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

J Med Microbiol. 2013 May;62(Pt 5):773-777. doi: 10.1099/jmm.0.049361-0. Epub 2013 Jan 17.


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.

MeSH terms

  • Anti-Bacterial Agents / pharmacology*
  • Bacteriological Techniques*
  • Drug Resistance, Bacterial*
  • Gram-Negative Bacteria / classification
  • Gram-Negative Bacteria / drug effects
  • Gram-Negative Bacteria / isolation & purification*
  • Gram-Positive Bacteria / classification
  • Gram-Positive Bacteria / drug effects
  • Gram-Positive Bacteria / isolation & purification*
  • Humans
  • Microbial Sensitivity Tests
  • Sensitivity and Specificity


  • Anti-Bacterial Agents