Radiometric Method and a Tubed Broth Method

As the result of a comparative study, it was found that a radiometric method utilizing an aerobic and an anaerobic vial was much more efficient than a tubed broth method in detecting bacteremia. The radiometric method detected 97 ( 92.4 percent) of 105 isolants as compared to 58 ( 55.2 percent) for the tubed broth method. Forty-seven (44.8 percent) of the isolants were detected only by the former system, whereas 50 isolants (47.6 percent) were detected by both systems. Of the media for the radiometric method, the aerobic vial detected 84 (91.3 percent) of 92 isolants detected by the com­ bination of aerobic and anaerobic vials. The anaerobic vial detected 46 (50.0 percent) of these isolants. Strains of Escherichia coli, coagulase positive Staphylococcus and Pseudomonas sp. were much more efficiently isolated by the radiometric method, which also presented better isolation rates for fastid­ ious organisms such as Diplococcus pneumoniae, Neisseria meningitidis and Haemophilus influenzae, the latter in the absence of added V factor in the media. Serious deficiencies of the radiometric method were the occurrence of a high rate of false positive results and occasional false negative results. These situations prevented the realization in a clinical environment of the method’s potential efficiency in detecting bacteremia.