The emergence of ESBL and carbapenemase-producing Acinetobacter baumannii from cattle and environmental sources in Lagos, Nigeria

The detection of Acinetobacter baumannii among livestock and the surrounding environment poses an emerging public health threat. This study determined the prevalence, virulence, and antimicrobial resistance determinants in ESBL and carbapenemase-producing A. baumannii from ready-to-slaughter cattle and environmental sources. Between April 2022 and March 2023, 1,180 samples (840 cattle, 260 abattoir effluents, and 80 lagoon water samples) were collected and analyzed using standard methods. Antibiotic susceptibility testing was conducted, and RTPCR was used to detect resistance and virulence gene markers. Fifteen A. baumannii isolates were identified based on the presence of the blaOXA-51-like intrinsic gene, and all harbored the OmpA virulence gene. The prevalence of A. baumannii was 0.95% (8/840) in ready-to-slaughter cattle and 2.06% (7/340) in environmental samples, including 1.15% (3/260) in abattoir effluent and 5% (4/80) in lagoon water. No significant relationship was found between A. baumannii detections and gender, age, or source (p>0.05). The isolates showed 93.33% susceptibility to piperacillin-tazobactam and imipenem, 86.67% to cefepime, and 73.33% to gentamicin. All isolates were 100% resistant to cefotaxime and 86.67% resistant to doripenem. Phenotypically, 60% and 50% of isolates were ESBL and carbapenemase producers, respectively. Most isolates harbored at least one carbapenemase gene (blaKPC, blaIMP, blaOXA-48) or ESBL-encoding gene (blaTEM, blaSHV), with a 20% co-existence rate. Interestingly, one isolate (MML02) from the lagoon water that harbored blaKPC, blaIMP, blaOXA-48, blaSHV, and blaTEM developed resistance to piperacillin-tazobactam and imipenem, and also exhibited a resistant profile CIP-PIT-T/S-CTXFOX-IMP-DOR-MEM. The study highlights the emergence of ESBL and carbapenemaseproducing A. baumannii strains in non-human-associated sources. Continuous surveillance, early detection, and antibiotic stewardship are crucial in mitigating the spread.