Implementing the Bruker MALDI Biotyper in the Public Health Laboratory for C. botulinum Neurotoxin Detection

Abstract

Currently, the gold standard method for active botulinum neurotoxin (BoNT) detection is the mouse bioassay (MBA). A Centers for Disease Control and Prevention-developed mass spectrometry (MS)-based assay that detects active BoNT was successfully validated and implemented in a public health laboratory in clinical matrices using the Bruker MALDI-TOF MS (Matrix-assisted laser desorption ionization–time of flight mass spectrometry) Biotyper. For the first time, a direct comparison with the MBA was performed to determine MS-based assay sensitivity using the Bruker MALDI Biotyper. Mice were injected with BoNT/A, /B, /E, and /F at concentrations surrounding the established MS assay limit of detection (LOD) and analyzed simultaneously. For BoNT/B, /E, and /F, MS assay sensitivity was equivalent or better than the MBA at 25, 0.3, and 8.8 mLD50, respectively. BoNT/A was detected by the MBA between 1.8 and 18 mLD50, somewhat more sensitive than the MS method of 18 mLD50. Studies were performed to compare assay performance in clinical specimens. For all tested specimens, the MS method rapidly detected BoNT activity and serotype in agreement with, or in the absence of, results from the MBA. We demonstrate that the MS assay can generate reliable, rapid results while eliminating the need for animal testing.

Molecular Characterization of Clostridium botulinum Harboring the bont/B7 Gene

“…Single colonies were inoculated into Trypticase Peptone Glucose Yeast broth and incubated overnight anaerobically at 35°C. The presence of C. botulinum genes and toxin in the isolate from New York (BAC04- 07755) were detected by multiplex polymerase chain reaction and mass spectrometry as described previously (Davis et al , 2016; Perry et al , 2017).…”

Detection of Active BoNT/C and D by EndoPep-MS Using MALDI Biotyper Instrument and Comparison with the Mouse Test Bioassay

“…This lethality assay possesses high sensitivity, can measure toxin activity, and can detect toxin serotype by means of specific antitoxins. However, it does pose ethical issues because it requires the sacrifice of many animals, it is time consuming since four days are needed for confirmation of negative samples, and it requires a large volume of sample [ 11 ]. Furthermore, other substances in the sample, e.g., other toxins or irritating ingredients such as spices in foods, can occasionally lead to inconclusive results [ 12 , 13 ].…”

Outbreak of botulism type A in dairy cows detected by MALDI-TOF mass spectrometry

“…Toxin testing was performed using the Bruker matrix-assisted laser desorption/ionization timeof-flight mass spectrometer (MALDI-TOF MS; Biotyper; Bruker Daltonics). 15 BoNT/A was detected in rumen contents [1][2][3] and was inconclusive in rumen contents from 1 of 3 cows. BoNT/B, /E, and /F were not detected (0 of 3 cows), and we did not test for BoNT/C and /D because there was insufficient sample volume.…”

“…3,4,10 There are documented geographic differences in the type of botulism toxin prevalent in soil, with type A found in the western United States and type B found in the eastern United States. 17 Humans are affected by BoNT/A, /B, /E, and /F, 1,15 and cases of human BoNT/A are not uncommon on the east coast. 15 Human botulism is primarily linked to ingestion of preformed toxin in food.…”

“…17 Humans are affected by BoNT/A, /B, /E, and /F, 1,15 and cases of human BoNT/A are not uncommon on the east coast. 15 Human botulism is primarily linked to ingestion of preformed toxin in food. Human illness may also be caused by introduction of spores through open wounds in the skin, inadvertent intoxication through therapeutic or cosmetic use, or colonization of spores in the intestinal tract of infants.…”