Abstract:
Several species of atypical mycobacteria have been isolated from wild and captive amphibians. In captive anurans,
cutaneous and visceral mycobacteriosis are common and can result in significant mortality, particularly
when animals are immunocompromised. Mycobacterial arthritis and synovitis are reported rarely in amphibians.
We describe 20 cases in painted reed frogs (Hyperolius marmoratus), which presented with cachexia, limb
paresis or paralysis or ‘spindly leg syndrome’. Histopathology revealed multifocal histiocytic to granulomatous
synovitis affecting appendicular, rib or spinal intervertebral joints. Periarticular granulomata, granulomatous
cellulitis and skeletal muscle atrophy, necrosis and degeneration were also present. In one case, granulomatous
spinal osteomyelitis was recorded. ZiehleNeelsen stains showed large numbers of acid-fast bacteria in macrophages
and histiocytes. The mycobacterial isolates obtained from culture were identified as members of the
Mycobacterium chelonae complex (either M. chelonae or Mycobacterium abscessus). This was confirmed by 50
-16S ribosomal
ribonucleic acid (rRNA) sequencing. In 17 cases mycobacterial lesions were present only in the joints
and skeleton, highlighting the importance of not ruling out mycobacterial infection on the basis of absence of
cutaneous or visceral lesions.
