FACULTATIVELY ANAEROBIC GRAM-NEGATIVE RODS

A General Introduction has been added to each disease chapter in an attempt to give a brief updated overview of the taxonomic, biological and other characteristics of the virus family or group of bacteria /protozoa that cause disease in livestock and, where relevant, involve wildlife. As the text of the three-volume book Infectious Diseases of Livestock is currently under revision the Editors are aware that there are inconsistencies between the updated introductions to chapters and the content of the chapters themselves. Once the chapters have been updated – a process that is currently underway – these inconsistencies will be removed.

The genera of three families (Enterobacteriaceae, Pasteurellaceae and Vibrionaceae) are classified as facultatively anaerobic, Gram-negative rods. As far as is currently known, only the genera within the families Enterobacteriaceae and Pasteurellaceae contain bacteria that are pathogenic to terrestrial animals.⁶

Family Enterobacteriaceae

Bacteria that belong to this family are Gram-negative, straight rods, 0,3–1,0 × 1,0–6,0 µm in size, which are motile as a result of the presence of peritrichous flagella. They do not form endocysts, nor are they acid-fast. They are ubiquitous in nature, occurring in soil, water, fruit, vegetables, grains, flowering plants, trees, insects and mammals. Thirty genera are currently recognized.⁴

Of the over 30 genera, such as (Escherichia, Shigella, Salmonella, Klebsiella, Enterobacter, Serratia, Proteus and Yersinia) belonging to the Enterobacteriaceae that contain members which infect humans and animals, only Escherichia, Salmonella and Klebsiella are important in terms of causing economically important diseases in livestock. Members of the other genera are associated with rare sporadic and often opportunistic infections in animals. Shigella dysenteriae often causes enterocolitis in a variety of captive, non-human primates.⁵ Enterobacter and Serratia spp. are occasionally reported as a cause of mastitis in cattle, while infection with Proteus spp., and particularly Proteus mirabilis,may cause severe enteritis following prolonged antibiotic treatment, and mastitis in goats. Proteus spp. are also commonly associated with the spoilage of meat.² Infection by the various Yersinia spp. is common, but these bacteria do not regularly infect livestock species. Yersinia pestis, the cause of bubonic plague in humans, is specific for humans, rats, cats and dogs.

Yersinia enterocolitica, a cause of terminal ileitis in humans, has been occasionally identified as the cause of severe enteritis in sheep, goats and pigs.²

Yersinia pseudotuberculosis, which is a common intestinal inhabitant of various animal species, is the cause of a septicaemic disease, sometimes accompanied by abscessation, in birds and rodents.Infection by it has been recorded as a very rare, sporadic cause of abortions in cattle and sheep, mastitis in goats, epididymitis and orchitis in rams, and abscessation, lymphadenitis and pneumonia in cattle.^{5, 8}

Among other genera, Cedecea, Citrobacter, Ewingella, Hafnia, Kluyvera, Leclercia, Morganella, Pantoea and Providentia have all caused opportunistic infections in humans.⁴ Not enough is known about their pathogenic potential in animals, but it is likely that they would also act as opportunists in animals.

Family Pasteurellaceae

This family consists of more than 80 named species distributed in 17 genera (Pasteurella, Haemophilus, Actinobacillus, Mannheimia, Lonepinella¹ and Phocoenobacter such as ‘and others’ Histophilus and Bibersteinia). Lonepinella has only been described from koala bears,⁷ and Phocoenobacter from porpoises,³ and will not be discussed further.

General information about the characteristics of each of the genera is contained in the introductions to the respective sections.

Family Vibrionaceae

The five genera in this family do not contain any species that are important in livestock.

Vibrionaceae are primarily aquatic inhabitants, and are generally associated with or cause disease in aquatic animals and amphibians. Aeromonas, Pleisiomonas and Vibrio spp. have been associated sporadically with opportunistic disease in animals.⁴

Other facultatively anaerobic, Gram-negative rods, such as Chromobacterium and Eikenella, also act as opportunists in humans and animals.⁴

References

1. ANGEN, Ø., MUTTERS, R., CAUGANT, D.A., OLSEN, J.E. & BISGAARD, M., 1999. Taxonomic relationships of the (Pasteurella) haemolytica complex as evaluated by DNA-DNA hybridizations and 16s rRNA sequencing, with proposal of Mannheimia haemolytica gen. nov., Mannheimia granulomatis comb. nov., Mannheimia glucosida sp. nov., Mannheimia ruminalis sp. nov. and Mannheimia varigena sp. nov. International Journal of Systematic Bacteriology, 49, 67-86.
2. BLOOD, D.C. & RADOSTITS, O.M., 1989. Veterinary Medicine, 7th edn. London, Philadelphia, Sydney, Tokyo, Toronto: Baillière Tindall.
3. FOSTER, G., ROSS, H.M., MALNICK, H., WILLEMS, A., HUTSON, R.A., REID, R.J. & COLLINS, M.D., 2000. Phocoenobacter uteri gen. nov., sp. nov., a new member of the family Pasteurellaceae Pohl (1970) 1981 isolated from a harbour porpoise (Phocoena phocoena). International Journal of Systematic and Evolutionary Microbiology, 50, 135-139.
4. HOLT, J.G., KRIEK, N.R., SNEATH, P.H.A., STALEY, J.T. & WILLIAMS, S.T., 2000. Bergey’s Manual of Determinative Bacteriology. 9th edn. Baltimore: Williams & Wilkins.
5. HUNGERFORD, T.G....