Investigating antimicrobial use and occurrence of extended spectrum beta lactamase (esbl)-escherichia coli in commercial and small-scale poultry farms in selected districts of Zambia.
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Date
2024
Authors
Sinyawa, Taona
Journal Title
Journal ISSN
Volume Title
Publisher
The University of Zambia
Abstract
Antimicrobial resistance (AMR) among Escherichia coli (E. coli) from food animals is a rising problem with overuse, underuse, or prolonged usage of one type of antimicrobial in poultry as a contributing factor. In Zambia, studies linking poultry-associated AMR and antimicrobial use (AMU) are rare. This study aimed to investigate commercial and small-scale poultry farmers‘ usage of antimicrobials using a pre-tested structured questionnaire in ten districts of Zambia. A total of 119 questionnaires were administered to 35 commercial farmers and 84 small-scale farmers. In addition, the study detected extended-spectrum β-lactamase (ESBL)-producing E. coli isolates obtained from poultry in the same districts. Further, three cloacal swabs were collected in each of the 269 poultry houses and pooled into a single sample for analysis of the presence of E. coli and resistance profiles. A total of 232/269 (86.2%) E. coli isolates were isolated and tested for antimicrobial susceptibility using eight antibiotic classes and stored. The overall prevalence of AMR was 98% and Multidrug resistance (MDR) was identified in 70.7% of the E. coli isolates. However, 150/232 (64.7%) E. coli isolates were recovered and further screened for ESBL production by streaking them on cefotaxime (CTX)- supplemented MacConkey agar, 20% (30/150) of the third-generation cephalosporins (3GC) resistant isolates were ESBLs. Of these isolates, those with CTX Minimum Inhibitory Concentration (MIC) ≥ 4 µg/mL were then subjected to sequencing on a NextSeq. The questionnaire information showed that more small-scale than commercial poultry farmers used antimicrobials (OR = 7.70, 95% CI = 2.88–20.6, p < 0.001 but less prescriptions (OR = 0.02, 95% CI = 0.00–0.08, p < 0.001). Altogether, the questionnaire survey results showed a higher proportion of AMU and lower prescription usage among small-scale farmers. Overall, susceptibility testing revealed that resistance was highest to ampicillin (128/148, 86.5%) and tetracycline (101/136, 74.3%) and that the presence of multidrug-resistance (MDR) (28/30, 93.3%) among the third generation cephalosporins (3GC) (28/150) was high. Whole-genome sequencing (WGS) of eight
(8/30, 26.7%) revealed (6/8,75%) the presence of ESBL-encoding genes blaCTX-M-14, blaCTX-M-55 and blaTEM. WGS also detected other AMR genes for quinolones, aminoglycosides, phenicols, tetracycline, macrolides, and folate-pathway antagonists. Survey results indicated that there was higher usage of antimicrobials without prescription. In addition, the results give insights into the occurrence of ESBLproducing E. coli strains with associated MDR in both commercial and small-scale poultry farms. It will be important to educate farmers on AMR risks and to encourage
responsible usage of antimicrobials. There is a need to strengthen regulations limiting access to antimicrobials and establish a one health system to guide public health response.
Description
Thesis of Master of Science Degree in Microbiology.