Predictors of septic shock in patients with methicillin-resistant Staphylococcus aureus bacteremia

Risk factors for septic shock associated with methicillin-resistant Staphylococcus aureus (MRSA) bacteremia are not well described. We designed this study to assess the independent predictors of septic shock in patients with MRSA bacteremia.

This retrospective chart review included 234 patients with MRSA bacteremia admitted to a tertiary care academic medical center. Cases of septic shock and non-septic shock MRSA bacteremia were compared in terms of patient baseline characteristics and co-morbidities, modes of acquisition, and MRSA genotyping. Independent risk factors were determined by multivariable analysis.

On univariate analysis the presence of chronic kidney disease, respiratory failure, acute renal failure, staphylococcal cassette chromosome (SCCmec) type II, and higher APACHE II scores were significantly correlated with the presence of septic shock. On multivariate analysis, baseline APACHE II score (adjusted odds ratio (AOR) for 1-point increase 1.13, 95% confidence interval (CI) 1.04-1.22, p=0.005), acute renal failure (AOR 2.57, 95% CI 1.02-6.48, p=0.045), and SCCmec type II (AOR 2.60, 95% CI 1.01-6.75, p=0.049) were independently associated with MRSA bacteremic septic shock.

The development of septic shock associated with MRSA bacteremia was independently correlated with baseline severity of illness, presence of acute renal failure, and an MRSA genotyping consistent with nosocomially acquired MRSA infection.