A SAMPLE PREPARATION METHOD WHICH FACILITATES DETECTION OF BACTERIA IN BLOOD CULTURES BY THE POLYMERASE-CHAIN-REACTION

A sample preparation method was developed to remove the effect of PCR inhibitors in blood cultures, and to concentrate the bacterial cells p rior to PCR. This method was based on a combination of dilution, centr ifugation, washing with NaOH and the addition of bovine serum albumin. The efficiency of this sample preparation was evaluated with S. pneum oniae and N. meningitidis added to a culture medium containing whole b lood. The detection level of both bacteria was 1 CFU per mi of blood c ulture medium. Without this treatment, the PCR could not detect 10(7) CFU of S. pneumoniae per reaction tube when 10 mu l of culture medium containing human whole blood was added directly to the PCR mixture. Wh en the sample preparation was evaluated with culture medium containing whole blood inoculated with approximately 0.3 CFU of S. pneumoniae pe r mi and incubated at 37 degrees C, a positive PCR product was detecte d after 8 h. (C) 1998 Elsevier Science B.V.