Impact of Peptide Nucleic Acid Fluorescence in Situ Hybridization Testing for Coagulase-Negative Staphylococci in a Pediatric Setting

Abstract

Background Coagulase-negative staphylococci (CoNS) are common blood culture contaminants, whereas Staphylococcus aureus is a pathogen with isolation from blood requiring therapy. Peptide nucleic acid fluorescence in situ hybridization (PNA-FISH) permits distinction of CoNS and S. aureus and has been demonstrated to decrease hospital costs, vancomycin use, and length of stay when paired with antimicrobial stewardship intervention. The impact of this testing in a children's hospital in the absence of stewardship intervention is unknown. The objective of this study was to determine the impact of PNA-FISH in a setting without an antimicrobial stewardship protocol for response to rapid testing. Methods This retrospective cohort study included pediatric patients with at least 1 CoNS-positive blood culture between January 1, 2012, and August 1, 2016. Patients were categorized based on the use of Staphylococcus QuickFISH, a rapid PNA-FISH method of identification. The primary outcome was hours of vancomycin exposure. Secondary outcomes included time-to-therapy change, time to culture result, and hospital length of stay. Results Of the 211 identified patients who had at least 1 blood culture bottle positive for CONS, 179 (85%) received vancomycin. Median hours of vancomycin exposure decreased between groups (63 rapid diagnostic testing group vs 81 conventional testing group; P = 0.019). Conclusions Despite an observed decrease in vancomycin exposure with use of rapid PNA-FISH testing, the full benefits of rapid diagnostic testing are unrealized in the absence of an appropriate stewardship protocol. Further studies may allow determination of the full impact of rapid diagnostic testing in pediatric settings.