Protothecal Infections Research Articles

Protothecosis in four dogs in New Zealand

ABSTRACT Case histories Medical records of four dogs diagnosed with protothecosis in New Zealand were reviewed. The dogs were aged between 4 and 9 years and three of the four dogs were female. Breeds were one Labrador, one Miniature Schnauzer and two crossbreeds. The reasons for initial veterinary evaluation were a cough and opaque appearance of the right eye (Case 1), diarrhoea (Cases 2 and 3), and cutaneous disease (Case 4). Clinical findings The ocular signs were characterised by panuveitis, retinal detachment and secondary glaucoma. Gastrointestinal signs included chronic haemorrhagic diarrhoea due to colitis. Three cases had disseminated infection and developed both bilateral, blinding, ocular disease and chronic gastrointestinal disease. Cutaneous signs consisted of draining fistulae over the olecranon, multifocal cutaneous nodules, and ulceration and tracts of the foot pads. Disseminated protothecosis was confirmed by histopathology of biopsied ocular tissues in Cases 1 and 2 and by gastrointestinal biopsies in Case 3. Prototheca spp. were also identified in cytological specimens from Cases 1 and 4 and recovered by culture in Cases 2 and 4. Cutaneous protothecosis was diagnosed in Case 4 initially by cytology and histopathology of skin lesions, and Prototheca zopfii was confirmed by PCR of cultured organisms. Treatment and outcome Prior to diagnosis of protothecosis, a variety of treatments were prescribed to treat the gastrointestinal and ocular signs. After diagnosis, only Cases 2 and 4 received medication aimed at treating the protothecal infection, which was itraconazole in both cases. Following the progression of clinical signs and concerns about quality of life, all four dogs were euthanised. Diagnosis Disseminated protothecosis in three dogs, cutaneous protothecosis in one dog. Clinical relevance Canine protothecosis is rarely reported, despite the ubiquity of the causal algae, and the disease usually carries an extremely grave prognosis when infection is generalised. In New Zealand, protothecosis should be considered as a differential diagnosis in dogs with panuveitis, chorioretinitis or retinal detachment, colitis, or nodular, ulcerative or fistulating cutaneous lesions.

Prototheca Infections and Ecology from a One Health Perspective.

Prototheca microalgae were only recognized as pathogens of both humans and animals in the 1960s; however, since then, these microbes have been drawing increasing interest in both human and veterinary medicine. The first human outbreak of protothecosis in a tertiary care chemotherapy ward in 2018 further highlighted the need to understand in more depth and detail their ecology, etiology, pathogenesis and routes of transmission between different hosts, environments and habitats from a One Health perspective. Protothecal infections have been reported in a growing number of cattle herds around the world in recent decades, and Prototheca has become an important bovine mastitis pathogen in certain countries and regions. The survival of Prototheca in the environment and its ability to spread in the herd pose a serious challenge to the management of infected dairy farms. Prevention of the disease is particularly important, as there is no effective and reliable treatment for it and the chances of self-healing are minimal. Therefore, the development of more effective drugs is needed for the treatment of human and animal protothecosis. The prudent use of antibiotics and their replacement by alternative or preventive measures, when possible, may further contribute to the control of protothecal infections.

Prototheca from bovine milk and associated minimal algaecide concentration of chlorhexidine and povidone-iodine in Taiwan.

Protothecal mastitis has emerged and affected the dairy industries globally in last decades; however, little is known about the occurrence of Prototheca in Taiwan. The present study identified the Prototheca isolated from bovine milk and revealed the algaecide efficacy of 2 disinfectants. From 2011 to 2014, a total of 176 Prototheca isolates were obtained from 10 625 milk samples collected from dairy cows in 24 Taiwanese dairy farms. Of these, 149 isolates were identified by biochemical tests and genotype differentiation with a specific PCR protocol. Minimal algaecide concentration (MAC) of chlorhexidine and povidone-iodine were obtained from 16 isolates by microdilution method. Almost all (n = 147) isolates were P. zopfii, and remaining 2 isolates were P. wickerhamii and unidentified, respectively. Based on molecular genotyping, all P. zopfii isolates belonged to genotype 2. The MAC of 2 commonly used disinfectants, chlorhexidine and povidone-iodine, against 16 P. zopfii isolates was 1.56-3.13 and 48.83-390.63 µg/ml, respectively. This report revealed for the first time the prevalence and the predominant P. zopfii genotype 2 of bovine protothecal infection in Taiwan. In vitro algaecide efficacy indicated that both tested disinfectants were effective against P. zopfii.

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.

In Vitro Activity of 30 Essential Oils against Bovine Clinical Isolates of Prototheca zopfii and Prototheca blaschkeae

Protothecal mastitis poses an emergent animal health problem in dairy herds, with a high impact on dairy industries, causing heavy economic losses. Current methods of treating protothecal infections are ineffective, and no drug is licensed for use in cattle. The aim of the present study was to check the antialgal activity of 30 chemically defined essential oils (EOs) against Prototheca zopfii and Prototheca blaschkeae isolated from the milk of dairy cows with mastitis. A microdilution test was carried out to estimate the antialgal effectiveness of the selected chemically defined EOs. The microdilution test showed different degrees of inhibition among the examined Prototheca species. The activity of some of the examined EOs seem interesting. In particular, Citrus paradisi yielded the lowest minimal inhibitory concentration values (0.75%) for both algal species. P. zopfii appeared to be more sensitive to EOs in comparison to P. blaschkeae. The present study investigated the in vitro susceptibility of P. zopfii and P. blaschkeae to a wide range of EOs, obtained from different botanical families. Further investigations are necessary to evaluate the efficacy of EO-based formulations intended for the disinfection of both udder and milking products.

Protothecal peritonitis in child after bone marrow transplantation: case report and literature review of paediatric cases.

The case presented here illustrates a protothecal infection caused by Prototheca wickerhamii in a paediatric haematopoietic stem cell recipient followed by a review of the literature of all 13 paediatric cases published since 1980. Protothecosis is a rare disease caused by algae, not described in this setting before. Infection was proven additionally post-mortem from peritoneal dialysis fluid. Even though no death of a paediatric patient due to this infection has been reported and the mortality rate associated with protothecosis is low, our patient died from multiorgan failure as a result of numerous post-transplant complications and a strain of cultivated alga that was highly resistant to antifungal agents. Prototheca spp. show various susceptibility profiles, and there is no direct correlation between in vitro activity and clinical response. There are different treatment regimens described but there are no clear published guidelines of specific therapy of protothecosis. Paediatric cases were successfully treated mostly with amphotericin B and azoles. As the number of immunocompromised patients increases, it is necessary to think more about unusual pathogens such as Prototheca.

Cutaneous protothecosis in a patient with previously undiagnosed HIV infection

Protothecosis is an uncommon condition resulting from infection by achlorophyllous algae of the Prototheca species. Immunocompromised individuals are generally most susceptible to protothecal infection and tend to develop severe and disseminated disease. However, the association between protothecosis and HIV-induced immunosuppression is not clear, with only a handful of cases having been described to date. Here we report a case of cutaneous protothecosis in a Chinese man with previously undiagnosed HIV infection that responded well to oral itraconazole.

Prototheca wickerhamii algaemia presenting as cholestatic hepatitis in a patient with systemic lupus erythematosus: A case report and literature review

Human protothecal infection is uncommon and could be localized or systemic disease. Disseminated Prototheca algaemia tends to occur in immunocompromised patients (solid organ transplants, hematological malignancies) with high mortality. Diagnosis could be missed or delayed due to unusual clinical presentation and/or under-recognition of characteristic microscopic features of Prototheca species. Combined approach that includes removal of source of infection and intravenous amphotericin B provides the best chance of cure.

Prototheca wickerhamii Infection of a Corneal Graft

Algae are generally noninfectious agents in mammals, with few known pathogenic algae. Prototheca is an achlorophylic nonphotosynthetic algae, globally ubiquitous, and readily isolated from rivers, lakes, ponds, and soil. Although canine and bovine protothecosis have been reported more widely, infections in humans are rare, particularly in patients with an intact immune system. The majority of protothecal infections in humans is associated with Prototheca wickerhamii. We report an unusual case of P. wickerhamii infection in an immunocompetent corneal transplant patient.

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

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.

Outbreak of endemic form of protothecal mastitis on a dairy farm

In this paper an outbreak of mastitis in cows resistant to antibiotic treatment on a Holstein-Friesian cattle farm in Vojvodina (Serbia and Montenegro) was described. Microbiological examination of 73 milk samples from lactating cows revealed the presence of Prototheca zopfii in 22 samples (30.13%). Identification of the isolates was performed on the basis of growth features, microscopic appearance, assimilation patterns and antimicrobial susceptibility. Protothecal infection of the mammary gland resulted in clinical symptoms of chronic mastitis in 19 animals. Histopathological findings revealed distinct granulomatous inflammations of the mammary gland interstitium.