Rapid determination of AB₅ enterotoxins using membrane electrospray ionization mass spectrometry

Toxigenic bacterial pathogens play important role in enteric infections which remain a major cause of morbidity around the world. Although many methods have been reported for detection of enterotoxins, rapid analyses of AB₅ enterotoxins on protein-level in real samples is still challenging. A rapid quantitative method was developed in this study to determine bacterial AB₅ enterotoxins targeting at their unique peptides using membrane electrospray ionization mass spectrometry (MESI-MS). Precursor/product-ion pairs of peptides HDDGYVSTSISLR (HR), TPNSIAAISMEN (TN), MASDEFPSMCPADGR (MR) and AVNEESQPECQITGDRPVIK (AK) unique to enterotoxins Ctx, LT, Stx1 and Stx2 respectively were used for both toxin identification and quantitative analysis. The methodologies were validated including sensitivity, accuracy, precision and recovery in detection of simulated real samples. Larger scaled real sample detections with statistical analysis demonstrated that target peptides in developed enterotoxins analyses method are reliable.