Serotyping and antibiotic susceptibility pattern of Salmonella serovars from children diagnosed of typhoid fever in Lagos, Nigeria

Abstract

Typhoid fever is a major health problem in developing countries especially in Nigeria where this infectious disease is endemic, with more concern in children. This prospective study was conducted in 3 Primary Health Centres on children diagnosed clinically of typhoid fever between January, 2017 and December, 2019. The aim of this study was to determine the incidence of Salmonella serovars and antibiotic susceptibility pattern from faecal specimens of children diagnosed clinically based on symptoms of typhoid fever, while demographic information was recovered from their case notes and their mothers. The children were randomly selected having obtained informed consent from their mothers. Four hundred and twenty (420) stool specimens of children aged between 6 months and five years were cultured and serotyped using standard microbiological procedures for isolation and characterization of Salmonella and other enteric bacterial pathogens. The bacteria were isolated by using cultural methods on selective media using a series of biochemical tests and confirmed by using Microgen identification kits and API20E. Serological tests were carried out on suspected Salmonella and Vibrio isolates. Antibiotic susceptibility of the bacterial isolates was determined by using the Kirby-Bauer disc diffusion technique. Bacteriological analysis of the faecal specimens revealed a total of 381 bacterial isolates, among which were 180 (42.9%) Salmonellae. Salmonella enteritidis was the most frequently isolated serovar, 84 (22%), followed by S. typhi, 56 (14.7%), S. paratyphi A, 30(7.9%), and S. typhimurium 10 (2.6%). Other bacteria recovered from the children included Shigella dysenteriae, 64 (16.8), Proteus mirabilis, 60(15.8%), Klebsiella oxytoca, 15(3.9%), Klebsiella ozaenae, 12( 3.2%) and Vibrio parahaemolyticus, 10(2.6%) shows that the Salmonellae and other enteric bacteria showed sensitivity ranging from 70-96% for ampicillin, ciprofloxacin (83.3%-96.4%), gentamicin (56-97.5%), sparfloxacin (83.3-100%), ceftriaxone (83.3-96%) and cefuroxime (80-94%). They were however highly resistant to ampiclox, amoxicillin, and septrin which are over-the-counter drugs. The high incidence of multidrug resistance among Salmonellae and corresponding multidrug resistance among other enteric bacteria, thus posing problems of treatment failures are of great public health significance in a developing country like Nigeria.