[Effect of anaerobiosis in 6 blood-culture media on the recovery rate of aerobic microorganisms (author's transl)].

Commercially manufactured blood-culture bottles with 6 different culture media have been considered in this study. The bottles were respectively supplemented with 10% fresh human blood and inoculated with obligate aerobic and facultative anaerobic microorganisms known to cause bacteremia and fungemia. The inoculum size ranged from less than 10 to 10(2) CFU per blood-culture bottle. The study was carried out by alternately incubating one set of bottles anaerobically for two days before being vented, while the other set was vented immediately after inoculation. The effect of anaerobic and aerobic atmospheres on growth intensity, recovery rate and survival durability of the 11 microbial strains has been studied. The maintenance of anaerobic atmosphere for 2 days before venting the blood-culture bottles caused: a) 2 to 4 days delay in detecting nonfastidious bacteria and fungi; b) rapid death of acid-sensitive bacteria in poorly buffered culture media; c) inability of fastidious bacteria to grow in any of the 6 culture media. On the other hand venting the blood-culture bottles immediately after inoculation enabled: a) rapid detection of bacteria by an early subculture after 8 hours of incubation; b) diagnostic advantage of at least 2 days with rapidly growing bacteria which make more than 50% of the whole microbial spectrum; c) good growth of fastidious bacteria. Collectively, brain heart dipeptone broth proved to be the most effective culture medium for detection of obligate aerobic microorganisms responsible for bacteremia.