Genotypic and Phenotypic Comparison of Enteroaggregative Escherichia coli Isolates from HIV-Positive and Non-HIV Diarrheal Samples
Enteroaggregative Escherichia coli (EAEC) have been isolated from both HIV-positive and non-HIV diarrheal
samples. In this study a collection of 18 isolates from these two groups were compared for biofilm formation and
antibiotic resistance and for the presence of 14 virulence-related genes. All the HIV-positive and over 66% of the non-
HIV strains were PCR-negative for adhesion-related sequences indicating that as yet unknown adhesins may play a role.
However, despite some variations, the prevalence rate of the virulence-related genes was not significantly different in the
two groups. HIV-positive isolates were biofilm producer but only a single weak biofilm former was observed among the
non-HIV strains. The rate of resistance to most of the antibiotics used was higher among the HIV-positive group than the
non-HIV isolates, but was significantly higher for amoxicillin-calvulanic acid (100%) and nalidixic acid (55.5%). Pulse
field gel electrophoresis of the isolates produced 17 unique profiles reflecting the exiting heterogeneity of the isolates.
Keywords: Antibiotic resistance, biofilm, Enteroaggregative Escherichia coli, EAEC, HIV-positive diarrhea, non-HIV
diarrhea, virulence-related genes.
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