Protothecosis: a report of two cases in Japan and a review of the literature

Disseminated protothecosis: Case report and review of the literature

BACKGROUND

Human protothecosis is an uncommon infection caused by Prototheca spp that rarely infects humans.

AIM

Description of a rare disease and a review of its articles.

MATERIALS AND METHODS

We reported a 24-year-old man who presented with red-brown papules and plaques on the trunk's lateral side. We reviewed the literature about disseminated protothecosis and reported our experience with a patient with protothecosis between 2021 and 2023.

RESULTS

Overall, 54 cases of disseminated protothecosis were evaluated, 39 were due to P. wickerhamii, 12 were due to P. zopfii (22.2%), and three were due to Prototheca spp. We found that males were more affected (37 cases, 68.5%) than females (16 cases, 29.6%). The mean age of patients was 39.53 ± 22.48 years. However, disseminated protothecosis can affect people of any age (1-80 years). In contrast to P. wickerhamii, which causes blood, skin, brain, and gastrointestinal tract infections, P. zopfii was mainly found in the blood (7/22) and did not have a significant difference in the mortality rate (P = 0.11).

DISCUSSION

Disseminated protothecosis is a rare disease in immunocompromised patients but is generally rarer in immunocompetent hosts. Several underlying disorders include immunocompromised patients, prolonged application of steroids, diabetes mellitus, malignancies, organ transplantation, AIDS, and surgeries. Amphotericin B has been the most effective agent for protothecosis and is reserved for visceral and disseminated infections. Regarding localized cutaneous types, excision or surgical debridement is used.

CONCLUSION

Mulberry's appearance and appropriate cultural environments are helpful in diagnosing it.

Human Disseminated Protothecosis: The Skin is the "Window"?

Human disseminated protothecosis is a rare infection caused by members of the genus Prototheca, an achlorophyllic algae always associated with debilitated hosts. The presence of non-budding cells and large, spherical cells (sporangia) with endosporulation (morula) in histology is proof of Prototheca infection. Regrettably, due to the lack of specificity of clinical features and low awareness among clinicians, protothecosis is always underestimated and misdiagnosed. The available data on a species-specific analysis of this infection are limited. In this review, we summarize the etiological, epidemiological, and clinical aspects of disseminated protothecosis. The potential pathogenicity and clinical differences between P. zopfii and P. wickerhamii were observed. Additionally, the skin not only became the main invasion site but also the most involved organ by the pathogen. With the increasing numbers of immunocompromised individuals throughout the world, the incidence of disseminated infection caused by Prototheca is bound to increase, and disseminated protothecosis that accompanies skin symptoms should be taken into account by clinicians.

Medical phycology 2017

In 2014, ISHAM formed a new working group: "Medical Phycology: Protothecosis and Chlorellosis." The purpose of this working group is to help facilitate collaboration and communication among people interested in the pathogenic algae, to share ideas and work together. Here we present reports on recent work we have done in five areas. 1. The history of medical phycology as a branch of science. 2. Aspects of the genetics of Prototheca. 3. Aspects of the proteins of Prototheca. 4. Human infections caused by Prototheca. 5. Dairy cow mastitis caused by Prototheca.

Clinicopathological features and course of cutaneous protothecosis

BACKGROUND

Protothecosis is an uncommon infection caused by the achlorophyllic algae found more commonly in tropical areas. Only a limited number of cases have been reported.

OBJECTIVE

We aimed to evaluate the clinicopathological features and treatment outcomes of cutaneous protothecosis.

METHODS

We retrospectively identified 20 pathology-confirmed cases of cutaneous protothecosis based on skin biopsies in two tertiary medical centres in Taiwan from 1997 to 2015.

RESULTS

The age of the patients at the time of diagnosis ranged from 48 to 85 years (mean age of 74 years). All lesions developed on the limbs. Twelve (60%) patients had adrenal insufficiency, but no patients had active malignancy at diagnosis. Interestingly, four (20%) patients had concurrent scabies infestation. Clinically, most lesions were erythematous plaques studded with punctate ulcers. Microscopically, the most common finding was granulomatous inflammation. Nineteen (95%) cases were successfully treated with itraconazole for 14-148 days with only one case of recurrence. Concomitant scabies should be suspected if pruritus is recalcitrant despite itraconazole treatment.

CONCLUSION

Despite its rarity, cutaneous protothecosis has become more significant due to an increased prevalence of immunocompromised individuals. Steroid overuse or iatrogenic adrenal insufficiency predisposes individuals to high-risk infections. Neglecting the disease leads to a chronic and incurable state. Protothecosis should be suspected in chronic eczematous and ulcerative plaques on the limbs refractory to conventional antibacterial and antiviral treatments, especially in patients with adrenal insufficiency. Clinical suspicion should be confirmed by skin biopsies, and confirmed cases can be successfully treated with itraconazole.

[A case of cutaneous protothecosis]

The paper describes a case of a rare opportunistic infection, such as skin lesion caused by achlorophyllic unicellular algae of the genus Prototheca. It provides a detailed pathologic description of the foci of cutaneous protothecosis, such as pandermal inflammatory infiltrate, granulomas, pseudoepitheliomatous hyperplasia, and intraepidermal abscesses. Criteria for pathogen detection in histological sections are given.

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.

Identification of harmless and pathogenic algae of the genus Prototheca by MALDI-MS

The only plants infectious for mammals, green algae from the genus Prototheca, are often overseen or mistaken for yeast in clinical diagnosis. To improve this diagnostical gap, a method was developed for fast and reliable identification of Prototheca. A collection of all currently recognized Prototheca species, most represented by several strains, were submitted to a simple extraction by 70% formic acid and ACN; the extracts were analyzed by means of MALDI-MS. Most of the peaks were found in the range from 4 to 20 kDa and showed a high reproducibility, not in absolute intensities, but in their peak pattern. The selection of measured peaks is mostly due to the technique of ionization in MALDI-MS, because proteins in the range up to 200 kDa were detected using gel electrophoresis. Some of the proteins were identified by peptide mass fingerprinting and MS(2) analysis and turned out to be ribosomal proteins or other highly abundant proteins such as ubiquitin. For the preparation of a heatmap, the intensities of the peaks were plotted and a cluster analysis was performed. From the peak-lists, a principal component analysis was conducted and a dendrogram was built. This dendrogram, based on MALDI spectra, was in fairly good agreement with a dendrogram based on sequence information from 18S DNA. As a result, pathogenic and nonpathogenic species from the genus Prototheca can be identified, with possible consequences for clinical diagnostics by MALDI-typing.

Serial MRI and CSF analysis in a dog treated with intrathecal amphotericin B for protothecosis

A 3 yr old female spayed English setter mixed-breed dog presented with diarrhea, weight loss, side stepping to the right, and a right head tilt. Rectal and cerebrospinal fluid cytology and culture confirmed a diagnosis of Prototheca zopfii. MRI of the brain showed inflammation of the brain and meninges, ventriculomegaly, and syringomyelia. Treatment with prednisone, itraconazole, and amphotericin B lipid complex administered intrathecally yielded transient improvement. Progressive brainstem signs were noted, and a repeat MRI and cerebrospinal fluid analysis documented persistent disease. This is the first description of the MRI findings and treatment with intrathecal amphoteracin B lipid complex for protothecosis of the central nervous system. Protothecosis should be considered in dogs with chronic diarrhea and compatible MRI findings.

Algaemia in a dairy cow by Prototheca blaschkeae

We describe the first known case of an algaemia by Prototheca blaschkeae in a dairy cow, which occurred after a chronic episode of mastitis caused by this pathogen. The organism was isolated from milk, joint fluid and blood samples, and microbiologic and molecular methods were performed to obtain a definitive identification of the algae. The affected cow was culled only after confirmation of a systemic infection by Prototheca.

[A brief history of time: 1945-2008--studies, manuscripts, and publications]

I (the author), Tadahiko Matsumoto, who is a winner of the 2008 Japanese Society for Medical Mycology (JSMM) Award, was born in 1945 and graduated in 1969 from Kyushu University in Fukuoka, Japan with an M.D. degree. At the Department of Dermatology, Kyushu University I studied dermatology and medical mycology. In Tokyo (1970-1971) at the Department of Microbiology, National Institute of Hygienic Sciences I learned general mycology. During the period from 1981 to 1983 I further studied medical mycology at the Division of Mycotic Diseases (Director: Dr. Libero Ajello), Center for Infectious Diseases, Centers for Disease Control (CDC) in Atlanta, Georgia in the United States. During the period from 1991 to 2005 while working as Director of Dermatology of Toshiba Hospital in Tokyo I was affiliated with several medical schools as a clinical and adjunct professor. Being a unique physician-scientist eager to publish my manuscripts in highly-regarded mycology journals, my studies were accurately reported as to description, taxonomy, and identification. My articles were published in journals carefully chosen for my purposes. As I became better known, I was frequently invited to contribute review articles in leading journals and chapters in authoritative textbooks of dermatology, infectious diseases, and microbiology. I was also invited to be a member and/or chairperson of various symposia in international congresses and one of the lecturers in seminars. I have established many friendly personal relationships among scientists, and we are always ready to help each other whenever necessary.

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.

Human protothecosis

Human protothecosis is a rare infection caused by members of the genus Prototheca. Prototheca species are generally considered to be achlorophyllic algae and are ubiquitous in nature. The occurrence of protothecosis can be local or disseminated and acute or chronic, with the latter being more common. Diseases have been classified as (i) cutaneous lesions, (ii) olecranon bursitis, or (iii) disseminated or systemic manifestations. Infections can occur in both immunocompetent and immunosuppressed patients, although more severe and disseminated infections tend to occur in immunocompromised individuals. Prototheca wickerhamii and Prototheca zopfii have been associated with human disease. Usually, treatment involves medical and surgical approaches; treatment failure is not uncommon. Antifungals such as ketoconazole, itraconazole, fluconazole, and amphotericin B are the most commonly used drugs to date. Among them, amphotericin B displays the best activity against Prototheca spp. Diagnosis is largely made upon detection of characteristic structures observed on histopathologic examination of tissue.

Emended phenotypic characterization of Prototheca zopfii: a proposal for three biotypes and standards for their identification

A representative selection of Prototheca zopfii strains isolated from different environmental habitats or clinical cases was characterized in a polyphasic approach in order to assess their intraspecies taxonomic position. Recently, the recognition of distinct phenotypic clusters has been reported as the assignment of 'variants'. In the present study, 11 strains were compared by a number of phenotypic and genetic criteria, including growth characteristics, biochemical reactions and serotyping results. Based on emended standards for biotype identification, P. zopfii strains showed auxanographic differences and distinct assimilation patterns with respect to utilization of amino acids and glycerol. Serotyping by means of immunoblotting revealed that all isolates of variant II obtained from clinical cases, i.e. isolates from bovine mastitis or from human enteropathia, showed specific antigen patterns. They were found to be different from strains assigned to the other two variants with respect to their immunogenic antigens. Furthermore, comparison of partial 18S rDNA sequences confirmed distinct differences between the former variants. Based on these results, it is proposed that P. zopfii merits classification as a species comprising three biotypes.

Protothecosis

Intravenous amphotericin B remains the most effective drug for eradicating Prototheca infections. It should be used as a first-line agent in cases of disseminated disease and in patients with severe underlying illness or with immunosuppression or immunocompromise. Azole antifungals and surgery should be reserved for patients with more localized disease. Itraconazole appears to be the most effective agent of this drug class, and it should be administered at 200 mg/day for 2 months. Surgical excision should be considered as a first-line therapy in patients who present with olecranon bursal infections.

Protothecosis in human medicine

Prototheca spp. are ubiquitous achlorophyllous algae that produce disease in humans and animals. In the past years infections with Prototheca have obtained increasing importance in human medicine. The cases have been classified into three clinical forms: cutaneous and/or subcutaneous infection, synovitis of olecranon bursa or other fibrous tissue and systemic infection. Patients with a mild degree of immunosuppression may become colonized by Prototheca spp. with a subsequent worsening of their immune surveillance and spread of the disease. Among the numerous pharmacologic agents tried, amphotericin B is the most promising. Successful treatment of protothecosis involves radical excision of the involved structures.

Cutaneous protothecosis: report of the second Brazilian case

The present report describes a case of cutaneous protothecosis caused by Prototheca wickerhamii in a non-immunocompromised female from the state of Bahia, Brazil. This is the second case described in Brazil. Dermatological examination revealed diffusely infiltrated erythematous plaques on the flexor aspect of the right arm and forearm. The authors emphasize the pathological aspects that can lead to misdiagnosis this condition. The patient was successfully treated with fluconazole.

Immunodiagnostic identification of dairy cows infected with Prototheca zopfii at various clinical stages and discrimination between infected and uninfected cows

Protothecosis is a severe form of mastitis in cattle that is caused by colorless algae of the genus Prototheca. So far, no suitable serological test for the identification of infected animals is available for routine diagnosis. In this study an indirect enzyme-linked immunosorbent assay (ELISA) for the identification of infected cows and for discriminating among infected cows at various clinical stages was developed. Immunoglobulin G (IgG) in serum and IgA and IgG1 in whey were used as antibody isotypes. The ELISA was evaluated using serum and whey from animals at different clinical stages of infection. A total of 12 cows with acute clinical manifestation of protothecal mastitis, 22 cows with clinical signs of chronic mastitis, 40 Prototheca zopfii-negative cows, and 18 cows with chronic clinical signs and earlier cultures positive for P. zopfii but with presently negative culturing results were investigated. A sensitivity of 96% and a specificity of 94% were calculated for the ELISA based on IgA levels. Intra-assay and interassay variations were calculated to be 6.08 and 6.32%, respectively. Based on these data, this ELISA was found to be suitable for discrimination between infected and uninfected animals and might therefore be useful for screening affected herds.

Canine protothecosis

Canine protothecosis remains a difficult condition to manage. The paucity of clinical cases hinders the development of successful treatment strategies. The clinical signs associated with the disease are nonspecific, and the course is so insidious that, by the time a definitive diagnosis is reached, the organism has often disseminated throughout the body. At this point, the condition is beyond treatment, and death occurs owing to failure of any number of organ systems, including the gastrointestinal, cardiovascular, renal, and central nervous systems. It is of some encouragement that the few patients that have undergone aggressive early treatment have survived longer than patients presenting late in the disease course. Nevertheless, the outlook for any dog with protothecosis is grave, and it remains to be determined whether early diagnosis can truly provide a better long-term prognosis. By including protothecosis as a consideration for dogs initially brought in with a history of chronic diarrhea or acute blindness and with a subsequent finding of exudative retinal separation, early diagnosis is possible. This recognition potentially affords the opportunity for an immune status work-up and intervention with increasingly better treatment options.

Algaemia due to Prototheca wickerhamii in a patient with myasthenia gravis

Prototheca wickerhamii is a rare cause of systemic infection in humans. While some cases occur in previously healthy individuals, others are associated with a variety of preexisting diseases. Here we present, for the first time, a case of P. wickerhamii algaemia in a patient with myasthenia gravis. The patient was successfully treated with amphotericin B.

Canine cutaneous protothecosis: an immunohistochemical analysis of the inflammatory cellular infiltrate

In this immunohistochemical study, the distribution of the cellular inflammatory infiltrate associated with cutaneous canine protothecosis (Prototheca wickerhamii) was evaluated by consecutive biopsies taken before, during and after treatment. Antibodies specific to canine immunoglobulins (IgG, IgM, IgA), human CD3 antigen (pan T-lymphocyte marker) and human myeloid/ histiocyte antigen (macrophage/neutrophil marker) were used. Before treatment, cellular infiltrate was very scanty in the inflamed areas, but it increased during the treatment, whereas the number of protothecal organisms decreased. Statistical analysis revealed an inverse relation between the number of protothecal organisms and the number of infiltrating macrophage/neutrophils (P < 0.004), T lymphocytes (P < 0.001), and cells containing immunoglobulin G (P < 0.001), M (P < 0.001) and A (P < 0.001) at different stages of the disease. These findings suggest either that protothecal organisms inhibit the migration or proliferation of cellular inflammatory infiltrate or that only dead protothecal organisms induce an effective local immune response.

Cutaneous protothecosis in a dog

A dog was infected systemically with Prototheca wickerhamii but showed only cutaneous protothecosis. The lesions appeared progressively and consisted of non-pruritic scrotal swelling and ulceration, cutaneous nodules, crusty ulcerative lesions over the trunk and serous rhinitis. The diagnosis was based on skin biopsy findings and specific culture. Microscopic examination revealed a diffuse pyogranulomatous dermatitis and numerous protothecal organisms of different sizes within the cytoplasm of phagocytic cells. Treatment with oral ketoconazole for six months resolved all the clinical signs except the scrotal granuloma which, although it was significantly reduced, had to be removed surgically. However, after five months the condition returned.

Two cases of protothecosis in Nagoya, Japan

Two cases of protothecosis caused by Prototheca wickerhamii have been reported from Nagoya in a 12 year period in both cases the infection presented on the cheeks of otherwise healthy women. Biopsies showed numerous PAS positive staining organisms with the distinctive mulberry like endosporulation in the dermis. Prototheca wickerhamii was identified on sugar assimilation tests of colonies isolated from tissue on Sabouraud agar. Case 1 responded to 11 months of oral ketoconazole therapy. Case 2 might not respond to itraconazole. The source of the infections has not been identified.

Diagnosis of systemic mycoses by specific immunohistochemical tests

Immunohistochemistry has proved to be a powerful tool for the accurate diagnosis of a number of important mycoses in humans and animals, such as aspergillosis, candidosis, cryptococcosis, blastomycosis, coccidioidomycosis, histoplasmosis capsulati and duboisii, paracoccidioidomycosis, fusariosis, pseudallescheriosis (scedosporiosis), sporotrichosis, trichosporonosis, penicilliosis, and zygomycosis (mucormycosis). These techniques are also applicable to pneumocystosis and to non-mycotic infections caused by algae such as protothecosis. Apart from the specificity of immunohistochemistry, the application of fluorochromes is highly effective for the localization of typical or atypical fungal elements in lesions with only few organisms present. Occasionally, a dual aetiology of fungal infections may be suspected on the basis of morphological study, and dual staining techniques have the capacity for resolving this question by simultaneous and differential staining of two fungal species present in a tissue specimen.

Chronic Prototheca meningitis

A case of chronic meningitis caused by the achloric alga Prototheca wickerhamii is described, which has persisted for more than 6 years despite treatment with various antifungal agents. For the last year no treatment has been given, but the patient has no complaints.

Cutaneous manifestations of Prototheca infections

The genus Prototheca comprises several species, the most prevalent of which is Prototheca wickerhamii. These achlorophyllic algae are found in the slime flux of trees and in freshwater environs. Cutaneous infection with these microbes was first reported 30 years ago. Subsequent case reports have described other manifestations including systemic disease. Asymptomatic and stationary cutaneous plaques may be seen in otherwise healthy patients. Susceptibility to infection is ill defined but may involve an inability of neutrophils to effectively eradicate phagocytosed organisms. Characteristic morula are seen histologically. Antifungal medications are the most effective therapy.