In vitro evaluation of the BACTEC resin-containing blood culture bottle

The BACTEC resin-containing blood culture bottle (16B; Johnston Laboratories) was designed to bind antibiotics and to support bacterial growth. However, only modest increases in the recovery rates of pathogens have been found in clinical studies. This in vitro study evaluated the ability of the 16B to recover organisms from human serum containing clinically achievable concentrations of antibiotics. Escherichia coli, Enterobacter cloacae, Klebsiella pneumoniae, Pseudomonas aeruginosa, Haemophilus influenzae, Staphylococcus aureus, Streptococcus faecalis, and a viridans streptococcus were added to serum containing antibiotic(s), and at various time intervals of antibiotic exposure, portions were removed and inoculated into both the 16B and the 6B (conventional aerobic) bottles. The studies of the kinetics of killing of the bacterial strains by the various antibiotics showed a good correlation between those combinations of bacteria-antibiotic(s) which produced slow killing and the combinations of bacteria-antibiotic(s) which were recovered preferentially in the 16B bottles. Low recovery rates were noted when the antibiotics killed the organisms rapidly. The indications for use of the resin-containing blood culture bottle should be limited to those situations in which the patient is receiving antibiotics and the bacteremia is suspected to involve a pathogen which is killed slowly by the administered drug(s) or when the bacteremia is continuous. The failure of the BACTEC 16B blood culture bottle to recover organisms may in part reflect the bactericidal activity of the antibiotics administered.