Prevalence, Antibiotic Susceptibility Profile, and Multiple Antibiotic Resistance Index of Gram-Negative Bacteria Isolated from Skin and Nasal Samples of Goats Bred in Abakaliki, Ebonyi State, Nigeria

Antimicrobial resistance (AMR) is a critical global public health threat, with food-producing animals recognized as important reservoirs of multidrug-resistant (MDR) bacteria. In Nigeria, indiscriminate antibiotic use and weak regulatory frameworks have exacerbated resistant pathogen spread. Goats (Capra hircus) are widely reared in Abakaliki, Ebonyi State, serving as major meat and income sources, yet limited data exist on the prevalence, antibiotic susceptibility profile, and multiple antibiotic resistance index (MARI) of Gram-negative bacteria Gram-negative bacteria colonizing their skin and nasal passages. Thirty samples (20 skin, 10 nasal swabs) were aseptically collected from goats in Abakaliki urban markets. Gram-negative bacteria were isolated using standard microbiological techniques, confirmed by VITEK® 2 COMPACT, and subjected to antibiotic susceptibility testing via Kirby-Bauer disc diffusion against 13 antibiotics. MARI was calculated for each isolate. Thirty-one Gram-negative isolates were recovered: Escherichia coli 12 (38.7%), Klebsiella pneumoniae 8 (25.8%), Shigella flexneri 7 (22.6%), and Salmonella Enteritidis 4 (12.9%). All isolates (100%) exhibited resistance to amoxicillin-clavulanic acid. High resistance rates were observed against ceftazidime, ceftriaxone, azithromycin, and levofloxacin. Shigella flexneri showed complete susceptibility to imipenem, while Salmonella Enteritidis was fully susceptible to levofloxacin. Mean MARI values ranged from 0.48 (K. pneumoniae) to 0.62 (Salmonella Enteritidis), all exceeding the 0.2 high-risk threshold. All isolates were resistant to three or more antibiotic classes and classified as MDR. Goats in Abakaliki harbor clinically significant MDR Gram-negative bacteria with high antibiotic resistance indices, highlighting zoonotic transmission risks and the urgent need for antimicrobial stewardship and One Health surveillance in Nigeria.