Molecular characterization of extended-spectrum beta-lactimase (ESBL) producing extra-intestinal pathogenic Escherichia coli

Despite the frequent isolation of extended-spectrum beta-lactamase producing Escherichia coli from extra-intestinal infections (ESBL-ExPEC), the virulent properties or the antibiotic resistance mechanisms or its phylogenetics is rarely studied in Malaysia. In the present investigation, we characterized 95 clinical isolates of ESBL-ExPEC collected over a one year period time from a tertiary hospital through Clermont dichotomous phylogenetic grouping, virulent gene profiling and ESBL production mechanisms. The highest frequency of E. coli isolation was observed among urine (40% / n=38), while the lowest was among tissue and peritoneal dialyses fluid (1.05% / n= 1). Phylogenetic grouping revealed that 42 (44.21%) isolates belonged to group D, while 26 (27.36%), 14(14.73%) and 13 (13.68) belonged to A, B2 and B1. All isolates were multi drug resistant, whereby 58.9% harboured CTX-M-1 and 22.10% CTX-M-9. None of the isolates carried CTX-M-2 or CTX-M-8 clusters. Eight (7.6%) isolates were positive for blaTEM-1 and two (1.9%) produced SHV-12 beta-lactamase. The CTX-M-9 cluster was found to be significantly (P=0.005) associated with pathogenic group. Majority of the isolates (48.42%) carried class 1 integrons, while 3 (3.15%) isolates showed positive for class 2-encodedintI2 integrase and no signal for class 3 integron. Virulence factors profiling identified iutA56 (58.94%) and kpsMII33 (34.73%) as frequent pathogenic determinants. Virulence studies on Caenorhabditis elegans showed that antibiotic susceptible E. coli strains have short life span than pathogenic or commensal ones. In conclusion, it is found that commensals are becoming multiple drug resistant and carries several virulent genes which warn the spread of drug resistance or virulent factors to the normal flora.

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