Management of Gram-Negative Bloodstream Infections in the Era of Rapid Diagnostic Testing: Impact With and Without Antibiotic Stewardship

Background. Verigene Blood-Culture Gram-Negative is a rapid diagnostic test (RDT) that detects gram-negatives (GNs) and resistance within hours from gram stain. The majority of the data support the use of RDTs with antimicrobial stewardship (AMS) intervention in gram-positive bloodstream infection (BSI). Less is known about GN BSI. Methods. This was a retrospective quasi-experimental (nonrandomized) study of adult patients with RDT-target GN BSI comparing patients pre-RDT/AMS vs post-RDT/pre-AMS vs post-RDT/AMS. Optimal therapy was defined as appropriate coverage with the narrowest spectrum, accounting for source and co-infecting organisms. Time to optimal therapy was analyzed using KaplanMeier and multivariable Cox proportional hazards regression. Results. Eight-hundred thirty-two patients were included; 237 pre-RDT/AMS vs 308 post-RDT/pre-AMS vs 237 post-RDT/AMS, respectively. The proportion of patients on optimal antibiotic therapy increased with each intervention (66.5% vs 78.9% vs 83.2%; P < .0001). Time to optimal therapy (interquartile range) decreased with introduction of RDT: 47 (7.9-67.7) hours vs 24.9 (12.4-55.2) hours vs 26.5 (10.3-66.5) hours (P = .09). Using multivariable modeling, infectious diseases (ID) consult was an effect modifier. Within the ID consult stratum, controlling for source and ICU stay, compared with the pre-RDT/AMS group, both post-RDT/pre-AMS (adjusted hazard ratio [aHR], 1.34; 95% CI, 1.04-1.72) and post-RDT/AMS (aHR, 1.28; 95% CI, 1.01-1.64), improved time to optimal therapy. This effect was not seen in the stratum without ID consult. Conclusions. With the introduction of RDT and AMS, both proportion and time to optimal antibiotic therapy improved, especially among those with an existing ID consult. This study highlights the beneficial role of RDTs in GN BSI.