Prevalence and antimicrobial resistance profile of foodborne salmonella enterica and escherichia coli from rodents and shrews in Morogoro municipality, Tanzania

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Date

2024-05

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Publisher

Sokoine University of Agriculture

Abstract

Rodents and shrews were identified as transmitters and carriers of Salmonella enterica, Escherichia coli (E. coli), and their antimicrobial resistant strains; however, few researchers have examined rodents feces infections. Antimicrobial resistance (AMR) is a pressing issue in the field of global public health, impacting both human and animal health. Small mammals such as rodents and shrews excrements constitute a significant reservoir of zoonotic pathogens, including bacteria resistant to antimicrobials. To date, there is a need for more documented research specifically addressing Escherichia coli (E. coli) and Salmonella enterica strains derived from small mammal feces samples collected in Morogoro Municipality. This study aimed to determine the prevalence and antimicrobial resistance profile of Salmonella enterica and E. coli associated with rodents and shrews in five wards selected in Morogoro Municipality, Tanzania, from March to November 2023. Questionnaires were used to assess risk factors of Salmonella enterica and E. coli associated with house rodents and shrews. This study isolated bacteria extracted from fecal samples of rodents and shrews by using a culture test and identified them with biochemical tests. Molecular tests were used to screen out bacteria-targeted. The isolates bacteria were analyzed for AMR using the disc diffusion method for susceptibilities test to the selected antibiotics. Molecular analysis was used to identify the species of bacteria using 16S rRNA and InvA. Polymerase chain reaction (PCR) was used to find resistance genes in each isolate, including Bla TEM, Bla SHV, Bla CTXM, Sul 1, and Sul 2. A total of 148 small mammals were captured, 145 (98%) were rodents and 3(2%) were shrews. These small mammals were captured from domestic, peri-domestic, and marketplaces. Salmonella enterica was detected in 3/148 (2%), and E. coli was found in 54/148 (36.5%) samples. Most rodents infected by E. coli and Salmonella enterica were Mus species, with 16.2% and 1.3% respectively. Regarding habitat, the high prevalence of E. coli was bserved in open markets, at 16.9%, while Salmonella enterica was high inside households, with 1.3%. Regarding the risk factors associated with house rodents and shrews, 83.7% of respondents found rodents feces in uncooked or cooked food, 30.4% found rodents feces in the water storage, 93.2% found food eaten by rodents, whereby 66.9 % of households used food contaminated with feces or eaten by rodents. Twenty-seven percent (27%) of the respondents were diagnosed with Diarrhea, which may be linked with pathogens from rodents and shrews. The AMR on Amoxicillin was observed in shrews at 100%, in Rattus rattus was 89.5%, and Mus spp was 87.5%, while AMR to Ampicillin on Rattus rattus was 74% and in Mus spp was 62.5%. Salmonella Enterica was more resistant than E. coli for Sulphamethoxazole/Trimethoprim, Ciprofloxacin, and ampicillin. E. coli was more resistant to Amoxicillin than Salmonella Enterica. Concerning the genes linked to E. coli and Salmonella enterica, the results showed that Salmonella Enterica harbored more resistance genes (20%) than E. coli (12%). Two (2) isolates, out of 13 contained Sulphonamide-resistant genes as follows: Sul 1 (n=1) of Salmonella enterica and Sul 2 (n=1) of E. coli, both representing 15.4% of the total resistant gene analyzed in this study. β- lactamases (Bla TEM , Bla SHV, Bla CTXM) were found in 7 isolates (53.8%), with Salmonella enterica harboring more resistance genes than E. coli. The results of this study indicated that the public health significance of pathogens in rodents and shrews from the study area requires further investigation because these animals live close to humans and are also able to move from one place to another, which can increase the transmission of pathogens harbored by them to humans or the environment. Also, this research reveals the presence of resistant Escherichia coli and Salmonella enterica in small mammals, which indicate the potential role of rodents and shrews as a reservoir for AMR E. coli and Salmonella enterica that can be transferred to humans.

Description

MSc. Public Health Pest Management

Keywords

antimicrobial resistance profile, foodborne salmonella enterica, Morogoro municipality, Tanzania

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