Characteristics and importance of the genus Prototheca in human and veterinary medicine

Abstract

Prototheca spp. are strange algae, assigned to the genus Prototheca, family Chlorelaceae. They are ubiquitous in nature, living predominantly in aqueous locales containing decomposing plant material. Prototheca spp. were isolated from skin scarificates, sputum and feces of humans in absence of infection as well as in a variety of domestic and some wild animals. Prototheca spp. are unicellular organisms, oval or spheric in shape. They differ from bacteria and fungi in size, shape and reproductive characteristics. Of the five known species of the genus, only P. wickerhamii and P. zopfii are considered pathogenic, and they are the only known plant causative agents of human and animal infections. Over the past 25 years medical references reported more than 100 cases of human protothecoses, mostly induced by P. wickerhamii and rarely by P. zopfii. A half of the reports on human protothecoses relates to localized cutaneous infections and oleocranon bursitis. The rarest and most severe form of the infection is disseminated or systemic protothecosis, described in patients with durable course of primary disease or immune disfunction. In veterinary medicine, Prototheca zopfii and rarely also P. wickerhamii are reported as causative agents of cutaneous protothecosis in dogs and cats, systemic protothecosis in dogs and mastitis in dairy cows. Protothecal infections are diagnosed by histopathology examination or, more exactly, by isolation of the agent, although the organism cannot be distinguished from the yeasts by its cultural characteristics. Final diagnosis is made by the carbon-hydrate assimilation test. Protothecal infections are easily missed in routine practice. Pharmacological protocol for therapy of this rare infection has not been developed yet either in human or in veterinary medicine. Several antifungal agents are applied for treatment; however, the effects are variable. Where possible, surgical excision is treatment of choice. Prognosis is promising in patients with localized infection, and healing is often achieved. Prognosis is less predictable, mostly bad, in patients with other diseases and in immunocompromized patients. Sensitivity of Prototheca spp. in vitro does not necessarily correlate with its efficacy in vivo

Mastitis associated with Prototheca zopfii - an emerging health and economic problem on dairy farms

“…nov. (8,12,30). The species P. blaschkeae, P. wickerhamii, P. zopfii, and P. cutis are considered causal agents of local human and/or animal infections (18,21,28,30,31). Systemic infections associated with these organisms are relatively rare.…”

Prototheca zopfii as a Cause of Pneumonia and Disseminated Infection in Febrile Neutropenia: A Case Report and Literature Review

“…Unlike the previous series on patients infected with P. Wickerhamii , mortality from disseminated P. zopfii infection was much higher [ 12 ]. Milk and dairy products contaminated with P. zopfii primarily cause skin diseases, and can be a source of infection in humans and milking cows, then are disseminated in immune-compromised hosts [ 15 ]. In our patient, the contaminated food may have been the source of infection, and the colon ulcerations were a possible portal of entry.…”

A New Modified Staining Technique for Demonstration of Prototheca Spp. Algae on Paraffin Sections First Record.

“…Hematoxylin and eosin (H&E) stainispoor for Prototheca spp. in tissue section [5]. In this note Imodify Chromotrope 2R -Aniline blue solution for staining of Prototheca spp.…”