[Bact-Alert automatized system for blood cultures: 5 vs 7 days of incubation. First Argentine multicentre study]

Bact-Alert automatized system for blood cultures: 5 vs 7 days of incubation. First Argentine multicentre study. Between January and December 2001, we analyzed 80,141 blood cultures by the Bact-Alert system (14,960 FAN aerobics, 3,855 FAN anaerobic, 11,114 standards aerobics, 11,367 standards anaerobic, 12,054 pediatrics and 26,791 FAN pediatrics bottles) and 44.235 series from 27.615 patients at eight hospitals of Buenos Aires city, one of La Plata city and three of the Buenos Aires province. A total of 13,657 blood cultures yielded a positive result. Only 181 of them had been detected as positive between the 5th and 7th day of incubation and only 26 (0.19%) had clinical significance (Staphylococcus aureus 3; coagulase negative staphylococci 2; Enterococcus faecalis 1; Streptococcus pneumoniae 2; Campylobacter spp 1; Escherichia coli 1; Enterobacter cloacae 1; Enterobacteraerogenes 1; Citrobacter freundii 1; Klebsiella pneumoniae 1; Proteus mirabilis 1; Serratia marcescens 4; yeasts 7, including one strain of Cryptococcus neoformans). Of the total of contaminants, 38% were isolated by the anaerobic standard (65% were Propionibacterium spp and 29% coagulase negative staphylococci), 31.2% by the FAN aerobic (33.3% difphteroids and 28.9% Bacillus spp), 11.8% by the pediatric, 9% by FAN pediatric, 8.33% by aerobic standard and 1.4% by FAN anaerobic bottle. Our results show that the prolonged incubation of blood cultures for more than 5 days using the Bact-Alert system is unnecessary.