Clinical Characteristics, Outcomes, and Microbiologic Features Associated with Methicillin-Resistant
            <i>Staphylococcus aureus</i>
            Bacteremia in Pediatric Patients Treated with Vancomycin

Welsh, Kerry J.; Abbott, April N.; Lewis, Evan M.; Gardiner, Jeanelle M.; Kruzel, Mark C.; Lewis, Cole T.; Mohr, John; Wanger, Audrey; Armitige, Lisa Y.

doi:10.1128/jcm.01949-09

Cited by 40 publications

(49 citation statements)

References 40 publications

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“…The isolates were from Memorial Hermann Hospital, a 700-bed, private, tertiary care, universityaffiliated teaching hospital located within the Texas Medical Center in Houston, Texas, between August 2005 and May 2007. Diversilab sequencing according to the manufacturer's instructions yielded at least seven clones (data not shown), as found in other studies of MRSA isolates from our institution (15). Vancomycin MICs were determined by broth microdilution (BMD) trays prepared commercially and in-house, agarbased methods including Etest (bioMérieux, Durham, NC) and agar dilution, as well as automated BMD methods BD Phoenix, Vitek 2, and Microscan.…”

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confidence: 60%

Determination of Vancomycin and Daptomycin MICs by Different Testing Methods for Methicillin-Resistant Staphylococcus aureus

Kruzel¹,

Lewis²,

Welsh³

et al. 2011

J Clin Microbiol

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Vancomycin and daptomycin MICs from 161 isolates of methicillin-resistant Staphylococcus aureus (MRSA)were compared using commercial and in-house broth microdilution, Etest, and common automated methods. Vancomycin Etest MICs were higher than those of other methods, whereas the MICs for daptomycin testing were comparable. Vancomycin MICs vary depending on the testing methodology.Vancomycin is the gold standard for the treatment of serious infections due to methicillin-resistant Staphylococcus aureus (MRSA). Recent guidelines from the Infectious Diseases Society of America (IDSA) state that patients infected with MRSA strains that have a vancomycin MIC of Ն2 g/ml have a higher probability of treatment failure and recommend changing to alternate therapy (9). It is essential that clinical microbiology laboratories accurately determine vancomycin MICs to guide appropriate therapy.Trends toward increasing vancomycin MICs have been noted over the past 5 to 10 years (13). Hypotheses for the increase in vancomycin MICs include "MIC creep," clonal shift, and variation in vancomycin MICs demonstrated with various testing methods (3,10,14). It is critical for laboratorians to be aware of the normal distribution of vancomycin MICs observed by the testing system in use in their institution to properly assess the possibility of MIC creep or strains of MRSA with falsely elevated vancomycin MICs. A "falsely" elevated MIC could lead to an unnecessary change in treatment.The purpose of this study was to compare vancomycin and daptomycin MICs obtained by a variety of testing methods. A total of 161 consecutive blood culture isolates of MRSA were included in this study. The isolates were from Memorial Hermann Hospital, a 700-bed, private, tertiary care, universityaffiliated teaching hospital located within the Texas Medical Center in Houston, Texas, between August 2005 and May 2007. Diversilab sequencing according to the manufacturer's instructions yielded at least seven clones (data not shown), as found in other studies of MRSA isolates from our institution (15). Vancomycin MICs were determined by broth microdilution (BMD) trays prepared commercially and in-house, agarbased methods including Etest (bioMérieux, Durham, NC) and agar dilution, as well as automated BMD methods BD Phoenix, Vitek 2, and Microscan. Daptomycin MICs were determined by commercially prepared BMD trays, Etest, and Microscan. Etest inoculums were performed by hand plating. Agar and broth methods were performed according to CLSI standards using strain ATCC 29213 for quality control with each day of testing (2). All MIC determinations were performed in duplicate, and all commercial systems were used according to the manufacturer's instructions. Agar plates were prepared by serially diluting vancomycin hydrochloride hydrate (Sigma, St. Louis, MO) in Mueller-Hinton (BBL) agar at the following concentrations: 0.25, 0.5, 0.75,1, 1.5, and 2.0 g/ml. Custom-made frozen broth microdilution trays with an expanded dilution range of vancomycin and daptomycin were purchased...

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confidence: 60%

Determination of Vancomycin and Daptomycin MICs by Different Testing Methods for Methicillin-Resistant Staphylococcus aureus

Kruzel¹,

Lewis²,

Welsh³

et al. 2011

J Clin Microbiol

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“…Although vancomycin treatment failure was documented in a small pediatric series (n ϭ 22) of MRSA-B, the mortality rate seemed similar to those of other reported data, at13.6%. Treatment failure was associated with prematurity and pvl-positive infections but not a high vancomycin MIC (by either the Etest or broth microdilution) (315).…”

Section: Role Of Infectious Disease Consultationmentioning

confidence: 91%

Predictors of Mortality in Staphylococcus aureus Bacteremia

et al. 2012

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SUMMARY Staphylococcus aureus bacteremia (SAB) is an important infection with an incidence rate ranging from 20 to 50 cases/100,000 population per year. Between 10% and 30% of these patients will die from SAB. Comparatively, this accounts for a greater number of deaths than for AIDS, tuberculosis, and viral hepatitis combined. Multiple factors influence outcomes for SAB patients. The most consistent predictor of mortality is age, with older patients being twice as likely to die. Except for the presence of comorbidities, the impacts of other host factors, including gender, ethnicity, socioeconomic status, and immune status, are unclear. Pathogen-host interactions, especially the presence of shock and the source of SAB, are strong predictors of outcomes. Although antibiotic resistance may be associated with increased mortality, questions remain as to whether this reflects pathogen-specific factors or poorer responses to antibiotic therapy, namely, vancomycin. Optimal management relies on starting appropriate antibiotics in a timely fashion, resulting in improved outcomes for certain patient subgroups. The roles of surgery and infectious disease consultations require further study. Although the rate of mortality from SAB is declining, it remains high. Future international collaborative studies are required to tease out the relative contributions of various factors to mortality, which would enable the optimization of SAB management and patient outcomes.

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“…[1][2] Evidence from the literature suggests that central venous catheter removal, 3 prompt initiation of antimicrobial therapy, 4 and selection of optimal antimicrobial agents can help to mitigate these complications. [5][6] Although vancomycin is an acceptable therapeutic choice for methicillin-resistant S aureus (MRSA) bacteremia, adult data suggest that treatment failures can be significantly reduced in methicillin-susceptible S aureus (MSSA) bacteremia by initiating narrow-spectrum agents, such as cefazolin or nafcillin, when methicillin-susceptible status is known.…”

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confidence: 99%

Rapid Detection of Methicillin-Resistant Staphylococcus aureus (MRSA) and Methicillin-Susceptible Staphylococcus aureus (MSSA) Using the KeyPath MRSA/MSSA Blood Culture Test and the BacT/ALERT System in a Pediatric Population

Sullivan

Turner

Roundtree

et al. 2013

Archives of Pathology &Amp; Laboratory Medicine

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Context.-Timely initiation of directed antimicrobial therapy for Staphylococcus aureus bacteremia is dependent on rapid identification of S aureus to ascertain methicillin-susceptibility status.Objective.-To investigate the performance of the rapid KeyPath (MicroPhage, Inc, Longmont, Colorado) methicillin-resistant S aureus (MRSA) and methicillin-susceptible S aureus (MSSA) blood culture test (MMBT).Design.-Positive BacT/ALERT Pediatric FAN (fastidious antibiotic neutralization) blood culture bottles (bioMérieux, Inc, Durham, North Carolina) were tested prospectively using MMBT and routine bacterial identification and antibiotic susceptibility testing procedures as the gold standard. The MMBT uses an S aureus-specific bacteriophage cocktail that infects bacterial cells and replicates them, resulting in cellular lysis. Bacteriophagespecific antibodies detect the increase in bacteriophage concentration in an immunoassay device. Phage amplification, in both the presence and absence of cefoxitin, indicates the presence of MRSA. The sensitivity, specificity, positive predictive value, and negative predictive value of MMBT in detecting S aureus, MSSA, and MRSA were calculated.Results.-Of 188 positive blood cultures tested, 199 (63%) had Gram-positive cocci in clusters, 46 (24%) grew S aureus (26 MSSA [57%], 20 MRSA [43%]) with the MMBT detecting 40 of 46 (87%). The sensitivity, specificity, positive predictive value, and negative predictive value among blood cultures with Gram-positive cocci in clusters were 87%, 100%, 100%, and 92% for S aureus; 81%, 100%, 100%, and 95% for MSSA; and 95%, 100%, 100%, and 99% for MRSA. All blood cultures without growth of S aureus tested negative by MMBT.Conclusions.-The MMBT detected MSSA and MRSA directly from positive BacT/ALERT PF bottles with positive predictive values of 100%, suggesting that positive results could be reported immediately, but the sensitivity of this assay limited immediate reporting of negative results.

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Clinical Characteristics, Outcomes, and Microbiologic Features Associated with Methicillin-Resistant Staphylococcus aureus Bacteremia in Pediatric Patients Treated with Vancomycin

Abstract: Vancomycin is the first-line therapy for methicillin-resistant

Cited by 40 publications

References 40 publications

Determination of Vancomycin and Daptomycin MICs by Different Testing Methods for Methicillin-Resistant Staphylococcus aureus

Determination of Vancomycin and Daptomycin MICs by Different Testing Methods for Methicillin-Resistant Staphylococcus aureus

Predictors of Mortality in Staphylococcus aureus Bacteremia

Rapid Detection of Methicillin-Resistant Staphylococcus aureus (MRSA) and Methicillin-Susceptible Staphylococcus aureus (MSSA) Using the KeyPath MRSA/MSSA Blood Culture Test and the BacT/ALERT System in a Pediatric Population

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