The present study was designed to compare a fully automated identification/antibiotic susceptibility testing (AST) system BD Phoenix (BD) for its efficacy in rapid and accurate identification and AST with conventional manual methods and to determine if the errors reported in AST, such as the (very major errors) VME (false susceptibility), (major errors) ME (false resistance), and (minor errors) MiE (intermediate category interpretation) were within the range certified by FDA. Identification and antimicrobial susceptibility test results of eighty-five clinical isolates including both gram-positive and negative were compared on Phoenix considering the results obtained from conventional manual methods of identification and disc diffusion testing of antibiotics as standards for comparison. Phoenix performed favorably well. There was 100% concordance in identification for gram-negative isolates and 94.83% for gram-positive isolates. In seven cases, Phoenix proved better than conventional identification. For antibiotic results, categorical agreement was 98.02% for gram-positive and 95.7% for gram-negative isolates. VME was 0.33%, ME 0.66%, MiE 0.99% for gram-positive isolates and 1.23% VME, 1.23% ME, and 1.85% MiE for gram-negative isolates. Therefore, this automated system can be used as a tool to facilitate early identification and susceptibility pattern of aerobic bacteria in routine microbiology laboratories. 1. Introduction Two million people in India die each year due to infectious diseases [1]. There is a need to integrate medicine and innovative technology in our public health system to provide rapid, efficient, accurate, and cost-effective results for identification and antimicrobial susceptibility testing (AST) of pathogens. Automated identification/AST systems can aid in rapid diagnosis of bacterial pathogens. Since Phoenix (BD) was first installed in India at our institute, a comparison study to evaluate it in reference to conventional manual methods was done. 2. Material and Methods Eighty-five clinical isolates were studied on Phoenix (BD Diagnostics, Gurgaon, India) of which 58 were gram-positive (PMIC panels) and 27 were gram-negative isolates (NMIC panels). Isolates were processed directly from the primary plates, and purity testing was done simultaneously by standard methods. Identification by conventional methods was confirmed on the basis of results obtained by performing routine biochemical tests [2] and AST was performed by the disc diffusion test based on Kirby-Bauer method in compliance with CLSI guidelines [3]. Identification in
References
[1]
S. Durand, “Executive summary—the globalization of infectious disease,” 2000, http://www.prcdc.org/files/Infectious_Disease.pdf.
[2]
W. Winn, S. Allen, W. Janda et al., “Guidelines for the collection, transport, processing, analysis and reporting of cultures from specific specimen sources,” in Koneman's Color Atlas and Textbook of Diagnostic Microbiology, pp. 68–111, Williams & Wilkins, 6th edition, 2006.
[3]
Clinical and Laboratory Standards Institute Performance Standards For Antimicrobial Susceptibility Testing, vol. 29 of Nineteenth informational supplement, M 100-S19, Clinical and Laboratory Standards Institute, Wayne, Pa, USA, 2009.
[4]
J. L. Donay, D. Mathieu, P. Fernandes et al., “Evaluation of the automated Phoenix system for potential routine use in the clinical microbiology laboratory,” Journal of Clinical Microbiology, vol. 42, no. 4, pp. 1542–1546, 2004.
[5]
K. M. Kuper, D. M. Boles, J. F. Mohr, and A. Wanger, “Antimicrobial susceptibility testing: a primer for clinicians,” Pharmacotherapy, vol. 29, no. 11, pp. 1326–1343, 2009.
[6]
S. E. Sharp, Cumitech 31A: Verification and Validation of ProcEdures in the Clinical Microbiology Laboratory, ASM press, 2009.
[7]
H. S. Sader, T. R. Fritsche, and R. N. Jones, “Accuracy of three automated systems (MicroScan WalkAway, Vitek, and Vitek 2) for susceptibility testing of Pseudomonas aeruginosa against five broad-spectrum beta-lactam agents,” Journal of Clinical Microbiology, vol. 44, no. 3, pp. 1101–1104, 2006.
[8]
S. Juretschko, V. J. Labombardi, S. A. Lerner et al., “Accuracies of β-lactam susceptibility test results for Pseudomonas aeruginosa with four automated systems (BD Phoenix, MicroScan WalkAway, Vitek, and Vitek 2),” Journal of Clinical Microbiology, vol. 45, no. 4, pp. 1339–1342, 2007.
[9]
S. Brisse, S. Stefani, J. Verhoef, A. Van Belkum, P. Vandamme, and W. Goessens, “Comparative evaluation of the BD Phoenix and VITEK 2 automated instruments for identification of isolates of the Burkholderia cepacia complex,” Journal of Clinical Microbiology, vol. 40, no. 5, pp. 1743–1748, 2002.
[10]
S. D. Dallas, P. M. Pekarek, T. J. Mills, et al., “Comparison of BD Phoenix to biomereux VITEK for the identification and susceptibility testing of common bacterial isolates,” in Proceedings of the 105th General Meeting of the American Society for Microbiology, 2005.
[11]
S. A. Mittman, R. C. Huard, P. Della-Latta, and S. Whittier, “Comparison of BD Phoenix to vitek 2, MicroScan MICroStREP, and etest for antimicrobial susceptibility testing of Streptococcus pneumoniae,” Journal of Clinical Microbiology, vol. 47, no. 11, pp. 3557–3561, 2009.
[12]
K. C. Carroll, A. P. Borek, C. Burger et al., “Evaluation of the BD Phoenix automated microbiology system for identification and antimicrobial susceptibility testing of staphylococci and enterococci,” Journal of Clinical Microbiology, vol. 44, no. 6, pp. 2072–2077, 2006.
[13]
K. C. Carroll, B. D. Glanz, A. P. Borek et al., “Evaluation of the BD Phoenix automated microbiology system for identification and antimicrobial susceptibility testing of Enterobacteriaceae,” Journal of Clinical Microbiology, vol. 44, no. 10, pp. 3506–3509, 2006.
