Mucormycosis in the platypus and the anuran (frogs and toads) is a major fungal disease caused by the dimorphic Mucorale, Mucor amphibiorum. First reported from a German Zoo in 1972, M. amphibiorum infection resulted in a disseminated mycosis in a green tree frog imported from Australia. Since 1994, naturally occurring infections in wild anurans from Queensland and Northern Territory, and captive frogs from Melbourne and Perth have been recorded. A severe ulcerative skin condition was first reported in platypuses from the Elizabeth River in Tasmania in 1982, however the causative agent was not confirmed as M. amphibiorum until a decade later. The granulomatous and ulcerative dermatitis may progress to involve underlying muscle or disseminate to internal organs. The sudden emergence of mucormycosis in Tasmanian platypuses may have been by accidental introduction with ‘banana box frogs’ from Queensland or due to an endemic Tasmanian strain that mutated becoming pathogenic for platypuses. Only positive mating types have been isolated from Tasmanian platypuses, while both mating strains have been isolated from mainland anurans. The ecologic niche of M. amphibiorum on the mainland is soil and anurans, whereas in Tasmania (other than platypus lesions) its niche is currently unknown.
Differentiating species of Mucor was traditionally based on phenotypic characters. More recently genotypic analysis has been shown to be reliable and discriminating. Isolates of Mucor sp. were genotyped by sequencing of the internal transcribed spacer (ITS) region, followed by inter-simple sequence repeats polymerase chain reaction (ISSR-PCR) for diversity analysis. Recently, PCR followed by high-resolution melt (HRM) curve analysis has been used for detection and/or genotyping of a variety of microorganisms including filamentous fungi. We investigated a PCR targeting ITS regions of rDNA genes and HRM analysis for subsequent Mucor species identification.
The use of evolving molecular tools to detect M. amphibiorum in the environment, tissue lesions, and aquatic vectors, would improve our understanding of mucormycosis epidemiology, leading to better surveillance and control.