ISSN 2398-2950      

Arthritis: bacterial L-form

ffelis
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Introduction

  • Progressive non-responsive polyarthritis.
  • Cause: ?bacterial L-forms, ?hematogenous spread from bite wounds.
  • Diagnosis: culture difficult, light microscopy, electron microscopy.
  • Signs: swollen, painful, crepitant joints; non-specific systemic illness.
  • Treatment: often no response to antibiotic or steroid therapy.
  • Prognosis: guarded.

Pathogenesis

Etiology

  • ?Bacterial L-forms - cell wall-deficient bacteria that morphologically resemble mycoplasmas.

Specific

  • Formation of L-forms is aided by both antimicrobials that act on cell wall and by host immune responses.

Pathophysiology

  • Bite wound   →   bacterial L-forms   →   hematogenous spread   →   joint infection.
  • Initially affects synovial membrane, later joint cavity.
  • Infection   →   inflammation of synovium   →   hypercellular synovial fluid (polymorphs).
  • Lysosomal granules released by polymorphs and synovial cells engulf bacteria   →   enzyme release   →   destruction of cartilage matrix   →   mechanical damage by pressure and grinding of joint movement.
  • Fibrin deposits form in synovial fluid   →   deposited on cartilage surface   →   limit normal exchange of cartilage metabolites and nutrients to and from synovial fluid   →   further cartilage degeneration.
  • Degree of articular damage depends on number, type and virulence of organism; local and general resistance of patient.
  • Ligaments may be weakened by infection   →   joint instability, eg cranial cruciate rupture   →   significant progression of lameness.
  • Cartilage destruction and exposure of subchondral bone - bony bridge develop between adjacent bones and around abscesses which form within exudate   →   fibrous or bony ankylosis   →   decreases range of joint movement.

Diagnosis

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Treatment

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Outcomes

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Further Reading

Publications

Refereed papers

  • Recent references from PubMed and VetMedResource.
  • Carro T, Pedersen N C, Beaman B L et al (1989) Subcutaneous abscesses and arthritis caused by a probable bacterial L-form in cats. JAVMA 194 (11), 1583-1588 PubMed.

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