Antimicrobial Usage, Susceptibility Profiles, and Resistance Genes inCampylobacter Isolated from Cattle, Chicken, andWater Samples in Kajiado County, Kenya

Abstract

Campylobacter organisms are the major cause of bacterial gastroenteritis and diarrhoeal illness in man and livestock. Campylobacter is growingly becoming resistant to critically crucial antibiotics; thereby presenting public health challenge. Tis study aimed at establishing antimicrobial use, susceptibility profles, and resistance genes in Campylobacter isolates recovered from chicken, cattle, and cattle-trough water samples. Te study was conducted between October 2020 and May 2022 and involved the revival of cryopreserved Campylobacter isolates confrmed by PCR from a previous prevalence study in Kajiado County, Kenya. Data on antimicrobial use and animal health-seeking behaviour among livestock owners (from the same farms where sampling was done for the prevalence study) were collected through interview using a pretested semistructured questionnaire. One hundred and three isolates (29 C. coli (16 cattle isolates, 9 chicken isolates, and 4 water isolates) and 74 C. jejuni (38 cattle isolates, 30 chicken isolates, and 6 water isolates)) were assayed for phenotypic antibiotic susceptibility profle using the Kirby–Bauer disk difusion method for ampicillin (AX), tetracycline (TE), gentamicin (GEN), erythromycin (E), ciprofoxacin (CIP), and nalidixic acid (NA). Furthermore, detection of genes conferring resistance to tetracyclines (tet (O), β-lactams (blaOXA-61), aminoglycosides (aph-3-1), (fuoro)quinolones (gyrA), and multidrug efux pump (cmeB) encoding resistance to multiple antibiotics was detected by mPCR and confrmed by DNA sequencing. Te correlation between antibiotic use and resistance phenotypes was determined using the Pearson’s correlation coefcient (r) method. Tetracyclines, aminoglycosides, and β-lactam-based antibiotics were the most commonly used antimicrobials; with most farms generally reported using antimicrobials in chicken production systems than in cattle. Te highest resistance amongst isolates was recorded in ampicillin (100%), followed by tetracycline (97.1%), erythromycin (75.7%), and ciprofoxacin (63.1%). Multidrug resistance (MDR) profle was observed in 99 of 103 (96.1%) isolates; with all the Campylobacter coli isolates displaying MDR. All chicken isolates (39/39, 100%) exhibited multidrug resistance. Te AX-TEE-CIP was the most common MDR pattern at 29.1%. Te antibiotic resistance genes were detected as follows: tet (O), gyrA, cmeB, blaOXA-61, and aph-3-1 genes were detected at 93.2%, 61.2%, 54.4%, 36.9%, and 22.3% of all Campylobacter isolates, respectively. Te highest correlations were found between tet (O) and tetracycline-resistant phenotypes for C. coli (96.4%) and C. jejuni (95.8%). A moderate level of concordance was observed between the Kirby–Bauer disk difusion method (phenotypic assay) and