Diversity of Moraxella spp. strains recovered from infectious bovine keratoconjunctivitis cases in Uruguay

Abstract

Background: Infectious bovine keratoconjunctivitis (IBK) is the most common ocular disease that affects cattle throughout the world and it has a very significant economic impact. IBK is caused by members of the genus Moraxella and therapeutic and preventive measures have shown limited success. Vaccines, most of them chemically inactivated bacterins, generally induce a limited protection. Methodology: In this study, the genetic diversity of Uruguayan clinical Moraxella bovis and Moraxella bovoculi isolates was assessed by RAPD-PCR, ERIC-PCR and BOX-PCR fingerprinting. Also, antibiotic resistance of the Moraxella spp. isolates was assessed utilizing the disk diffusion method. Results: When interspecific molecular diversity was assessed, different bands patterns were observed even within a single outbreak of IBK, showing the coexistence of different genotypes of Moraxella spp. The high genetic diversity within M. bovis and M. bovoculi isolates did not permit to correlate isolates DNA fingerprints with geographical origins, dates or even with both different Moraxella species. Antibiotics resistance patterns showed significant differences between M. bovis and M. bovoculi. Conclusions: This is the first study of diversity that includes M. bovis and M. bovoculi associated to IBK cases. Genetic diversity did not allow to correlate DNA fingerprints of the isolates with geographical origins, isolation dates or even both different Moraxella species. Antibiotics resistance patterns showed differences between M. bovis and M. bovoculi. This remarkable variation within isolates could explain the partial protection induced by commercial vaccines. All these findings could be important for the design of prevention or treatment strategies against IBK.

Moraxella bovoculi em casos de ceratoconjuntivite infecciosa bovina no Rio Grande do Sul

“…Mundialmente são escassos os estudos a respeito da ocorrência de M. bovoculi. Na América do Sul, apenas Sossa et al (2010) relatam surtos de CI causados por M. bovoculi em bovinos.…”

Moraxellaspp. isolated from field outbreaks of infectious bovine keratoconjunctivitis: a retrospective study of case submissions from 2010 to 2013

“…in other countries but have not examined these on a herd or individual animal level. 27 It was observed in the current study that M. bovoculi was the only Moraxella sp. isolated from the majority of case submissions, when evaluated at either the herd or individual level.…”

Phylogenetic analysis and genetic diversity of 3′ region of rtxA gene from geographically diverse strains of Moraxella bovis, Moraxella bovoculi and Moraxella ovis

“…Interestingly, both M. bovoculi and M. ovis strains were isolated from the same sheep eye lesion. Since the first description of M. bovoculi, studies from different parts of the world reported its isolation from eye lesions in cattle Libardoni et al, 2012;Sosa and Zunino, 2013); however, the exact role played by this species in the pathogenesis of IK is still not fully understood. Similar results were found for South American strains showing a hyper conservation of the MbxA-3 0 region .…”

“…Although early investigations proposed M. ovis, bacterium involved in sheep eye disease, might be the case (Elad et al, 1988), more recent investigations isolated and identified M. bovoculi in cattle lesions Libardoni et al, 2012;Sosa and Zunino, 2013).…”