Lapis ISSN 2398-2969

Actinomyces spp

Contributor(s): Sarah Pellett, Livia Benato

Introduction

Classification

Taxonomy

  • In rabbitsArcanobacterium pyogenes(formerly known asActinomyces pyogenes) andActinomyces israeliihave been isolated from facial abscesses. They are gram-positive, non-spore forming, short rod, aerobic and facultative anaerobic pathogenic bacteria.

A. pyogenes

  • Order: Actinomycetales.
  • Family: Actinomycetaceae.
  • Genus:Aracnobacteirum.
  • Species:pyogenes.

A. israelii

  • Order: Actinomycetales.
  • Family: Actinomycetaceae.
  • Genus:Actinomyces.
  • Species:israelii.

Etymology

A. pyogenes

  • Gk: pyogenes - pus-producing.

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Clinical Effects

Epidemiology

Habitat

  • Actinomycetes are part of the normal bacterial flora of the mucous membranes of mammals, especially respiratory tract and reproductive tract.

Lifecycle

  • Reproduces on the mucous membranes and skin by binary fission.

Transmission

  • Endogenous infection.

Pathological effects

  • Killed by phagocytes.
  • Active infection concurrent with other bacteria causes pyogranulomatous reaction   →   fibrous capsule forms containing the pus   →    neutrophils and other leukocytes continue to migrate into the abscesses from blood vessels in the capsule   →    abscess capsule becomes thick and fibrous and is composed of fibroblasts and inflammatory cells, with an inner layer of degenerating neutrophils.
  • Periapical abscesses of mandibular and maxillary teeth often associated with jaw and skull abscesses are common and often reported.
  • Chronic abscesses do not respond to systemic antibiotics because of the thick fibrous capsule enclosing the infection.
  • In rabbits, clinical signs include subcutaneous soft swelling in the head or neck region, anorexia, ptyalism and secondary gastrointestinal stasis due to anorexia.
  • Infections of spinal column and limbs have also been reported. Common clinical signs are anorexia, reluctance to move and poor body condition.
  • In rabbits, it can rarely develop reproductive tract disease to include mucopurulent vaginal discharge, anorexia, weight loss, abdominal distension and reduced fertility.

Control

Control via chemotherapies

  • Antibiotic therapy alone is unlikely to be successful and surgical excision/debridement as well as dental surgery, including removal of infected teeth, are necessary in treating infection.
  • Systemic antibiotics chosen depending on bacteriological culture and sensitivity results.
  • Antibiotics that are effective against mostActinomycesspp in other species include penicillins   Penicillin  , erythromycin   Erythromycin  , clindamycin, ampicillin, tetracycline   Tetracycline   (tetracyclines are not effective forA. pyogenes), doxycycline   Doxycycline  , chloramphenicol   Chloramphenicol   and first generation cephalosporins   Therapeutics: antimicrobials  .
  • One study (on several bacteria that cause facial abscess in rabbits) showed they were 100% sensitive to clindamycin, 96% to penicillin, 54% to ciprofloxacin, and only 7% were sensitive to trimethoprim-sulfa   Trimethoprim / sulfadiazine   drugs.

These antibiotics are not licensed for use in rabbits.

The responsibility for prescribing unlicensed products lies with the prescribing veterinarian.

Clindamycin, despite its effective antimicrobial properties should never be used in rabbits due ot it causing antibiotic-associated diarrhea. Some sources implicate its placement into cavities within AIPPMA beads or as capsules, but if the cavities open into the oral cavity fatal dysbiosis can occur.

  • Cephalosporins are a useful antibiotic class in penetrating abscesses; they must be infected and never given orally in rabbits.
  • Penicillins are also advocated if sensitivities indicate it; they must be injected and never given orally in rabbits.
  • Ampicillin and amoxicillin/clavulanate carry a risk of antibiotic associated dysbiosis. Oral and topical formulation must not be used in rabbits. If sensitivities indicate they can be used parenterally.
  • Chloramphenicol aqueous eye drops can be used topically for abscess cavities.

Many drugs discussed are not licensed for use in rabbits, unless stated.

The legal implications regarding the cascade should be considered when prescribing these medications for pet rabbits. Written consent should always be obtained before prescribing these drugs.

Antibiotic-associated dysbiosis is a risk when using antibiotics in rabbits.

Other countermeasures

  • Surgical excision/debridement and dental surgery essential in treatment.
  • Euthanasia in severe cases.

Diagnosis

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Further Reading

Publications

Refereed papers

  • Recent references fromPubMedandVetMedResource.
  • Shahbazfar A Aet al(2013)Multi abscessation with multinodular abscesses in a New Zealand white rabbit (Oryctolagus cuniculus) followingArcanobacterium pyogenesinfectionRevue Méd Vét164(1), 23-26VetMedResource.
  • Tyrell K L, Citron D M, Jenkins J R & Goldstein E J C (2002)Periodontal bacteria in rabbit mandibular and maxillary abscesses.J Clin Microbiol40(3), 1044-1047PubMed.
  • Hong I Het al(2009)Actinomycosis in a pet rabbit.J Vet Dentistry26(2), 110-111PubMed.

Other sources of information

  • Knott T (2014)Ophthalmology. In:BSAVA Manual of Rabbit Medicine. Eds: Meredith A & Lord B. BSAVA, Gloucester. pp 232-254.
  • Mancinelli E & Lord B (2014)Urogenital System and Reproductive Disease. In:BSAVA Manual of Rabbit Medicine. Eds: Meredith A & Lord B. BSAVA, Gloucester. pp191-204.
  • Meredith A (2014)Dermatoses. In:BSAVA Manual of Rabbit Medicine. Eds: Meredith A & Lord B. BSAVA, Gloucester. pp 255-263.
  • Varga M (2014)Textbook of Rabbit Medicine. 2nd edn.  Butterworth Heinemann Elsevier, Edinburgh.
  • Harcourt-Brown F & Chitty J (2013)Facial Abscesses.In:BSAVA Manual of Rabbit Surgery, Dentistry and Imaging. Eds: Harcourt-Brown F & Chitty J. BSAVA, Gloucester. pp 395-422.
  • Jekl V, Minarikova A, Hauptman K & Knotek K (2012)Microbial Flora of Facial Abscesses in 30 Rabbits - A Preliminary Study. In:Proceedings 22nd European Congress of Veterinary Dentistry.  Lisbon, pp 133-135.
  • Jekl V (2012)Treatment of Abscesses and Antibiotic Selection. In:Proceedings of the WSAFA/FECAVA/BSAVA World Congress 2012. Birmingham.
  • Kelleher S A (2008)Rabbit Abscess. In:Proceedings of the Western Veterinary Conference.
  • DeLong D & Manning P J (1994)Bacterial diseases.In:The Biology of the Laboratory Rabbit. 2nd edn. Eds: Anning P J, Ringler D H & Newcomer C E. Academic Press Limited, London. pp 131-170.

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