Bacteriemias por Staphylococcus aureus sensible a meticilina: epidemiología y factores pronósticos. Estudio prospectivo 2000-2003

Importance of appropriate empirical antibiotic therapy for methicillin-resistant Staphylococcus aureus bacteraemia

OBJECTIVES

To document the effects of appropriate and inappropriate empirical antibiotic therapy on mortality in a cohort of patients with bacteraemia due to methicillin-resistant Staphylococcus aureus (MRSA) and to summarize effects with previous studies.

METHODS

In the retrospective cohort study, episodes of clinically significant MRSA bacteraemia during a 15 year period were included. Polymicrobial episodes were excluded unless MRSA was isolated in more than one bottle and co-pathogens were given appropriate empirical antibiotic treatment. Appropriate empirical treatment was defined as matching in vitro susceptibility and started within 48 h of blood-culture taking, except for single aminoglycosides or rifampicin. We assessed univariate and multivariate associations between appropriate empirical therapy and 30 day all-cause mortality. Multivariable analysis was conducted using backward stepwise logistic regression. We reviewed all studies assessing the effects of appropriate empirical antibiotic treatment on mortality for MRSA infections and compiled adjusted odds ratios (ORs) using a random effects meta-analysis.

RESULTS

Five hundred and ten episodes of MRSA bacteraemia were included. There were no cases of community-acquired infection. The 30 day mortality was 43.9% (224/510) and was stable throughout the study period. Mortality was significantly higher among patients receiving inappropriate (168/342, 49.1%) compared with those receiving appropriate (56/168, 33.3%) empirical antibiotic treatment, P = 0.001. In the adjusted analysis the OR was 2.15 [95% confidence interval (CI) 1.34-3.46]. Pooling of six studies using adequate methodology for the adjusted analysis resulted in an OR of 1.98 (95% CI 1.62-2.44).

CONCLUSIONS

Appropriate empirical antibiotic treatment has a significant survival benefit in MRSA bacteraemia. Treatment guidelines should consider this benefit.

[Fever in Emergency Department: screening for severe disease]

BACKGROUND

To identify variables associated to severe disease in adult patients with fever in the Emergency Department.

MATERIAL AND METHODS

Observational, perspective study. Data from all the adult patients with fever (axillary temperature 37.8 degrees C or higher) seen in the medical area of the Emergency Department was collected from January 28th to April 30th of 2006 and included in a logistic regression analysis, the dependent variable being "severe disease". Based on the corresponding risk, a score was assigned to each variable to design a risk of severe disease model.

RESULTS

A total of 11271 patients were seen, 786 (7.0%) of whom had fever. Median age was 39 years (37-40), 57% male. Of these, 31% were admitted and 27% had severe disease. Based on the symptoms and signs, upper airways infection was suspected in 309 (39%) and lower airways infection in 130 (17%), abdominal infection in 117 (15%), urinary tract infection in 40 (5%) and no source of infection in 145 (18%). Comorbidity (OR 3.6, 95% CI -1.8-7.2) (4 points), C-reactive protein higher than 10 mg/dl (OR 1.8, 95% CI 1.1-3.7) (2 points) and age (OR 1.02, 95% CI 1.01-1.04) (age older than 60 years 3 points) were associated with severe disease. Fever having a probable upper respiratory origin was a protector factor (OR 0.4, 95% CI 0.2-0.9) (fever from other foci 3 points). Three percent of the patients with less than 3 points had severe disease versus 72% with more than 7 points.

CONCLUSIONS

Comorbidity, C-reactive protein higher than 10 mg/dl, age and suspicion of source of infection different of upper airways infection were associated to severe disease in adults with fever in the Emergency Department.