Antimicrobial Susceptibility Pattern of Pseudomonas aeruginosa Isolated from ICU Patients

Abstract

Background: Pseudomonas aeruginosa is a major cause of healthcare-associated infections in intensive care units (ICUs) and is associated with significant morbidity, mortality, and antimicrobial resistance. Continuous surveillance of susceptibility patterns is essential for guiding empirical therapy and infection control practices.
Aim: To determine the antimicrobial susceptibility pattern of Pseudomonas aeruginosa isolated from ICU patients and evaluate the prevalence of multidrug-resistant strains.
Methods: A prospective observational study was conducted at Patna Medical College and Hospital (PMCH) from July 2025 to March 2026. A total of 100 non-duplicate Pseudomonas aeruginosa isolates obtained from ICU patients were included. Clinical specimens including endotracheal aspirates, sputum, urine, blood, wound swabs, and pus samples were processed using standard microbiological techniques. Antimicrobial susceptibility testing was performed using the Kirby-Bauer disk diffusion method according to CLSI guidelines. Resistance patterns and multidrug resistance (MDR) rates were analyzed.
Results:Respiratory samples constituted the majority of isolates (42%). Highest susceptibility was observed for colistin (98%), polymyxin B (96%), and ceftolozane-tazobactam (88%). Resistance was highest against ciprofloxacin (62%), levofloxacin (58%), and ceftriaxone (74%). Multidrug-resistant Pseudomonas aeruginosa was identified in 38% of isolates. Carbapenem resistance was observed in 32% of isolates and was significantly associated with prolonged ICU stay (p=0.004).
Conclusion: Pseudomonas aeruginosa isolated from ICU patients demonstrated high resistance to commonly used antibiotics while retaining susceptibility to polymyxins. The substantial prevalence of MDR strains highlights the need for antimicrobial stewardship, routine surveillance, and rational antibiotic utilization.