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Int J Infect Dis. 2015 Sep;38:125-8. doi: 10.1016/j.ijid.2015.05.002. Epub 2015 May 11.

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

Author information

1
Department of Laboratory Medicine, Division of Clinical Microbiology, Karolinska Institutet, Karolinska University Hospital, Huddinge, SE-141 86 Stockholm, Sweden; Infection Prevention and Control Department, King Abdul Aziz Specialist Hospital, Taif, Saudi Arabia. Electronic address: waleedmazi@ki.se.
2
Faculty of Health and Life Sciences, Northumbria University, Newcastle upon Tyne, UK.
3
Department of Laboratory Medicine, Division of Clinical Microbiology, Karolinska Institutet, Karolinska University Hospital, Huddinge, SE-141 86 Stockholm, Sweden.
4
Department of Laboratory Medicine, Division of Clinical Microbiology, Karolinska Institutet, Karolinska University Hospital, Huddinge, SE-141 86 Stockholm, Sweden; University of Medical Sciences and Technology, Department of Microbiology, Khartoum, Sudan.
5
Strathclyde Institute of Pharmacy and Biomedical Sciences, University of Strathclyde, Glasgow, UK.

Abstract

OBJECTIVE:

spa-typing of methicillin-resistant Staphylococcus aureus (MRSA) has been used widely in clinical diagnostics and epidemiological studies. The aim of this study was 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 the spa gene was amplified by colony PCR using the SensiMix HRM kit, and the melting temperature (Tm) and melting curves of the amplicons were analyzed in close tubes using a Rotor-Gene 6000 instrument.

RESULTS:

Fifteen out of 19 spa-types each had a distinct Tm, which was sufficient to unambiguously type each of these spa-types. The remaining four spa-types could not be separated by Tm alone: t008 and t2770 shared a Tm (80.3°C) and t021 and t311 shared a Tm (80.0°C). However, they could be separated based on the shapes of their melting curves. There are discrepancies between the findings of the present study and those of previous studies, suggesting that standardization remains a challenge for cross-referencing.

CONCLUSION:

HRM-based 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-referencing between laboratories globally.

KEYWORDS:

High-resolution melting (HRM); Melting temperature (Tm); Methicillin-resistant Staphylococcus aureus (MRSA); spa-types

PMID:
25975652
DOI:
10.1016/j.ijid.2015.05.002
[Indexed for MEDLINE]
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