ABSTRACT
The Oxoid CO2 Gen system is compared with BBL GasPak and a carbon dioxide (CO2) incubator to evaluate its ability to support and enhance the growth of capnophilic bacteria. Clinical samples (n = 109) from various anatomical sites and 23 spiked samples are evaluated. The criteria used to compare the systems include amount of growth, colony size, colony morphology and haemolysis. Isolation rates, amounts of growth and morphology were similar in each system, but colony diameter was significantly larger in the jar-based systems. Significantly larger colonies grew in CO2 Gen than in BBL GasPak. alpha-Haemolytic zones were significantly larger in jar-based systems than in the CO2 incubator, and significantly larger in CO2 Gen than in BBL GasPak. beta-haemolytic zones were significantly larger in CO2 Gen than in the CO2 incubator. The CO2 Gen system appears to be an excellent alternative to established methods for generating an environment for capnophilic incubation.
Subject(s)
Bacteria/drug effects , Carbon Dioxide/pharmacology , Bacteria/growth & development , Bacteriological Techniques , Evaluation Studies as Topic , Female , HumansABSTRACT
The recovery rates and times to detection of microorganisms isolated from two similar blood culture media, one containing saponin, were compared. A total of 2117 blood cultures were analysed in a prototype automated blood culture system. Significantly more gram-positive organisms (P<0.05) and gram-negative organisms (P<0.05), including Enterobacteriaceae (P<0.05) were recovered from the lytic medium. Average time to detection in the lytic medium was 15.8 h, compared to 22.7 h in the other medium (P<0.001). The improved recovery of microorganisms was most pronounced in blood samples obtained from patients being treated with antibiotics at the time of venesection. In vitro experiments on antibiotic affected bacteria confirmed the protective effect of saponin.