Corynebacterium pseudotuberculosis infections

Previous authors: M W PATON, M G COLLETT, M PÉPIN AND G F BATH

Current authors:
M W PATON - Retired Senior Veterinary Officer, BVSc, MANZCVS, Grad Cert Animal Welfare, PhD, 31 Clipson Mundaring, Western Australia, 6073, Australia
M G COLLETT - Senior Lecturer, BVSc, MMedVet (Path), Med (CAI), School of Veterinary Science, Massey University, Private Bag 112222, Palmerston North, Manawatu, 4442, New Zealand
T M ELLIS - Retired Specialist Veterinary Consultant in Microbiology and Pathobiology, BVSc, MSc, 30 St Leonards Street, Mosman Park, Western Australia, 6012, Australia
M PÉPIN - Professor of Microbiology / Immunology and Infectious Diseases, DVM, PhD, VETAGRO SUP / Campus Vétérinaire de Lyon, Marcy-L’Etoile, F-69280, France

GENERAL INTRODUCTION: IRREGULAR, NON-SPORING, GRAM-POSITIVE RODS

Introduction

Corynebacterium pseudotuberculosis was first described in 1888 by the French veterinarian Edward Nocard, who isolated it from a case of bovine farcy (ulcerative lymphangitis). Three years later the same organism was isolated from a renal abscess in a sheep by the Bulgarian bacteriologist Hugo Von Preïsz,^{14, 36, 51} hence the original designation ”Preïsz-Nocard” bacillus. Subsequently, it was called Bacillus pseudotuberculosis. The organism was renamed C. ovis in 1923, and in 1948 the name was changed to C. pseudotuberculosis.^{14, 36}

Table 1 Summary of natural infections caused by C. pseudotuberculosis

Corynebacterium pseudotuberculosis causes different conditions and lesions in animals and humans (see Table 1). Caseous lymphadenitis (CLA), caused by C. pseudotuberculosis, is a chronic disease of sheep and goats that occurs worldwide wherever small ruminants are farmed. Caseous lymphadenitis characteristically involves superficial or internal lymph nodes. Affected animals may also have non-lymph node abscesses in subcutaneous tissues and/or internal organs. Several other Bovidae species can acquire C. pseudotuberculosis infections, notably cattle (ulcerative lymphangitis) and water buffalo (“oedematous skin disease”), the latter being important in Egypt, the Middle East and South-East Asia. Certain wild Bovidae, Cervidae and even domestic pigs can be infected. Corynebacterium pseudotuberculosis is also the cause of ulcerative lymphangitis, pectoral abscesses, folliculitis and furunculosis (referred to as "contagious acne"), mastitis and abortion in horses. Pectoral abscesses and contagious acne have only ever been recorded in the Western USA and Canada. Caseous lymphadenitis can be zoonotic and affected people usually acquire infection following contact with sheep or goats.

The nature of CLA is of an insidious disease that is difficult to investigate and control. The research done on vaccine development and epidemiology in Australia has led to significant advances in the understanding and control of CLA. However, because of the non-clinical nature of CLA in most Australian sheep, the greatest challenge for the sheep industry is to convince farmers that they have a problem worth dealing with. The research done into CLA immunopathology in France has made major advances in the understanding of the behaviour of the sheep immune system in response to C. pseudotuberculosis. In the future, this may lead to improved tests and vaccines to fight this organism.

In Africa, UK, Netherlands, Canada, France, USA, South America, the Middle East and Scandinavia researchers and field veterinarians are dealing with outbreaks of CLA in sheep, goats, camelids and other species. In these flocks or herds, the production systems are vastly different from those in Australian sheep, so the epidemiology of CLA can be expected to have some differences. The challenges for those dealing with this disease are to learn from the methods or findings of the research done thus far and apply it to assist in solving the complex problems that C. pseudotuberculosis infection causes in their production systems.

Aetiology

Corynebacterium pseudotuberculosis is a short (0,5 to 0,6 x 1,0 to 3,0 micrometre), irregular, ovoid, non-sporulating, non-capsulated, Gram-positive rod almost resembling a coccus. It is facultatively intracellular and anaerobic. Although non-motile it has fimbriae.⁷¹ In smears...