Conjugal transferability of multiple antibiotic resistance in three genera of Enterobacteriaceae in Nigeria.

Ninety-eight enteric bacteria were isolated from stool samples of 3,000 diarrhoeal patients during 1988-1989 in Ibadan, Nigeria. The isolates were: 20 Salmonella, 28 Shigella and 50 Escherichia coli. S. typhi and S. Flexneri were most prevalent while serotypes 055, 026 and 0128 were most common among the E. coli. Eight resistance patterns to ampicillin (Ap), streptomycin (Sm), tetracycline (Tc) and chloramphenicol (Cm), the four commonly used drugs in this environment were observed in the isolates. Resistance to all four drugs was common in the Shigella isolates. Conjugation experiments showed that 92% of the isolates tested were able to transfer all or part of their resistance to the recipient E. coli. The Salmonella and Shigella isolates were more efficient in this respect as all the isolates tested (100%) transferred all or part of their resistance character. Ability of the latter two genera to transfer the Ap, Sm, Tc, Cm complete linkage might be enhanced by using more efficient recipient or by mobilisation. Control of antibiotic usage and improvement of personal hygiene were recommended to prevent the spread of drug resistance among the enteric pathogens.