Antimicrobial resistance pattern of escherichia coli and salmonella species, isolated from domestic and peridomestic rodents in Iringa municipality, Tanzania
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Date
2024-05
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Sokoine University of Agriculture
Abstract
Escherichia coli (E. coli) and Salmonella species are two of the most
common causes of foodborne illness worldwide. E. coli is a Gram-
negative bacterium that is found in the intestines of humans and
animals. Most strains of E. coli are harmless, but some strains can
cause serious infections, such as food poisoning and urinary tract
infections. Salmonella species is a gram-negative bacterium that is
found in the environment and in the intestines of animals.
Salmonella species can cause a variety of infections, including
gastroenteritis, typhoid fever, and paratyphoid fever. Antimicrobial
resistance is a major concern in the treatment of E. coli and
Salmonella infections. When E. coli and Salmonella species become
resistant to antimicrobials, they are more difficult to treat, which can
lead to more severe infections and even death.
Rodents are known to be reservoirs of E. coli and Salmonella spp.
bacteria. Rodents can transmit E. coli and Salmonella spp. to
humans and other animals through their faeces, urine, and saliva.
The aim of this study was to determine the prevalence and
antimicrobial resistance pattern of E. coli and Salmonella spp.
isolated from domestic and peridomestic rodents in Iringa, Tanzania.
A cross-sectional study design was used in this study. The study
sites possessing favourable rodents habitats were purposively
selected. A total of eight wards (sampling sites) were selected. The
target study population was rodents, a total of 153 rodents were
trapped in Iringa municipality, Tanzania. The rodents were trapped
in both domestic and peridomestic settings. Following euthanization,
rats were identified to genus/species level using morphological and
morphometric features. Faecal swab samples were collected from
the rodents and pre-enriched in buffered peptone water, followed by
culture and biochemical tests for identification of E. coli and
Salmonella spp. Molecular confirmation tests were done using
16RrRNA PCR identification methods. The antimicrobial
susceptibility test was performed by disk diffusion method comprising five antimicrobials, including tetracycline (30μg),
ciprofloxacin (5μg), gentamicin (10μg), ceftriaxone (30μg), and
trimethoprim-sulfamethoxazole (25μg). Seven resistant genes were
analyzed by PCR, which were blaCTX-M, blaSHV, sul1, sul2, tetA,
acr(A), and aac(3)-1 in each isolate. Three rodent species, Rattus
rattus (75.2%), Mastomys natalensis (23.5%), and Mus musculus
(1.3%), were captured. 17 (11.1%) E. coli were detected, and no
Salmonella species were isolated. All 17 isolates were susceptible to
Gentamycin, while Sulphamethaxazole/Trimethoprim was highly
resistant (52.9%). Four E. coli isolates exhibited multidrug resistance
(MDR), whereby 75% of these MDR isolates originated from the
same area. Six resistant genes were detected: blaCTX-M, sul1, sul2,
tetA, acr(A), and aac (3)-1, where the acr(A) resistant gene was the
most abundant. There were co-occurrences of the resistant genes
per isolate such as sul2, acr(A), and aac(3)-1. This study reveals the
antimicrobial resistance of E. coli isolated from rodents, providing
preliminary data on the prevalence and antimicrobial resistant
features of these pathogens in their respective reservoirs in Iringa
municipality. The study recommends observation of regular
antimicrobial resistance screening and improvement in rodent
management and control programs in the studied area.
Description
Master of Science in Public Health and Pest Management
Keywords
Rodent, E. coli, Salmonella spp., antimicrobial- resistance, resistance gene, multidrug resistance