The association of positive sepsis PCRs tests with patient mortality, length of stay, and antibiotic management in a medical intensive care unit

Abstract

Background: Polymerase chain reaction (PCR) testing amplifies a specific DNA segment through heat cycling to identify pathogens for the diagnosis of infection.  This testing allows for rapid detection of pathogens, before conventional blood culture results become available. The high mortality associated with severe sepsis and septic shock stresses the importance of early diagnosis and initiation of early antibiotic therapy.  This study analyzed the association of the sepsis PCR results and antibiotic management, length of stay, and mortality outcomes in a medical intensive care unit (MICU).

Methods: This study is a retrospective, cross-sectional study on patients diagnosed with severe sepsis and septic shock based on ICD-10 codes, aged 18 years and older, admitted to the MICU at University Medical Center, Lubbock, Texas, between December 2016 to December 2020.

Results: Clinical information from 268 patients with the diagnosis of sepsis or septic shock was collected and analyzed. The mean age was 60.9 ± 15.6 years with a predominance of men (144, 53.7%) and Caucasian race (193,73.4%). A total of 101 patients (37.6%) had positive PCR results; overall, PCR test results had a diagnostic sensitivity of 91.2 %. The concordance between positive blood culture and positive PCR was 93.3 % (p <.0001). There was a significant correlation between PCR positivity and increased serum lactate levels (p=0.03), changes in antibiotics (P<0.00010), and increased mortality rate (p=0.04).  There was no significant correlation between PCR positivity and length of stay (p=0.84).

Conclusion: In this study, PCR testing was an accurate tool for early identification of bacterial pathogens. A positive PCR was associated with higher serum lactate levels, higher mortality rates, and an increased frequency of antibiotic changes but was not associated with shorter ICU length of stay.

 Key words: Sepsis, septic shock, PCR testing, outcomes