Cephalosporin, Colistin, and Beta-Lactamase Inhibitor Resistance in Clinical Pseudomonas aeruginosa Isolates: Associations with Patient Age and Gender in a Nigerian Tertiary Hospital

Pseudomonas aeruginosa is a leading cause of healthcare-associated infections with remarkable capacity for antimicrobial resistance. This study investigated the resistance profiles of clinical P. aeruginosa isolates, focusing on cephalosporins, colistin, and beta-lactamase inhibitors, and examined associations with age group and gender. A total of 250 clinical samples (150 urine, 100 wound swabs) were collected from patients at Alex Ekwueme Federal University Teaching Hospital Abakaliki (AE- FUTHA), Ebonyi State, Nigeria. P. aeruginosa was isolated using standard microbiological techniques and identified by Gram staining and biochemical tests. Antimicrobial susceptibility testing was performed using the Kirby-Bauer disk diffusion method according to CLSI guidelines. Statistical analysis was conducted using SPSS version 25. Out of 250 samples, 58 (23.2%) yielded P. aeruginosa isolates. High- level resistance was observed to cephalosporins: ceftriaxone (96.6%), cefotaxime (93.1%), cefepime (91.4%). Colistin resistance was detected in 89.7% of isolates. Beta-lactamase inhibitor combinations showed limited efficacy: amoxicillin-clavulanic acid (98.3% resistance), ticarcillin-clavulanic acid (96.6% resistance), and piperacillin-tazobactam (72.4% resistance). Amikacin demonstrated the highest susceptibility (100%). Statistical analysis revealed significant associations between age group and colistin resistance (p=0.041), and between gender and piperacillin-tazobactam resistance (p=0.038). This study reveals alarmingly high resistance rates to cephalosporins, colistin, and beta-lactamase inhibitors among clinical P. aeruginosa isolates, with significant demographic associations, emphasizing the urgent need for antimicrobial stewardship and continuous surveillance.