Abstract

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 36MRSA strains unrelated to nosocomial out breaks, isolated from hospitalized patients at the County Hospital of Valdivia (Chile). Results: The strains were classified into 15pulse types (A-O) and 5genotypes (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 Cramers Vstatistic and the contingency coefficient.In both cases, avaluenear 1(0.84 and 0.78,respectively) was btained, indicating a high association between these genotypic screenings. Thus these are complementary, note xclusionary 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.