No effect of vancomycin MIC ≥ 1.5 mg/L on treatment outcome in methicillin-susceptible Staphylococcus aureus bacteraemia.

The vancomycin minimum inhibitory concentration (MIC) has been shown to affect the outcome of methicillin-susceptible Staphylococcus aureus (MSSA) bacteraemia. In this study, the outcomes of patients with MSSA bacteraemia with a vancomycin MIC ≥ 1.5 mg/L were assessed. A prospective cohort of patients with MSSA bacteraemia in two tertiary-care hospitals was collected. The vancomycin MIC was determined by Etest. Staphylococcus aureus strains were categorised as low (<1.5 mg/L) or high (≥1.5 mg/L) vancomycin MIC. First- and second-line treatments were recorded and classified as optimal, appropriate and inappropriate. The primary endpoint was 30-day mortality. A total of 250 patients with S. aureus bacteraemia were analysed, of whom 64 (25.6%) had strains with a high vancomycin MIC. History of dialysis (P = 0.001) and ultimately fatal disease (P = 0.005) were associated with strains with a high vancomycin MIC. The 30-day mortality was 24.7% (46/186) in patients with a low vancomycin MIC versus 28.1% (18/64) in patients with a high vancomycin MIC (P = 0.592) and did not differ significantly after adjustment for the appropriateness of the antibiotic treatment. Patients with a high vancomycin MIC were less frequently associated with complicated bacteraemia (15.6% vs. 39.2%; P = 0.001). In conclusion, vancomycin MIC ≥ 1.5 mg/L was not associated with 30-day mortality but was associated with uncomplicated bacteraemia in MSSA bacteraemia, regardless of the first- and second-line treatment.

Evolving epidemiology and antimicrobial resistance in spontaneous bacterial peritonitis: a two-year observational study.

BACKGROUND: Current recommendations for empirical antimicrobial therapy in spontaneous bacterial peritonitis (SBP) are based on quite old trials. Since microbial epidemiology and the management of patients have changed, whether these recommendations are still appropriate must be confirmed. METHODS: An observational study that exhaustively collected the clinical and biological data associated with positive ascitic fluid cultures was conducted in four French university hospitals in 2010-2011. RESULTS: Two hundred and sixty-eight documented positive cultures were observed in 190 cirrhotic patients (median age 61.5 years, 58.5% Child score C). Of these, 57 were classified as confirmed SBP and 140 as confirmed bacterascites. The predominant flora was Gram-positive cocci, whatever the situation (SBP, bacterascites, nosocomial/health-care related or not). Enteroccocci (27.7% E. faecium) were isolated in 24% of the episodes, and in 48% from patients receiving quinolone prophylaxis. E. coli were susceptible to amoxicillin-clavulanate and to third-generation cephalosporins in 62.5% and 89.5% of cases, respectively. No single antibiotic allowed antimicrobial coverage of more than 60%. Only combinations such as amoxicillin + third-generation cephalosporin or cotrimoxazole allowed coverage close to 75-80% in non-nosocomial episodes. Combinations based on broader spectrum antibiotics should be considered for empirical therapy of nosocomial infections. CONCLUSIONS: Our study confirmed the changing spectrum of pathogens in SBP and bacterascites, and the need for more complex antibiotic strategies than those previously recommended. Our findings also underline the need for new clinical trials conducted in the current epidemiological context.