Evaluation of spa-typing of methicillin-resistant Staphylococcus aureus using high-resolution melting analysis

Mazi, Waleed and Sangal, Vartul and Sandstom, Gunnar and Saeed, Amir and Yu, Jun (2015) Evaluation of spa-typing of methicillin-resistant Staphylococcus aureus using high-resolution melting analysis. International Journal of Infectious Diseases. pp. 1-18. S1201-9712(15)00109-5. ISSN 1201-9712

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    Abstract

    OBJECTIVE: spa-typing of methicillin-resistant Staphylococcus aureus (MRSA) has been widely used in clinical diagnostics and epidemiological studies. We aimed to evaluate high-resolution melting (HRM) as a rapid and cost effective method, to replace DNA-sequencing, for spa-typing in a global collection of 50 MRSA isolates. METHODS: The polymorphic X region of spa gene was amplified by colony PCR using SensiMix™ HRM kit and melting temperature (Tm) and melting curves of the amplicons was analyzed in close tubes using a Rotor-Gene 6000 instrument. RESULTS: Fifteen out of nineteen spa-types each had distinct Tm, which was sufficient to unambiguously type each of these spa-types. The remaining 4 spa-types cannot be separated by Tm alone: t008 and t2770 shared Tm (80.3°C) and t021 and t311 shared Tm (80.0°C). But, they can be separated based on the shapes of their melting curves. There are discrepancies between ours and previous studies, suggesting that standardization reminds a challenge for cross references. CONCLUSION: HRM-spa-typing is reproducible, simple, rapid and cost-effective. t037 is prevalent in Brazil and Sudan while diverse spa-types are found in Scotland and Saudi Arabia. Standardization is required for cross-references between labs globally.