Critically Endangered Christmas Island Reptile Killer Identified –

Critically Endangered Christmas Island Reptile Killer Identified

Lister's Gecko

One of Australia’s native and critically endangered species of lizards: the Lister’s gecko. Credit: Parks Australia

Bacteria responsible for the death of critically endangered species.

With wild populations decimated, the Lister’s gecko and blue-tailed skink only exist in captivity. Researchers at the University of Sydney have discovered a bacterium that could cause its potential extinction.

Native reptile populations on Christmas Island have declined severely with two species, the Lister’s gecko and the blue-tailed skink, having completely disappeared from the wild. While previously the main driver of this decline was likely predation by invasive species and habitat destruction, a silent killer now threatens to wipe out the species entirely.

Those bred in captivity in the Australian Territory in the Indian Ocean have also been mysteriously dying, leaving the two species, which number only around 1,000 each, in danger of extinction. Veterinary scientists from the University of Sydney, the Australian Wildlife Health Registry and the Taronga Conservation Society of Australia have now discovered the cause of these deaths: a bacterium, Enterococcus lacertideformus (ME. lacertideformus).

Infected gecko

Infected gecko showing intense head and face swelling associated with Enterococcus lacertideformus infection Credit: Jessica Agius

The bacteria was discovered in 2014 after captive reptiles developed facial deformities and lethargy, and some even died. The samples were collected and analyzed by microscopy and genetic testing. The researchers’ findings, published in Frontiers in microbiology, will report antibiotic trials on reptiles to see if the infection can be treated.

The bacteria grow on the animal’s head, then on its internal organs, before eventually causing death. It can be transmitted by direct contact, including through the reptiles’ mouths or when the reptiles bite each other, often during breeding season fights.

“This means that healthy captive animals should be kept separate from infected ones and should also be kept away from areas where infected animals have been,” said Jessica Agius, co-lead researcher and PhD candidate at the Sydney School of Veterinary Sciences. .

Jessica agius

PhD researcher Jessica Agius highlights critically endangered lizards in the field on Christmas Island to find out if they are infected with Enterococcus lacertideformus. Credit: Jessica Agius

Ms Agius and the research team not only identified the bacteria, they decoded its genetic makeup by sequencing the entire genome.

Specific genes were identified that are likely associated with the bacteria’s ability to infect its host, invade its tissues, and bypass the immune system.

“We also discovered that the bacteria can surround itself with a biofilm, a ‘community of bacteria’ that can help it survive,” said Ms Agius.

“Understand how E. lacertideformus producing and maintaining biofilm can provide information on how to treat other species of biofilm-forming bacteria. “

The search for the genetic code suggested that the killer bacteria was susceptible to most antibiotics.

Professor David Phalen, Ms Agius’ co-director of research and PhD supervisor, said: “This suggests that infected animals could be successfully treated. That is what we have to determine now. “

In another effort to protect endangered reptiles on Christmas Island, a population of blue-tailed skinks was established on the Cocos Islands. Ms Agius played a pivotal role in the translocation, testing reptiles on the Cocos Islands to make sure they were free of E. lacertideformus.

“It is critical that we act now to make sure these native reptiles survive,” Agius said.

Reference: “Genomic knowledge about the pathogenicity of a new biofilm formation Enterococcus sp. Bacteria (Enterococcus lacertideformus) Identified in reptiles ”by
Jessica Esther Agius, David Norton Phalen, Karrie Rose and John-Sebastian Eden, March 2, 2021, Frontiers in microbiology.
DOI: 10.3389 / fmicb.2021.635208

Statement: The authors thank the Westmead Institute for Medical Research, the Sydney School of Veterinary Sciences – University of Sydney, the Australian Wildlife Health Registry – Taronga Conservation Society Australia and Christmas Island National Park – Parks Australia for their support. logistical and financial.

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