Identification of Clinical Staphylococcal Isolates from Humans by Internal Transcribed Spacer PCR

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Abstract
The emergence of coagulase-negative staphylococci not only as human pathogens but also as reservoirs of antibiotic resistance determinants requires the deployment and development of methods for their rapid and reliable identification. Internal transcribed spacer-PCR (ITS-PCR) was used to identify a collection of 617 clinical staphylococcal isolates. The amplicons were resolved in high-resolution agarose gels and visually compared with the patterns obtained for the control strains of 29 staphylococcal species. Of the 617 isolates studied, 592 (95.95%) were identified by ITS-PCR and included 11 species: 302 isolates ofStaphylococcus epidermidis, 157 ofS. haemolyticus, 79 ofS. aureus, 21 ofS. hominis, 14 ofS. saprophyticus, 8 ofS. warneri, 6 ofS. simulans, 2 ofS. lugdunensis, and 1 each ofS. caprae,S. carnosus, andS. cohnii. All species analyzed had unique ITS-PCR patterns, although some were very similar, namely, the groupS. saprophyticus,S. cohnii,S. gallinarum,S. xylosus,S. lentus,S. equorum, andS. chromogenes, the pairS. schleiferiandS. vitulus, and the pairS. piscifermentansandS. carnosus. Four species,S. aureus,S. caprae,S. haemolyticus, andS. lugdunensis, showed polymorphisms on their ITS-PCR patterns. ITS-PCR proved to be a valuable alternative for the identification of staphylococci, offering, within the same response time and at lower cost, higher reliability than the currently available commercial systems.