Analysis of genomic fingerprint patterns of coagulase-negative Staphylococci strains isolated from pediatric patients blood cultures using repetitive sequence-based PCR

Introduction and objective: Coagulase negative Staphylococci (CoNS) are often isolated from blood cultures which may represent either contamination or bacteremia. Repetitive sequence-based PCR (rep-PCR) as a suitable and potential tool permit differentiation of isolates to species, subspecies and strain level. The aim of this study was analysis of DNA fingerprint patterns and detection of similarity or differentiation of CoNS strains isolated from pediatric patients blood cultures.

Materials and methods: In this study, coagulase-negative Staphylococci isolated from hospitalized pediatric patients, were examined. DNA was extracted by using a DNA extraction kit and then diverse-sized DNA fragments consisting of sequences between the repetitive elements were amplified by rep-PCR. Amplified PCR products in different sizes were separated in agarose gels.

Results: Forty-seven strains of CoNS were differentiated by DNA fingerprints generated by rep-PCR. Rep-PCR generated 2-12 different-sized PCR products visible on ethidium bromide stained agarose gels and 29 different fingerprint patterns. A unique fragment was identified in multiple blood cultures from each of seven different patients. Three patients each had two isolates that were closely related, one patient had two isolates that were possibly different, and three patients each had two isolates that were different.

Conclusion: Rep-PCR is a rapid and suitable technique for epidemiological studies and this method with high discrimination could detect similarity or differentiation of strains isolated from bacteremic patients consequently.