 Shigella isolates, of which 47 (43%) were S. flexneri, 61 (55%) were S. sonnei, 1 (1%) was S. dysenteriae and 1 (1 %) was S. boydii. The majority of patients were children between < 1 to 5 years, 76 (69%), followed by those between 6 to 10 years 13 (12%). In children up to 10 years, S. sonnei was confirmed in 52 cases (59%) and S. flexneri in 36 cases (41%). Overall, 53 (48%) males and 57 (52%) females were infected.
ARTICLE | doi:10.20944/preprints202202.0321.v1
Subject: Life Sciences, Microbiology Keywords: Enteroinvasive Escherichia coli; Shigella flexneri; Caco-2 cells; icsB; autophagy; WGCNA; gene co-expression network
Online: 25 February 2022 (03:16:26 CET)
Escherichia coli and Shigella are common diarrhea-causing pathogens in children and adults. Enteroinvasive Escherichia coli (EIEC) shares a similar pathogenic mechanism with Shigella. However, EIEC are less virulent than Shigella. The aim of this work was to get a better understanding of the virulence differences between EIEC and S. flexneri. We investigated i) the bacterial gene co-expression networks (GCNs) and ii) the the transcriptional modules (WGCNA) of Caco-2 cells infected with EIEC or with S. flexneri during a three-hour period of bacterial infection. The GCN analysis showed that EIEC and S. flexneri networks presented different topologies. Additionally, the EIEC network revealed that pINV genes are not connected with chromosomal genes. WGCNA and eigengene analysis showed enterocyte gene expression variation along the three-hour bacterial post-infection period. Additionally, at one-hour post-infection EIEC induced a higher number of gene expression changes in Caco-2 cells than S. flexneri. Several of these genes are involved in autophagy. This study showed that the lower virulence of EIEC is associated with a lack of functional cooperation between pINV and chromosomal genes, differently from what was observed in S. flexneri. Consequently, EIEC becomes less efficient in subverting host-cell bacterial recognition as well as defense mechanisms such as autophagy.