A Case of Mortality Caused by Aeromonas hydrophila in Wild-Caught Red-Eyed Crocodile Skinks (Tribolonotus gracilis)

Abstract

Aeromonas hydrophila, a Gram-negative bacterium commonly found in aquatic environments, is pathogenic to amphibians, reptiles, and mammals. In human medicine, the clinical symptoms of aeromonad infection include not only gastroenteritis but also extraintestinal infections, such as wounds, cellulitis, and septicemia, in immunocompromised and immunocompetent individuals. In this study, ten red-eyed crocodile skinks (Tribolonotus gracilis) that shared the same space were found dead 7 days after being shipped from Indonesia. The necropsy revealed A. hydrophila to be the causative agent, and the isolates were susceptible to most antibiotics, based on an antimicrobial susceptibility test. Seven virulence factors (act, ast, alt, aerA, fla, gcaT, and ahyB) considered to be associated with virulence were detected by PCR. Microscopic examination revealed several necrotic lesions and melano-macrophage centers in the tissue slides. Reptiles caught in the wild for trade experience captivity stress. Furthermore, in the winter, reptiles are easily exposed to the cold atmosphere. These stresses can negatively impact the immunity of these ectotherms, making them vulnerable to A. hydrophila infections. Therefore, to avoid such opportunistic infections and mortality following exposure to severe stress, medical care is recommended. The studies of alternatives, such as bacteriophage and bacteriocin, are needed for a preventive application.

Virulence and Antimicrobial Resistance Pattern of Aeromonas spp. Colonizing European Pond Turtles Emys orbicularis and Their Natural Environment. First Study from Poland

“…In animals, Aeromonas infections are also common, and numerous virulence factors are also demonstrated in the isolates in these cases. Nevertheless, the symptoms of Aeromonas infection develop most often in the presence of other factors, e.g., stress associated with captivity, the transport of animals, or an inappropriate ambient temperature [58].…”

Melanomacrophage Centers: Comparative Histological Insights among Three Reptilian Species

“…MMCs aggregates contained approximately equal proportions of melanin and hemosiderin granules in the center of the portal tract in the hepatic parenchyma of freshwater turtles (Trachemys scripta) (Divers et al, 2010). Red-eyed crocodile skinks (Tribolonotus gracilis) appeared in two forms, large polymorphic MMCs aggregates and small diffused macrophages scattered all over the hepatic tissue (Kwon et al, 2019). Akiyoshi et al (2015) designed a study on the livers of 23 reptilian species and they revealed the distribution of MMCs in different zones in hepatic parenchyma.…”

Zoonotic Parasites of Reptiles: A Crawling Threat

“…For example, some species of tick (Ixodidae and Argasidae) and mites (Macronyssidae, Trombiculidae) often feed on reptiles as well as on humans (Table 1). The macronyssid mite Ophionyssus natricis, one of the most widely distributed mite species of snakes, is a mechanical vector of Aeromonas hydrophila, the causative agent of hemorrhagic disease in reptiles as well as of gastroenteritis, and in rare cases, of necrotizing fasciitis in humans [20,21]. In the past decade, the epidemiological role of argasid and ixodid ticks as vectors of zoonotic pathogens has received great attention.…”