A simple blood-culture bacterial pellet preparation for faster accurate direct bacterial identification and antibiotic susceptibility testing with the VITEK 2 system

Abstract

An ammonium chloride procedure was used to prepare a bacterial pellet from positive blood cultures, which was used for direct inoculation of VITEK 2 cards. Correct identification reached 99 % for Enterobacteriaceae and 74 % for staphylococci. For antibiotic susceptibility testing, very major and major errors were 0.1 and 0.3 % for Enterobacteriaceae, and 0.7 and 0.1 % for staphylococci, respectively. Thus, bacterial pellets prepared with ammonium chloride allow direct inoculation of VITEK cards with excellent accuracy for Enterobacteriaceae and a lower accuracy for staphylococci.