Impact of a Rapid Blood Culture Diagnostic Test in a Children's Hospital Depends on Gram-Positive versus Gram-Negative Organism and Day versus Night Shift

Abstract

Rapid diagnostic tests (RDTs) for bloodstream infections (BSIs) decrease the time to organism identification and resistance detection. RDTs are associated with early deescalation of therapy for Gram-positive BSIs. However, it is less clear how RDTs influence antibiotic management for Gram-negative BSIs and whether RDT results are acted on during off-hours. We performed a single-center, retrospective review of children with BSI and Verigene (VG) testing at a children’s hospital. Of the 301 positive cultures included in the study (196 Gram-positive, 44 Gram-negative, 32 polymicrobial, and 29 non-VG targets), the VG result had potential to impact antibiotic selection in 171 cases; among these, antibiotic changes occurred in 119 (70%) cases. For Gram-negative cultures, the Verigene result correlated with unnecessary antibiotic escalation and exposure to broader-spectrum antibiotics than needed. In contrast, for Gram-positive cultures, the VG results correlated with appropriate antibiotic selection. VG results permitted early deescalation for methicillin-susceptible Staphylococcus aureus (MSSA) (19/24 [79%]) and avoidance of antibiotics for skin contaminants (30/85 [35%]). Antibiotic changes occurred more quickly during the day than at night (4.6 versus 11.7 h, respectively; P < 0.05), and antibiotic escalations occurred more quickly than did deescalations (4.1 versus 10.1 h, P < 0.01). In a pediatric institution with a low prevalence of Gram-negative resistance, the VG RDT facilitated antibiotic optimization for Gram-positive BSIs but led to unnecessary escalation of antibiotics for Gram-negative BSIs. The time to action was slower for RDT results reported at night than during the day. Laboratories should consider these factors when implementing blood culture RDTs.

Educational Case: Staphylococcus aureus Bacteremia: Utilization of Rapid Diagnostics for Bloodstream Pathogen Identification and Prediction of Antimicrobial Susceptibility

“…34 Multiple studies have demonstrated reductions in time to de-escalation for treatment of methicillin-susceptible S aureus (MSSA) BSIs upon implementation of molecular assays to detect mecA. [35][36][37] The ability to rapidly differentiate S aureus from CoNS has also been shown to reduce unnecessary antimicrobial administration to patients whose isolates represent contaminants. 35 Taken together, rapid diagnostics with antimicrobial stewardship interventions reduce time to appropriate therapy, but not all studies have been able to demonstrate reduced length of stay or mortality which may be due to limitations in study design or differences in patient populations.…”

Modern Blood Culture

“…However, whether this rapid turnaround time (TAT) translates into more favorable clinical outcomes remains to be determined. 46 , 47 …”

Panels and Syndromic Testing in Clinical Microbiology

“… 4 , 6 , 8 , 9 Passive reporting of syndromic blood culture panel information results in rapid antibiotic escalation, but deescalation and discontinuation of unnecessary antimicrobials is much slower if it happens at all. 10 , 11 The biggest lesson these outcome studies have taught us is the critical value of antimicrobial stewardship programs in the timely optimization or discontinuation of antibiotics. 12 …”