Introduction

• Anaerobic bacteria do not require oxygen for growth.
• There are three types of anaerobic bacteria, obligate anaerobes, aerotolerant anaerobes and facultative anaerobes:
  • Obligate anaerobes cannot use oxygen for growth and will not survive in areas of high oxygen content or high redox potential.
  • Aerotolerant anaerobes cannot use oxygen for growth but will tolerate the presence of it.
  • Facultative anaerobes can grow without oxygen, but may utilize oxygen if it is present.
• Obligate anaerobes can be either gram-positive or gram-negative rods or cocci.
• Bacteria produce toxic metabolites from oxygen. Obligate anaerobes lack certain enzymes, such as catalase and superoxide dismutase, that detoxify these metabolites.
• Obligate anaerobes make up a significant portion of the normal bacteria flora of dogs. They form 95-99% of the total bacterial mass in the normal flora of the intestine, and also inhabit the oral cavity, respiratory tract and genitourinary tract.
• Most anaerobes in the normal flora do not form spores.
• Anaerobic bacteria play an important role in protection of mucosal surfaces from interactions with other pathogens.
• The majority of anaerobic infections begin with a break in the skin or mucous membranes that permits normally present bacteria to invade underlying tissues.
• The virulence of anaerobic infections increases if they produce enzymes or toxins capable of destroying surrounding tissue, eg Bacteroides, Fusobacterium and Clostridium, all release enzymes or toxins.
• Wounds may be contaminated with spore-forming anaerobic bacteria such as Clostridium spp, which are common in the environment.

Common anaerobic bacteria from dogs

Pathogenesis

Clinical findings associated with anaerobic infections

Diseases associated with anaerobic bacterial infections

Diagnosis and treatment

Further Reading

Publications

Refereed papers

• Recent references from PubMed and VetMedResource.
• Nagy E, Urbán E, Nord C E et al (2011) Antimicrobial susceptibility of Bacteroides fragilis group isolates in Europe: 20 years of experience. Clin Microbiol Infect 17 (3), 371-9 PubMed.
• McKenzie E, Riehl J, Banse H et al (2010) Prevalence of diarrhea and enteropathogens in racing sled dogs. J Vet Intern Med 24 (1), 97-103 PubMed.
• Wang A L, Ledbetter E C, Kern T J (2009) Orbital abscess bacterial isolates and in vitro antimicrobial susceptibility patterns in dogs and cats. Vet Ophthalmol 12 (2), 91-96 PubMed.
• Ledbetter E C, Scarlett J M (2008) Isolation of obligate anaerobic bacteria from ulcerative keratitis in domestic animals. Vet Ophthalmol 11 (2), 114-122 PubMed.
• Meyers B, Schoeman J P, Goddard A et al (2008) The bacteriology and antimicrobial susceptibility of infected and non-infected dog bite wounds: fifty cases. Vet Microbiol 127 (3-4), 360-368 PubMed.
• Radice M, Martino P A, Reiter A M (2006) Evaluation of subgingival bacteria in the dog and susceptibility to commonly used antibiotics. J Vet Dent 23 (4), 219-224 PubMed.
• Conrads G, Citron D M, Mutters R et al (2004) Fusobacterium canifelinum sp. nov., from the oral cavity of cats and dogs. Syst Appl Microbiol 27 (4), 407-413 PubMed.
• Radaelli S T, Platt S R (2002) Bacterial meningoencephalomyelitis in dogs: a retrospective study of 23 cases (1990-1999). J Vet Intern Med 16 (2), 159-163 PubMed.
• Weese J S, Staempfli H R, Prescott J F et al (2001) The roles of Clostridium difficile and enterotoxigenic Clostridium perfringens in diarrhea in dogs. J Vet Intern Med 15 (4), 374-378 PubMed.
• Walker R D, Ortiz B L, Render A E (1999) Anaerobic infections in Animals and Therapeutic Considerations. Anaerobe 5 (3/4), 279-286 VetMedResource.
• Jang S S, Breher J E, Dabaco L A et al (1997) Organisms isolated from dogs and cats with anaerobic infections and susceptibility to selected antimicrobial agents. J Am Vet Med Assoc 210 (11), 1610-1614 PubMed.
• Hariharan H, Lamey K & Heaney S (1995) Isolation of obligate anaerobic bacteria from clinical specimens. Can Vet J 36 (3), 173 PubMed.
• Jang S S & Hirsh D C (1994) Characterization, distribution, and microbiological associations of Fusobacterium spp. in clinical specimens of animal origin. J Clin Microbiol 32 (2), 384-387 PubMed.
• Jang S S & Hirsh D C (1991) Identity of Bacteroides isolates and previously named Bacteroides spp in clinical specimens of animal origin. Am J Vet Res 52 (5), 738-741 PubMed.
• Goldstein E J, Citron D M, Finegold S M (1984) Role of anaerobic bacteria in bite-wound infections. Rev Infect Dis 6 (Suppl 1), S177-183 PubMed.