Differences in antibiotic susceptibility among gut-colonizing Acinetobacter baumannii isolated from hospital and community populations in Kenya

Abstract

Introduction: Acinetobacter baumannii is a critical priority multidrug-resistant bacterium. Colonization with resistant strains increases the risk of infection and facilitates transmission within healthcare and community settings. However, data on human colonization with drug-resistant A. baumannii remain limited, particularly in low-and middle-income countries. This study investigated and compared the antibiotic susceptibility profiles, resistance patterns, and genetic determinants of gut-colonising A. baumannii isolates from hospital and community settings across urban and rural areas in Kenya. Methods: a total of 125 A. baumannii isolates were analysed, comprising 86 community (54 urban, 32 rural) and 39 hospital (21 urban, 18 rural) isolates. Confirmatory identification and antimicrobial susceptibility testing were performed using VITEK®2 system. Conventional polymerase chain reaction (PCR) was employed to detect resistance genes, including blaCTX-M, blaNDM1, blaOXA-23, blaOXA-48, blaSHV, and blaTEM. Results: significant differences in antibiotic resistance were observed between hospital and community isolates (p≤0.003) across several antibiotics, including ampicillin/sulbactam, ciprofloxacin, ceftriaxone, cefepime, gentamicin, imipenem, meropenem, and sulfamethoxazole/trimethoprim. Rural community isolates showed near-universal susceptibility to most antibiotics tested, except for cefazolin and sulfamethoxazole/trimethoprim. All isolates were resistant to cefazolin but remained susceptible to tigecycline. No statistically significant differences in resistance were observed between urban and rural isolates within hospital or community settings (p > 0.05). Multidrug resistance was exclusively found in hospital isolates, 4 from rural, and 8 from urban, and among these, the blaCTX-M gene was identified in five urban isolates, and blaNDM1 in two rural isolates. Conclusion: this study highlights the significant impact of the immediate environment (hospital vs. community) on A. baumannii antibiotic resistance profiles and underscores the need for tailored setting-specific interventions to address the evolving challenge of multidrug-resistant A. baumannii.