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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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