Investigation of Antibiotic Resistance Profiles of Acinetobacter Strains Isolated from ICU Samples in Mashhad, Iran (October 2018–May 2019)

Background & Objectives: Acinetobacter spp. are non-fermentative, Gram-negative, opportunistic pathogens characterized by high levels of antibiotic resistance and are frequently associated with nosocomial infections in intensive care units (ICUs). This study aimed to investigate the antibiotic resistance profiles of Acinetobacter strains isolated from ICU patients using the BD Phoenix system, which determines antimicrobial susceptibility based on the Minimum Inhibitory Concentration (MIC) method. Materials & Methods: A descriptive, cross-sectional study was conducted from October 2018 to May 2019 involving 60 ICU patients at Mehr-e Hazrat Abbas Hospital in Mashhad, Iran. Clinical specimens—including blood, bronchoalveolar lavage, tracheal secretions, wound swabs, biopsies, pleural fluid, and sternum swabs—were collected under sterile conditions. Acinetobacter species were identified through standard culture techniques and confirmed via PCR targeting the blaOXA-51-like gene. Antimicrobial susceptibility testing against 21 antibiotics was performed using the BD Phoenix system in accordance with CLSI guidelines. Data were analyzed using SPSS software employing chi-square tests (p < 0.05). Results: All 60 isolates were confirmed as Acinetobacter spp. Colistin demonstrated the highest susceptibility rate (90%). The highest resistance rates were observed against aminoglycosides, carbapenems, and quinolones (each 55%), followed by cephalosporins, macrolides, and β-lactamase inhibitors (54%), sulfonamides (43%), and monobactams (40%). Multidrug-resistant A. baumannii represents a serious threat in ICUs owing to its environmental persistence, genetic adaptability, and plasmid-mediated resistance mechanisms. Although colistin remains one of the most effective therapeutic options, its use is limited by toxicity and the emergence of resistance. Conclusion: The findings underscore the alarming rise in antibiotic resistance among Acinetobacter strains and highlight the necessity of implementing targeted antibiotic stewardship programs and localized surveillance systems to optimize treatment outcomes and curb the spread of resistance.