Objectives: To evaluate BACTEC 9050 system capacity for detection of bacteremia due to Brucella spp.
Material and methods: 16 febrile patients were studied during an epidemic infection for Brucella spp. Suspicious of brucellosis was serologically confirmed with Rose Bengal test and agglutination tube test. Only one blood culture was processed per patient. Ten millilitres of blood were inoculated in a Bactec Plus aerobic/F bottle and incubated in BACTEC 9050 automatic system. The bottles were kept in incubation during 21 days, and they were subcultured when the machine detected its growth; if not, a blind subculture was performed after 21 days.
Results: 13 of 16 patients showed bacteriemia (81.2%): 11 patients were detected by BACTEC 9050 system and 2 patients by blind subculture after 21 days. A positive result appeared in 149.8 hours (6.2 days) as a mean. Earlier detections were seen in 83 hours (3.4 days) and the latest ones at 245 hours (10.2 days). The aetiology agent of the epidemic infection was Brucella mellitensis biotype 1. We found significative differences comparing the BACTEC 9050 with BACTEC 9120/9240 systems (p<0.03).
Conclusions: Incubation protocols of 5 days are not useful for BACTEC 9050 system in the case brucellosis suspicious. Protocols of 7 would detect only 69.2% of the cases.