IMPROVED RECOVERY OF ANTIBIOTIC-STRESSED MICROORGANISMS ON INCLUSION OF SAPONIN IN AEROBIC BLOOD CULTURE MEDIA

The recovery rates and times to detection of microorganisms isolated f rom two similar blood culture media, one containing saponin, were comp ared. A total of 2117 blood cultures were analysed in a prototype auto mated blood culture system. Significantly more gram-positive organisms (P<0.05) and gram-negative organisms (P<0.05), including Enterobacter iaceae (P<0.05) were recovered from the lyric medium. Average time to detection in the lytic medium was 15.8h, compared to 22.7h in the othe r medium (P<0.001). The improved recovery of microorganisms was most p ronounced in blood samples obtained from patients being treated with a ntibiotics at the time of venesection. In vitro experiments on antibio tic affected bacteria confirmed the protective effect of saponin.