Molecular characterization of Staphylococcus aureus isolates from nosocomial and community-acquired infections using accurate, reproducible, and rapid typing methods is essential for the fast identification of prevalent and epidemic strains. Although… Click to show full abstract
Molecular characterization of Staphylococcus aureus isolates from nosocomial and community-acquired infections using accurate, reproducible, and rapid typing methods is essential for the fast identification of prevalent and epidemic strains. Although sequence-based spa typing is highly effective, PCR-based techniques (such as high-resolution melting curve analysis, HRM) are simpler, less expensive, faster, and can be performed in a single and closed-tube assay format, thereby reducing the risk of contamination. A total of 51 methicillin-resistant S. aureus (MRSA) (n = 26) and methicillin-sensitive S. aureus (MSSA) (n = 25) isolates from Karaj (n = 10) and Yasuj (n = 41), Iran, were subjected to HRM. All selected isolates were identified by the standard spa-typing method. Among the 51 tested isolates, 11 genotype profiles were distinguished from 12 spa types. Strains t1077 and t1816 exhibited the highest and lowest melting temperatures (81.8°C and 79.4°C), with 46.7% and 39.8% G + C contents, respectively. Strains t706 and t1816, with almost identical G + C contents, had the same HRM genotypes, but their curves differed due to different G + C distributions. Four standard spa types (strains t030, t037, t701 and t5598) were differentiated correctly and their melting temperatures were 81.2°C, 81.4°C, 80.4°C and 80.1°C, respectively. We demonstrated that HRM profiling is a rapid method which enables the accurate screening of certain strains (especially the endemic ones), and may be used for bacterial surveillance. However, it cannot replace sequence-based spa typing, especially for newly emerging spa types, and therefore cannot be used as a standardized global method.
               
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