Molecular characterization and antibiotic resistance of Salmonella in children with acute gastroenteritis in Abuja, Nigeria

Abstract

Introduction: In Nigeria, acute gastroenteritis in children under five years of age is a major cause of mortality and morbidity; identification and characterization of microbial agents of acute gastroenteritis, including Salmonella, remains a powerful tool for effective management, surveillance, and control.

Methodology: Diarrheal stool samples were directly plated onto differential and selective media to isolate Salmonella. Extended-spectrum beta-lactamases were screened using the double disk diffusion technique and by PCR targeting the bla_TEM and bla_CTX-M genes. Pulsed-field gel electrophoresis (PFGE) was performed usingthe PulseNet Canada Laboratory protocol for molecular subtyping using the restriction enzymes XbaI and BlnI.

Results: The serotypes identified were Salmonella enterica serovar Zanzibar (n = 5), Salmonella Brancaster (n = 3), and one isolate of Salmonella Enteritidis (phage type 1). The following levels of resistance were found among the Salmonella strains: amoxicillin, five strains (55.6%); amoxicillin-clavulanic acid, two strains (22.2%); cephalexin, five strains (55.6%); and cefuroxime, five strains (55.6%). Intermediate resistance was found in five strains (55.6%) only to amoxicillin-clavulanic acid. All isolates were susceptible to nalidixic acid, ciprofloxacin, and ceftriaxone, and no ESBL-producing Salmonella were detected.

Conclusions: Our findings demonstrated the involvement of three Salmonella serovars in acute gastroenteritis; resistance to penicillins and cephalosporins was common.