Rapid Detection of Carbapenemase-Producing Enterobacteriacae Based on Surface-Enhanced Raman Spectroscopy with Gold Nanostars

The emergence and rapid spread of antibiotic resistance poses a serious threat to healthcare systems across the globe. The existence of carbapenemase-producing Enterobacteriaceae (CPE) such as Klebsiella pneumoniae renders the use of carbapenems, the last-resort class of beta-lactam antibiotics, ineffective against bacterial infections, often leading to CPE-associated mortalities. Current methods of detection such as the Carba NP test and modified Hodge's test require hours to days to detect, which delays the response to isolate patients for rapid intervention. Here, we developed a surface-enhanced Raman scattering (SERS)-based detection scheme which utilizes gold nanostars conjugated to a beta-lactam antibiotic ceftriaxone (CRO) as a beacon for rapid detection of bacterial beta-lactamase secreted by Delhi metalloproteinase (NDM)-producing Escherichia coli as our CPE model with carbapenemase activity. The cleavage of beta-lactam ring in CRO by NDM (Class B beta-lactamase) caused a detectable reduction in SERS intensities at 722, 1358, and 1495 cm(-1) within 25 min. Ratiometric analysis of the SERS peaks at 722, 1358, and 1495 cm(-1) normalized against the Raman peak of polystyrene cuvette at 620 cm(-1) showed the peak at 1358 cm(-1) having the most significant change in intensity upon CPE detection. This reduced detection time has not been reported to date for CPE detection, and our novel approach using SERS could be extended to detect the activity of other classes of beta-lactamases to broaden its clinical utility.