Tehran University of Medical Sciences Iranian Journal of Microbiology 2008-3289 15 6 2023 11 20 779 787 Ibiam Amadi Department of Otorhinolaryngology, Alex Ekwueme Federal University, Ndufu Alike Ikwo, Nigeria Obasikene Catherine Nchedo Department of Radiology, Nnamdi Azikiwe University, Awka, Nigeria Ariom Obaji Department of Microbiology, Institute of Food Security, Environmental Resources and Agricultural Research, Federal University of Agriculture, Abeokuta, Ogun State, Nigeria Monday Agbonifo Department of Otorhinolaryngology, Ambrose Ali University, Ekpoma, Nigeria Egwu Eze Department of Medical Laboratory Science, Alex Ekwueme Federal University, Teaching Hospital Abakaliki, Nigeria Iroha Stacy Department of Pharmacy, Alex Ekwueme Federal University, Teaching Hospital, Abakaliki, Nigeria Moses Benjamin Department of Applied Microbiology, Faculty of Sciences, Ebonyi State University, Abakaliki, Nigeria Iroha Romanus Department of Applied Microbiology, Faculty of Sciences, Ebonyi State University, Abakaliki, Nigeria 2022 12 19 2023 10 21 Background and Objectives: AmpC-producing Gram-negative bacterial (GNB) pathogens are distributed worldwide, especially in clinical settings. This study aimed to determine the antibiogram and the type of AmpC-β-lactamase gene harboured by GNB pathogens implicated in chronic suppurative otitis media (CSOM) cases. Materials and Methods: Ear swab samples (300) collected from patients with active CSOM were analysed using standard microbiological techniques. Phenotypic and molecular detection of AmpC β-lactamase production was done by cefoxitin/cloxacillin double-disk synergy test and PCR respectively. Antibiogram was determined by disk diffusion technique. Results: Among the GNB pathogens isolated from CSOM patients, P. aeruginosa was the most predominant (36.3%); followed by K. pneumoniae (22.3%), and E. coli (13.7%). Patients with active CSOM showed increased bacteria isolation rate from bilateral ear discharges than unilateral ear discharges. E. coli and P. aeruginosa were more prevalent among patients with duration of discharge >2 weeks; recording 9.0% and 20.3% respectively. AmpC β-lactamase producers accounted for 14.0%; they were highly resistant (60%-100%) to cephalosporins, trimethoprim-sulfamethoxazole, ofloxacin, amoxicillin, and tetracycline, but very susceptible (70.4%-100%) to ciprofloxacin, imipenem, and amikacin. Multiple antibiotic resistance indices of isolates ranged from 0.7-0.8. FOX-AmpC-β-lactamase gene was detected in 3.9% of the isolates. Conclusion: The detection of AmpC β-lactamase-producing multidrug-resistant GNB pathogens harbouring FOX-AmpC-β-lactamase gene among patients with CSOM infections in our study is a serious public health problem which needs urgent intervention. https://ijm.tums.ac.ir/index.php/ijm/article/view/4046 https://ijm.tums.ac.ir/index.php/ijm/article/download/4046/1625