A Survey of Genotype and Resistance Patterns of VentilatorAssociated Pneumonia Organisms in ICU Patients


1 Infectious Diseases and Tropical Medicine Research Center, Shahid Beheshti University of Medical Sciences, Tehran, Iran,

2 Department of Microbiology, School of Medicine, Shahid Beheshti University of Medical Sciences, Tehran, Iran


Background: Ventilator-Associated Pneumonia (VAP) occurs in hospitalized patients who have undergone intubation and mechanical ventilation for more than 48 hours. Patients referred to the Intensive Care Unit (ICU) are also affected by VAP due to specific conditions, especially by Gram-negative pathogens with advanced drug resistance. In this study, the pattern of antibiotic resistance of gram negative bacteria isolated from tracheal culture of VAP patients was investigated in ICU. Materials and Methods: In this cross-sectional study, tracheal samples were collected from VAP patients admitted in the hospital's ICU from March 2017- February 2018. After isolation, bacterial isolates were identified using biochemical tests. Then, antimicrobial resistance pattern of these isolates was investigated using standard disc diffusion and E-test methods. Multiplex PCR were used to detect the blaOXA-23-like, blaOXA-51-like, blaOXA-24-like, and blaOXA-58-like genes among Acinetobacter baumannii (A. baumannii) isolates. Results: A total of 29 bacterial isolates were isolated from ICU patients, which were A. baumannii, Pseudomonas aeruginosa (P. aeruginosa), Klebsiella pneumoniae (K. pneumoniae) and candida spp, with prevalence of 38, 27.5, 13.8, and 20.7%, respectively. Antibiotic susceptibility test of isolates indicated that almost all isolates showed Multi-Drug Resistance (MDR) pattern. The A. baumannii isolates were resistant to ciprofloxacin and piperacillin-tazobactam, but ampicillin-sulbactam and colistin had better results. Ciprofloxacin, meropenem and colistin were effective against P. aeruginosa isolates, but other antibiotics were less effective and Colistin, Levofloxacin (LVX) and Piperacilin/Tazobactam were the best antibiotics that were effective on the isolates of K. pneumonia. Conclusion: According to the present study, high resistance to most antibiotics in gram negative bacilli showed that antibiotic therapy should be based on the type of bacteria isolated by tracheal culture and, as far as possible, combination therapies should be used to maximize the coverage of other possible pathogens, and antibiotic resistance in ICU.