Epidemiology and Outcome of Pneumonia Caused by Methicillin-Resistant Staphylococcus aureus (MRSA) in Canadian Hospitals

Abstract

BackgroundMRSA remains a leading cause of hospital-acquired (HAP) and healthcare-associated pneumonia (HCAP). We describe the epidemiology and outcome of MRSA pneumonia in Canadian hospitals, and identify factors contributing to mortality.MethodsProspective surveillance for MRSA pneumonia in adults was done for one year (2011) in 11 Canadian hospitals. Standard criteria for MRSA HAP, HCAP, ventilator-associated pneumonia (VAP), and community-acquired pneumonia (CAP) were used to identify cases. MRSA isolates underwent antimicrobial susceptibility testing, and were characterized by pulsed-field gel electrophoresis (PFGE) and Panton-Valentine leukocidin (PVL) gene detection. The primary outcome was all-cause mortality at 30 days. A multivariable analysis was done to examine the association between various host and microbial factors and mortality.ResultsA total of 161 patients with MRSA pneumonia were identified: 90 (56%) with HAP, 26 (16%) HCAP, and 45 (28%) CAP; 23 (14%) patients had VAP. The mean (± SD) incidence of MRSA HAP was 0.32 (± 0.26) per 10,000 patient-days, and of MRSA VAP was 0.30 (± 0.5) per 1,000 ventilator-days. The 30-day all-cause mortality was 28.0%. In multivariable analysis, variables associated with mortality were the presence of multiorgan failure (OR 8.1; 95% CI 2.5-26.0), and infection with an isolate with reduced susceptibility to vancomycin (OR 2.5, 95% CI 1.0-6.3).ConclusionsMRSA pneumonia is associated with significant mortality. Severity of disease at presentation, and infection caused by an isolate with elevated MIC to vancomcyin are associated with increased mortality. Additional studies are required to better understand the impact of host and microbial variables on outcome.

Pneumonia and hospitalizations in the elderly

“…26 Methicillin-resistant S. aureus (MRSA) is among the most frequently identified pathogens causing healthcare-associated pneumonia (HCAP), HAP, and VAP worldwide. 33 Although it appears to be a relatively uncommon cause of CAP, 34 MRSA may be an important emerging respiratory pathogen in the community, associated with severe necrotizing infection especially following recent influenza. 35 …”

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“…3 In terms of the impact of specific organ system failure on VAP outcomes, Gursel et al described a 38% incidence of acute renal failure (ARF) in this patient population. 16 High APACHE scores, MDRO and sepsis were independent risk factors for development of ARF during VAP episodes in that series.…”

“…2 Amongst MDRO, methicillin-resistant Staphylococcus aureus (MRSA) has emerged as a significant etiologic agent in nosocomial infections worldwide. 3 MRSA has been reported as a common cause of VAP, along with Enterobacteriaceae (usually the most common cause) and Pseudomonas aeruginosa in several series. [3][4][5] In this context, it is important to better understand the determinants of clinical failure in VAP.…”

“…3 MRSA has been reported as a common cause of VAP, along with Enterobacteriaceae (usually the most common cause) and Pseudomonas aeruginosa in several series. [3][4][5] In this context, it is important to better understand the determinants of clinical failure in VAP. Septic shock has been linked to VAP clinical failure, as measured by a mortality predictive score, such as the Acute Physiology and Chronic Health Evaluation II (APACHE II) Score.…”

Infection in a Pre-Antibiotic Era

“…The WHO found that national data obtained for E. coli, K. pneumoniae and S. aureus showed that the proportion resistant to commonly used antibacterial drugs exceeded 50% in many settings [4]. It is associated with high morbidity and mortality [31,32]. One study found in the wars of Iraq and Afghanistan cases of infection were predominantly due to multi-drug resistant pathogens, likely acquired within the military healthcare system [33].…”