Evaluation of the effectiveness of the RENDER automatic blood culture system

Abstract

This study aimed to evaluate the effectiveness of RENDER system (Zhuhai Meihua Medical Technology Limited, Zhuhai, China), an automatic hemoculture system by determining the time to detection (TTD) when using certain amount of bacterial inoculum, and testing the effectiveness of resin in the presence of antimicrobial agents. A total of 8 species of bacteria which are frequently isolated from blood including: Staphylococcus epidermidis, Streptococcus pneumoniae, viridians Streptococcus, Listeria monocytogenes, Escherichia coli, Pseudomonas aeruginosa, Haemophilus influenzae, Burkholderia pseudomallei and one strain of Candida albicans were studied. Each of the 2 inoculum sizes, approximately 100 and 10 colony forming unit (CFU), was injected into the culture bottles before incubated in the automatic system. In addition, bottles with and without ceftriaxone (CRO), ceftazidime (CAZ) and ofloxacin (OFX) were inoculated with 100-1000 CFU of P. aeruginosa ATCC 27853, E. coli ATCC 25922 and Staphylococcus aureus ATCC 29213. The results showed that RENDER system detected bacterial growth with small inoculum sizes as 100-700 CFU. Among the bacteria tested, E. coli gave the shortest time to positive (11 hrs), whereas H. influenzae showed sigh of positive lastly (48 hrs). The culture bottles of E. coli ATCC 25922, P. aeruginosa ATCC 27853 and S. aureus ATCC 29213 (with 5000, 700 and 3000 CFU inoculum, respectively) demonstrated the sign of growth under without/with CRO at 9 /9, 16/17 and 11/11 hrs respectively; under without/with OFX at 9/9, 16/16 and 11/13 hrs respectively; and under without/with CAZ at 9/66, 16/30 and 11/27 hrs respectively. The delayed growth under the presence of CAZ may be due to the incomplete absorption of the resin combining with the highly sensitive property of the bacteria to CAZ. This study provided primary information of the effectiveness of RENDER automatic system for hemoculture and the efficacy of resin to absorb three antimicrobials. This information will be useful for considered using automatic culture system for blood culture which helps shorten the time to report the results and support the appropriate treatment for patients.

Keywords: bacteremic, hemoculture, automate culture