The antimicrobial susceptibility and virulence traits of 150 strains of Escherichia coli
characterized as commensals recovered from faecal samples from pre-school age children in Ile-Ife,
Nigeria were evaluated in order to determine their potentials for pathogenicity and their contribution to
antibiotic resistance in the community.
The isolates were identified using conventional biochemical methods. The presence or
absence of virulence traits was determined using phenotypic and genotypic (polymerase chain reaction)
methods. Their susceptibility to antibiotics was determined using the disk diffusion method.
Possession of virulence properties including encapsulation (89.3 %), haemolysin production
(24.8 %) and colicinogenicity (11.3 %) was detected among the strains and susceptibility of the strains
to multiple antibiotics showed that the strains were highly resistant to cefalothin (100 %), streptomycin
(94.0 %), tetracycline (92.0 %), and trimethoprim (89.3 %) while resistance to the quinolones was low
(3.3 - 14.0 %).
The possession of virulence properties by antibiotic resistant strains of commensal E. coli
may enhance their potential as extraintestinal pathogens.