Efficacy of chemical disinfectants for the containment of the salamander chytrid fungus Batrachochytrium salamandrivorans

Abstract

The recently emerged chytrid fungus Batrachochytrium salamandrivorans (Bsal) causes European salamander declines. Proper hygiene protocols including disinfection procedures are crucial to prevent disease transmission. Here, the efficacy of chemical disinfectants in killing Bsal was evaluated. At all tested conditions, Biocidal®, Chloramine-T®, Dettol medical®, Disolol®, ethanol, F10®, Hibiscrub®, potassium permanganate, Safe4®, sodium hypochlorite, and Virkon S®, were effective at killing Bsal. Concentrations of 5% sodium chloride or lower, 0.01% peracetic acid and 0.001–1% copper sulphate were inactive against Bsal. None of the conditions tested for hydrogen peroxide affected Bsal viability, while it did kill Batrachochytrium dendrobatidis (Bd). For Bsal, enzymatic breakdown of hydrogen peroxide by catalases and specific morphological features (clustering of sporangia, development of new sporangia within the original sporangium), were identified as fungal factors altering susceptibility to several of the disinfectants tested. Based on the in vitro results we recommend 1% Virkon S®, 4% sodium hypochlorite and 70% ethanol for disinfecting equipment in the field, lab or captive setting, with a minimal contact time of 5 minutes for 1% Virkon S® and 1 minute for the latter disinfectants. These conditions not only efficiently target Bsal, but also Bd and Ranavirus.

Presence of low virulence chytrid fungi could protect European amphibians from more deadly strains

“…During the fieldwork, each individual was handled with a new pair of nitrile gloves. At the end of each field visit, boots, dipnets, funnel traps and other equipments were disinfected with a 1% Virkon® solution for at least 5 min 50 .…”

Instant killing of pathogenic chytrid fungi by disposable nitrile gloves prevents disease transmission between amphibians

“…Bd and Bsal possess a chitin-binding module, CBM18, which is suspected to confer the ability to survive on amphibian hosts. As, other pathogenic fungi’s CBMs compete with chitinases, by binding to their own chitin in their cell wall, it has been suggested that Bd’ s CBM18 provide protection against amphibian host chitinases [ 28 ]. Fungal catalases and peroxidases are also able to degrade certain antifungal compounds.…”

“…Also, the clustering of zoosporangia may insulate or buffer the more centrally located zoosporangia from exposure to the antifungal compounds and limit contact, compared to the more peripherally located zoosporangia. These factors contribute to and may explain the need for prolonged periods of exposure to and higher concentrations of antifungal chemicals to achieve complete mortality of Bsal compared to Bd [ 28 ].…”

“…The same actions as described above were performed in the non-gloved group, except that the infected source-animals were manipulated with bare hands that had been washed with neutral soap (Soft Care™, Diversey) and thoroughly rinsed with water. After manipulation of each contact animal, hands were disinfected using Disolol ® [ 28 ]. Between each replicate, a minimal pause of 2 hours was respected, as multiple disinfection cleansing of the hands might negatively affect the antimicrobial function of the amphibian skin [ 14 ].…”

Sensitivity of mycelial growth of mushroom Agrocybe semiorbicularis to different concentrations of different disinfectants

“…Moreover, some studies on fungi revealed that Hypo at concentrations between 0.03 and 2.4% were effective at killing Penicillium, Cladosporium, Mucor, Rhizopus, Stachybotrys, Alternaria, Aspergillus, Helminthosporium, Trichophytonand Batrachochytrium spp. (Reynolds et al, 2004;Becker, and Gratwicke, 2017;Van Rooij et al, 2017).…”