An isolate of Prototheca wickerhamii from systemic canine protothecosis

Identification of Prototheca from the Cerebrospinal Fluid of a Cat with Neurological Signs

Prototheca infections are rare in cats, and they are usually associated with cutaneous or subcutaneous infections by P. wickerhamii, with no evidence of neurological signs or systemic disease. In this study, we report the identification of prototheca in the cerebrospinal fluid (CSF) of a cat with neurological symptoms. Fourteen CSF samples were gathered from cats presented with neurological disease between 2012 and 2014. The inclusion criteria for the samples were an increase in CSF protein and cell number (pleocytosis), suggestive of an infectious inflammatory status of the central nervous system (CNS). Nine samples fulfilled the inclusion criteria (inflammatory samples), while five samples, used as control, did not (non-inflammatory samples). All the samples were screened molecularly for different pathogens associated with CNS disease in cats, including prototheca. Out of 14 CSF samples, only one inflammatory sample tested positive for prototheca. Upon sequence and phylogenetic analysis of the amplicon, the strain was characterized as P. bovis. This report is the first documented evidence of prototheca in the cerebrospinal fluid of a cat with neurological signs. Prototheca should be considered in the diagnostics procedures on the CNS of cats presented with infectious diseases.

Molecular characterization of Prototheca in 11 symptomatic dogs

Protothecosis is an uncommon disease caused by algae of the genus Prototheca. In dogs, the infection is usually first localized to the colon but has the propensity to later disseminate hematogenously to many other organs, with marked tropism for the eyes and central nervous system. Diagnosis is established by culture and/or evidence of Prototheca organisms in cytologic or histologic preparations. Species characterization, however, requires molecular investigations. Our laboratory set up a real-time PCR targeting portion D1/D2 of the 28S rRNA for identification of Prototheca species from both positive cultures (of rectal swabs and urine) and formalin-fixed, paraffin-embedded tissue. Prototheca bovis, P. ciferrii, and P. wickerhamii were characterized in 11 dogs with systemic or cutaneous protothecosis. Prototheca identifications were phylogenetically consistent with the new taxonomy proposed for this genus based on the mitochondrial cytochrome b gene. As a pilot study, we screened feces and rectal scrapes from 200 asymptomatic dogs, using 2 cohorts of stray and owned animals, to determine the prevalence of intestinal carriage of Prototheca spp. The Prototheca-negative results from both cohorts of healthy dogs suggest that predisposing factors related to the host probably contribute more to the acquisition of clinical disease than exposure to contaminated environments.

Protothecosis in Dogs and Cats-New Research Directions

Protothecosis refers to disease of humans and animals caused by infection with fungus-like, colourless microalgae of the genus Prototheca. Although protothecosis remains an uncommon infection, increasing numbers of human and animal cases are being diagnosed worldwide. This review summarises major new findings in basic science (sequencing analyses of sterol 14α-demethylase (CYP51/ERG11) genes and organelle genomes of Prototheca wickerhamii) to elucidate taxonomic features of this pathogen. Furthermore, this review updates and summarises the clinical features, diagnosis and treatment of protothecosis in dogs and cats. This content of this review is based on information presented at the medical phycology symposium held in the 20th Congress of the International Society for Human and Animal Mycology ( https://www.isham.org/ ).

Cytologic, histologic, microbiologic, and electron microscopic characterization of a canine Prototheca wickerhamii infection

An adult dog was presented for chronic cough and a recent development of ulcerated, erythematous nares with nasal discharge. Cytology of enlarged peripheral lymph nodes revealed many intracellular and extracellular organisms. These round or rarely oval organisms measured approximately 5-9 µm in diameter and frequently contained several globular structures, ranging from deeply basophilic to magenta. A thin, clear halo was present. Smaller 1-2 µm, magenta forms were also observed. Fungal culture yielded small, wet, raised, irregularly shaped, white to pale tan colonies. Microbiologic staining of cultured material revealed features suggestive of algae. Histopathology of the lymph nodes revealed marked granulomatous inflammation with intralesional algal organisms suggestive of Prototheca. Electron microscopic findings were also consistent with protothecosis. Polymerase chain reaction, followed by direct DNA sequencing, identified the organism as Prototheca wickerhamii. A brief literature review discussing protothecosis in veterinary medicine is included.

Emergence of Fungal-Like Organisms: Prototheca

The genus Prototheca consists of achlorophyllic algae that are ubiquitous in the environment and animal intestines. However, this organism has forfeited its photosynthetic ability and switched to parasitism. In 1894, Krüger described two microorganisms isolated in Germany from mucous flux of Tilia and Ulmus spp., namely Prototheca moriformis and P. zopfii. Based on their yeast-like colony morphology, Krüger classified these organisms as fungi. The genus is now included within the class Trebouxiophyceae, order Chlorellales, and family Chlorellaceae. Historically, protothecosis and infections caused by green algae have been studied in the field of medical mycology. Prototheca spp. have been found to colonize human skin, fingernails, the respiratory tract, and digestive system. Although human infection by Prototheca is considered rare, an increase in infections has been noted among immunosuppressed patients, those on corticosteroid treatment, or both. Moreover, the first human outbreak of protothecal algaemia and sepsis was recently reported in a tertiary care chemotherapy oncology unit in 2018. Prototheca is also a causative pathogen of bovine disease. Prototheca zopfii and P. blaschkeae are associated with bovine mastitis, which causes a reduction in milk production and secretion of thin, watery milk containing white flakes. Economic losses are incurred either directly via reduced milk production and premature culling of affected animals or indirectly as a result of treatment and veterinary care expenses. Thus, knowledge of this fungal-like pathogen is essential in human and veterinary medicine. In this mini-review, I briefly introduce human and animal protothecoses.

cytb as a New Genetic Marker for Differentiation of Prototheca Species

Achlorophyllous unicellular microalgae of the genus Prototheca (Trebouxiophyceae, Chlorophyta) are the only known plants that cause infections in both humans and animals, collectively referred to as protothecosis. Human protothecosis, most commonly manifested as cutaneous, articular, and disseminated disease, is primarily caused by Protothecawickerhamii, followed by Protothecazopfii and, sporadically, by Protothecacutis and Protothecamiyajii In veterinary medicine, however, P. zopfii is a major pathogen responsible for bovine mastitis, which is a predominant form of protothecal disease in animals. Historically, identification of Prototheca spp. has relied upon phenotypic criteria; these were later replaced by molecular typing schemes, including DNA sequencing. However, the molecular markers interrogated so far, mostly located in the ribosomal DNA (rDNA) cluster, do not provide sufficient discriminatory power to distinguish among all Prototheca spp. currently recognized. Our study is the first attempt to develop a fast, reliable, and specific molecular method allowing identification of all Prototheca spp. We propose the mitochondrial cytb gene as a new and robust marker for diagnostics and phylogenetic studies of the Prototheca algae. The cytb gene displayed important advantages over the rDNA markers. Not only did the cytb gene have the highest discriminatory capacity for resolving all Prototheca species, but it also performed best in terms of technical feasibility, understood as ease of amplification, sequencing, and multiple alignment analysis. Based on the species-specific polymorphisms in the partial cytb gene, we developed a fast and straightforward PCR-restriction fragment length polymorphism (RFLP) assay for identification and differentiation of all Prototheca species described so far. The newly proposed method is advocated to be a new gold standard in diagnostics of protothecal infections in human and animal populations.

Internal transcribed spacer sequence-based rapid molecular identification of Prototheca zopfii and Prototheca blaschkeae directly from milk of infected cows

The increasing incidence of rare mastitis-causing pathogens has urged the implementation of fast and efficient diagnostic and control measures. Prototheca algae are known to be associated with diseases in humans and animals. In the latter, the most prevalent form of protothecosis is bovine mastitis with Prototheca zopfii and Prototheca blaschkeae representing the most common pathogenic species. These nonphotosynthetic and colorless green algae are ubiquitous in different environments and are widely resistant against harmful conditions and antimicrobials. Hence, the association of Prototheca with bovine mastitis represents a herd problem, requiring fast and easy identification of the infectious agent. The purpose of this study was to develop a reliable and rapid method, based on the internal transcribed spacer (ITS) sequences of ribosomal DNA, for molecular identification and discrimination between P. zopfii and P. blaschkeae in bovine mastitic milk. The complete ITS sequences of 32 Prototheca isolates showed substantial interspecies but moderate intraspecies variability facilitating the design of species-specific PCR amplification primers. The species-specific PCR was successfully applied to the identification of P. zopfii and P. blaschkeae directly from milk samples. The intraspecific ITS phylogeny was compared for each species with the geographical distribution of the respective Prototheca isolates, but no significant correlation was found.

Disseminated Protothecosis Associated With Diskospondylitis in a Dog

A 6 yr old female Labrador retriever was evaluated for an acute onset of difficulty walking and a head tilt. Initial physical examination revealed bilateral retinal detachment, a left-sided head tilt, positional rotary nystagmus, and lumbar hyperpathia. Pertinent preliminary diagnostic findings included systemic hypertension, bony lysis and adjacent sclerosis of the vertebral endplates of the first and second lumbar vertebrae, and positive urine and blood cultures for a yeast identified as Candida spp. Concerned about disseminated candidiasis after subsequent subretinal aspirates confirmed the presence of a yeast-like organism, therapy with voriconazole was initiated. Because of progressive clinical deterioration and the poor prognosis for recovery, the dog was eventually euthanized. Postmortem histological examination of tissues, including the affected vertebral endplates, revealed numerous intralesional algae compatible with Prototheca spp. To the authors' knowledge, this report is the first to document a case of protothecal diskospondylitis with possible concurrent candidiasis in a dog. Although typically associated with signs referable to the gastrointestinal tract, this report underscores the importance of not excluding protothecosis as a differential diagnosis when such signs are absent. Lastly, the use of voriconazole appears ineffective for reversing the clinical course of late-stage disseminated protothecosis.

Ribosomal internal transcribed spacer of Prototheca wickerhamii has characteristic structure useful for identification and genotyping

Prototheca species are achlorophyllous algae ubiquitous in nature and known to cause localized and systemic infection both in humans and animals. Although identification of the Prototheca species in clinical specimens is a challenge, there are an increasing number of cases in which molecular techniques have successfully been used for diagnosis of protothecosis. In this study, we characterized nuclear ribosomal DNA (rDNA) of a strain of Prototheca (FL11-0001) isolated from a dermatitis patient in Japan for its species identification. When nuclear rDNA of FL11-0001 and that of various other Prototheca strains were compared by polymerase chain reaction (PCR), the results indicated that the sizes of ribosomal internal transcribed spacer (ITS) were different in a species-dependent manner, suggesting that the variation might be useful for differentiation of Prototheca spp. Especially, ITS of P. wickerhamii, the most common cause of human protothecosis, was distinctively larger than that of other Prototheca spp. FL11-0001, whose ITS was comparably large, could easily be identified as P. wickerhamii. The usefulness of the PCR analysis of ITS was also demonstrated by the discovery that one of the clinical isolates that had previously been designated as P. wickerhamii was likely a novel species. Furthermore, our data demonstrated that nucleotide sequences of P. wickerhamii ITS are heterogenous between different rDNA copies in each strain and also polymorphic between strains. Phylogenetic analysis suggested that the ITS sequences could be classified to four clades, based on which P. wickerhamii strains might be grouped into at least two genotypes. Comprehensive characterization of Prototheca rDNA may provide valuable insights into diagnosis and epidemiology of protothecosis, as well as evolution and taxonomy of Prototheca and related organisms.

Algal Meningoencephalitis due toProtothecaspp. in a Dog

A 6-year-old Boxer was examined because of progressive neurologic signs, with severe hindlimb ataxia and head tilt on presentation. There was no history of diarrhea or vomiting. MRI of the brain revealed multifocal ill-defined T1-enhancing lesions affecting the cerebrum, brainstem, and cervical meninges, without associated mass effect. Meningoencephalitis was considered the most likely diagnosis. Multiple algae were observed on the cytology of the CSF and were most consistent withProtothecaspp. Antiprotozoal treatment was denied by the owners, and 5 weeks after diagnosis, the dog was euthanized due to progression of the neurologic deficits, and a necropsy was performed. Histological changes in the brain were compatible with severe multifocal protothecal meningoencephalitis. The specificProtothecaspecies was not identified. The gastrointestinal tract was unremarkable on histology. According to this report,Protothecaspp. should be included in the differentials for neurological deficits even in the absence of gastrointestinal signs.

Prototecose: uma doença emergente

Prototecose, causada por Prototheca zopfii ou P. wickerhamii, é uma doença emergente em animais e humanos. Em bovinos, P. zopfii é uma importante causa de mastite ambiental. Em cães e gatos, a prototecose é causada principalmente por P. zopfii. Em cães, causa infecção cutânea ou uma forma sistêmica envolvendo diversos órgãos. Em gatos, predominam as lesões tegumentares na região da face e plano nasal. No homem, a prototecose, causada principalmente por P. wickerhamii, manifesta-se sob três formas: cutânea, articular com bursite do olécrano e sistêmica. Pode ocorrer em indivíduos imunocompetentes, os quais podem apresentar bursite e/ou infecções cutâneas localizadas, ou em indivíduos imunossuprimidos, nos quais a enfermidade pode ser disseminada e/ou com envolvimento visceral. A prototecose causada por P. wickerhamii foi descrita recentemente em caprinos como causa de rinite afetando o vestíbulo nasal, união mucocutânea, pele da face e orelha. Nesta revisão são abordadas as características microbiologias e susceptibilidade a antimicrobianos do agente, e a epidemiologia, sinais clínicos, patologia, diagnóstico, tratamento e controle da prototecose em animais domésticos e no homem.

Large-scale screening of the in vitro susceptibility of Prototheca zopfii towards polyene antibiotics

A large scale screening of the in vitro susceptibility of 105 strains of Prototheca zopfii to a panel of polyene antibiotics (amphotericin B, nystatin, primaricin and filipin) was conducted. Strains studied were isolated from dairy-associated environments in five different localities. Groups 1-4 included strains recovered from four separate regions of Italy, while group 5 included isolates from Belgium. Amphotericin B and primaricin exhibited the highest activity, with th MIC90 ranging from 4 and 8 microg/ml, respectively. On the other hand, the MIC90 of nystatin and filipin were from two to four times higher. Two strains were resistant to all four polyenes tested. The above results are compared with those in the literature and the importance of carrying out large-scale screening surveys to assess polyene susceptibility patterns within the species P. zopfii is discussed.

Cutaneous and nasal protothecosis in a goat

A case of protothecosis is reported in an adult goat with inspiratory dyspnea and stertor. Dermatitis with prominent ulcerated nodules up to 3 cm in diameter was observed in the muzzle at the mucocutaneous junctions of nasal and lip skin, and in the border of the pinna. Histologic lesions were necrotizing pyogranulomatous dermatitis and rhinitis with myriads of walled sporangia, characteristic of Prototheca wickerhamii. This seems to be the first report of protothecosis in a goat.

Bovine mastitis associated with Prototheca blaschkeae

Bovine mastitis is an important and complex disease responsible for economic losses in the dairy industry. Biotype II strains of the green alga Prototheca zopfii can be involved, most often resulting in chronic mastitis of difficult treatment associated with reduced milk production. This type of infection is rare, but the number of reported cases is increasing worldwide. In order to determine the kind of species involved in mastitis by Prototheca in northwest Portugal, 41 Prototheca isolates were genetically characterized. The algae are part of Prototheca isolates that were collected during a 6-year period, isolated from the milk of 41 dairy cows in a total of 22 herds with a history of increasing somatic cell counts, mild clinical signs of udder infection, and unsuccessful response to the usual therapy. PCR amplification of the 18S ribosomal DNA (rDNA), amplified rDNA restriction analysis, and phylogenetic analyses of the 18S rDNA sequences were performed. Thirty-seven isolates were identified as P. zopfii var. hydrocarbonea and four as Prototheca blaschkeae. These data suggest a high incidence of P. zopfii var. hydrocarbonea mastitis in the region and demonstrate for the first time the involvement of P. blaschkeae with bovine mammary gland infections.