Abstract:
(e rise in the spread of antibiotic-resistant pathogens such as Escherichia coli is one of the very important dynamics off-putting
treatment and prophylaxis possibilities, hence posing a threat to the modern human medicine, veterinary medicine, and food
safety. (erefore, the aim of this study was to determine antimicrobial resistance profiles in E. coli isolates obtained from broiler
and layer chickens in Mwanza and Arusha regions in Tanzania. A cross-sectional study was carried out from February to March,
2021, in 402 poultry farms in Mwanza (201) and Arusha (201) regions in Tanzania. All samples that tested positive for E. coli were
confirmed using MALDI-TOF MS, and two hundred and four (204) E. coli isolates were randomly chosen and subjected to
antimicrobial susceptibility testing by disc diffusion method. Data were entered in Microsoft Excel® and analyzed using SPSS
version 20. Isolates were tested against seven antimicrobial agents belonging to seven classes of antimicrobials. All the tested
isolates (n � 204) were resistant to at least one antimicrobial agent. Overall, the highest resistance was observed in ampicillin
(100%), whereas the lowest resistance was recorded for gentamicin (10.3%). Majority of the isolates (86.76%) were multidrug
resistant. Antimicrobial resistance of E. coli to four classes of antimicrobial agents was the highest in this study (31.1%). Six of the
177 tested isolates (2.9%) were resistant to the seven classes of antimicrobial agents. 21 of the 204 (10.29%) isolates were ESBL
producers where 21/21 (100%) isolates expressed blaTEM genes and only two isolates expressed (2/21) blaCTX-M gene. (e isolates
obtained in this study displayed high resistance to commonly used antimicrobial agents in veterinary and human medicine. (is
implies that there is existence of practices that accelerate antimicrobial resistance in the production of the sampled birds and
therefore integration of appropriate use of antimicrobial agents and other measures that curb the spread of resistant genes
is necessary
