Beta-lactamase production and conjugative ability of multidrug resistant Salmonella Typhi in Southern Benue, Nigeria

Abstract

Objective: To examine multidrug resistant (MDR) Salmonella (S.) Typhi isolates obtained from the stool samples of patients attending secondary health centers in Southern Benue, Nigeria, for extended spectrum beta-lactamase (ESBL) production and conjugative ability. Methods: The double disc synergy test was used to screen for ESBL production in MDR isolates. The ability of S. Typhi to transfer resistance gene was determined by conjugation experiments using standard protocols, with slight modifications. Escherichia (E.) coli ATCC 25922 was used as the recipient organism. Result: The donor S. Typhi isolates showed resistance to all the classes of antibiotics except aminoglycosides and carbapenems. All isolates except TKP 106, APA 55, APA 78 and OGB 106 were positive for ESBL production. Reduction in the zones of inhibition of E. coli after incubation with S. Typhi showed evidence of conjugation and transfer of antibiotic resistance from S. Typhi to E. coli. Conclusions: The presence of ESBL-producing S. Typhi capable of conjugation poses a significant risk to the treatment and management of typhoid fever, which highlights the need for the regulation of antibiotic use through relevant policies and strategies that aim at halting the spread of MDR and ESBL-producing S. Typhi in such rural settings.

Keywords

• salmonella typhi; antimicrobial resistance; plasmid; multidrug resistance; extended spectrum beta-lactamase