Antimicrobial Susceptibility Pattern of Multidrug-Resistant Acinetobacter Species Isolated From Intensive Care Units in a Tertiary Care Hospital

Background: Multidrug-resistant (MDR) Acinetobacter species are important healthcare-associated pathogens, particularly in intensive care units (ICUs), where invasive procedures, prolonged hospitalization, and exposure to broad-spectrum antimicrobial agents may facilitate the emergence and transmission of antimicrobial-resistant organisms.Increasing antimicrobial resistance among Acinetobacter isolates has substantially narrowed therapeutic options, making local antimicrobial susceptibility surveillance important for guiding antimicrobial therapy and infection prevention strategies.This study evaluated the distribution of MDR Acinetobacter isolates and their antimicrobial susceptibility patterns among patients admitted to ICUs of a tertiary care hospital.Methods: A cross-sectional observational study was conducted on 121 Acinetobacter isolates recovered from clinical specimens of ICU patients at a tertiary care teaching hospital.The isolates were identified using conventional microbiological methods.Antimicrobial susceptibility testing was performed using the Kirby-Bauer disk diffusion method on Mueller-Hinton agar and interpreted according to the Clinical and Laboratory Standards Institute 2024 guidelines.Results: Among the 121 Acinetobacter isolates recovered from ICU patients, 98 (80.99%) were classified as MDR.Acinetobacter baumannii was the predominant species among the MDR isolates, accounting for 92 (93.88%) isolates, followed by Acinetobacter haemolyticus (5; 5.10%) and Acinetobacter lwoffii (1; 1.02%).Endotracheal tube specimens were the most frequent source of MDR Acinetobacter isolates, accounting for 41 (41.84%) isolates, followed by sputum and pus (15 each; 15.31%).The Medical ICU contributed the largest proportion of MDR isolates (53; 54.08%).Antimicrobial susceptibility testing demonstrated extensive resistance, with 100% resistance to both imipenem and meropenem.Minocycline demonstrated the highest proportion of susceptible isolates (35; 35.71%) among the tested antimicrobial agents.Conclusion: The study demonstrated a high proportion of MDR Acinetobacter among ICU-derived clinical isolates, with A. baumannii being the predominant species.The high level of resistance to commonly tested antimicrobial agents, particularly the complete resistance observed to imipenem and meropenem, highlights the importance of routine antimicrobial susceptibility testing, continuous local resistance surveillance, antimicrobial stewardship, and rigorous infection prevention and control measures in ICU settings.