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We investigated the prognostic role of high MICs for antistaphylococcal agents in patients with methicillin-sensitive Staphylococcus aureus catheter-related bloodstream infection (MSSA CRBSI). We prospectively reviewed 83 episodes from 5 centers in Spain during April 2011-June 2014 that had optimized clinical management and analyzed the relationship between E-test MICs for vancomycin, daptomycin, oxacillin, and linezolid and development of complicated bacteremia by using multivariate analysis. Complicated MSSA CRBSI occurred in 26 (31.3%) patients; MICs for vancomycin and daptomycin were higher in these patients (optimal cutoff values for predictive accuracy = 1.5 μg/mL and 0.5 μg/mL). High MICs for vancomycin (hazard ratio 2.4, 95% CI 1.2-5.5) and daptomycin (hazard ratio 2.4, 95% CI 1.1-5.9) were independent risk factors for development of complicated MSSA CRBSI. Our data suggest that patients with MSSA CRBSI caused by strains that have high MICs for vancomycin or daptomycin are at increased risk for complications.

Objectives: Limited data exist regarding the role of agr dysfunction in reducing susceptibility to vancomycin in methicillin-susceptible Staphylococcus aureus (MSSA). This study investigated the clinical and molecular epidemiology of MSSA causing bacteraemia, with emphasis on the reduced susceptibility to vancomycin (RSV) phenotype (MIC ≥ 1.5 mg/L) and its relationship with agr dysfunction., Methods: All MSSA bloodstream isolates obtained at our hospital during 2010 were analysed. Antimicrobial susceptibility was determined and time-kill experiments were performed for oxacillin. Multilocus sequence type and agr genotype were determined and DNA microarray analysis of virulence factors was performed. agr dysfunction was assessed phenotypically and by RT-PCR quantification of RNAIII., Results: Of 84 MSSA, 55 (65.5%) exhibited the RSV phenotype, comprising 13 clonal complexes. agr II polymorphism was more prevalent in RSV than non-RSV isolates (41.8% versus 17.2%, P = 0.023) and average levels of RNAIII gene expression were higher in RSV than non-RSV isolates (ΔCt 4.05 ± 3.29 versus 1.5 ± 2.11, P = 0.005), implying greater agr dysfunction in RSV MSSA., Conclusions: We demonstrated a correlation between RSV phenotype in MSSA and reduced agr expression, particularly in association with the agr II genotype. These results may help to understand the role of agr dysfunction in the increased mortality in MSSA infections.

We conducted a retrospective study of 99 patients with methicillin-suseptible Staphylococcus aureus catheter-related bacteremia in which vancomycin MIC was determined by Etest. High vancomycin MIC (>1.5 ug/mL) was the only independent risk factor for development of complicated bacteremia caused by methicillin-susceptible S. aureus (odds ratio 22.9, 95% confidence interval 6.7-78.1).

Recurrent diarrhea is a common complication of Clostridium difficile infection (CDI). Recurrent CDI (r-CDI) may be produced by the persistence of spores (relapse) or by the acquisition of a new strain (reinfection). In this study, we analyze epidemiological, clinical, microbiological and laboratory data from patients with r-CDI, relapse, and reinfection-CDI over 5 years and compared with a control group (non r-CDI). Among 60 patients with r-CDI, 36 patients had stool samples collected from two or more episodes, which were molecularly analyzed. Based on ribotyping, 63.9% of the samples were relapse, and 36.1% reinfection. In a multivariable logistic regression analysis, previous antibiotic exposure was found to be a risk factor for r-CDI (OR: 2.23; 95% CI: 1.0–4.9; p = 0.04). Patients with relapse had previous antibiotic exposure more frequently than did patients with reinfection (p = 0.03), and patients with reinfection suffered more frequently from chronic liver disease (p = 0.02) than did relapse patients. Relapse patients compared with the control group had a higher percentage of previous antibiotic exposure, although the difference was statistically no significant (73.9% vs. 91.3 p = 0.06). No significant differences for the selected variables were observed between the reinfection and control groups, although we observed a higher percentage of patients with chronic liver disease (30.8% vs 13.3%; p = 0.08). All isolates were sensitive to metronidazole and vancomycin. No significant differences in antibiotic susceptibility were found between the different groups. Sporulation and germination frequency of r-CDI were higher than non r-CDI (p = 0.02 and p < 0.01, respectively). Nevertheless, there were statistically not significant differences between the relapse and reinfection groups. Both frequencies were compared between the first and second episode of CDI for the relapse and reinfection groups, but differences were not observed to be statistically significant. In conclusion, our study showed that the recurrence of CDI was associated with antibiotic use and sporulation/germination frequency, regardless of relapse or reinfection. The use of antibiotics would produce a dysbiosis and favor the persistence of the C. difficile spores and relapse. A possible alteration of the intestinal microbiota and the bile salts produced by chronic liver disease could favor reinfection. [ABSTRACT FROM AUTHOR]

A response by Jose Maria Aguado to a letter to the editor about his article on the relationship between vancomycin and outcome of Staphylococcus aureaus bacteremia in a previous is presented.