Osteoarticular Infection in Three Young Thoroughbred Horses Caused by a Novel Gram Negative Cocco-Bacillus

Bernard J. Hudson,Brendon A. O’Rourke,Christopher B. O’Sullivan,Angela P. Begg,Angus R. Adkins,Thomas Karagiannis,Anna Blishen,Andrew Edgar,Benjamin Raymond,Leonie Chan,Piklu Roy Chowdhury,Ian G. Charles,Katerina Mitsakos,Catherine Chicken,Daniel Bogema,Kristen H. Todhunter,Steven P. Djordjevic

doi:10.1155/2020/9785861

Abstract

We describe three cases of osteoarticular infection (OAI) in young thoroughbred horses in which the causative organism was identified by MALDI-TOF as Kingella species. The pattern of OAI resembled that reported with Kingella infection in humans. Analysis by 16S rRNA PCR enabled construction of a phylogenetic tree that placed the isolates closer to Simonsiella and Alysiella species, rather than Kingella species. Average nucleotide identity (ANI) comparison between the new isolate and Kingella kingae and Alysiella crassa however revealed low probability that the new isolate belonged to either of these species. This preliminary analysis suggests the organism isolated is a previously unrecognised species.

Highlights

Septic arthritis in equines has a high mortality rate (22–58%) despite treatment [1,2,3]
Septic arthritis is associated with a reduced likelihood of ever starting in a race compared to controls [6]
HACEK represents a group of Gram negative bacteria (GNB) that are part of normal human flora: Haemophilus species, Aggregatibacter actinomycetemcomitans, Cardiobacterium hominis, Eikenella corrodens, and Kingella species. ese organisms can be readily identified by commercial systems such as API NH and VITEK 2 and matrix-assisted laser desorption ionization-time of flight mass spectrometry [12,13,14,15]. e initial isolate (Isolate 1 from Case 1) failed to propagate a er repeated subculture, but the Isolate 2 and Isolate 3 survived repeated subculture on supplemented Columbia horse blood agar [16] in 5% carbon dioxide atmosphere. ese isolates were sent to the laboratory at St

Summary

Introduction

Septic arthritis in equines has a high mortality rate (22–58%) despite treatment [1,2,3]. Septic arthritis occurs following trauma, especially penetrating injuries of the joint, spread from a contiguous focus of infection, and by haematogenous seeding of microorganisms [1, 4, 7]. E latter may be from a remote site of infection, but likely occurs in many individuals via symptomatic or asymptomatic bacteraemia [1, 3, 4, 8]. Con rmation of a bacterial cause is by positive microscopy, together with culture of synovial uid (SF) or synovial tissue [9]. Bacterial culture of SF is negative in 33–60% of Cases [1, 3, 10, 11]

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Conclusion