Utility of a Cell-Direct Polymerase Chain Reaction-Based Nucleic Acid Lateral Flow Immunoassay for Detection of Bacteria in Peripheral Blood Leukocytes of Suspected Sepsis Cases

Haruka Imai,1 Yuji Watanabe,2 Daishi Shimada,1 Jun Suzuki,1 Shiro Endo,1 Mitsuo Kaku,1 Masafumi Seki1 1Division of Infectious Diseases and Infection Control, Tohoku Medical and Pharmaceutical University Hospital, Sendai City, Miyagi, Japan; 2Laboratory for Clinical Microbiology, Tohoku Medical and Pharmaceutical University Hospital, Sendai City, Miyagi, JapanCorrespondence: Masafumi SekiDivision of Infectious Diseases and Infection Control, Tohoku Medical and Pharmaceutical University, 1-15-1 Fukumuro, Miyagino-ku, Sendai City, Miyagi, 983-8536, JapanTel +81-22-983-1221Fax +81-22-290-8959Email m-seki@tohoku-mpu.ac.jp; seki@hosp.tohoku-mpu.ac.jpBackground: The detection of the pathogens in the blood is essential for the management of septic patients; however, conventional blood culture takes 2– 3 days. Therefore, rapid and convenient methods may be useful to aid clinical decision-making.Methods: Blood samples with sepsis clinically diagnosed in cases that fulfilled the diagnostic criteria were used and analyzed the utility of a novel bacterial nucleic acid identification test using a cell-direct polymerase chain reaction (cdPCR)-based nucleic acid lateral flow immunoassay (NALFIA) which were named as “DiagnoSep” to detect representative bacteria in peripheral blood leukocytes in patients admitted to our hospital and compared the conventional blood culture results simultaneously taken from the patients.Results: We analyzed the total 42 samples in the terms of this study and found 18 (42.8%) were positive on cdPCR-NALFIA, and 24 (57.1%) were positive on blood cultures. Although the positive rate was higher with blood cultures, 15 samples showed positive results from both blood cultures and cdPCR-NALFIA, and the identified bacteria agreed for 10 samples. Of the 18 cdPCR-NALFIA-positive cases, the results for 8 samples differed from the results of blood cultures; four of them had an implanted pacemaker or prosthetic joint and were positive for Staphylococcus aureus or Staphylococcus epidermidis on cdPCR-NALFIA.Conclusion: Blood culture tests are probably the gold standard in identifying causative organisms in sepsis, but the rapid results from cdPCR-NALFIA simultaneously used with blood culture may make it an important auxiliary diagnostic tool for identifying infecting organisms and lead to the improvement of mortality of the septic patients, because these combined results provide the wide information on the possible pathogens in early phase.Keywords: bacteremia, blood culture, rapid diagnosis