Evaluation of a blood culture medium BHI-S-Lysis for BCB Release System Roche.

The new blood culture medium BHI-S Lysis for the BCB Release System (F. Hoffmann-La Roche AG., Basel, Switzerland), which lyses blood cells, was compared with the Hémoline performance Duo (BioMérieux, Marcy l'Etoile, France) including a diphasic medium and a modified Wilkins Chalgren broth. A total of 1998 sets were each inoculated with 7 ml of blood. In the laboratory, agar-coated paddles were attached to the BHI-S-Lysis. Overall, there was a statistically significant difference between the BHI-S-Lysis and the diphasic medium, or Wilkins Chalgren broth, in the recovery of clinically important microorganisms. The yield of pathogens with the BHI-S-Lysis, diphasic medium and Wilkins Chalgren broth was 115, 68 and 58, respectively. Staphylococci were detected by the BHI-S-Lysis significantly more frequently. Out of 50 bacteraemias, 12 were diagnosed with the BHI-S-Lysis only, three with the diphasic medium only, and three with the Wilkins Chalgren broth only. Contaminant isolates occurred with significantly greater frequency in the BHI-S-Lysis than in the two BioMérieux systems, in particular with coagulase-negative staphylococci. No speed advantage was present for all groups of micro-organisms and blood culture media. This good performance of the BHI-S-Lysis medium in detecting a larger number of pathogens should be confirmed by further evaluations.