Recovery and Characterization of Moraxella Species from Bovine Specimens

Authors

Laura G. Leger, University of Nebraska-LincolnFollow

First Advisor

John Dustin Loy

Committee Members

Matthew Hille, Greg Somerville

Date of this Version

12-2025

Document Type

Thesis

Citation

A thesis presented to the faculty of the Graduate College at the University of Nebraska in partial fulfillment of requirements for the degree of Master of Science

Major: Veterinary Science

Under the supervision of Professor John Dustin Loy

Lincoln, Nebraska, December 2025

Comments

Copyright 2025, Laura G. Leger. Used by permission

Abstract

The family Moraxellaceae is made up of a diverse group of 24 named species that fall into three phylogenetic groups. While most Moraxella spp. act as commensal respiratory and/or ocular flora of mammals, some are associated with disease. One of these diseases, infectious bovine keratoconjunctivitis (IBK), has significant welfare and economic impacts to both cattle and cattle producers. Moraxella bovis is the only experimentally determined cause of IBK, however, an association of Moraxella bovoculi with disease has been proposed. Currently, available vaccines do not have high levels of efficacy in the field. Culture based methods are the gold standard for diagnosis of bacterial infections, however, the lack of sensitivity in samples from non-sterile sites is problematic. One objective of this work was to develop a selective culture medium to inhibit the growth of contaminants to increase the frequency of isolation of Moraxella spp. The developed medium, Moraxella Selective Vancomycin Agar (MSVA), decreased the amount of bacterial contamination present while increasing the frequency of isolations of Moraxella spp., particularly that of M. bovoculi. Another objective of this work was to characterize previously unidentifiable Moraxella spp. that had been recovered from bovine specimens. The characterization of these organisms identified the different strains as Moraxella oculi, Moraxella haemolytica, and a likely identification of Moraxella nasibovis. Two of these strains had not been reported in the United States or in bovine specimens previously. The increased recovery and characterization of different Moraxella strains within ruminant populations can help us better understand the role of different Moraxella spp. involved with IBK and lead to the possibility of additional preventative and/or treatment options for this disease.

Advisor: John Dustin Loy