Antibiotic Resistance Patterns of <i>Pseudomonas aeruginosa</i> Isolated from Clinical Samples in Khyber Pakhtunkhwa, Pakistan

Background: Pseudomonas aeruginosa is a major opportunistic pathogen responsible for a wide range of nosocomial infections. Its increasing multidrug resistance (MDR) poses significant treatment challenges, especially in low-resource settings like Khyber Pakhtunkhwa, Pakistan, where updated surveillance data are limited. Objective: This study aimed to determine the prevalence and antibiotic resistance patterns of Pseudomonas aeruginosa isolated from various clinical specimens, and to assess the distribution of MDR strains across different sample types in tertiary care hospitals of Khyber Pakhtunkhwa. Methods: A cross-sectional observational study was conducted from February 2024 to February 2025 using 107 non-duplicate clinical isolates of P. aeruginosa. Isolates were collected from five tertiary hospitals, confirmed through standard biochemical tests, and tested for antimicrobial susceptibility using the Kirby-Bauer disk diffusion method following CLSI M100 guidelines (34th edition, 2024). MDR was defined as resistance to at least one agent in three or more antibiotic classes. Ethical protocols adhered to biosafety standards consistent with the Declaration of Helsinki. Data were analyzed using SPSS v27.0 with descriptive and chi-square statistical analyses. Results: Colistin showed the highest sensitivity (83.2%), followed by meropenem (64.5%) and imipenem (53.3%), while ciprofloxacin (89.7%) and levofloxacin (87.9%) had the highest resistance. MDR was most frequent in sputum (53.8%) and pus (51.8%) samples. No significant association was found between MDR distribution and sample type (χ² = 4.93, p = 0.553). Conclusion: The study underscores the alarming resistance trends in P. aeruginosa, highlighting colistin and carbapenems as the most reliable treatment options. These findings advocate for targeted antimicrobial stewardship and periodic resistance surveillance to mitigate therapeutic failures in clinical practice.