Multidrug resistant Proteus and Aeromonas biotypes from patients attending diagnostic health facilities in Umuahia Metropolis, Abia State, Nigeria

Abstract

This study investigated the prevalence, phenotypic characterization, and antimicrobial resistance patterns of Proteus and Aeromonas species isolated from clinical samples collected at two healthcare facilities in Umuahia, Nigeria, over 12-months period. A total of 400 samples from the Federal Medical Centre and 100 from the Abia State Specialist Hospital and Diagnostic Centre, comprising midstream urine (n=150), stool (n=150), blood (n=100), and hand swab (n=100) specimens, were processed using standard microbiological methods. Isolates were cultured on CLED and Aeromonas differential agar, identified by Gram staining and biochemical profiling, including tests for arginine dihydrolase, citrate utilization, urease production, and carbohydrate fermentation. Antimicrobial susceptibility was determined by disk diffusion against a panel of 16 antibiotics, following CLSI guidelines. Among 115 Proteus isolates recovered, most originated from urine (59.1%), followed by stool (27.0%), hand swab (9.6%), and blood (11.0%). Eighteen Aeromonas strains were identified, predominantly from hand swabs (n=10). Biochemical testing revealed seven variable traits among Proteus biotypes, while Aeromonas showed uniformity in 10 of 16 phenotypic tests. Resistance to oxytetracycline (13.4%) and florfenicol (9.7%) was notable among Proteus; cephem resistance (8.7%) and erythromycin susceptibility (8.6%) were also observed. Aeromonas isolates displayed high oxacillin resistance (10.3%) and variable susceptibility to other antibiotics. Multiple antibiotic resistance (MAR) indices ranged up to 0.87, with 71.8% of Proteus and all Aeromonas isolates resistant to multiple drugs. These findings highlight multidrug resistance among clinical Proteus and Aeromonas isolates in this region.