Rapid Antibiotic Combination Testing for Carbapenem-Resistant Gram-Negative Bacteria within Six Hours Using ATP Bioluminescence

• Published in: Antimicrobial agents and chemotherapy 2018-09, Vol.62 (9)
• Main Authors: Cai, Yiying, Seah, Celene L, Leck, Hui, Lim, Tze-Peng, Teo, Jocelyn Q, Lee, Winnie, Tan, Thuan-Tong, Koh, Tse-Hsien, Ee, Pui Lai Rachel, Kwa, Andrea L
• Format: Article
• Language: English
• Subjects: Adenosine Triphosphate; Anti-Bacterial Agents; Carbapenems; Clinical Therapeutics; Drug Resistance, Multiple, Bacterial; Gram-Negative Bacteria; Gram-Negative Bacterial Infections
• ISSN: 0066-4804; 1098-6596
• DOI: 10.1128/AAC.00183-18

To guide the timely selection of antibiotic combinations against carbapenem-resistant Gram-negative bacteria (CR-GNB), an test with a short turnaround time is essential. We developed an ATP bioluminescence assay to determine effective antibiotic combinations against CR-GNB within 6 h. We tested 42 clinical CR-GNB strains (14 , 14 , and 14 strains) against 74 single antibiotics and two-antibiotic combinations. Bacteria (approximately 5 log CFU/ml) were incubated with an antibiotic(s) at 35°C; ATP bioluminescence was measured at 6 h and 24 h; and the measurements were compared to viable counts at 24 h. Receiver operating characteristic (ROC) curves were used to determine the optimal luminescence thresholds ( ) for distinguishing between inhibitory and noninhibitory combinations. The areas under the 6-h and 24-h ROC curves were compared using the DeLong method. Prospective validation of the established thresholds was conducted using 18 additional CR-GNB. The predictive accuracy of for the 6-h ATP bioluminescence assay was 77.5% when all species were analyzed collectively. Predictive accuracies ranged from 73.7% to 82.7% when each species was analyzed individually. Upon comparison of the areas under the 6-h and 24-h ROC curves, the 6-h assay performed significantly better than the 24-h assay ( < 0.01). Predictive accuracy remained high upon prospective validation of the 6-h ATP assay (predictive accuracy, 79.8%; 95% confidence interval [CI], 77.6 to 81.9%), confirming the external validity of the assay. Our findings indicate that our 6-h ATP bioluminescence assay can provide guidance for prospective selection of antibiotic combinations against CR-GNB in a timely manner and may be useful in the management of CR-GNB infections.