Risk factors for acquisition of ventilator-associated pneumonia in adult intensive care units

Objective: Ventilator Associated Pneumonia (VAP) has an imperative place amongst nosocomial infections leading to increase morbidity and mortality rates. The present study aimed to determine risk factors for acquisition of ventilator-associated pneumonia in an intensive care unit (ICU). Methods: A nested case-control study was carried out from September 2007 to June 2008. All 183 patients hospitalized at the adult ICU ward in Be'sat Hospital, Sanandaj city western Iran over a 48 hour period were included. Bacteriologic diagnosis and antibiotic susceptibility patterns were performed based on Edward & Ewing's methods and CLSI system guidelines. Results: Of the 149 samples which were taken from endotracheal tubes of 183 patients, 48 cases were diagnosed for VAP with an incidence rate of 26.2%. Mean duration of hospitalization was 23.4 +/- 10.2 days. The maximum and minimum antibiotic resistance for the gram negative bacteria was 93.3% for Cefalotin and 50% for Amikacin. The main risk factors for acquisition of ventilator-associated pneumonia were mechanical ventilation (Adjusted OR: 1.55, 95% CI: 1.37-1.74), history of antibiotic consumption (AOR: 8.92, CI: 1.16-66.66) and fever (AOR: 3.11, CI: 1.22-7.93). Conclusions: VAP is significantly related to ICU hospitalization, mechanical ventilation and history of antibiotics consumption. Cefalotin and Amikacin showed the highest and lowest antibiotic resistance against gram negative bacteria respectively.