Associated factors and mortality in elderly patients with methicillin-resistant vs. methicillin-susceptible Staphylococcus aureus bacteraemia

Abstract number: 1134_02_214

Marí B., Serrate G., Canals M., Bejarano G., Barè M., Antón E., Segura F.

Objectives:

To assess the impact of methicillin-resistance on selected aspects of the infectious process and outcome in patients over 65 years of age with S. aureus bacteraemia.

Methods:

Prospective case-control study of patients older than 65 years with methicillin-resistant S. aureus (MRSA) or methicillin-susceptible S. aureus (MSSA) bacteraemia, matched for age and sex. Microbiologically documented bloodstream infections between 1997 and 2004 were used to search for patients. Death was attributed to the infection if it occurred before the resolution of symptoms or within 7 days of the onset of bacteraemia in the absence of other explanations.

Results:

There were 51 patients in each group. Mean age was 77.2 + 7 and most (68.6%) were male. Bacteremia was hospital-0acquired in 51%. Differential characteristics of patients are shown in the table 1 A quarter of the patients in each group had a Barthel Index < 55. A high-risk source of bacteremia was observed in 17% of the MRSA group and 23% of MSSA (p = NS). No differences were found between groups for in-hospital mortality (45% vs 41%) or for mortality associated with bacteremia (29% vs 27%). The results of the univariate analyses of the association between clinical variables and associated mortality are show in the table 2. MRSA was not an independent predictor of mortality. In the logistic regression analysis, inappropriate therapy and high-risk source of bacteraemia were independently associated with mortality due to bacteraemia.

Conclusions:

Our results confirm that MRSA bacteraemia is associated to factors previously reported to predispose to MRSA infection.

In our series of elderly patients, high-risk source of bacteraemia and inappropriate therapy were related to increased mortality due to S. aureus bacteraemia, regardless of whether the bacteria were susceptible or resistant to methicillin.