Detection of Intermediately Vancomycin-Susceptible and Heterogeneous Staphylococcus aureus Isolates: Comparison of Etest and Agar Screening Methods
| Autor: | A. Mar, Riad Khatib, S. Shemes, Adina C. Musta, P. Chase, Kathleen Riederer |
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| Rok vydání: | 2011 |
| Předmět: |
Microbiology (medical)
Staphylococcus aureus Micrococcaceae Population Microbial Sensitivity Tests Staphylococcal infections Sensitivity and Specificity Microbiology chemistry.chemical_compound medicine Humans Mass Screening education Etest Mass screening Antibacterial agent education.field_of_study biology Bacteriology Vancomycin Resistance Staphylococcal Infections biology.organism_classification medicine.disease Culture Media Agar chemistry Brain heart infusion Vancomycin medicine.drug |
| Zdroj: | Journal of Clinical Microbiology. 49:2147-2150 |
| ISSN: | 1098-660X 0095-1137 |
| DOI: | 10.1128/jcm.01435-10 |
| Popis: | Detection of Staphylococcus aureus isolates with intermediate vancomycin susceptibility (VISA) and heteroresistance (hVISA) remains problematic. The population analysis profile/area under the curve (PAP/AUC) is the gold standard but is cumbersome. We compared the performance of two Etest screening methods (macromethod [MAC] and glycopeptide resistance detection [GRD]) plus brain heart infusion (BHI) agars supplemented with 3 (BHI-V3) or 4 (BHI-V4) mg/liter vancomycin in detecting hVISA and/or VISA phenotypes. Etest hVISA screenings were done in parallel for 485 saved methicillin-resistant S. aureus (MRSA) blood isolates according to the manufacturer's instructions. The PAP/AUC was measured for all isolates according to the modified method. PAP/AUC test isolate/Mu3 ratios of 1.3 were considered positive for susceptible MRSA (S-MRSA), hVISA, and VISA, respectively. PAP/AUC revealed seven VISA and 33 hVISA phenotypes. MAC screening was positive for 30 (75.0%) hVISA/VISA and 49 (11.0%) S-MRSA isolates. GRD screening was positive for 28 (70.0%) hVISA/VISA and 63 (14.2%) S-MRSA isolates. Growth on BHI-V3 was noted in all hVISA/VISA and 24 (5.4%) S-MRSA isolates. Growth on BHI-V4 was noted in all VISA and four (12.1%) hVISA isolates. None of the S-MRSA isolates grew on BHI-V4 agar. The sensitivity, specificity, and positive (PPV) and negative (NPV) predictive values were 75.0%, 89.0%, 38.0%, and 97.5% for MAC; 70.0%, 85.8%, 30.8%, and 97.0% for GRD; 100%, 94.6%, 62.5%, and 100% for BHI-V3; and 100, 99.2%, 63.6%, and 100% for BHI-V4 (for detecting VISA). These findings suggest that both Etest screening methods have excellent NPV, but positive results require confirmation. BHI-V3 and BHI-V4 agars provide more precise identification of hVISA and VISA, respectively; they may be reasonable alternatives to PAP/AUC. |
| Databáze: | OpenAIRE |
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