Etiology and resistance patterns of bacteria causing ventilator-associated pneumonia in a respiratory intensive care unit

Ventilator-associated pneumonia (VAP) incidence, causative pathogens, and resistance patterns are different between countries and intensive care units (ICUs). In Europe, resistant organisms have progressively increased in the last decade. However, there is a lack of data from Serbian ICUs. The aims of this study were to evaluate etiology and antimicrobial resistance for pathogens causing VAP in ICU patients, to examine whether there were differences between pathogens in early-onset and late-onset VAP and to identify mortality in patients with VAP after 30 and 60 days of hospitalisation. A retrospective cohort study was conducted in the respiratory ICU and all adult patients diagnosed with VAP from 2009 to 2014, were included. Gram negative organisms were the major pathogens (80.3%). The most commonly isolated was Acinetobacter spp (59.8%). There was statistical significant increase in incidence of infection with Klebsiella pneumoniae (8.9% vs 25.6%, p = 0.019). Extensively drug-resistant strains (XDR) were the most common (78.7%). Late-onset VAP was developed in 81.1% of patients without differences between pathogens in comparison with early-onset VAP. Acinetobacter spp was susceptible to tigecycline and colistin with a significant increase in resistance to ampicillin/sulbactam (30.2% vs 58.6%; p = 0.01). Resistance rate of Pseudomonas aeruginosa and Klebsiella pneumoniae to carbapenems was 38% and 11%, respectively. In methicillin-resistant Staphylococcus aureus no resistance was observed against vancomycin and linezolid. In conclusion, Gram negative organisms were the primary cause of bacterial VAP of which the most common was the XDR strain of Acinetobacter spp. Patients with early- and late-onset VAP have the same pathogens.