Progress toward Rapid and Accurate Staphylococcus aureus Strain Typing

Abstract

Staphylococcus aureus , especially methicillin-resistant S. aureus (MRSA),1 continues to be one of the most important bacterial pathogens in humans and is responsible for a constantly increasing number of nosocomial and community-acquired infections. Bacterial strain typing, or subspecies identification, has become an important clinical tool for investigating suspected outbreaks and evaluating nosocomial transmission. Adequate and precise typing of S. aureus isolates that permits the monitoring of local outbreaks and wider-scale dissemination of specific dangerous clones is of great concern (1)(2)(3). Similar to typing in other microbial organisms, S. aureus typing has been greatly influenced and improved by molecular techniques. Differences in the various molecular methods used to define different genomic characteristics greatly affect their essential parameters, including discriminatory power and test turnaround time (1)(2)(3). The most important methods currently used for MRSA typing are pulsed-field gel electrophoresis (PFGE) (4)(5)(6)(7), multilocus sequence typing (MLST) (8)(9), spa (staphylococcal surface protein A) typing (1)(6)(10)(11), multilocus variable tandem repeat analysis (MLVA) (12)(13), and repeat-element PCR (rep-PCR) typing (7)(14)(15). These methods have been used to investigate the evolution of the MRSA clones that have emerged since the 1960s and to study their worldwide dissemination. Tremendous progress in molecular-typing methods has been made, with optimization and standardization of sequence-based technologies offering broad applicability and high throughput; however, no single S. aureus typing method has yet provided rapid and reliable information that is sufficient to permit prompt action to control infections. Because S. aureus has a highly clonal population structure, many different chromosomal markers indexing polymorphisms …