Rapid Species Identification of Coagulase Negative Staphylococci by rRNA Spacer Length Polymorphism Analysis

Abstract

Objectives: The identification of coagulase-negative staphylococci (CNS) is carried out mainly through conventional methods, commercial identification kits, and molecular biology-based methods. We evaluated the efficiency of PCR analysis of tRNA intergenic spacer length polymorphism (tDNA-ILP) and 16S-23S intergenic spacer length polymorphism (16S-23S ILP), and also that of restriction analysis of 16S-23S intergenic spacer amplification products (RA 16S-23S), for the rapid and accurate identification of CNS species.Methods: The PCR assays of rRNA spacer length polymorphisms were tested with nine reference type strains and 122 clinical isolates. The results were compared with those obtained by conventional methods and the Vitek system for clinical isolates.Results: Seventy-eight (63.9%) of 122 strains were identified as the same species with conventional identification, the Vitek GPI system, tDNA-ILP, and RA 16S-23S. The 16S-23S ILP analysis did not produce distinguishable PCR fragments. The results of tDNA-ILP analysis were in agreement with those of RA 16S-23S to the species level for 98.2% except for unknown patterns (eight isolates).Conclusions: These results indicate that tDNA-ILP and RA 16S-23S analysis are potentially valuable tools for rapid and accurate CNS identification.