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PubMed1994

Human pythiosis in Thailand.

Pythium insidiosum is a protoctista and causes diseases in plants and animals. In Thailand it can cause a unique human infection of three types. The first type is a subcutaneous lesion in thalassaemic patients, with the pathological findings of a granulomatous reaction, diffuse infiltration, and oedema of the vessel walls. The patients responded to a saturated solution of potassium iodide. The second type is chronic inflammation and occlusion of blood vessels mainly in the lower extremities which results in gangrene or aneurysm formation. This type of infection is only found in thalassaemic patients and leads to amputation of the affected extremities or resection of the involved arteries. The third type is keratitis. This type of infection may or may not be associated with thalassaemia. The clinical signs and symptoms do not differentiate it from other types of myocotic keratitis. The patients end up with keratoplasty, evisceration or enucleation. Thailand is an agricultural country, and there are plenty of swampy areas and several plants to support the life cycle of Pythium. Moreover, many people suffer from thalassaemia, and there is no drug available for Pythium. Pythiosis plays an important role in medicine in Thailand.

Adult↗

PubMed2003

Hydroponic chrysanthemum production: cultural and pathological issues.

Hydroponic culture has not replaced soil culture in greenhouse production of chrysanthemum (commonly known as 'mum'). This study examines cultural or pathological conditions that might have affected the conversion from soil to hydroponic production. Cultural factors investigated included hydroponic container size and shape and oxygenation of the nutrient solution. Disorders encountered during the studies included salt wicking during rooting of the cuttings and severe Pythium infection in the third and successive crops in a hydroponic system. Mums did not appear to respond to various shapes and sizes of containers and troughs in which they were grown. Also, increased oxygenation had little effect on pythium root rot and plant growth. Rooting of cuttings in a polyethylene covered hydroponic system reduced wilting, whereas salt wicking was severe without a plastic covering. Pythium disease was severe in the third and successive crops in the same hydroponic system. The disease could be overcome by raising the cuttings in a peat-based growing medium in perforated plastic cells and then transplanting the seedlings along with the peat moss cubes into a hydroponic system.

Chrysanthemum↗

PubMed1988

Use of immunohistochemical methods for diagnosis of equine pythiosis.

Excisional biopsy specimens were received from 8 horses with lesions suspected of being caused by Pythium sp. Pythium sp was isolated from all specimens. An indirect peroxidase technique was applied to formalin-fixed tissues from the biopsy material and there was distinct staining of hyphal cell walls in all specimens. Sections containing hyphae, other than those of Pythium sp, failed to stain. The indirect peroxidase technique could be used for confirmation of suspected cases of pythiosis.

Animals↗

PubMed1992

Immunodiffusion test for diagnosing basidiobolomycosis.

An immunodiffusion test was developed for the diagnosis of basidiobolomycosis. When culture filtrate antigen (CFA) from Basidiobolus ranarum was reacted against two human patient and two rabbit antisera, 2 precipitin bands, inner (N) and outer (Y), were revealed for both patient and rabbit antisera. A line of identity was also observed between precipitin bands obtained with patient and rabbit sera. When CFA from B. ranarum (B CFA) was reacted against rabbit sera which contained antibody to Conidiobolus coronatus and Pythium insidiosum, 1 precipitin band corresponding to inner band (N) was observed. This finding showed that B. ranarum, C. coronatus and P. insidiosum shared at least one common antigen. After B CFA was absorbed with Pythium rabbit antiserum, the inner precipitin line that occurred between B CFA and rabbit antisera of Pythium and Conidiobolus disappeared. However, with Basidiobolus rabbit antiserum, the result did not change. The antigens which could be demonstrated by inner (N) and outer (Y) precipitin bands were heat stable at 56 degrees C for 30 min. The titer of the antibodies specific to these antigens decreased as the lesions subsided. When B. ranarum CFA was reacted against sera from 20 apparently normal persons, 20 diabetes mellitus patients, 5 aspergillosis patients, 2 candidosis patients and 3 pythiosis patients, no precipitin band was found. B. ranarum CFA was also treated with each rabbit antiserum specific to Candida albicans, Malassezia furfur and Aspergillus fumigatus. No precipitin bands occurred with any of these antisera. Thus, this test was found to be practical, sensitive and specific, and can be used to monitor patients infected with Basidiobolus ranarum.

Adult↗

PubMed2005

Potassium homeostasis influences the locomotion and encystment of zoospores of plant pathogenic oomycetes.

Zoospores of plant pathogenic oomycetes exhibit distinct swimming speeds and patterns under natural conditions. Zoospore swimming is influenced by ion homeostasis and changes in the ionic composition of media. Therefore, we used video microscopy to investigate swimming patterns of five oomycete species in response to changes in potassium homeostasis. In general, zoospore speed tended to be negatively correlated with zoospore size. Three Phytophthora species (Phytophthora palmivora, Phytophthora megakarya, and Phytophthora infestans) swam in straight patterns with speeds ranging from 50 to 250 microm/s whereas two Pythium species (Pythium aphanidermatum and Pythium dissotocum) swam at similar speeds ranging from 180 to 225 microm/s with a pronounced helical trajectory and varying amplitudes. High external concentrations of potassium salts reduced the swimming speed of Ph. palmivora and induced encystment. This was not observed for Py. aphanidermatum. Application of the potassium ionophores gramicidin, nigericin and valinomycin resulted in reduced swimming speeds and changes in the swimming patterns of the Phytophthora species. Therefore, potassium ions play a key role in regulating zoospore behavior.

Anti-Infective Agents↗

PubMedDate not supplied

Aquatic fungi parasitic on temperate fishes of Kumaun Himalaya, India.

Eighty isolates of different species of aquatic fungi belonging to Achlya, Aphanomyces, Dictyuchus, Protoachlya, Saprolegnia, Thraustotheca and Pythium are observed as parasites of certain temperate fish of Kumaun Himalaya, India. The parasitic ability of each isolate was confirmed by artificial inoculation experiments under laboratory conditions. The genera of Saprolegnia and Achlya were more virulent fish parasites than Aphanomyces, Dictyuchus, Protoachlya, Thraustotheca and Pythium. All the fish species observed are new hosts for these pathogens. Protoachlya paradoxa, Achlya klebsiana, Thraustotheca clavata and Pythium undulatum are reported for the first time as natural pathogens of fish.

Animals↗

PubMed1996

Improved delivery of biocontrol Pseudomonas and their antifungal metabolites using alginate polymers.

Alginate polymer was evaluated as a carrier for seed inoculation with a genetically modified strain Pseudomonas fluorescens F113LacZY, which protects sugar-beet against Pythium-mediated damping-off. F113LacZY survived in alginate beads at 5 log10 CFU/bead or higher counts for 8 weeks of storage, regardless of the conditions of incubation. In plant inoculation experiments, colonisation of the growing area of the root by F113LacZY, derived from alginate beads placed in the soil next to the seed or from an alginate coating around the seeds, was improved compared with application of just free cells of the strain. F113LacZY trapped in alginate beads was an effective producer of antifungal phloroglucinols as indicated by direct HPLC quantification of phloroglucinols and in vitro inhibition of both the indicator bacterium Bacillus subtilis A1 and the pathogenic fungus Pythium ultimum. Alginate polymer represents a promising carrier for the delivery of biocontrol inoculants for root colonisation and production of antifungal metabolites.

Alginates↗

PubMed2003

Human pythiosis, a rare cause of arteritis: case report and literature review.

OBJECTIVE: To present a case of Pythium insidiosum arteritis and review reported cases of human pythiosis. METHODS: Search of MEDLINE (PubMed) and the Thai Index Medicus was performed using the words "pythiosis" and "pythium." Search of abstracts from a scientific meeting also was performed. Only reported cases in the English or Thai language, with enough clinical information for analysis, were included. RESULTS: There were a total of 32 cases of human pythiosis, with 31 identified in the literature. Twenty-five cases were Thai. Twenty of 21 patients with known occupations were farmers. There was ocular infection in 9 cases, subcutaneous infection in 5 cases, arterial infection in 17 cases, and cardiopulmonary infection in 1 case. Thalassemia was a common associated finding. In addition to systemic antifungal therapy, surgery was required in most cases. The highest mortality rate was seen in the arteritic form, particularly in patients with arterial lesions proximal to the superficial femoral artery. CONCLUSIONS: Human pythiosis is rare. Physicians should be suspicious of pythiosis in individuals, particularly farmers in Thailand, who develop nonhealing cutaneous ulcers or keratitis, which do not respond to conventional treatment. P insidiosum infections should be listed as a rare cause of infectious arteritis.

Adult↗

PubMed2004

Ocular pythiosis: is it under-diagnosed?

PURPOSE: To increase awareness of ocular pythiosis by presenting a typical case and summarizing clinical data of 11 ocular pythiosis cases in Ramathibodi Hospital. DESIGN: Interventional case report. METHODS: A 48-year-old healthy woman with a history of 3-week painful corneal ulcer of left eye was treated with enucleation. RESULTS: The histopathology of enucleated eye revealed endophthalmitis and ulcerative keratitis with numerous hyphae in full-thickness of corneal stroma. The culture identification of the causative organism was Pythium insidiosum. The final diagnosis was ocular pythiosis. CONCLUSIONS: Pythium insidiosum is a causative agent of pythiosis and is distributed worldwide. Ocular pythiosis may not be uncommon, as it may be underdiagnosed due to unfamiliarity among clinicians and microbiologists. Diagnosis of pythiosis is difficult. The disease has high morbidity, as evidenced by nearly evisceration or enucleation among all patients at Ramathibodi Hospital. Early detection and effective treatment are needed for possible cure.

Adult↗

PubMed2000

Identification of conserved traits in fluorescent pseudomonads with antifungal activity.

A collection of 29 fluorescent pseudomonads, some with known biological control activity against a range of phytopathogenic fungi, were characterized phenotypically and genotypically by comparing carbon source utilization patterns, suppression of Pythium ultimum both in planta and in vitro and the potential to produce known secondary metabolites. Fatty acid profiling and restriction fragment length polymorphism (RFLP) analysis of the ribosomal DNA operon (ribotyping) were used to determine the diversity of isolates. A small group of genetically related Pseudomonas spp. with similar properties was identified; each isolate produced a diffusible bioactive product in vitro and was active against Pythium ultimum in planta. However, other isolates that were able to suppress damping off disease but did not inhibit hyphal extension in vitro clustered outside this group. Phenotypic analyses revealed that the accumulation of C17:0 cyclopropane fatty acid (17CFA) and the production of hydrogen cyanide correlated significantly with biological control activity and with the antagonism of fungal development. The potential of 17CFA as a marker for the selection of fluorescent pseudomonads with biocontrol agent (BCA) potential was demonstrated by the isolation of a novel active strain. This was selected after the screening of 13 clonal groups of fluorescent pseudomonads identified from 500 isolates from the phytosphere of sugar beet. Levels of 17CFA synthesis possibly reflect the efficacy of the rpoS allele in particular strains.

Cyclopropanes↗

PubMed1995

The sigma factor sigma s affects antibiotic production and biological control activity of Pseudomonas fluorescens Pf-5.

Pseudomonas fluorescens Pf-5, a rhizosphere-inhabiting bacterium that suppresses several soilborne pathogens of plants, produces the antibiotics pyrrolnitrin, pyoluteorin, and 2,4-diacetylphloroglucinol. A gene necessary for pyrrolnitrin production by Pf-5 was identified as rpoS, which encodes the stationary-phase sigma factor sigma s. Several pleiotropic effects of an rpoS mutation in Escherichia coli also were observed in an RpoS- mutant of Pf-5. These included sensitivities of stationary-phase cells to stresses imposed by hydrogen peroxide or high salt concentration. A plasmid containing the cloned wild-type rpoS gene restored pyrrolnitrin production and stress tolerance to the RpoS- mutant of Pf-5. The RpoS- mutant overproduced pyoluteorin and 2,4-diacetyl-phloroglucinol, two antibiotics that inhibit growth of the phytopathogenic fungus Pythium ultimum, and was superior to the wild type in suppression of seedling damping-off of cucumber caused by Pythium ultimum. When inoculated onto cucumber seed at high cell densities, the RpoS- mutant did not survive as well as the wild-type strain on surfaces of developing seedlings. Other stationary-phase-specific phenotypes of Pf-5, such as the production of cyanide and extracellular protease(s) were expressed by the RpoS- mutant, suggesting that sigma s is only one of the sigma factors required for the transcription of genes in stationary-phase cells of P. fluorescens. These results indicate that a sigma factor encoded by rpoS influences antibiotic production, biological control activity, and survival of P. fluorescens on plant surfaces.

Amino Acid Sequence↗

PubMed1989

Human pythiosis associated with thalassemia hemoglobinopathy syndrome.

Pythium infection (pythiosis) in humans has not previously been described, even in areas endemic for animal pythiosis. We report five patients with a unique presentation of fungal arteritis. The medium- to large-sized arteries were involved, and in some cases this involvement led to gangrene of the limbs, aneurysm formation, and ultimately fatal arterial leakage. All five patients were farmers. All patients, with the possible exception of one who had hemoglobin typing performed after receiving a blood transfusion, had thalassemia hemoglobinopathy syndrome. Fungal isolation was difficult. Amphotericin B treatment seemed to be ineffective. Radical surgical removal of infected tissues and oral administration of a saturated solution of potassium iodide are proposed therapy. In the tropics, where Pythium is ubiquitous, one should actively look for this fungal infection in patients with unexplained arterial occlusion, especially in the case of patients with thalassemia hemoglobinopathy syndrome.

Amphotericin B↗

PubMed1995

Characterization of streptomyces lydicus WYEC108 as a potential biocontrol agent against fungal root and seed rots.

The actinomycete Streptomyces lydicus WYEC108 showed strong in vitro antagonism against various fungal plant pathogens in plate assays by producing extracellular antifungal metabolites. When Pythium ultimum or Rhizoctonia solani was grown in liquid medium with S. lydicus WYEC108, inhibition of growth of the fungi was observed. When WYEC108 spores or mycelia were used to coat pea seeds, the seeds were protected from invasion by P. ultimum in an oospore-enriched soil. While 100% of uncoated control seeds were infected by P. ultimum within 48 h after planting, less than 40% of coated seeds were infected. When the coated seeds were planted in soil 24 h prior to introduction of the pathogen, 96 h later, less than 30% of the germinating seeds were infected. Plant growth chamber studies were also carried out to test for plant growth effects and for suppression by S. lydicus WYEC108 of Pythium seed rot and root rot. When WYEC108 was applied as a spore-peat moss-sand formulation (10(8) CFU/g) to P. ultimum-infested sterile or nonsterile soil planted with pea and cotton seeds, significant increases in average plant stand, plant length, and plant weight were observed in both cases compared with untreated control plants grown in similar soils. WYEC108 hyphae colonized and were able to migrate downward with the root as it elongated. Over a period of 30 days, the population of WYEC108 colonized emerging roots of germinating seeds and remained stable (10(5) CFU/g) in the rhizosphere, whereas the nonrhizosphere population of WYEC108 declined at least 100-fold (from 10(5) to 10(3) or fewer CFU/g). The stability of the WYEC108 population incubated at 25 degrees C in the formulation, in sterile soil, and in nonsterile soil was also evaluated. In all three environments, the population of WYEC108 maintained its size for 90 days or more. When pea, cotton, and sweet corn seeds were placed into sterile and nonsterile soils containing 10(6) or more CFU of WYEC108 per g, it colonized the emerging roots. After a 1-week growing period, WYEC108 populations of 10(5) CFU/g (wet weight) of root were found on pea roots in the amended sterile soil environment versus 10(4) CFU/g in amended nonsterile soil. To further study the in vitro interaction between the streptomycete and P. ultimum, mycelia of WYEC108 were mixed with oospores of P. ultimum in agar, which was then used as a film to coat slide coverslips.(ABSTRACT TRUNCATED AT 400 WORDS)

Antifungal Agents↗

PubMed2003

Biochemical, genetic, and zoosporicidal properties of cyclic lipopeptide surfactants produced by Pseudomonas fluorescens.

Zoospores play an important role in the infection of plant and animal hosts by oomycetes and other zoosporic fungi. In this study, six fluorescent Pseudomonas isolates with zoosporicidal activities were obtained from the wheat rhizosphere. Zoospores of multiple oomycetes, including Pythium species, Albugo candida, and Phytophthora infestans, were rendered immotile within 30 s of exposure to cell suspensions or cell culture supernatants of the six isolates, and subsequent lysis occurred within 60 s. The representative strain SS101, identified as Pseudomonas fluorescens biovar II, reduced the surface tension of water from 73 to 30 mN m-1. The application of cell suspensions of strain SS101 to soil or hyacinth bulbs provided significant protection against root rot caused by Pythium intermedium. Five Tn5 mutants of strain SS101lacked the abilities to reduce the surface tension of water and to cause lysis of zoospores. Genetic characterization of two surfactant-deficient mutants showed that the transposons had integrated into condensation domains of peptide synthetases. A partially purified extract from strain SS101 reduced the surface tension of water to 30 mN m-1 and reached the critical micelle concentration at 25 micrograms ml-1. Reverse-phase high-performance liquid chromatography yielded eight different fractions, five of which had surface activity and caused lysis of zoospores. Mass spectrometry and nuclear magnetic resonance analyses allowed the identification of the main constituent as a cyclic lipopeptide (1,139 Da) containing nine amino acids and a 10-carbon hydroxy fatty acid. The other four zoosporicidal fractions were closely related to the main constituent, with molecular massesranging from 1,111 to 1,169 Da.

Amino Acid Sequence↗

PubMed1986

Immunodiffusion test for diagnosing and monitoring pythiosis in horses.

A practical, sensitive, and specific immunodiffusion test was developed for diagnosing and monitoring pythiosis in horses. Culture filtrates, a soluble cell mass, and trypsinized Pythium sp. antigens were evaluated against prepared rabbit anti-Pythium sp. serum and pythiosis horse case sera. The culture filtrate antigens demonstrated the greatest capacity for detecting precipitins and the greatest stability during storage. In contrast, the trypsinized antigens had the weakest capability for detecting multiple precipitins and the poorest stability. The 13 sera from horses with proven active pythiosis were positive in immunodiffusion tests with the culture filtrate antigens. Each serum contained from three to six precipitins. Treated horses lost precipitins, and some became antibody negative. No false-positive reactions were noted in tests with sera from normal horses and humans or with sera from a variety of heterologous horse and human infections.

Animals↗

PubMed2004

Indigenous bacteria with antagonistic and plant-growth-promoting activities improve slow-filtration efficiency in soilless cultivation.

In tomato soilless culture, slow filtration allows one to control the development of diseases caused by pathogenic microorganisms. During the disinfecting process, microbial elimination is ensured by mechanical and biological factors. In this study, system efficacy was enhanced further to a biological activation of filter by inoculating the pozzolana grains contained in the filtering unit with 5 selected bacteria. Three strains identified as Pseudomonas putida and 2 as Bacillus cereus came from a filter whose high efficiency to eliminate pathogens has been proven over years. These 5 bacteria displayed either a plant growth promoting activity (P. putida strains) or antagonistic properties (B. cereus strains). Over the first months following their introduction in the filter, the bacterial colonisation of pozzolana grains was particularly high as compared to the one observed in the control filter. Conversely to Bacillus spp. populations, Pseudomonas spp. ones remained abundant throughout the whole cultural season. The biological activation of filter unit very significantly enhanced fungal elimination with respect to the one displayed by the control filter. Indeed, the 6-month period needed by the control filter to reach its best efficacy against Fusarium oxysporum was shortened for the bacteria-amended filter; in addition, a high efficacy filtration was got as soon as the first month. Fast colonization of pozzolana grains by selected bacteria and their subsequent interaction with F. oxysporum are likely responsible for filter efficiency. Our results suggest that Pseudomonas spp. act by competition for nutrients, and Bacillus spp. by antibiosis and (or) direct parasitism. Elimination of other fungal pathogens, i.e., Pythium spp., seems to differ from that of Fusarium since both filters demonstrated a high efficacy at the experiment start. Pythium spp. elimination appears to mainly rely on physical factors. It is worth noting that a certain percentage of the 5 pozzolana-inoculated bacteria failed to colonise the filter unit and were, thus, driven to the plants by the nutrient solution. Their contribution to the establishment of a beneficial microbial community in the rhizosphere is discussed.

Antibiosis↗

PubMed1984

The comparative pathology of equine cutaneous phycomycosis.

Pythiosis (204 cases, 77%), basidiobolomycosis (48 cases, 18%), and conidiobolomycosis (14 cases, 5%) were diagnosed morphologically from 266 horses with phycomycosis. All lesions were cutaneous ulcerative granulomas and three horses with pythiosis had metastatic lesions in regional lymph nodes. Lesions of pythiosis contained characteristic yellow, coral-like coagula and had a fibrotic surface containing sinus tract openings. Basidiobolomycosis was characterized by infrequent small yellow coagula and a yellow line of fungal invasion beneath an edematous surface. Lesions of conidiobolomycosis had numerous small coagula and a nasal location. There were minor differences in inflammatory cell populations within the granulomatous lesions. Most differences were associated with coagula size and fungal morphology. Coagula were composed of collagen, fibrin, cellular debris, degranulated and whole eosinophils and hyphae. Histochemistry revealed no major differences among the three diseases. Pythium sp hyphae were 2.6 to 6.4 micrometers in diameter, had thick walls, and occasionally were septate. Basidiobolus haptosporus hyphae were 5.1 to 20.5 micrometers in diameter, had thin walls, and commonly were septate. Conidiobolus coronatus hyphae were 5.1 to 12.8 micrometers in diameter, had thin walls, and commonly were septate. A perihyphal eosinophilic cuff ( Splendore - Hoeppli phenomenon) with a radius of up to 20 micrometers was associated with the latter two fungi. Ultrastructurally, Pythium sp was composed of a thick, single density cell wall while B. haptosporus and C. coronatus had thin, double-layered cell walls.

Animals↗

PubMed2005

Pythiosis in Africa.

We report the first case of pythiosis from Africa in an 8-month-old dog with a chronic and ulcerative cutaneous lesion. The etiologic agent belonged to the genus Pythium. Phylogenetic analysis placed the isolate in a sister group to the other P. insidiosum strains. However, the isolate may belong to a new Pythium species.

Animals↗