Vet Guide 2025: Mycobacterial (Pseudacidomycosis) Infections in Reptiles & Amphibians 🦎🐸 by Dr Duncan Houston 🩺

Hello! I’m Dr Duncan Houston, BVSc and founder of Ask A Vet. Mycobacterial infections—also called pseudacidomycosis—are caused by atypical (nontuberculous) Mycobacterium species in reptiles and amphibians. These intracellular bacteria often cause granulomatous lesions of skin, internal organs, or lungs, with chronic weight loss and lethargy. In 2025, we look at how to recognize, diagnose, manage, and prevent these challenging diseases—with attention to both animal welfare and zoonotic risk.

1. What Are Mycobacterial Infections?

Reptiles and amphibians can be infected by various non-tuberculous Mycobacteria—such as M. marinum, M. chelonae, M. fortuitum, M. genavense, or M. goodii—which are environmental bacteria often found in soil and water :contentReference[oaicite:3]{index=3}.

2. Who Is Affected?

• Reptiles: snakes, turtles, lizards—with granulomas in skin, respiratory tract, liver or intestines :contentReference[oaicite:4]{index=4}.
• Amphibians: clawed frogs (*Xenopus spp.*) and toads, often showing skin nodules and internal lesions :contentReference[oaicite:5]{index=5}.
• Immunocompromised or stressed animals are more susceptible due to chronic disease or poor husbandry :contentReference[oaicite:6]{index=6}.

3. How Infection Occurs

The organisms typically enter through skin wounds, ingestion of contaminated water/food, or inhalation. In many cases, diagnosis only occurs at necropsy—granulomatous lesions develop over months :contentReference[oaicite:7]{index=7}.

4. Recognizing Clinical Signs

• Chronic weight loss, lethargy, decreased appetite.
• Granulomatous nodules—visible on skin or deeper on X‑ray/ultrasound :contentReference[oaicite:8]{index=8}.
• Respiratory signs—wheezing, discharge—if lungs involved :contentReference[oaicite:9]{index=9}.
• Non-specific signs: anorexia, emaciation, soft tissue swellings :contentReference[oaicite:10]{index=10}.

5. Diagnosis

• Skin scrapings or biopsies: acid-fast staining reveals characteristic bacilli :contentReference[oaicite:11]{index=11}.
• Culture & PCR: identifies organism—though slow growers take weeks :contentReference[oaicite:12]{index=12}.
• Imaging: X‑rays/ultrasound detect internal granulomas, lung involvement, or organ enlargement.
• Necropsy: most definitive diagnosis; reveals granulomas throughout tissues.

6. Treatment Challenges

There is no consistently effective cure in reptiles. Treatment is often unrewarding and may worsen animal stress :contentReference[oaicite:13]{index=13}.

• Antimicrobials: clarithromycin, rifampin, ethambutol, fluoroquinolones have been used—treatment prolonged but rarely curative.
• Surgery: excision of accessible granulomas may improve comfort.
• Supportive care: warmth, nutrition support, hydration for quality of life.

7. Zoonotic Risk & Safety

Atypical mycobacteria from reptiles/amphibians can infect humans—especially immunocompromised individuals via skin contact, causing localized granulomas or lymphadenitis :contentReference[oaicite:14]{index=14}.

Strict hygiene protocols—wear gloves, wash hands, disinfect enclosures—are essential, especially after handling or cleaning habitats :contentReference[oaicite:15]{index=15}.

8. Management & Prevention

• Quarantine new or sick animals for ≥60 days with acid-fast screening.
• Maintain optimal husbandry—temperature, humidity, hygiene reduce stress & infection risk.
• Avoid co-housing species and share water sources.
• Prompt clean-up of wounds and habitat soiling.
• Disinfect with high-level agents effective against Mycobacteria (e.g. bleach or phenolic disinfectants).

9. When to Contact Ask A Vet 🩺

If your reptile shows chronic weight loss, nodules, or respiratory issues—or if you're unsure about zoonotic risk—upload photos, habitat details, and diagnostics via the Ask A Vet app. Get expert guidance on testing protocols, treatment options, and client safety strategies. Visit AskAVet.com 📱

10. Final Thoughts

Mycobacterial infections in reptiles and amphibians are chronic, difficult-to-treat conditions marked by granulomas, weight loss, and significant zoonotic potential. Diagnosis relies on biopsy, staining, and culture, but treatment often focuses on palliative care and management. Preventing disease through strong husbandry and biosecurity is crucial. In 2025, Ask A Vet offers tailored support to identify, manage, and mitigate these challenging infections—protecting both animal and human health. 🩺🌿

— Dr Duncan Houston, BVSc