Aim: Escherichia coli is a commensal bacteria in the gastrointestinal tract of humans, but some strains cause diseases ranging from diarrhea to extra-intestinal infections under certain condition. Diarrheagenic E. coli strains are acquired by consuming contaminated food or water, therefore, food contamination is a major public health concern. Antibiotic resistance in E. coli from human or animal origins has been increasingly reported worldwide, and it is a cause of concern. The aim of this work was to study a collection of E. coli from animal origins in order to investigate antibiotic susceptibilities, genes encoding antibiotic resistance and virulence factors as well as their phylogenetic groups Material and Methods: 39 isolates of E .coli were collected from healthy animals and food-products of animal origin in Tunisia. The isolated were incubated at 37°C for 18 to 24 hours on MacConkey agar. Antibiotic susceptibility was carried out by disc diffusion method according to CLSI guidelines. Phylogenetic groups of E. coli (A, B1, B2, and D), genes encoding antibiotic resistance, and a set of 32 genes encoding virulence factors were investigated using PCR technique following the protocol described in literature. Results: High rates of antibiotic resistance were detected for ampicillin, tetracycline, trimethoprim/sulfamethoxazole, gentamicin, and streptomycin as well as multidrug-resistant isolates. The tetA and tetB genes, encoding tetracycline resistance were detected in 8 and 7 isolates, respectively. However, phenotypic resistance was not detected in 3 tet-harboring isolates. Sulfonamide resistance was encoded by sul1, sul2, and sul3 genes in 1, 4, and 1 isolate, respectively. Interestingly, plasmid mediated quinolone resistance was detected in 6 isolates, where qnrS was in 3, qnrB in 2 and qnrA in only one strain. The majority of isolates belongs to the phylogenetic groups A and B1, considered as commensal isolates. Genes encoding virulence factors fimH (type 1 fimbria), cvaC (colicin V), traT (serum resistance), fyuA (yersiniabactin), and east1 (enteroaggregative heat-stable enterotoxin) were harbored by 36 (92.3%), 2 (5%), 10 (25.6%), 10 (25.6%), 16 (41%), respectively. Interestingly, the ipaH (invasion plasmid antigen), specific for enteroinvasive E. coli (EIEC), and ibeA (brain microvascular endothelial cells invasion), were detected, each, in one isolate. Conclusion: These finding showed the importance of food-products of animal origin as reservoir of antibiotic-resistant and virulent E. coli isolates.
Escherichia coli from healthy animals and food-products of animal origin as reservoir of antibiotic resistance and virulence
Paola Cremonesi;
2013
Abstract
Aim: Escherichia coli is a commensal bacteria in the gastrointestinal tract of humans, but some strains cause diseases ranging from diarrhea to extra-intestinal infections under certain condition. Diarrheagenic E. coli strains are acquired by consuming contaminated food or water, therefore, food contamination is a major public health concern. Antibiotic resistance in E. coli from human or animal origins has been increasingly reported worldwide, and it is a cause of concern. The aim of this work was to study a collection of E. coli from animal origins in order to investigate antibiotic susceptibilities, genes encoding antibiotic resistance and virulence factors as well as their phylogenetic groups Material and Methods: 39 isolates of E .coli were collected from healthy animals and food-products of animal origin in Tunisia. The isolated were incubated at 37°C for 18 to 24 hours on MacConkey agar. Antibiotic susceptibility was carried out by disc diffusion method according to CLSI guidelines. Phylogenetic groups of E. coli (A, B1, B2, and D), genes encoding antibiotic resistance, and a set of 32 genes encoding virulence factors were investigated using PCR technique following the protocol described in literature. Results: High rates of antibiotic resistance were detected for ampicillin, tetracycline, trimethoprim/sulfamethoxazole, gentamicin, and streptomycin as well as multidrug-resistant isolates. The tetA and tetB genes, encoding tetracycline resistance were detected in 8 and 7 isolates, respectively. However, phenotypic resistance was not detected in 3 tet-harboring isolates. Sulfonamide resistance was encoded by sul1, sul2, and sul3 genes in 1, 4, and 1 isolate, respectively. Interestingly, plasmid mediated quinolone resistance was detected in 6 isolates, where qnrS was in 3, qnrB in 2 and qnrA in only one strain. The majority of isolates belongs to the phylogenetic groups A and B1, considered as commensal isolates. Genes encoding virulence factors fimH (type 1 fimbria), cvaC (colicin V), traT (serum resistance), fyuA (yersiniabactin), and east1 (enteroaggregative heat-stable enterotoxin) were harbored by 36 (92.3%), 2 (5%), 10 (25.6%), 10 (25.6%), 16 (41%), respectively. Interestingly, the ipaH (invasion plasmid antigen), specific for enteroinvasive E. coli (EIEC), and ibeA (brain microvascular endothelial cells invasion), were detected, each, in one isolate. Conclusion: These finding showed the importance of food-products of animal origin as reservoir of antibiotic-resistant and virulent E. coli isolates.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
