Physician

GPCC - S. aureus PNA FISH

For in vitro diagnostic use.

S. aureus PNA FISH™ (Cat. No. KT001) is a qualitative nucleic acid hybridization assay intended for identification of Staphylococcus aureus from blood cultures.

S. aureus PNA FISH provides rapid identification of S. aureus on smears made directly from Gram-positive cocci in clusters (GPCC) positive blood culture bottles and is compatible with all major blood culture media.  The 2.5 hours fluorescence in situ hybridization (FISH) assay uses fluorescently labeled peptide nucleic acid (PNA) probes that target the species-specific ribosomal RNA (rRNA) in S. aureus.  Results are visualized using fluorescence microscopy.  Green fluorescing cells identify S. aureus, while no fluorescence indicates another species, e.g. Coagulase-Negative Staphylococci (CNS), is present in the positive blood culture.

Features and Benefits

In the United States more than 60% of S. aureus isolates are now methicillin-resistant (MRSA) and result in significant costs to the healthcare system.  Bloodstream infections due to S. aureus, including MRSA, can result in high mortality and morbidity and lead to significant additional costs to hospitals.  S. aureus PNA FISH allows for identification of S. aureus that includes MRSA, within hours instead of days of a blood culture turning positive.  The rapid results can quickly be reported to attending physicians and help ensure early and aggressive therapy for the infections.(1) 

Early Detection of Contaminated Blood Cultures
- Reducing Vancomycin Use and Length of Stay (LOS)
- Improving Bed and Resource Utilization
- Reducing Hospital Bed, Pharmacy and Laboratory Costs

Positive blood cultures don’t always constitute true infections.  In fact, even though only about 10% of all blood cultures performed annually in the United States turn positive, indicating a bloodstream infection, 30% or more of those turn positive due to contamination with common skin bacteria known as Coagulase-Negative Staphylococci (CNS).  However, because these bacteria are closely related to S. aureus, which almost always causes true and serious infections, patients with CNS contaminated blood cultures are often unnecessarily treated with broad-spectrum antibiotics, especially vancomycin, leading to prolonged hospital stays.

Studies show that by ruling-out S. aureus from GPCC+ blood cultures, S. aureus PNA FISH helps physicians and pharmacists identify those patients where blood cultures turn positive due to contamination, and thereby avoid unnecessary therapy.  According to data first published in the July 2006 issue of the Journal of Antimicrobial Agents and Chemotherapy by the University of Maryland Medical Center (2), implementation of S. aureus PNA FISH to reduce costs related to CNS contaminated blood cultures resulted in:

• Significant reduction in unnecessary vancomycin use
• Reduction in median hospital length of stay of 2 days (from 6 to 4 days)
• Increased bed utilization
• Cost savings per patient of $4,005.  The cost savings included $2,704 in reduced bed costs, $985 in reduced pharmacy costs and $316 in reduced laboratory costs.

1. NNIS System.  http://www.cdc.gov/ncidod/dhqp/pdf/ar/ICU_RESTrend1995-2004.pdf
2. Forrest et al.  Impact of rapid in situ hybridization testing on coagulase-negative staphylococci positive blood cultures.  J Antimicrob Chemother. 2006 Jul;58(1):154-8