Utility of Multiplex PCR (mPCR) for Identification of Organisms in Positive Blood Cultures as a Part of an Antimicrobial Stewardship Program at a Community Hospital

Background:  Bacteremia can be associated with significant morbidity and mortality. Earlier identification of organisms using mPCR may help in improving patient’s outcome. The study was performed in a 150 bed hospital to evaluate the impact of mPCR testing in patient with positive blood culture. 

Methods:  Blood culture samples with two or more positive bottles for a gram positive organism or one or more positive bottles for a gram negative organism were tested using FilmArray® Blood Culture Identification Panel by BioFire which detects 27 targets including gram positive, gram negative, yeast, and antibiotic resistance genes.  A pharmacist was notified of positive PCR blood culture results and evaluated the patient’s antibiotic therapy.  A retrospective chart review of 6 month sample of patients with positive blood cultures prior to the PCR testing and a prospective review was performed on a 3 month sample of patients with positive blood cultures post implementation. 

Results:  A total 151 patients were evaluated with 45 patients in the mPCR group. The mean age in the control group 66 vs 64 yr. in mPCR group; ID was consulted in 42% vs 53%; associated UTI 24% vs 22%, respiratory infection 27% vs 13%, ABSSSI 19% vs 6%; repeat blood cultures was performed in 30% vs 64%; most common organisms in control group was Staphylococcus spp. (29%) and mPCR group was E. coli (18%), candidemia was detected in 2.8% vs 4.4%. The study showed a statistically significant reduction in mortality (18.87% vs 4.44%, p=0.0216), an increase in the number of patients whose of antibiotic therapy was narrowed (43.4% vs 64.44%, p=0.0180), and the duration of antibiotic therapy (8.62 vs 12.62 days, p=0.0123).  All other outcomes were not statistically different, including the time to narrow antibiotic therapy (3.21 vs 2.68 days, p=0.2951),   leukocytosis resolution (4.2 vs 4 days), fever resolution (3.9 vs 2.7 days) and time to negative blood culture (3.9 vs 4.3 days). There was no difference in 30 day re-admission rate.  

Conclusion: Even though the time to narrow antibiotic therapy was not statistically significant, patients were given more effective therapy allowing for possible reduction in mortality following the implementation of PCR testing in patients with bacteremia. Further studies needed to assess the utility and benefits of this test.