Performance of the Check-Direct ESBL Screen for BD MAX(TM) for detection of asymptomatic fecal carriage of ESBL producing Escherichia coli and Klebsiella pneumoniae.

OBJECTIVES: Accurate diagnostic methods are crucial for the detection of extended-spectrum beta-lactamase producing Enterobacterales (ESBL-E). Besides the culture-based gold standard methods, new molecular gene detection tests are reaching the market. The aim of this study was to investigate the performance of direct quantitative PCR based methods Check-Direct ESBL and CPE Screen for BD MAX(TM) in relation to traditional culture based methods for detection of ESBL-E faecal carriage. METHODS: Faecal samples were collected from healthy adult volunteers. Samples were cultured on chromogenic ESBL agar plates and screened for ESBL producing Escherichia coli (EC) and Klebsiella pneumoniae (KP). Confirmed ESBL and AmpC producing isolates were further analyzed using whole genome sequencing (WGS). In addition, faecal samples were analyzed using Check-Direct ESBL and CPE Screen for BD MAX(TM) and the results were compared with the gold standard that is culture-based method. RESULTS: Of the 176 faecal samples, 11 (6.3%) grew ESBL-producing EC or KP isolates. Among 173 analyzed samples, Check-Direct ESBL Screen for BD MAX(TM) detected 22 (12.7%) ESBL positive samples. No CPE producing isolates were detected. Two culture-positive samples remained negative with Check-Direct ESBL Screen for BD MAX(TM). Culture negative but qPCR positive discrepancy was observed in 12 (6.9%) samples. Altogether, concordant results were obtained from 158 samples (91.3%, 9 positive and 149 negative). CONCLUSIONS: Check-Direct ESBL Screen for BD MAX(TM) is a fast screening method for ESBL carriage. However, several discrepant results were observed which hinders interpretation. More clinical samples should be tested in combination with culture to evaluate the true benefits of this method.