Emergent multisystemic Enterococcus infection threatens endangered Christmas Island reptile populations

Abstract

Multisystemic infections with a morphologically unusual bacterium were first observed in captive critically endangered Lister’s geckos (Lepidodactylus listeri) on Christmas Island in October 2014. Since then the infection was identified in another captive critically endangered lizard species, the blue-tailed skink (Cryptoblepharus egeriae) and two species of invasive geckos; the four clawed gecko (Gehyra mutilata) and Asian house gecko (Hemidactylus frenatus), in a wide geographic range across the east side of the island. The Gram and periodic acid-Schiff positive cocci to diplococci have a propensity to form chains surrounded by a matrix, which ultrastructurally appears to be formed by fibrillar capsular projections. The bacterium was associated with severe and extensive replacement of tissues, but minimal host inflammatory response. Attempts to grow the organism in culture and in embryonated eggs were unsuccessful. Molecular characterisation of the organism placed it as a novel member of the genus Enterococcus. Disease Risk Analyses including this organism should now be factored into conservation management actions and island biosecurity.

Pharmacokinetic profile of enrofloxacin and its metabolite ciprofloxacin in Asian house geckos (Hemidactylus frenatus) after single-dose oral administration of enrofloxacin

“…Examples of conservation breeding programs threatened by disease are those for the Christmas Island endemic Lister's geckos ( Lepidodactylus listeri ) and blue-tailed skinks ( Cryptoblepharus egeriae ) ( Rose et al., 2017 ). These species are extinct in the wild on Christmas Island, but are sustained in captive breeding programs.…”

Multiple-antibiotic resistance of Enterococcus faecalis in an endangered olive ridley sea turtle (Lepidochelys olivacea): A case report

“…In reptiles, enterococci are known for their strong antimicrobial resistance (Prichula et al, 2016;Rose et al, 2017). The results of antimicrobial susceptibility tests performed in this study revealed that the E. faecalis isolate was resistant to 12 antibiotics (doxycycline, enrofloxacin, erythromycin, neomycin, oxytetracycline, gentamicin, amikacin, ciprofloxacin, spiramycin, chloramphenicol, ceftiofur, and azithromycin).…”

Endemic species of Christmas Island, Indian Ocean

“…A major disease threat emerged recently to the captive breeding program for two endemic Christmas Island reptile species. This invariably fatal disease was found to be due to infection with a previously unknown Enterococcus species, although the report documenting its occurrence did not formally describe it (Rose et al 2017). This unusual bacterium was recorded not only from individuals in the captive breeding program for threatened endemic lizards, but also in individuals of Christmas Island populations of introduced lizards (Rose et al 2017).…”

“…This invariably fatal disease was found to be due to infection with a previously unknown Enterococcus species, although the report documenting its occurrence did not formally describe it (Rose et al 2017). This unusual bacterium was recorded not only from individuals in the captive breeding program for threatened endemic lizards, but also in individuals of Christmas Island populations of introduced lizards (Rose et al 2017). Although the paper documenting its existence noted that there were no records of it from elsewhere, the current available information is insufficient to categorise it as native to Christmas Island, let alone endemic.…”