Outcome of late-onset hospital-acquired pneumonia related to causative organism.

Pneumonia caused by Pseudomonas spp. has been associated with an increase in mortality in critical care patients. Previous assessments, however, have failed to compare outcome solely with other pathogens associated with hospital-acquired pneumonia (HAP). We have performed a retrospective review of all critical care patients with late-onset HAP (hospital inpatient stay >72 h at time of diagnosis) due to pure respiratory cultures of Pseudomonas spp., meticillin-resistant Staphylococcus aureus (MRSA) or non-pseudomonal Gram-negative (NPGN) organisms from 1998 to 2007. Casenote review involved assessments of illness severity, clinical pulmonary infection scoring (CPIS), critical care and hospital survival, and critical care length of stay. Out of 252 casenotes, 204 were reviewed. There were 186 treated cases of pneumonia. Ten patients had both pseudomonal and NPGN pneumonias during the same admission and two patients presented with community-acquired infections due to these organisms. These 12 patients were excluded from further analysis. Of the remaining 174 patients, 80 were infected with pseudomonas, 40 with MRSA and 54 had NPGN organisms. The three groups of patients were well-matched, with similar age, sex, CPIS scores, incidence of bacteraemia and Acute Physiology and Chronic Health Evaluation II scores at diagnosis. There were no outcome differences between the groups with respect to hospital and critical care survival and critical care length of stay. In this series, there appears to be no survival disadvantage associated with pseudomonal pneumonia when compared with other hospital-acquired organisms associated with HAP, where disease severity between the groups is similar.