Bacterial etiology and antimicrobial resistance in hospital-acquired respiratory infections: A Six-year retrospective study in Northern Iran
Keywords:
Hospital-acquired infections, Respiratory tract infections, Ventilator-associated pneumonia, Antimicrobial resistance, Bacterial etiologyAbstract
Hospital-acquired respiratory infections are important healthcare-associated complications, particularly among critically ill patients, and are frequently associated with antimicrobial resistance. Local surveillance of bacterial pathogens and their antimicrobial susceptibility profiles is essential for informing infection prevention and antimicrobial stewardship. This study aimed to investigate the bacterial etiology and antimicrobial resistance patterns of hospital-acquired respiratory infections in Northern Iran. This retrospective descriptive study reviewed medical records and hospital infection-control data for patients with hospital-acquired respiratory infections at Razi Teaching Hospital, Rasht, Iran, between 2018 and 2023. Demographic characteristics, hospital ward, length of stay, discharge outcomes, bacterial isolates, and antimicrobial susceptibility results were extracted. Bacterial identification and susceptibility findings were obtained from routine microbiology laboratory records. Among 3,726 recorded hospital-acquired infections, 1,231 (33.0%) were classified as respiratory infections. Ventilator-associated pneumonia (VAP) accounted for 1,215 cases (98.7%). The mean patient age was 61.15 ± 17.55 years, and 61.0% of patients were male. The mean hospital stay was 30.88 ± 30.29 days, and in-hospital mortality was 60.2%. Klebsiella spp. was the most frequently recorded bacterial group (40.2%), followed by Pseudomonas aeruginosa (15.2%), Acinetobacter spp. (14.3%), and Enterobacter spp. (9.6%). High resistance rates were reported across several organism-antimicrobial combinations, including cefazolin resistance in Klebsiella spp. (99.1%) and imipenem resistance in Acinetobacter spp. (99.2%). Hospital-acquired respiratory infections represented a substantial proportion of recorded healthcare-associated infections and were characterized by the predominance of Gram-negative bacteria, high reported antimicrobial resistance, and considerable in-hospital mortality. Strengthening infection prevention, validating susceptibility data, and implementing continuous local microbiological surveillance may support more effective infection control and antimicrobial stewardship.
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