Rapid identification of bacteria and candida using pna-fish from blood and peritoneal fluid cultures: a retrospective clinical study

Abstract

BackgroundPeptide nucleic acid fluorescent in situ hybridization (PNA-FISH) is a rapid and established method for identification of Candida sp., Gram positive, and Gram negative bacteria from positive blood cultures. This study reports clinical experience in the evaluation of 103 positive blood cultures and 17 positive peritoneal fluid cultures from 120 patients using PNA-FISH. Our study provides evidence as to potential pharmaceutical cost savings based on rapid pathogen identification, in addition to the novel application of PNA-FISH to peritoneal fluid specimens.MethodsIdentification accuracy and elapsed time to identification of Gram positives, Gram negatives, and Candida sp., isolated from blood and peritoneal fluid cultures were assessed using PNA-FISH (AdvanDx), as compared to standard culture methods. Patient charts were reviewed to extrapolate potential pharmaceutical cost savings due to adjustment of antimicrobial or antifungal therapy, based on identification by PNA-FISH.ResultsIn blood cultures, time to identification by standard culture methods for bacteria and Candida sp., averaged 83.6 hours (95% CI 56.7 to 110.5). Identification by PNA-FISH averaged 11.2 hours (95% CI 4.8 to 17.6). Overall PNA-FISH identification accuracy was 98.8% (83/84, 95% CI 93.5% to 99.9%) as compared to culture. In peritoneal fluid, identification of bacteria by culture averaged 87.4 hours (95% CI −92.4 to 267.1). Identification by PNA-FISH averaged 16.4 hours (95% CI −57.3 to 90.0). Overall PNA-FISH identification accuracy was 100% (13/13, 95% CI 75.3% to 100%). For Candida sp., pharmaceutical cost savings based on PNA-FISH identification could be $377.74/day. For coagulase-negative staphylococcus (CoNS), discontinuation of vancomycin could result in savings of $20.00/day.ConclusionsIn this retrospective study, excellent accuracy of PNA-FISH in blood and peritoneal fluids with reduced time to identification was observed, as compared to conventional culture-based techniques. Species-level identification based on PNA-FISH could contribute to notable cost savings due to adjustments in empiric antimicrobial or antifungal therapy as appropriate to the pathogen identified.

Utilizing Rapid Diagnostics for Detection of Candida Species

“…The newer QuickFISH test identifies the three most commonly encountered species: C. albicans, C. glabrata, and C. parapsilosis. PNA FISH tests have demonstrated costsavings by reducing echinocandin use for fluconazole-susceptible species in several reports [12,39].…”

Integration of Technology Into Clinical Practice

“…These assays have been shown to have excellent analytical performance. [10][11][12][13] Given the emergent nature of bloodstream infections, rapid blood culture diagnostic methods may be one of the most important tests a clinical microbiology laboratory could implement. Indeed, several studies have shown that the use of these assays can improve patient care.…”

Counterinsurgency Doctrine Applied to Infectious Disease

“…In the clinical laboratory, counterinsurgency intelligence gathering would require new technology, a new electronic health record, and a new mindset. Various technologies for community characterization are already available -particularly high-throughput sequencing (Xu et al 2012), but also multiplexed PCR Hartley 2003, Lindsay et al 2013), hybridization arrays (Gardner et al 2010), microfluidic culture (Ho et al 2012), flow cytometry (Jolkkonen et al 2010, Nuutila et al 2012, and novel approaches to microscopy (Foreman et al 2010, Harris et al 2013. Each has limitations and none of them provide quite what would be desired to understand the function of a microbial community de novo.…”