[Community-onset and nosocomial bacteremia due to methicillin-resistant Staphylococcus aureus in Spanish hospitals]. / Bacteriemias de presentación comunitaria y nosocomial por Staphylococcus aureus resistente a meticilina en hospitales españoles.

INTRODUCTION: Community-onset infections caused by methicillin-resistant Staphylococcus aureus (MRSA) are increasing. However, there is little information about community-onset bacteremia (CB) due to MRSA in Spain. The objectives of this study were to evaluate the prevalence, clinical and molecular epidemiology, clinical features, and prognosis of CB due to MRSA in comparison with nosocomial bacteremia (NB). METHODS: Prospective multicenter cohort study; all new cases of bacteremia due to MRSA occurring during June 2003 in 59 Spanish hospitals were included. Episodes diagnosed during the first 48 hours of admission were considered CB, and otherwise, NB. Isolates were typed by pulsed field electrophoresis and multilocus sequence typing. Staphylococcal cassete chromosome mec types and Panton-Valentine leukocidin genes were studied by polymerase chain reaction. RESULTS: Sixty-four cases were included; 21 (33%) were classified as CB. In all CB cases, a relation was found with health care, or the isolate proved to be clonally related to nosocomial isolates. There were no significant differences between the groups in terms of demographic data, underlying conditions, prognosis, or characteristics of the isolates. Regarding the source of bacteremia, catheter-related cases were more frequent in NB than CB (39.5% vs 5%, P=0.005), whereas a urinary source was more frequent in CB than NB (25% vs 0%, P=0.001). Most isolates belonged to 2 clones related to the pandemic "pediatric" clone. CONCLUSION: MRSA should be considered in empiric treatment for certain infectious syndromes in patients with healthcare-associated community-onset sepsis.

Impact of inappropriate empirical therapy for sepsis due to health care-associated methicillin-resistant Staphylococcus aureus.

OBJECTIVES: We investigated the influence of empirical therapy on the mortality of patients with health care-associated (HCA) sepsis caused by methicillin-resistant Staphylococcus aureus (MRSA) infections in a multicenter cohort, and the variables associated with inappropriate empirical therapy. METHODS: All new cases of infection caused by HCA-MRSA presenting with sepsis syndrome in 59 Spanish hospitals during June 2003 were prospectively followed. The main outcome variable was mortality at day 30. Predictors of mortality and of inappropriate empirical therapy were studied using multivariate logistic regression. RESULTS: We included 209 cases. Crude mortality was 23%. After controlling for severity of the underlying condition, ICU stay, presentation with severe sepsis or shock, and site of infection, inappropriate empirical therapy was associated with an increased odds of mortality (OR=3.0; 95% CI: 1.01-9.0; p=0.04). Only 21.1% of the patients received appropriate empirical therapy. Variables independently associated with appropriate therapy were recent surgery, central venous catheter and certain sites of infection (primary bacteraemia, intraabdominal infections, and respiratory tract infections). Cancer patients were at an increased risk of receiving inappropriate therapy. CONCLUSIONS: Inappropriate empirical therapy was independently associated with increased mortality in this multicenter cohort. Clinicians should be aware of the need to consider coverage against MRSA more frequently.

Antibiotic combinations for serious infections caused by carbapenem-resistant Acinetobacter baumannii in a mouse pneumonia model.

OBJECTIVES: Successful therapy of carbapenem-resistant Acinetobacter baumannii strains has been reported with colistin, but recently we argued against its use as monotherapy because of the poor results obtained in a mouse pneumonia model. Our aim was to identify antibiotic combinations that were valid therapeutic alternatives in the same model. METHODS: We used two carbapenem-resistant A. baumannii strains (D and E; MICs of imipenem, 8 and 512 mg/L, respectively). MICs of tobramycin, rifampicin and colistin for both strains were 8, 8 and 0.5 mg/L, respectively. RESULTS: In infections caused by strain D, lung bacterial counts (log(10) cfu/g, mean +/- s.d.) were: controls (10.86+/-0.25), imipenem (5.99+/-0.59, P < 0.05 versus controls), and colistin (10.43 +/- 1.09); imipenem + tobramycin was the most active combination (5.46+/-0.62, P < 0.05 versus controls). In infections caused by strain E, results were: controls (10.82+/-0.33), rifampicin (5.62+/-0.26, P < 0.05 versus controls), colistin (8.38+/-1.22, P < 0.05 versus controls), and imipenem (11.01+/-0.2); rifampicin + imipenem (3.79+/-0.99) and rifampicin + tobramycin (3.96+/-0.30) were the most active combinations (P < 0.05); results with rifampicin + colistin (5.59+/-1.17) were similar to those with rifampicin alone. CONCLUSIONS: Our data indicate that imipenem can still be the best alternative for carbapenem-resistant A. baumannii infections with moderate levels of imipenem resistance, preferably combined with aminoglycosides. For strains highly resistant to imipenem, a combination of rifampicin with imipenem, tobramycin or colistin may be useful, if resistance to rifampicin is only moderate.

Bacteriemias de presentación comunitaria y nosocomial por Staphylococcus aureus resistente a meticilina en hospitales españoles / Community-onset and nosocomial bacteremia due to methicillin-resistant Staphylococcus aureus in Spanish hospitals

Introducción Las infecciones de presentación comunitaria por Staphylococcus aureus resistente a meticilina (SARM) son un fenómeno creciente. Sin embargo, existe escasa información acerca de las bacteriemias de presentación comunitaria (BPC) por SARM en nuestro medio. Los objetivos de este estudio son evaluar la frecuencia, la epidemiología clínica y molecular, las características clínicas y las características pronósticas de las BPC por SARM con respecto a las bacteriemias nosocomiales (BN).Métodos Estudio de cohorte prospectivo y multicéntrico; se incluyeron todos los casos incidentes de bacteriemia por SARM en 59 hospitales españoles durante el mes de junio de 2003. Se consideró BPC a aquella que se diagnosticó en las primeras 48h de ingreso del paciente, y BN cuando se realizó posteriormente. Las cepas se tiparon mediante electroforesis en campo pulsante y multilocus sequence typing; los tipos de casete cromosómico estafilocócico mec y producción de leucocidina de Panton-Valentine se estudiaron por reacción en cadena de la polimerasa. Resultados Se incluyeron 64 bacteriemias; 21 (33%) de ellas se consideraron como BPC. En todos estos casos se encontró relación con la atención sanitaria o bien se detectó una cepa genotípicamente relacionada con las nosocomiales. No se observaron diferencias significativas entre los 2 grupos en cuanto a los datos demográficos, las características intrínsecas, el pronóstico o las características de las cepas. En relación con el foco de origen, las originadas en un catéter vascular fueron más frecuentes en las BN (el 39,5 versus el 5%; p = 0,005) y las originadas en el aparato urinario fueron más frecuentes en las BPC (el 25 versus el 0%; p = 0,001). La mayoría de las cepas perteneció a 2 clones relacionados con el clon pandémico denominado “pediátrico” (..) (AU)

Introduction Community-onset infections caused by methicillin-resistant Staphylococcus aureus (MRSA) are increasing. However, there is little information about community-onset bacteremia (CB) due to MRSA in Spain. The objectives of this study were to evaluate the prevalence, clinical and molecular epidemiology, clinical features, and prognosis of CB due to MRSA in comparison with nosocomial bacteremia (NB).Methods Prospective multicenter cohort study; all new cases of bacteremia due to MRSA occurring during June 2003 in 59 Spanish hospitals were included. Episodes diagnosed during the first 48 hours of admission were considered CB, and otherwise, NB. Isolates were typed by pulsed field electrophoresis and multilocus sequence typing. Staphylococcal cassete chromosome mec types and Panton-Valentine leukocidin genes were studied by polymerase chain reaction. Results Sixty-four cases were included; 21 (33%) were classified as CB. In all CB cases, a relation was found with health care, or the isolate proved to be clonally related to nosocomial isolates. There were no significant differences between the groups in terms of demographic data, underlying conditions, prognosis, or characteristics of the isolates. Regarding the source of bacteremia, catheter-related cases were more frequent in NB than CB (39.5% vs 5%, P=0.005), whereas a urinary source was more frequent in CB than NB (25% vs 0%, P=0.001). Most isolates belonged to 2 clones related to the pandemic “pediatric” clone. Conclusion MRSA should be considered in empiric treatment for certain infectious syndromes in patients with healthcare-associated community-onset sepsis (AU)