Clinical and Laboratory Characteristics of Invasive Infections Due to Methicillin-Resistant Staphylococcus aureus Isolates Demonstrating a Vancomycin MIC of 2 Micrograms per Milliliter: Lack of Effect of Heteroresistant Vancomycin-Intermediate S. aureus Phenotype

Emory University School of Medicine, Atlanta, Georgia 30033, USA.
Journal of clinical microbiology (Impact Factor: 3.99). 02/2011; 49(4):1583-7. DOI: 10.1128/JCM.01719-10
Source: PubMed


We describe clinical and laboratory characteristics of invasive methicillin-resistant Staphylococcus aureus (MRSA) infections with vancomycin MICs of 2 μg/ml and compare heteroresistant-intermediate S. aureus (hVISA) to non-hVISA. Health care-associated community-onset infections were the most common and resulted in frequent complications and relapses. hVISA-infected patients were more likely to have been hospitalized in the year prior to MRSA culture.

Download full-text


Available from: Ghinwa Dumyati
  • Source

    Full-text · Article · Mar 2012 · Clinical Infectious Diseases
  • [Show abstract] [Hide abstract]
    ABSTRACT: The effective management of complicated Staphylococcus aureus bacteremia and native valve endocarditis requires an appropriate course of antimicrobial agents (proper agent, duration, and dose) and, where possible, timely removal of foci of infection. Treatment options for methicillin-susceptible S. aureus (MSSA) bacteremia, methicillin-resistant S. aureus (MRSA) bacteremia, and MRSA complications are discussed. The use of vancomycin for the treatment of MRSA bacteremia and the challenges associated with its use are described (ie, decreased susceptibility, emergence of heteroresistant vancomycin-intermediate S. aureus [hVISA] isolates, and nephrotoxicity). The use of aminoglycosides or rifampin as adjunct therapy with vancomycin to treat S. aureus bacteremia does not appear to be supported by data in the medical literature. The optimal length of therapy for S. aureus infections is presented, and the need for periodic reassessment of vancomycin and daptomycin minimum inhibitory concentrations (MICs) is emphasized. The author suggests an approach to treatment of persistent MRSA bacteremia based on recent data.
    No preview · Article · Mar 2012 · Infectious Disease in Clinical Practice
  • [Show abstract] [Hide abstract]
    ABSTRACT: The clinical implications of reduced vancomycin susceptibility amongst methicillin-resistant Staphylococcus aureus (MRSA) are controversial, and crossresistance to daptomycin amongst such strains has been reported. As a consequence of 'MIC creep', higher trough levels were recommended for serious infections. This review focusses on the new data published in the past 18 months that pertain to these issues. Heteroresistant vancomycin-intermediate Staphylococcus aureus reduces the clinical response rates to vancomycin in bacteraemic MRSA patients without impacting on mortality as opposed to 'MIC creep' with vancomycin minimum inhibitory concentration (MIC) levels of ≥1.5 mg/l that are significantly associated with mortality. Although daptomycin resistance is rare, 'concomitant MIC creep' amongst MRSA isolates with increasing vancomycin MICs may occur or exist concurrently amongst such strains. The aggressive vancomycin dosing regimens are still associated with unacceptable high microbiological failure rates and it is not currently possible to achieve probability of target attainment at higher vancomycin MICs of 2 mg/l. The nephrotoxic impact of high-dose vancomycin therapy has been confirmed. Continued monitoring of patients on aggressive vancomycin dosing schedules is advised. Unless alternative dosing strategies prove otherwise efficacious, an alternative antibiotic should be considered for severe MRSA infections with vancomycin MICs greater than 1 mg/l. The utility of vancomycin may be waning but will depend on the prevalence of resistant MRSA phenotypes in a specific ICU.
    No preview · Article · Aug 2012 · Current opinion in critical care
Show more