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TDK conference 2021

Molecular investigation of protozoa and bacteria of veterinary-medical inportance from the faeces of captive reptiles
Kelly Hannah - year 6
University of Veterinary Medicine Budapest, Department of Parasitology and Zoology
Supervisor: Dr. Barbara Tuska-Szalay


Reptiles are frequently kept as pet animals. Adding to parasites and bacteria causing disease in reptiles themselves, they are considered as important reservoirs of pathogens with veterinary-medical significance. The aim of this study was to contribute to our knowledge on reptiles in the latter context.

During this study, 98 reptiles and one amphibian were sampled in a non-invasive way at the National Reptile Zoo in Ireland. These animals represented 44 species and belonged to four orders (Testudines, Squamata, Crocodilia, Anura). From these animals, faecal samples were collected in artificial enclosures, with an attempt to exclude soil contamination, into 2 ml sterile Sarstedt tubes. DNA was extracted from the central part of the sample, whenever possible, to minimize the chances of environmental contamination, using the Qiagen Fast Stool Mini Kit. All DNA samples were screened with conventional PCRs to detect broad range eukaryotic DNA (based on amplifying the cytochrome c oxidase subunit I, i.e., the cox1 gene), protozoan parasite DNA (of Trichomonas and Trypanosoma spp.), as well as bacterial DNA (from Anaplasmataceae, Rickettsiaceae and related families).

All samples were negative in the tests for Trichomonas and Trypanosoma species. The cox1 gene PCR detected host DNA (i.e., was suitable to identify the host of origin) in four samples. From one faecal sample, the DNA of insect prey items was successfully amplified with this method. In addition, the cox1 PCR detected an important opportunistic Acanthamoeba genotype in a yellow anaconda (Eunectes notaeus). This finding was confirmed by a PCR targeting the 18S rRNA gene (ASA.S1 region in Rns) of the genus Acanthamoeba, and the species was identified with sequencing as A. hatchetti. This species is known to have clinicopathological significance in both humans and animals.

Concerning bacteria, the faecal sample of a crested gecko (Correlophus ciliatus) contained the DNA of Citrobacter freundii. The presence of Citrobacter spp. is known in the normal gut flora of several vertebrate classes, but these bacteria are also considered as opportunistic pathogens. More importantly, three faecal samples (from savannah monitor: Varanus exanthematicus, carpet python: Morelia spilota, Burmese python: Python bivittatus) contained DNA from the genus Gordonibacter which, to the best of our knowledge, was hitherto only identified in the human gut flora. At least G. pamelaeae is also able to cause bacteraemia in men. The above findings of opportunistic pathogens highlight the importance to monitor protozoa and bacteria in the faeces of pet reptiles, most importantly from the point of view of other animals or humans living nearby. Furthermore, these data might even have epidemiological relevance in natural ecosystems, e.g., when raw juice is made for human consumption from fruits that may have become contaminated with the faeces of arboreal reptiles.

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