Antimicrobial susceptibility and plasmids from Escherichia coli isolated from rats

Abstract

To determine if antimicrobial resistance occurs in E. coli isolated from rats and if this resistance is transferable via plasmids.

Sixty Escherichia coli isolates obtained from 215 rats trapped in and around Nairobi, Kenya, were analysed for antimicrobial susceptibility to eleven commonly used antimicrobials. Plasmid DNA analysis and in-vitro conjugation tests were conducted on twenty two resistant isolates.

A total of 12 (20%) E. coli were resistant to at least one of the commonly used drugs including ampicillin, sulphamethoxazole and streptomycin. Eight (13.3%) isolates were multidrug resistant. The drug resistant E. coli fell into five plasmid profile groups with plasmids ranging between two and 98 megadaltons (Mda). Resistance to ampicillin was transferable.

The results of this study show that rats from the study area may form an important reservoir for drug-resistant E. coli that could pose a public health hazard.