Occurrence and antimicrobial susceptibility of Enterobacteriaceae from public transport in Dar es Salaam, Tanzania.

Abstract

Background and objective: This study aims to investigate the occurrence and antimicrobial susceptibility of clinically relevant Enterobacteriaceae from public transport in Dar es Salaam, Tanzania. Methods: A total of 100 pooled swab samples were collected from public buses in Dar es Salaam from January 2023 to April 2023. Enterobacteriaceae (Escherichia coli, Enterobacter spp., and Klebsiella spp.) were isolated and identified using standard microbiological techniques. Antimicrobial susceptibility testing was performed using the Kirby-Bauer disk diffusion method. PCR amplification was carried out to detect the presence of antibiotic resistance genes. Furthermore, the 16S rRNA gene of isolates that exhibited phenotypic resistance to all tested antibiotics was Sanger sequenced and a phylogenetic tree was constructed. Results: A high abundance of clinically important Enterobacteriaceae was revealed with high variability in the number of Escherichia coli (48), Enterobacter spp. (15), and Klebsiella spp. (68). Similarly, a high AMR profile was observed against ampicillin (100%) followed by Amoxicillin (97%). Also, isolates resistant to multiple drugs (MDR) were common and very prevalent, where out of 131 isolates, 129 (98%) were MDR. Furthermore, the findings showed a strong positive correlation between phenotypic resistance and the presence of resistance genes (rs = 0.66, P<0.05). Furthermore, the molecular identification confirmed the PDR isolates were distributed across three genera: Escherichia, Enterobacter, and Klebsiella. Also, the phylogenetic analysis indicated the PDR isolates interspersed with reference sequences within their respective genera Conclusions: The present findings highlighted the high abundance and prevalence of AMR clinically important Enterobacteriaceae and underscore the importance of instituting surveillance programs designed to combat AMR focusing on public transport in developing countries.