Abstract
The relatively long turnaround time and low sensitivity of traditional
blood culture may delay the effective antibiotic therapy in patients
with bloodstream infection (BSI). To reduce the morbidity and mortality
of BSI, a rapid and sensitive pathogen detection method is urgently
required. Acinetobacter baumannii and Klebsiella pneumoniaare two major microorganisms responsible for BSI. Here we reported a
novel droplet digital PCR (ddPCR) method that can detect A.
baumannii and K. pneumonia in whole blood samples within 4 h,
with a specificity of 100% for each strain and limit of detection at
0.93 copies/microliter for A. baumannii and 0.27
copies/microliter for K. pneumonia. Clinical validation in 170
patients with suspected BSIs showed that, compared with blood culture
that reported 4 (2.4%) A. baumannii cases and 7 (4.1%) K.
pneumonia cases, ddPCR detected 23 (13.5%) A. baumannii cases,
26 (15.3%) K. pneumonia cases, and 4 (2.4%) dual infection
cases, including the 11 positive patients reported by blood culture. In
addition, the positive patients reported by ddPCR alone (n = 42) had
significantly lower serum concentrations of procalcitonin and lactate,
SOFA and APACHE II scores, and 28-day mortality than those reported by
both blood culture and ddPCR (n = 11), suggesting that patients with
less severe manifestations can potentially benefit from the guidance of
ddPCR results. In conclusion, our study suggests that ddPCR represents a
sensitive and rapid method to identify causal pathogens in blood samples
and to guide the treatment decisions in the early stage of BSI.
Keywords: Acinetobacter baumannii, Klebsiella pneumonia,droplet digital PCR, Bloodstream infection, pathogen