The performance of 4 different supplements and 5 blood culture bottles types in detection of bacteria and Candida spp. in simulated sterile body fluid cultures

Abstract

The purpose of this investigation was to evaluate the performance of 4 supplements: horse blood, fastidious organisms supplement (FOS), haemin isovitalex albumine (HIA), and brain heart infusion-haemin isovitalex albumine (BHI-HIA) and 5 blood culture bottles: Bactec Mycosis IC/F, Plus Aerobic/F, Peds Plus/F from the Bactec 9240 system, and BacT/Alert FA and BacT/Alert PF from the BacT/Alert 3D system, in detection of bacteria and Candida spp. in simulated sterile body fluids other than blood models. In total, 8 reference strains (Staphylococcus aureus, Staphylococcus epidermidis, Streptococcus pneumoniae, Neisseria meningitidis, Haemophilus influenzae, Listeria monocytogenes, Candida albicans, and Candida parapsilosis) and 11 clinical bacteria and yeast isolates (6 isolates from cerebrospinal fluid and 5 isolates from blood) were included in this study. Horse blood, FOS, and HIA were significantly better than no supplements (P < 0.0001, P < 0.0002, and P = 0.05, respectively) in detection of bacteria. Interestingly, there was no significant difference between BHI-HIA and bottles without any supplements. Sixty bottles analyzed of which 59 (98.33%) bottles with horse blood, 53 (88.33%) with FOS, 45 (75.00%) with HIA, and 43 (71.67%) with BHI-HIA signaled positive. The positivity rates with horse blood were significantly higher than with HIA and BHI-HIA (P < 0.0005 and P < 0.0001, respectively). Similarly, the blood culture bottles with horse blood had shorter time to detection (TTD) compared to bottles with FOS and HIA (P < 0.05 and P < 0.0001, respectively). When yeasts were analyzed, almost all (124/125) blood culture bottles with Candida spp. signaled positive even in the absence of supplements. Bactec Mycosis IC/F had significantly shorter TTD compared to Bactec Peds Plus/F, Bactec Plus Aerobic/F, BacT/Alert FA, and BacT/Alert PF bottles in detection of Candida spp. (P < 0.005, P < 0.05, P < 0.001, and P < 0.001, respectively). The present study showed that horse blood was the most effective supplement in growth of bacteria in the blood culture bottles that were analyzed in the study.

Keywords: Blood culture bottles; Infection; Sterile body fluids.