[Association between genotype screening results obtained by PFGE and PCR for hypervariable regions of the mecA gene in methicillin-resistant Staphylococcus aureus].
BACKGROUND
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.
Instituto de Microbiología Clínica (Proyectos DID S-2004-64 y S-2007-63 UACh), Facultad de Medicina, Universidad Austral de Chile, Valdivia, Chile.
Gustavo
G
Medina
Carola
C
Otth
Pamela
P
Araya
Juan Carlos
JC
Hormazabal
Jorge
J
Fernández
Aurora
A
Maldonado
Heriberto
H
Fernández
Laura
L
Otth
Myra
M
Wilson
D001426:Bacterial Proteins / Q000235:genetics*; D002677:Chile / Q000453:epidemiology; D003428:Cross Infection / Q000453:epidemiology / Q000382:microbiology; D004269:DNA, Bacterial / Q000235:genetics; D016521:Electrophoresis, Gel, Pulsed-Field; D005838:Genotype; D016106:Methicillin Resistance / Q000235:genetics*; D055624:Methicillin-Resistant Staphylococcus aureus / Q000145:classification / Q000235:genetics*; D046915:Penicillin-Binding Proteins; D016133:Polymerase Chain Reaction; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D013045:Species Specificity; D013203:Staphylococcal Infections / Q000453:epidemiology / Q000382:microbiology
D001426:Bacterial Proteins; D004269:DNA, Bacterial; D046915:Penicillin-Binding Proteins; C487789:mecA protein, Staphylococcus aureus