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eBook details
- Title: An Evaluation of the Advandx Staphylococcus Aureus/Cns PNA FISH[TM] Assay (Research AND REPORTS)
- Author : Clinical Laboratory Science
- Release Date : January 01, 2009
- Genre: Engineering,Books,Professional & Technical,
- Pages : * pages
- Size : 186 KB
Description
Septicemia is one of the leading causes of death in the United States. (1) Staphylococcus aureus infections, including S. aureus septicemia, place economic and personal burdens on the healthcare system in terms of increased morbidity, mortality, length of hospital stay, and associated costs. (2-6) While coagulase negative staphylococcus (CNS) is the organism most commonly isolated from positive blood cultures it is often a contaminant. (7-9) Both S. aureus and CNS are seen as gram-positive cocci in clusters (GPCC) on a Gram stained smear and this is typically the first report that a clinician receives regarding a positive blood culture. Differentiation of contamination from true bacteremia is important in terms of treatment and there are differing opinions, even among infectious diseases experts, about the best strategy to follow. (10-13) Equally important is the differentiation of S. aureus and CNS in cases of true bacteremia. Concerns about the overuse or misuse of vancomycin must be weighed against the need for proper antimicrobial treatment of methicillin-resistant S. aureus (MRSA) bacteremia. Information supplied by the clinical microbiology laboratory to clinicians plays an important role in decision making. Traditional microbiology methods of identification involving subculture to solid media and biochemical testing take one to two days for an identification of S. aureus to be confirmed during which time the decision must be made whether or not to start empiric therapy. Evaluation of rapid methods for identification of S. aureus directly from blood culture bottles, including real-time polymerase chain reaction (PCR), peptide nucleic acid fluorescent in situ hybridization (PNA FISH), PNA FISH combined with flow cytometry, tube coagulase, and the API RAPIDEC staph system (bioMerieux, Durham NC), have been reported in the literature. (14-18) Rapid testing and providing a presumptive identification to the clinician within hours of positivity have the potential to improve management of S aureus bacteremia by decreasing the time to appropriate therapy. (19) S. aureus/CNS PNA FISH[TM] (AdvanDX, Woburn MA) is a FISH method that utilizes PNA probes specific for S. aureus and non-aureus 16S ribosomal RNA sequences. The test is performed on smears made directly from positive blood culture bottles and results are available in approximately three hours. The inclusion of probes for both S. aureus and CNS allows not only differentiation of the two organisms but also serves as a backup for Gram stain interpretation since nonstaphylococcal isolates which may be misinterpreted as GPCC will not stain with the S. aureus/CNS PNA FISH[TM] probes. This study evaluated the performance of the S. aureus/CNS PNA FISH[TM] assay when compared to traditional microbiology methods of identification. METHODS