Abstract

Background: The prevalence, the characterization of extended-spectrum β-lactamase (ESBL)-producing Esche-richia coli (E. coli) strains isolated from broiler chickens in the Casablanca-Settat region of Morocco, and their susceptibility to antibiotics were investigated.
Methods: A total of 216 intestinal samples were collected (100 samples in 2017 and 116 samples in 2019). E. coli isolates were screened for reduced susceptibility to Ceftazidime (CAZ) and subjected to antibiotic susceptibility testing. ESBL production was confirmed phenotypically and genotypically using PCR to detect blaTEM, blaCTX-M1, and blaSHV genes.
Results: Results revealed a high prevalence (83.5%) of E. coli, with a significant decrease in prevalence observed in 2019 compared to 2017 (69%). Reduced susceptibility to Ceftazidime assay showed that 37% (n = 66) of the 178 E. coli isolates were resistant to Ceftazidime (CAZ-R), which indicates the potential likelihood of having ESBL. ESBL phenotypic testing showed a prevalence of 10.32%, with a slight increase in 2019 (11.5%), compared to 2017 (9%, p > 0.05). Antibiotic susceptibility testing demonstrated high resistance levels, notably in 2019, observed for Amoxicillin (94%), Ceftazidime (81%), and Aztreonam (69%). Multidrug resistance (MDR) significantly increased from 2017 to 2019, with 93% of isolates tested in 2019 resistant to at least three antibiotic families. Genotypic analysis revealed the presence of the blaCTX-M15 (n = 1) and blaTEM1 (n = 2) genes in 2017, with an increase of blaTEM1 in 2019 (n = 9).
Conclusions: These findings highlight the emergence and the increases of ESBL-producing E. coli strains in Moroccan broiler chickens, signaling a growing concern for antimicrobial resistance in poultry farming. Enhanced surveillance and control measures are imperative to mitigate the spread of resistant pathogens in both animal and human populations.

DOI: 10.7754/Clin.Lab.2024.240804