Rapid detection of extended‐spectrum β‐Lactamases producers in Enterobacteriaceae using a calorimetry approach.

Aim: To design and assess a novel protocol that employs isothermal titration calorimetry (ITC) for rapid detection of extended‐spectrum β‐lactamase (ESBL)‐producers in clinical pathogens. Methods and Results: A total of 69 clinical Enterobacteriaceae isolates were examined in the new ESBL‐ITC test by examining the heat profiles associated with enzyme hydrolysis of different substrates (imipenem, cefotaxime and clavulanic acid). The presence of β‐lactamase genes in the bacteria tested was confirmed by PCR and DNA sequencing. Comparative analysis between ESBL‐ITC and conventional minimum inhibitory concentrations (MIC)/combined disk method (CDM) showed high agreement between the two assays. However, the ESBL‐ITC test had a remarkable advantage of providing testing result within 1 h, in comparison to the 32–48 h required by MIC/CDM. Conclusions: The ESBL‐ITC test developed in this work offers a new option for rapid and accurate detection of ESBL‐producers. Significance and Impact of the Study: Timely detection of ESBL‐producers is vital to guide the decision‐making process in clinical treatment as well as in hospital‐infection control. The new ESBL‐ITC test provides a rapid phenotypic assay that can be further adapted for clinical diagnosis of ESBL‐producing pathogens. [ABSTRACT FROM AUTHOR]