Korean J Lab Med.  2009 Feb;29(1):25-34. 10.3343/kjlm.2009.29.1.25.

Evaluation of MicroScan and Phoenix System for Rapid Identification and Susceptibility Testing Using Direct Inoculation from Positive BACTEC Blood Culture Bottles

• Chung JW
• Jeon HS
• Sung H
• Kim MN

• KMID: 1781590
• DOI: http://doi.org/10.3343/kjlm.2009.29.1.25

Abstract

BACKGROUND
Procedures for rapid identification and susceptibility testing by direct inoculation (DI) from positive blood culture bottles into an automated system have not been standardized. This study was purposed to evaluate DI from BACTEC 9240 blood culture system (BD, USA) into MicroScan (Dade Behring, USA) or Phoenix (BD, USA).
METHODS
From May to June 2006, bacterial pellets from positive aerobic bottles showing gram-positive cocci (GPC) or gram-negative rods (GNR) of single morphology were directly inoculated to MicroScan PosCombo1A and NegCombo32 and to Phoenix PMIC/ID-107 and NMIC/ID-53. In addition, the automated instruments were also inoculated from subcultures (standard inoculations, SI). Species identification and susceptibilities were compared between DI and SI and between MicroScan and Phoenix.
RESULTS
A total of 108, 104, and 78 specimens were tested with MicroScan, Phoenix, and both, respectively. When DI and SI were matched, 94.8% of GPC were correctly identified with MicroScan, compared to 80.7% with Phoenix, and 93.9% of GNR were correctly identified with MicroScan, compared to 95.7% with Phoenix. DI with MicroScan and Phoenix showed correct susceptibilities in 94.6% of 1,150 and 96.5% of 660 tests (with very major error [VME] of 1.1% and 1.1%), respectively, among GPC and in 94.4% of 942 and 96.3% of 781 tests (with VME of 0.6% and 0%), respectively, of GNR. Correlation of identification/susceptibilities between MicroScan and Phoenix using DI were 81.8%/98.0% for Staphylococcus aureus and 100.0%/95.6% for Escherichia coli.
CONCLUSIONS
DI warrants a reliable method for identification and susceptibility testing of both GPC and GNR in MicroScan, and those of only GNR in Phoenix.

Keyword

Blood culture; Direct inoculation; Identification; Susceptibility; MicroScan; Phoenix

MeSH Terms

Automation
Bacterial Typing Techniques/instrumentation/*methods
Culture Media
Gram-Negative Bacteria/*classification/drug effects/isolation & purification
Gram-Negative Bacterial Infections/blood/*microbiology
Gram-Positive Bacterial Infections/blood/*microbiology
Gram-Positive Cocci/*classification/drug effects/isolation & purification
Humans
Microbial Sensitivity Tests/instrumentation/*methods
Reagent Kits, Diagnostic
Sensitivity and Specificity

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