Prevalence and molecular identification of antibiotic resistant airborne bacteria at intensive care units

The importance of airborne transmission in the epidemiology of hospital acquired infections (HAI) has gained attention in the past two decades.The airborne transmission may have more effect on intensive care units (ICUs), because the patients who require intensive care have unstable clinical conditions and are more sensitive to infections.This study was designed to evaluate the prevalence of antibiotic resistant airborne bacteria in intensive care units.

A cross-sectional study was conducted at four teaching hospitals.The 32 air samples were collected by using all-glass impingers (AGI). Identification of airborne bacteria was conducted using cultured plates with and without five selected antibiotics. The resistant isolates were analyzed by Polymerase Chain Reaction (PCR) for the presence of seven most common antibiotic resistance genes.

The prevalence of antibiotic resistance airborne bacteria ranged from 6% to 37%. The oxacillin resistant isolates had the highest prevalence followed by ceftazidime-, vancomycin-, gentamicin- and cefazolin- resistant bacteria. Selected genes were detected in airborne resistant isolate with the highest and lowest frequency for OXA23 and AAC (3) -I, respectively. A high frequency of mecA (21%) and blaTEM (34%) genes was detected in isolates. Identification of OXA-51 demonstrated that the species of Acinetobacter were A. baumannii. Methicillin-resistant Staphylococcus (MRS) spp were the second most predominant resistant bacteria in all ICUs isolates.

In this study, identification of Staphylococcus spp and A. baumannii as the most dominant antibiotic resistant bacteria indicated the potential role of airborne bacteria in dissemination of nosocomial infections in ICUs