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

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 grampositive 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. (Korean J Lab Med 2009;29:25-34)

Direct inoculation on Phoenix panels for identification and antimicrobial susceptibility from positive BACTEC cultures: First study from India

“…However, further refinements are needed in the procedure for better results. The results are similar to a study of gram-negative isolates on Vitek 2 system [7] and Phoenix [8] where 82. 2% and 95.7% of these strains were correctly identified to species level, 80.7% gram-positive isolates were correctly identified by direct inoculation.…”

“…2% and 95.7% of these strains were correctly identified to species level, 80.7% gram-positive isolates were correctly identified by direct inoculation. [8] VMEs in the present study were 0.13%, 0.73% for gram-negative and gram-positive isolates, respectively. These values are comparable to 0% and 1.1% in a study.…”

“…These values are comparable to 0% and 1.1% in a study. [8] Another study comparing direct versus growth panels for gram-negative isolates has shown 0.1% very major errors, 0.1% major errors, and 0.8% minor errors. [3] Gram-positive organisms, such as Bacillus cereus, Pediococcus pentosaceus, Alloiococcus otitidis and Pasteurella pneumotropica were identified without susceptibility results in 5 direct panels; as they were not in Phoenix taxonomy.…”

Development and Evaluation of Oligonucleotide Chip Based on the 16S-23S rRNA Gene Spacer Region for Detection of Pathogenic Microorganisms Associated with Sepsis

“…Therefore, many automated identification and susceptibility testing systems are available (3,11). These can identify microorganisms and determine antibiotic susceptibility in hours; however, they require pure colonies, making overnight subculture of positive blood cultures inevitable.…”

Determination and Identification of Antibiotic Drugs and Bacterial Strains in Biological Samples

“…Moreover, advanced software with modern automated systems allows different ways of generating, processing, collecting and transmitting results. Unfortunately, in biochemical tests, the concentration and uniformity of suspension required for inoculation plays a very critical role in the accuracy of the identification [111][112][113].…”