Development of a MALDI-TOF MS model for differentiating haemorrhagic septicaemia-causing strains of Pasteurella multocida from other capsular groups

Authors: MADDOCK, KELLI - North Dakota State University; STENGER, BRIANNA - North Dakota State University; ROBERTS, JILL - University Of South Florida; Wynn, Emily; Clawson, Michael - Mike; LOY, JOHN - University Of Nebraska

Submitted to: Journal of Microbiological Methods
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 11/1/2024
Publication Date: 11/2/2024
Citation: Maddock, K., Stenger, B.L., Roberts, J.C., Wynn, E.L., Clawson, M.L., Loy, J.D. 2024. Development of a MALDI-TOF MS model for differentiating haemorrhagic septicaemia-causing strains of Pasteurella multocida from other capsular groups. Journal of Microbiological Methods. 227. Article 107067. https://doi.org/10.1016/j.mimet.2024.107067.
DOI: https://doi.org/10.1016/j.mimet.2024.107067

Interpretive Summary: Pasteurella multocida is an opportunistic bacterial pathogen that causes disease in birds, mammals, and reptiles. There are many different strain types of P. multocida that vary by the range of animals they typically infect and the severity of disease they can cause. In cattle, several strain types cause bovine respiratory disease (BRD), which is a world-wide animal health, well-being, and economic concern. Other types cause hemorrhagic septicemia (HS), a fast moving and often deadly disease that affects cattle and water buffalo primarily in Africa, Asia, the Middle East, and Southern Europe. HS is considered a foreign animal disease in the United States as cases have not been detected within its borders for over thirty years. An ability to quickly detect HS-causing P. multocida strains is part of a vital strategy to prevent the reemergence of HS in the U.S., as well as controlling outbreaks within endemic areas of the world. Additionally, detection of P. multocida strains causing BRD can lead to early interventions and more effective treatments. In this study, a test was developed to distinguish BRD and HS causing P. multocida strain types using matrix assisted laser desorption ionization time-of-flight mass spectrometry (MALDI-TOF MS). This method involves excitation of biological molecules of the bacteria with a laser, which creates unique and diagnostic patterns that are like a fingerprint. Importantly, MALDI-TOF MS is commonly used in veterinary diagnostic labs, thus, the test can be easily integrated into national and international diagnostic and surveillance programs that detect pathogens of veterinary importance. This could facilitate rapid detection and timely responses to HS and BRD outbreaks that occur in the U.S. or elsewhere in the world.

Technical Abstract: Pasteurella multocida capsular types A, D, and F cause disease in many animal hosts, including bovine respiratory disease in cattle, which is one of the most globally significant animal diseases. Additionally, P. multocida capsular types B and E cause haemorrhagic septicaemia, a devastating disease primarily of cattle, water buffalo, and bison that develops rapidly with high mortality. Haemorrhagic septicaemia mostly occurs in developing countries and has potential to emerge elsewhere in the world. The diagnosis of haemorrhagic septicaemia currently requires recognition of compatible gross or histologic lesions and serotyping or molecular characterization of strains. In this study, we performed genomic characterization of 84 P. multocida strains, which were then used to develop and validate a matrix assisted laser desorption ionization time-of-flight mass spectrometry (MALDI-TOF MS) biomarker-based method for differentiating non-haemorrhagic septicaemia strains of P. multocida from haemorrhagic septicaemia-causing strains. Haemorrhagic septicaemia strain types B:2,5, E:2,5, and B:3,4 were used to maximize diversity. Three automated classification models were generated and then used to develop an assisted model, which utilized two peaks (6419 and 7729 m/z) to accurately differentiate non-haemorrhagic septicaemia-causing strains from haemorrhagic septicaemia-causing strains of P. multocida. The assisted model performed with 98.2 % accuracy for non-haemorrhagic septicaemia strains, 100 % accuracy for classic B:2,5 and E:2,5 strains, and 84.4 % accuracy for combined haemorrhagic septicaemia-causing strains (B:2,5, E:2,5, andB:3,4) with an overall accuracy of 96.9 %. Our results suggest that MALDI-TOF MS may be used to routinely screen P. multocida isolated from diagnostic cases for initial identification of haemorrhagic septicaemia-causing strains, and to determine whether additional characterizations are warranted.