Identification of foodborne botulism with mixed serotypes A, B and E and their in vivo profiles in four types of clinical specimens

Abstract

Background Diagnosis of mixed botulism caused by multiple serotypes of botulinum neurotoxin (BoNT) is still a challenge due to the lack of reliable detection method. The present study develops a feasible laboratorial method to detect BoNTs in clinical samples and aims to provide insights into in vivo profiles of different toxin serotypes. Methods An isotope dilution Endopep-MS method for simultaneously detection of seven serotypes of BoNT was established and further applied to diagnosis of mixed botulism through one-step immunocapture procedure. A comprehensive analysis of four types of clinical specimens, i.e., serum, vomitus, urine, and gastric mucosa samples, from four suspected patients was performed. Results The established robust multiplex Endopep-MS method was applied to accurately identify and monitor BoNT/A, B and E in specimens during a clinically and therapeutically relevant timeframe. Serotypes and concentrations of BoNT in specimens revealed a good correlation with symptoms and progresses of disease. Additionally, serum was evidenced to be more suitable for detection BoNT/A with a detection window up to 12 days. Urine sample, although scarcely used in foodborne botulism diagnosis, was validated to be suitable for testing BoNTs with a longer detection window up to 25 days. Conclusions This is the first comprehensive analytical research on in vivo profiles of serotypes A, B and E in different types of specimens from mixed botulism cases to the best of our knowledge, and our method and findings facilitate the toxin detection and identification by clinical diagnostic laboratories.