Improved blood culture technique based on centrifugation: clinical evaluation

Abstract

A total of 3335 blood samples from 1180 patients suspected of having bacteremia were analyzed concurrently by 2 methods: supplemented peptone broth with sodium polyanethanol sulfonate and a CO2 atmosphere; and lysis centrifugation at 3000 .times. g for 30 min onto a high-density, hydrophobic cushion. The centrifugation technique recovered 80% of the positive cultures as compared with 67% for the broth method. The centrifugation technique showed an apparent increase in the isolation of Staphylococcus aureus, Pseudomonas and yeasts. In almost every instance, the time required for detection of a positive culture was shortest for the centrifugation method. Contamination rates for both systems were comparable (1.4%). Quantitation, offered only by the centrifugation method, proved useful on several occasions in discriminating between an opportunistic infection vs. a skin contaminant and in judging efficacy of antimicrobial therapy.