Evaluation of bacteria causing ventilator-associated pneumonia in patients admitted to internal icus and internal wards at Shiraz teaching hospitals, 2017-2018

Abstract

Background: Ventilator-associated pneumonia (VAP), a subset of hospital infections, occurs in patients who have been mechani-cally ventilated for at least 48 hours. Objectives: Our study aimed at determining the frequency and antibiotic susceptibility patterns of bacteria causing VAP in teaching hospitals of Shiraz. Methods: This was a descriptive cross-sectional study conducted in Shiraz for eight months (November 2017 to June 2018). Samples were detected according to diagnostic bacteriologic tests, and antibiotic susceptibility tests were performed by the disk diffusion (Kirby-Bauer) method based on the Clinical and Laboratory Standards Institute (CLSI). Results: A total of 51 patients with VAP were examined, of whom 10 and eight patients had a chronic obstructive pulmonary disease and acute respiratory distress syndrome, respectively. The late-onset VAP rate (61.7%) was higher than the early-onset VAP rate (38.3%). In our study, 45.2% of patients with VAP received antibiotics before the incidence of pneumonia, of whom 31.6% died. Of the remain-ing 54.8%, only 8.7% died. In other words, patients who received antibiotics before the incidence of pneumonia had higher mortality. The most frequently used antibiotics were meropenem (76.6%) and vancomycin (78.7%). Among 59 bacteria isolated, Acinetobacter and Pseudomonas were the most prevalent organisms. Conclusions: Our results showed that most of the isolates (40%) belonged to multi-drug resistant (MDR) pathogens. Probably, antimicrobial treatment before the onset of VAP led to the selection of these MDR pathogens.