Ventilator-associated pneumonia caused by high risk microorganisms: A matched case-control study

To determine the impact of ventilator-associated pneumonia (VAP) caused by high risk microorganisms (HRM) on patient outcome. Design: Matched case-control study. The study was conducted in a medical intensive care unit (ICU) of a university hospital. Thirty-five patients with VAP caused by HRM, including Pseudomonas aeruginosa, Acinetobacter spp., Stenotrophomonas maltophilia and/or methicillin-resistant Staphylococcus aureus were accepted as the case the patients. Thirty-five control patients, who did not develop VAP were matched to the case patients, according to APACHE II score, age, date of admission and duration of mechanical ventilation (MV). ICU and hospital mortality rates were similar between the case and the control patients (p= 0.58 and p= 1.00, respectively). However, length of ICU stay was longer in the case patients than in the control patients [20 (11-30) days (median -interquartile range-) and 13 (8-19) days, respectively; p<0.01]. Length of hospital stay was also longer in the case patients than in the control patients [29 (20-44) days and 22 (13-37) days, respectively; p= 0.05]. In addition, duration of MV was longer in the case patients than in the control patients [18 (1025) days and 8 (6-11) days, respectively; p< 0.01]. VAP caused by HRM independently prolonged ICU (OR: 6) and hospital stay (OR: 4) and duration of MV (OR: 11). VAP caused by HRM was not significantly associated with mortality. However, it was an independent risk factor, increasing length of ICU stay and hospital stay by seven days, and duration of MV by 10 days.