Detection of bacteremia in leukemic patients by early subcultures with a slide blood culture system.

During a three month study, 433 sets of blood culture were collected from 140 patients hospitalized in the hematology unit, most of these blood cultures were collected from leukemic patients being treated by chemotherapy producing aplasia. Blood was distributed into three bottles, one containing Schaedler Broth and the others tryptic soy broth (TS). We tried to compare two different blind subculture systems: conventional subculture (CS) onto Petri dishes chocolate agar and a coated agar slide (slide) attached onto the TS bottle, thus the blood culture broth can be subcultured by tipping the bottle. The first subculture was performed at the same time for both bottles after a mean time of incubation of 12,4 hours (st. dev. 3.3 hours). There was no statistically significant difference for the recovery of pathogens, 30 with the slide and 29 with CS. Among the 30 slide positive blood cultures, six: 4 pseudomonas, 2 streptococcus, were detected by direct observation of colonies before any evidence of broth disturbance. When comparison was made according to the detection observed with the first, second or third subculture, a slight advantage was obtained with CS since 72.4% of them were positive with the first subculture versus 60% with the slide. During the first round of evaluation an higher contamination rate was observed with the slide 6.4% versus 2% for CS. The great majority of contaminated bottles were collected in one of the three hematology subunits. Contamination rate dropped following a teaching campaign bout aseptic collection and distribution of blood into the bottles.(ABSTRACT TRUNCATED AT 250 WORDS)