An optimized algorithm with improved turnaround time for detection of carbapenemase-producing Enterobacterales using the NG Test CARBA 5 in a routine laboratory

• Published in: Journal of medical microbiology Vol. 69; no. 2; pp. 228 - 232
• Main Authors: Ratnayake, Lasantha, Ang, Hui Zhen, Ong, Chiou Horng, Chan, Douglas Su Gin
• Format: Journal Article
• Language: English
• Published: England 01-02-2020
• Subjects: Algorithms; Bacterial Proteins - genetics; Bacterial Proteins - metabolism; beta-Lactamases - genetics; beta-Lactamases - metabolism; Clinical Laboratory Techniques - economics; Clinical Laboratory Techniques - methods; Colony Count, Microbial - economics; Colony Count, Microbial - methods; Enterobacteriaceae - enzymology; Enterobacteriaceae - genetics; Enterobacteriaceae - growth & development; Enterobacteriaceae - isolation & purification; Enterobacteriaceae Infections - diagnosis; Enterobacteriaceae Infections - microbiology; Enzyme Assays - economics; Enzyme Assays - methods; Humans; Sensitivity and Specificity; CARBA Smart; CPE detection; CARBA 5; turnaround time
• ISSN: 0022-2615; 1473-5644
• DOI: 10.1099/jmm.0.001132

Rapid and reliable detection of carbapenemase-producing
(CPE) from surveillance cultures is critical in supporting a good infection control programme. We implemented a new algorithm for CPE detection incorporating the NG Test CARBA 5 in January 2019.
Our goals were to compare turnaround time (TAT), costs and staff requirements between the old and new algorithm, and to evaluate the performance of the CARBA 5 test directly on colonies grown on CARBA Smart agar.
We analysed and compared the TAT of CPE surveillance cultures processed using the old and new CPE screening algorithm. The total actual reagent costs and staff requirements for the new CPE algorithm were compared with the estimated costs and staff requirements of the old CPE algorithm.
Of 197 isolates included in the evaluation of the new algorithm, 64 were positive for carbapenemases by both CARBA 5 and Xpert Carba-R assay. Of the 133 that were negative, two were found to harbour NDM and IMI genotypes. Significant improvements in TAT were achieved with 88.7 % of cultures with CPE, reported on the same day as growth was observed on CARBA Smart agar compared to none in the old algorithm. The new algorithm incurred lower costs and, based on our workload, the new algorithm is estimated to save 28.9 man-hours annually.
CARBA 5 performs well on colonies growing on CARBA Smart agar and significant improvements in TAT can be achieved without incurring additional costs or staff requirements.