Prototheca Infections Research Articles

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.

Prototheca spp. in Bovine Infections

Prototheca microalgae, although still considered uncommon etiologic agents, represent an insidious intruder, threatening cattle herd health and determining productive losses. Increasing numbers of clinical cases globally identified would indicate these microalgae as emerging pathogens. They can be isolated from a wide variety of environmental and non-environmental sources, due also to their ability to produce biofilm. This ability to spread and contaminate a huge variety of substrates, as well as the high resistance to elevated temperatures, renders Prototheca prevention a very hard task. In addition, early infection signs are subtle and difficult to detect. The poor response to conventional antimycotic drugs represents an additional challenge when facing this infection. Although it would seem unrealistic to completely eradicate the exposure risk of cows to these microalgae, the adoption of proper on-farm protocols and management, with the highest attention to hygiene measures, would be beneficial in reducing the magnitude of this problem. Keeping the attention focused on early diagnosis, together with the development of new, alternative, and effective agents and formulations, would be strongly advised to prevent, treat, and control Prototheca infections.

Prototheca Infection: A Descriptive Study

Abstract Prototheca is a microalgae known to cause infections in humans, with protothecosis most commonly presenting as olecranon bursitis or localized soft tissue infection. Disseminated disease can be seen in immunocompromised patients. In this retrospective single-institution case series, we describe our experience with 7 patients with Prototheca infections.

Integration of transcriptomics, proteomics, and metabolomics data for the detection of the human pathogenic Prototheca wickerhamii from a One Health perspective.

Prototheca species are the only microalgae known to cause opportunistic infections in vertebrates and humans. Most cases of protothecosis in humans are caused by Prototheca wickerhamii, but knowledge of the pathogenicity and biology of Prototheca is limited. Globally, the diagnostic rate of Prototheca species infection is much lower than the actual rate of P. wickerhamii. The precise mechanisms underlying the pathogenesis of Prototheca infections remain unclear. In this study, we identified a strain of P. wickerhamii with atypical colony morphology. To reveal the morphological differences between P. wickerhamii S1 (mucous) and the molecular basis of its pathogenicity, the transcriptomics, proteomics, and metabolomics of two pathogenic P. wickerhamii strains and one environmental strain were analysed. Interestingly, mannan endo-1,4-β-mannosidase was significantly downregulated in P. wickerhamii S1, which contributes to a thinner cell wall in S1 compared to strains with typical colony morphology, and the toxicity of macrophages is reduced. Metabolite analysis revealed that the mucoid appearance of P. wickerhamii S1 may have been caused by an increase in linoleic acid, glycerol, and other metabolites. There is still a need to better understand the ecology, aetiology, and pathogenesis of P. wickerhamii, and in particular, its transmission between humans, animals, and the environment, from a One Health perspective.

The oldest patient infected with cutaneous protothecosis.

Human protothecosis is a rare achlorophyllic algal infection found in immunocompromised hosts; commonly those patients on glucocorticoids. Irradiation of the infection is uncommon, but has been previously attempted with antifungal therapy. We present a case of hard-to-heal wounds on an 89-year-old female patient taking glucocorticoids. A wound biopsy noted the wounds to be infected with Prototheca. The patient underwent operative debridement of her wounds, which began to improve and show signs of granulation. This report details the oldest known case of human protothecosis invasion, to our knowledge, and the successful treatment of a Prototheca infection by operative debridement.

High Prevalence of Prototheca bovis Infection in Dairy Cattle with Chronic Mastitis in Ecuador.

The genus Prototheca, a unicellular, non-photosynthetic, yeast-like microalgae, is a pathogen of concern for the dairy industry. It causes bovine mastitis that currently cannot be cured, and hence generates significant economic losses in milk production. In this study, for the first time in Ecuador, we identify Prototheca bovis as the etiologic agent of chronic mastitis in dairy cattle. Milk samples (n = 458) of cows with chronic mastitis were cultured on Sabouraud Dextrose Agar (SDA). Microscopy and cytB gene sequencing were used to identify Prototheca, whereby Prototheca bovis was isolated from 15.1% (n = 69) of the milk samples, one of the highest infection rates that can be found in the literature in a "non-outbreak" situation. No other Prototheca species were found. We were unable to isolate the alga from environmental samples. We showed that P. bovis was relatively resistant to disinfectants used to sterilize milking equipment on the cattle farms where it was isolated. We discuss how to avoid future infection and also hypothesize that the real prevalence of Prototheca infection in bovine mastitis is probably much higher than what was detected. We recommend a protocol to increase the diagnostic yield in the bacteriology laboratory.

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.

Streptococcus agalactiae and Prototheca spp. induce different mammary gland leukocyte responses in Holstein cows

In this study, we investigated the association between natural subclinical intramammary infection (IMI) caused by Streptococcus agalactiae and Prototheca spp. and milk differential cell counts assessed by cytofluorimetric analysis in Holstein cows. After an initial bacteriological screening on 188 animals and a second assessment carried out 2 wk later aimed at confirming the bacteriological status, we collected milk samples from 47 animals and performed (1) milk composition analyses; (2) somatic cell counts and differential somatic cell counts (DSCC); and (3) cytofluorimetric analyses. Before statistical analyses, animals with co-infections were filtered out. Bacteriological status (negative, positive for Strep. agalactiae, or positive for Prototheca spp.) significantly affected the investigated traits. Compared with culture-negative samples, those that were positive for Strep. agalactiae and Prototheca spp. had higher SCS (+61% and +49%, respectively), DSCC (+4% and +19%, respectively), log polymorphonuclear neutrophil (PMN)-lymphocyte (LYM) counts (+59% and +71%, respectively), and log macrophage (MAC) counts (+63% and +72%, respectively). The individual leukocyte populations determined by cytofluorimetric analysis confirmed that mastitis infection increased the proportion of PMN in the milk samples compared with culture-negative samples, particularly when caused by Strep. agalactiae (+51%). In the case of MAC, the 2 pathogens behaved in opposite ways: Strep. agalactiae increased MAC by 41%, whereas Prototheca decreased MAC by 25%. Prototheca infection strongly increased the proportion of total T lymphocytes (TL; +87%) and T-helper lymphocytes (+83%). Accordingly, the (PMN+MAC):TL ratio increased with Strep. agalactiae infection (+95%) and decreased with Prototheca infection (−43%) compared with culture-negative samples. These results suggest the prevalence of an adaptive immune response and chronic inflammation in Prototheca infection, and an innate immune response to Strep. agalactiae. This knowledge might provide an important contribution to the development of novel and effective diagnostics and therapeutics.

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.

3‐T MRI of protothecosis encephalic lesions in a Scottish shepherd dog

A four‐year‐old Scottish Shepherd dog was referred for acute onset of disorientation, blindness and chronic diarrhoea. The neurological examination was consistent with a multifocal neurolocalisation involving the prosencephalon and the brainstem. The ophthalmological exam showed bilateral chorioretinitis with retinal detachment. The brain MRI showed periventricular and left caudate nucleus lesions, increased thickness of the left III, IV, VI and opthalmic branch of V cranial nerves and bilateral multifocal lesions in the temporal and masseter muscles. Cerebrospinal fluid examination showed mild mixed pleocytosis. Faecal and urine cultures were positive for Prototheca zopfii genotype 2. Despite starting itraconazole therapy, the dog's conditions deteriorated and the owner elected euthanasia. Protothecosis should be suspected in young dogs with multifocal neurological signs, blindness and chronic diarrhoea.MRI study of the central nervous system (CNS), together with blood exam, cytology and cultures, is a useful tool to evaluate the CNS in disseminated form of Prototheca infection.

Successful Treatment of the Gastrointestinal Manifestation of Prototheca in a Kidney Transplant Recipient: A Case Report

IntroductionThe Prototheca species are achlorophyllic algae and they are recognized pathogens in animals. They have been reported to cause infections in humans; the majority of the infected patients are immunocompromised. Organ transplant recipients are at risk of infection caused by such unusual organisms. The caseHere we present a highly atypical case report of Prototheca mimicking a cecum tumor in a kidney recipient 7 years after the transplantation. Three years before this Prototheca infection, after a native nephrectomy, the patient underwent a complicated duodeno-jejunal reconstruction with feeding catheter jejunostomy. Imaging studies indicated a tumor-like space occupying lesion in the cecum. The patient was treated successfully with colon resection. Detailed histology excluded malignancy and proved Prototheca wickerhamii. DiscussionThe pathogenesis and many biological aspects of human protothecosis are unclear. Usually, treatment involves both medical and surgical approaches. The surgical treatment should be complete excision. The literature suggests an extremely high mortality rate, and therefore we advocate aggressive surgery in organ transplant recipients. This case is the first report of a successfully treated gastrointestinal manifestation of protothecosis in an organ transplant recipient.

The activity of silver nanoparticles against microalgae of the Prototheca genus.

To investigate the in vitro activity of silver NPs (AgNPs) against pathogenic microalgae of the Prototheca genus. The antialgal potential of AgNPs against Prototheca species of both clinical and environmental origin was assessed from minimum inhibitory (algistatic) and algicidal concentrations. The in vitro cytotoxicity of AgNPs against bovine mammary epithelial cell line was evaluated by means of the standard MTT assay. AgNPs showed a strong killing activity toward Prototheca algae, as the minimal algicidal concentration (MAC) values matched perfectly the corresponding minimum inhibitory concentration (MIC) values for all species (MAC = MIC, 1-4mg/l), except P. stagnora (MIC > 8mg/l). The concentrations inhibitory to pathogenic Prototheca spp. (MIC, 1-4mg/l) were below the concentrations at which any toxicity in epithelial cells could be observed (CC20 > 6mg/l). The study emphasizes the potential of AgNPs as a new therapeutic tool for the management of Prototheca infections.

Prototheca wickerhamii in a Patient With Chronic Hepatitis C

Abstract Protothecosis is an infection caused by members of the genus Prototheca. The organisms are achlorophyllic algae that are present in different environmental niches and are globally distributed. It is a rare cause of infection in humans with majority of reported cases occurring in immunocompromised individuals. More than half of the cases manifest as cutaneous lesions. Diagnosis is by microbiological culture and/or histopathology. Response to treatment, mostly with antifungal agents, is variable. We present a 66-year-old man with type 2 diabetes mellitus, severe chronic obstructive pulmonary disease on intermittent corticosteroids, and untreated chronic hepatitis C who had a nonresolving rash. This consisted of generalized pruritic, scaly and erythematous papules, and plaques for 15 years. Subsequent skin biopsy and microbiological isolation revealed Prototheca wickerhamii. To the best of our knowledge, this is the second known case of cutaneous Prototheca infection in a patient with chronic hepatitis C.

Biofilm formation by pathogenic Prototheca algae.

Prototheca microalgae are the only plants known to cause infections in humans and animals. The mechanisms of Prototheca infections are poorly understood, and no good treatments are available. Biofilms-surface-attached, three-dimensional microbial communities contributing to chronic infections-are formed by many pathogenic bacteria and fungi, but it is not known if Prototheca algae also have this ability. This study shows that various Prototheca species form biofilms composed of surface-attached cells in all growth phases, linked together by matrix containing DNA and polysaccharides. Biofilm formation was modulated by the presence of host plasma or milk. Compared to planktonic cells, Prototheca biofilms caused decreased release of IL-6 by mononuclear immune cells and responded differently to treatment with antimicrobials. Prototheca biofilms possibly contribute to chronic and hard-to-treat character of those algal infections. Prototheca algae are the only existing pathogenic plants. Almost nothing is known about mechanisms of Prototheca infections. This study identifies that, similar to pathogenic bacteria and fungi, Prototheca algae can form biofilms. These biofilms induce reduced immune cell activation relative to planktonic cells, and are also less susceptible to antimicrobials. Biofilm formation by Prototheca could be the first in vitro correlate of pathogenicity, opening a new research field for this pathogen.

Short communication: Dairy bedding type affects survival of Prototheca in vitro

Protothecae are algal pathogens, capable of causing bovine mastitis, that are unresponsive to treatment; they are believed to have an environmental reservoir. The role of bedding management in control of protothecal mastitis has not been studied. The purpose of this study was to evaluate the growth of either environmental or mastitis-associated Prototheca genotypes in dairy bedding materials that are commonly used in Maine. Prototheca zopfii genotypes 1 and 2 (gt1 and gt2) were inoculated into sterile broth only (control ), kiln-dried spruce shavings, “green” hemlock sawdust, sand, or processed manure-pack beddings with broth, and incubated for 2d. Fifty microliters of each isolate was then cultured onto plates and the resulting colonies counted at 24 and 48h postinoculation. Shavings were associated with significantly less total Prototheca growth than other bedding types. Growth of P. zopfii gt1 was significantly higher than that of gt2 in the manure-pack bedding material. Spruce shavings, compared with manure, sand, or sawdust, may be a good bedding type to prevent growth of Prototheca. Based on these in vitro findings, bedding type may affect Prototheca infection of cattle in vivo.

An unusual case of granulomatous lymphadenitis due to Prototheca zopfii var. portoricensis in an immunocompetent man in China

Protothecosis is an uncommon human infection caused by Prototheca. Prototheca spp can be considered as saprophytes, and in spite of their frequency in the environment, they are of low virulence and may cause chronic infection with low-grade inflammation in humans. At present, only three species are recognized: Prototheca wickerhamii, Prototheca zopfii and Prototheca stagnora. Of these, the former two have been associated with human disease. This study was an investigation of the clinical and microbiological features of a case of granulomatous lymphadenitis due to P. zopfii var. portoricensis in an immunocompetent man in China. We report the case of a 39-year-old male, who presented with swollen lymph nodes, from which the organism was isolated and identified by the RapidID Yeast Plus test (Remel, Santa Fe, NM, USA) and PCR molecular analysis. The pathogenicity of the isolate was confirmed in a mouse model and antifungal drug susceptibility testing was carried out. The pathogen was identified as Prototheca zopfii. The DNA sequence of the 18S SSU rDNA regions of the isolate strain were 100% (1205/1205) identical with Prototheca zopfii var. portoricensis. Antifungal susceptibility tests revealed that it was sensitive to amphotericin B, but resistant to 5-flucytosine, fluconazole, ketoconazole, and itraconazole. The patient responded to treatment with intravenous itraconazole and amphotericin B. Based on the patient's symptoms and microscopic evaluation, cultures, and molecular analyses of the isolate, granulomatous lymphadenitis due to P. zopfii var. portoricensis was diagnosed. P. zopfii var. portoricensis as a causative agent of human lymphadenitis in an immunocompetent case has not been reported, though a few cases of protothecosis have been reported in China. The real number of protothecosis cases may be greater than that reported in the literature. Thus, clinicians should be vigilant for any unknown cause of granulomatous lymphadenitis and should undertake an intensive histopathology, mycology examination, and even molecular analysis to rule out or confirm a potential Prototheca infection.

Protothecosis after liver transplantation

Prototheca species are unicellular algae of low virulence that are rarely associated with human infections. We report a liver transplant recipient with disseminated protothecosis and review the literature on this unusual opportunistic infection in transplant recipients. Of 9 cases, including ours, 5 had a localized infection, and 4 had disseminated protothecosis. Seven cases were due to Prototheca wickerhamii, and 2 were due to Prototheca zopfii. Overall mortality in transplant recipients with Prototheca infections was 88% (7/8). All 4 cases of disseminated protothecosis died despite therapy with amphotericin B. Posttransplant protothecosis is a rare but significant infection that is associated with a grave prognosis.