Intravenous literature: Lessa, F.C., Mu, Y., Ray, S.M., Dumyati, G., Bulens, S., Gorwitz, R.J., Fosheim, G., Devries, A., Schaffner, W., Nadle, J., Gershman, K. and Fridkin, S.K. (2012) Impact of USA300 Methicillin-Resistant Staphylococcus aureus on Clinical Outcomes of Patients with Pneumonia or Central Line-Associated Bloodstream Infections. Clinical Infectious Diseases. Apr 20. [Epub ahead of print].
Background: Many assumed high morbidity and mortality would accompany the emergence of MRSA USA300 infections as a cause of healthcare-associated infections (HAIs). We evaluated patients with invasive MRSA infections to assess differences in outcomes between infections caused by USA100 and USA300.
Methods: Population-based data for invasive MRSA infections were used to identify two cohorts: (1) non-dialysis patients with central line-associated bloodstream infections (CLABSI); and (2) patients with community-onset pneumonia (PNEUMO) during 2005-2007 from 6 US metropolitan areas. Medical records of patients with confirmed MRSA USA100 or USA300 were reviewed. Logistic regression and, when appropriate, survival analysis was performed to evaluate mortality, early and late complications, and length of stay.
Results: A total of 236 and 100 patients were included in the CLABSI and PNEUMO cohorts, respectively. USA300 was the only independent predictor of early complications for PNEUMO patients (OR=2.6, P=.02). Independent predictors of CLABSI late complications included intensive care unit (ICU) admission before MRSA culture (aOR=2.1, P=.01) and Charlson comorbidity index (aOR=2.6; P=.003), but not strain type. PNEUMO patients were significantly more likely to die if they were older (P=.02), black (P<.001) or infected with USA100 strain (P=.02); while those withÂ CLABSIÂ were more likely to die if they were older (P<.001), had comorbidities (P<.001) or had an ICU admission before MRSA culture (P=.001).ConclusionsUSA300 was associated with early complications in PNEUMO patients. However, it was not associated with mortality for either PNEUMO orÂ CLABSIÂ patients. Concerns regarding higher mortality from HAIs caused by USA300 may not be warranted.