Comparison of BD Phoenix automated system with conventional methods for identification & susceptibility testing of common bacteria.

Dr Mudshingkar Swati; Balsubramanium Usha; Dr Palewar Meghna; Dr Kongre Vaishali; Dr Bhardwaj Renu; Kulkarni Vandana

Volume : VI, Issue : IX, September - 2017

Comparison of BD Phoenix automated system with conventional methods for identification & susceptibility testing of common bacteria.

Dr Mudshingkar Swati, Balsubramanium Usha, Dr Palewar Meghna, Dr Kongre Vaishali, Dr Bhardwaj Renu, Kulkarni Vandana

Abstract :

Background–

As hospitals face the continuing challenge of treating sicker patients, the burden falls to clinical microbiology laboratories to provide accurate and rapid identification and susceptibility of the pathogens recovered. To accomplish this goal, many laboratories rely upon automated systems. The objective of this study was to evaluate the performance of the Phoenix Automated Microbiology System (BD Biosciences, USA) system for identification and antimicrobial susceptibility of pathogens from clinical specimens vis–�–vis conventional method.

Methodology–

A total of 81 isolates, 44 GNB and 37 GPC were tested by three types of phoenix panels for gram–negative bacilli (GNB), gram–positive cocci (GPC–Staphylocooci and Enterococci) and streptococci. The results were compared with conventional microbiological methods. To resolve discrepancy, tests were repeated by both methods.

Results–

The overall levels of agreement till genus– and species–level identifications for GNB, GPC (Staphylocooci and Enterococci) and Streptococci (n=13) were 90.4% and 94.7%, 91.6 and 84.6%, 84.6% and 75% respectively. There were 16 discrepant identification results by phoenix (GNB– 10, GPC– 6).All salmonella were identified only till genus level by Phoenix while all 3 viios were incorrectly identified as aeromonas species.

For AST results, very major Discrepancy VMD (false susceptible result with phoenix), major Discrepancy MD (false resistant with phoenix) and minor Discrepancy mD rates were calculated. For GNB susceptibility, VMD=2.8%, MD=4.4%, mD=1.1% were seen. For Gram–positive cocci VMD=1.5%, MD=3.1%, mD=2.3%. The mean duration of test for phoenix was 14.7 hours as compared to19 hours by conventional methods.

Conclusion–The phoenix performed favorably and faster than traditional methods for ID and AST of common pathogens with exception of identification of Viio spp.