Association between genotype screening results obtained by PFGE and PCR for hypervariable regions of the mecA gene in methicillin-resistant Staphylococcus aureus

INTRODUCTION: The emergence of methicillin-resistant Staphylococcus aureus (MRSA) has become a major epidemiological problem worldwide.

METHODS: We determined the degree of association between the genotype screening results obtained by pulse-field gel electrophoresis (PFGE) and polymerase chain reaction (PCR) for 7 hypervariable DNA regions associated with the mecA gene (HVR-mecA PCR), in the epidemiological analysis of 36 MRSA strains unrelated to nosocomial outbreaks, isolated from hospitalized patients at the County Hospital of Valdivia (Chile).

RESULTS: The strains were classified into 15 pulse types (A-O) and 5 genotypes (6, 14, 15, 16, and 17) by PFGE and HVR-mecA PCR, respectively. Most of the strains were grouped in pulse types D, E and I, which presented 85.7% similarity. The most common genotypes were 14 (36.1%) and 15 (33.3%). Each genotype detected by HVR-mecA PCR was distributed in more than one pulse type. The degree of association between genotypic screening by PFGE or HVR-mecA PCR was determined by calculating Cramer's V statistic and the contingency coefficient. In both cases, a value near 1 (0.84 and 0.78, respectively) was obtained, indicating a high association between these genotypic screenings. Thus these are complementary, not exclusionary techniques that can be equally applied.

CONCLUSIONS: PFGE is a standardized, high-technology molecular tool with considerable discriminatory power. HVR-mecA PCR is a fast, simple, accessible tool that has lower discriminatory power; nonetheless it can serve as an alternative method for epidemiological research in MRSA strains.

Medina G, Otth C, Araya P (ISP), Hormazabal JC (ISP), Fernández J (ISP), Maldonado A (ISP), Fernández H, Otth L, Wilson M.
Enfermedades Infecciosas y Microbiología Clínica. 2009 Apr;27(4):213-8.
Fecha Publicación: 
Enero, 2009