Documented Cessation of Mycobacterial Shedding with Antibiotic Treatment in a Mycobacteria tuberculosis-Positive Asian Elephant (Elephas maximus) by Serial Culture and Direct Real-Time Polymerase Chain Reaction Testing of Trunk Wash Samples
Routine mycobacterial culture of trunk wash (TW) samples yielded Mycobacteria tuberculosis organisms from a 45-yr-old female Asian elephant, Elephas maximus. The TW cultures (3–4 samples/wk) were used to monitor response to treatment once an antibiotic regimen commenced and verified cessation of mycobacterial shedding. In addition, the opportunity to compare and potentially validate a direct real-time polymerase chain reaction (qPCR) method to detect Mycobacterium tuberculosis (Mtb) DNA in TW samples with standard mycobacterial culture methods for TW samples was undertaken. The TW samples were collected by the standard method, frozen in a -20°C freezer and shipped overnight to the National Veterinary Services Laboratory (NVSL) for testing.2 The TW were processed and half of the centrifuged pellet was decontaminated with NVSL’s NaOH-NALC decontamination procedure and inoculated onto media for mycobacterial culture. The second half was subjected to a qPCR targeting IS1081 of the M. tuberculosis complex genome. Over 73 days, 39 TW samples were obtained and cultured and qPCR was performed 70 times on these same samples. M. tuberculosis was isolated prior to treatment by culture 10 times and DNA detected by qPCR 11 times however the two tests were not always in agreement. On day 34 isoniazid was started rectally as the first of a four-drug regimen and within 7 days all detectable shedding of Mtb had ceased.1 In this case attempts were made to compare two diagnostic modalities and that recommended antibiotic doses were efficacious and not associated with signs of toxicity in the animal.3
The authors would like to thank the Animal Care staff at the Endangered Ark Foundation, Hugo, OK for their dedication to the care and welfare to all of their elephants.
1. Stakeholders Task Force on Management and Research Priorities of Tuberculosis in Elephants. Considerations in treating elephants for Mtb. In: Backues KA, Wiedner EB, eds. Recommendations for the Diagnosis, Treatment and Management of Tuberculosis (Mycobacteria tuberculosis) in Elephants in Human Care. 2015:16–20.
2. Isaza R, Ketz C. A trunk wash technique for the diagnosis of tuberculosis in elephants. Verhandlungsbericht des Internationalen Symposiums uber die Erkrankungen der Zootiere. 1999:121–124.
3. Wiedner E, Schmitt DL. Preliminary report of side effects associated with drugs used in the treatment of tuberculosis in elephants. In: Proceedings from the Meeting of the International Elephant Foundation. 2007:15–20.