Identification ofMortierella wolfii, a causative agent of mycotic abortion in cattle

Abstract

Of several media tested for their ability to induce asexual reproduction in confirmed or suspected isolates of Mortierella wolfii obtained from cattle in various geographical locations, only silage extract agar worked consistently and rapidly. Its use should provide a simple reliable culturing procedure to assist with identification of clinical isolates of this fungus. Temperature growth response curves and electrophoretic patterns of soluble protein extracts of these isolates with characteristic morphological features of M. wolfii indicate substantial variation amongst them.Mortierella wolfii, Mehrotra and Baijal has been identified in aborting cattle in Britain [11] and in New Zealand [4] and Australia [9], where this fungus is considered to be one of the most important causes of systemic mycosis in cattle. However its incidence is probably underestimated. Many cases have remained undiagnosed because, although M. wolfii infection was suspected, it was not often identified with certainty. Even if the aborted placental tissue can be located for examination, the infecting hyphae are not distinctive enough to allow an unequivocal histological diagnosis [5]. Several serological procedures have been tried in attempts to recognize infected cattle, but with varying degrees of success [11,16]. Attempts to culture isolates and identify them on their reproductive morphology have been frustrated by the inability of many isolates to sporulate in culture on media such as potato glucose, Sabouraud or blood agar [6]. Therefore in many cases, M. wolfii has been tentatively identified mainly on the basis of the distinctive nature of the colonies, having the appearance of rosettes of overlapping lobes on some media [7].In this study, attempts were made to find a medium promoting sporulation in isolates of M. wolfii which could then be used to assist with positive identification.Polyacrylamide gel electrophoresis (PAGE) of mycelial proteins was also investigated as an alternative means of identifying isolates which would not sporulate in culture, but which would grow vegetatively.

Equine keratomycosis in Japan

“…However, M. wolfii isolated from horse 5 was resistant to voriconazole, both mycologically and clinically. This fungus is classified in the Phylum Zygomycota 33 and is one of the major causes of systemic mycosis in cattle 34–37 . We previously reported a case of Mortierella keratitis (horse 3 in this study) in which topical miconazole was clinically effective 22 .…”

Review of animal mycoses in Australia

“…Fertility following fungal abortion was apparently unimpaired. Seviour et al (1987) [ 112] in Victoria, tested several media for inducing sexual reproduction in confirmed or suspected isolates of M. wolfii obtained from cattle in various geographical locations. Only silage extract agar worked consistently and rapidly.…”

Zygomycetes in Human Disease

“…wolfii is recognized as a true animal pathogen and is considered to be the most common cause of mycotic abortion in northern New Zealand (327,392,419). This fungus has also been reported as an agent of bovine mycotic abortion in both the United States (513) and Great Britain (95) and has been shown to cause pneumonia in cattle (120).…”

“…Soil extract agar incubated above 25°C is necessary for sporulation, but some strains are difficult to identify because of poor spore formation even under the optimal growth conditions (175,392,412). Seviour et al (419) described silage extract agar which contains filtered silage at pH 4.5 to 4.7 as a good medium for sporulation.…”