| Autor: |
Yam, W. C., Siu, Gilman K. H., Ho, P. L., Ng, T. K., Que, T. L., Yip, K. T., Fok, Cathie P. K., Chen, Jonathan H. K., Cheng, Vincent C. C., Yuen, K. Y. |
| Zdroj: |
Journal of Clinical Microbiology; September 2013, Vol. 51 Issue: 9 p2869-2874, 6p |
| Abstrakt: |
ABSTRACTRapid detection of methicillin-resistant Staphylococcus aureus(MRSA) nasal colonization is crucial for the prevention and control of MRSA infections in health care settings. The LightCycler MRSA Advanced Test (Roche Diagnostics) is a commercially available real-time PCR assay for direct detection of MRSA nasal colonization by targeting of the staphylococcal cassette chromosome mec(SCCmec)-orfXjunction. The diagnostic performance of the assay was compared with that of ChromID MRSA agar (bioMérieux) culture and an in-house duplex real-time PCR assay. Among 1,246 nasal swab specimens collected from 2 general hospitals in Hong Kong, 174 (14%) were considered true positive for MRSA. Chromogenic culture and the in-house real-time PCR assay identified 147 (84.5%) and 133 (76.4%) true-positive cases with specificities of 100% and 98.6%, respectively. Based on the target melting temperature (Tm) values (57.0 to 62.0°C) defined by the manufacturer, the LightCycler MRSA Advanced Test identified only 85 (48.9%) true-positive specimens. Interestingly, an additional 60 (34.5%) true-positive specimens were detected despite atypical Tmvalues of 55°C, providing overall sensitivity and specificity values of 83.3% and 99%, respectively. Among isolates with Tmvalues of 55°C, most were typed as clonal complex 45 (CC45). By sequence analysis of the SCCmec-orfXjunction, characteristic single-nucleotide polymorphisms (SNPs) were identified only in isolates with Tmvalues of 55°C and not in those with typical Tmvalues. It is conceivable that those SNPs were located inside the target region of the proprietary hybridization probes, which resulted in a Tmshift in the melting curve analysis. Our study highlights the importance of a global evaluation of commercial kits so that the interpretation algorithm covers different lineages of MRSA clones prevalent in various geographical regions. |
| Databáze: |
Supplemental Index |
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