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Gurnani B, Kaur K. Anti-infective therapies for Pythium insidiosum keratitis. Expert Rev Anti Infect Ther 2024:1-13. [PMID: 39268901 DOI: 10.1080/14787210.2024.2403146] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2024] [Accepted: 09/08/2024] [Indexed: 09/15/2024]
Abstract
INTRODUCTION Pythium insidiosum keratitis (PIK) is a rapidly progressing ocular disease predominantly found in tropical and subtropical regions. Characterized by severe corneal damage and high morbidity, this infection poses significant challenges in diagnosis and management, necessitating effective anti-infective therapies. AREAS COVERED This report delves into the pathophysiology, clinical and microbiological diagnosis, and detailed insights into the anti-infective therapy for PIK, outlining current diagnostic challenges that complicate treatment. We review existing anti-infective therapies, including their efficacy and limitations, and discuss the role of surgical interventions in managing advanced cases. The report also highlights ongoing research into novel treatment approaches and the critical need for developing targeted therapies. EXPERT OPINION Despite advances in understanding PIK, treatment remains complex due to pathogen resistance and diagnostic hurdles. Future research should focus on innovative anti-infective strategies, improved diagnostic techniques, and global surveillance to enhance therapeutic outcomes. Collaboration between ophthalmologists, microbiologists, and pharmacologists is essential to advance treatment protocols and improve patient prognosis.
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Affiliation(s)
- Bharat Gurnani
- Cataract, Cornea, Refractive Services, Trauma, External Diseases, Contact Lens and Ocular Surface, Gomabai Netralaya, Neemuch, India
| | - Kirandeep Kaur
- Cataract, Pediatric Ophthalmology and Strabismus, Gomabai Netralaya, Neemuch, India
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Theophilopoulos J, King R, Citta A, Alford C, Dotson N, Cañete-Gibas C, Sanders C, Wiederhold N, Ligon JA, Trieu C. Cutaneous Lagenidium deciduum infection in a patient with relapsed acute myeloid leukemia. BMC Infect Dis 2024; 24:515. [PMID: 38778275 PMCID: PMC11112786 DOI: 10.1186/s12879-024-09281-5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/16/2023] [Accepted: 04/02/2024] [Indexed: 05/25/2024] Open
Abstract
BACKGROUND Lagenidium deciduum is an oomycete that can cause infections in mammals that present similarly to pythiosis and mucormycosis. Most of the existing case reports have occurred in canines and have been fatal. In animals, medical therapy has not been successful, so surgical excision is the mainstay of treatment. Lagenidium sp. infections in humans are rare. There is only one case of a human Lagenidium sp. infection in the literature, and it presented as an ocular infection. The human ocular infection was resistant to medical therapy and required a penetrating keratoplasty for cure. Additional reports of effective therapy are needed to guide management of this emerging pathogen. We present the first case of a cutaneous Lagenidium deciduum infection in a human patient, which is also the first documented case of a Lagenidium deciduum infection in an immunocompromised host of any species. CASE PRESENTATION An 18-year-old female with relapsed acute myeloid leukemia, awaiting a haploidentical stem cell transplant, presented with erythematous cutaneous lesions on her left hip and bilateral buttocks that enlarged and blackened over several days. About 1 week later, boil-like lesions appeared on her bilateral buttocks. The skin lesions were initially presumed to be bacterial in origin, so the patient was treated with clindamycin and cefepime with little improvement. Upon further investigation, fungal cultures and skin biopsies revealed aseptate hyphae, so the patient was switched to isavuconazole and amphotericin B due to concern for mucormycosis. Phenotypic characterization and DNA sequencing were performed by the Fungus Testing Laboratory, University of Texas Health Science Center at San Antonio, which identified the causal fungal organism as Lagenidium deciduum. All of her cutaneous lesions were surgically excised, and the patient was treated with micafungin, terbinafine, doxycycline, and azithromycin. Micafungin and terbinafine were continued until she achieved engraftment post-transplant. CONCLUSIONS We report the first successful treatment of a human Lagenidium infection in an immunocompromised host through a combination of aggressive surgical excision and prolonged antifungal therapy during the prolonged neutropenia associated with allogeneic stem cell transplant. Prompt diagnosis and management may prevent disseminated oomycosis.
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Affiliation(s)
| | - Rebekah King
- Department of Pediatrics, University of Florida College of Medicine, Gainesville, FL, USA
| | - Autumn Citta
- Department of Pediatrics, Division of Pediatric Hematology Oncology, University of Florida College of Medicine, Gainesville, FL, USA
| | - Constance Alford
- Department of Pediatrics, Division of Pediatric Hematology Oncology, University of Florida College of Medicine, Gainesville, FL, USA
| | - Natalie Dotson
- Department of Pediatrics, Division of Pediatric Hematology Oncology, University of Florida College of Medicine, Gainesville, FL, USA
| | - Connie Cañete-Gibas
- Fungus Testing Laboratory, Department of Pathology and Laboratory Medicine, University of Texas Health San Antonio, San Antonio, TX, USA
| | - Carmita Sanders
- Fungus Testing Laboratory, Department of Pathology and Laboratory Medicine, University of Texas Health San Antonio, San Antonio, TX, USA
| | - Nathan Wiederhold
- Fungus Testing Laboratory, Department of Pathology and Laboratory Medicine, University of Texas Health San Antonio, San Antonio, TX, USA
| | - John A Ligon
- Department of Pediatrics, Division of Pediatric Hematology Oncology, University of Florida College of Medicine, Gainesville, FL, USA
| | - Connie Trieu
- Department of Pediatrics, Division of Pediatric Infectious Diseases, University of Florida College of Medicine, Gainesville, FL, USA.
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Gurnani B, Natarajan R, Mohan M, Kaur K. Breaking-Down Barriers: Proposal of Using Cellulose Biosynthesis Inhibitors and Cellulase Enzyme as a Novel Treatment Modality for Vision Threatening Pythium Insidiosum Keratitis. Clin Ophthalmol 2024; 18:765-776. [PMID: 38495678 PMCID: PMC10941664 DOI: 10.2147/opth.s450665] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/03/2023] [Accepted: 03/05/2024] [Indexed: 03/19/2024] Open
Abstract
Pythium insidiosum, an Oomycete, causes severe keratitis that endangers vision. Its clinical, morphological, and microbiological characteristics are often indistinguishable from those of fungal keratitis, earning it the moniker "parafungus". Distinctive clinical hallmarks that set it apart from other forms of keratitis include radial keratoneuritis, tentacles, marginal infiltration, and a propensity for rapid limbal spread. The therapeutic approach to Pythium keratitis (PK) has long been a subject of debate, and topical and systemic antifungals and antibacterials have been tried with limited success. Approximately 80% of these eyes undergo therapeutic keratoplasty to salvage the eye. Hence, there is a need to innovate for alternative and better medical therapy to safeguard these eyes. The resistance of Pythium to standard antifungal treatments can be attributed to the absence of ergosterol in its cell wall. Cell walls of plants and algae have cellulose as an essential constituent. Cellulose imparts strength and structure and acts as the "skeleton" of the plant. Fungal and animal cell walls typically lack cellulose. The cellular architecture of Pythium shares a similarity with plant and algal cells through the incorporation of cellulose within its cell wall structure. Inhibitors targeting cellulose biosynthesis (CBI), such as Indaziflam, Isoxaben, and Quinoxyphen, serve as critical tools for elucidating the pathways of cellulose synthesis. Furthermore, the enzymatic action of cellulase is instrumental for the extraction of proteins and DNA. To circumvent this issue, we hypothesize that CBI's and cellulase enzymes can act on the Pythium cell wall and may effectively treat PK. The available literature supporting the hypothesis and proof of concept has also been discussed. We have also discussed these drugs' molecular mechanism of action on the Pythium cell wall. We also aim to propose how these drugs can be procured and used as a potential medical management option for this devastating entity.
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Affiliation(s)
- Bharat Gurnani
- Department of Cataract, Cornea and Refractive Surgery, ASG Eye Hospital, Jodhpur, Rajasthan, 342008, India
| | - Radhika Natarajan
- Department of Cornea and Refractive Surgery, Sankara Nethralaya Medical Research Foundation, Chennai, Tamil Nadu, 600006, India
| | - Madhuvanthi Mohan
- Department of Cornea and Refractive Surgery, Sankara Nethralaya Medical Research Foundation, Chennai, Tamil Nadu, 600006, India
| | - Kirandeep Kaur
- Department of Pediatric Ophthalmology and Strabismus, ASG Eye Hospital, Jodhpur, Rajasthan, 342008, India
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Vishwakarma P, Bagga B. Pythium insidiosum keratitis: Review of literature of 5 years' clinical experience at a tertiary eye care center. Semin Ophthalmol 2023; 38:190-200. [PMID: 36036721 DOI: 10.1080/08820538.2022.2116287] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
BACKGROUND Pythium insidiosum is an important cause of infectious keratitis from tropical and sub-tropical countries. Due to its closely mimicking clinical and microbiological features with fungus, it remained unidentified and managed as fungal keratitis for a long time. Previously all patients had poor outcomes with antifungal therapy and needed surgical treatment with higher rates of recurrences of infection leading to loss of an eye. Thus, a novel approach was required to treat it and, in this article, we would like to elaborate on the drastic change which these 5 years have brought in the management of this condition. METHODS In view of making a consolidated article comprising all the required information and also our clinical experience in the management of Pythium keratitis, we extensively reviewed several articles available on it over PubMed and Google scholars. Relevant literature describing details about Pythium, its clinical correlation, and recent advances from 52 articles including 12 articles from our group were finally included. RESULTS Our group identified and highlighted the unique clinical and microbiological features of Pythium insidiosum, performed several in-vitro, in-vivo studies along with clinical trials, and proposed the strategic way of its diagnosis and treatment. The use of antifungals was replaced with antibacterial medications and this resulted in better medical and surgical outcomes. CONCLUSION The diagnosis and management of Pythium insidiosum is constantly evolving with several recent works pointing out the possible changes in the practice patterns for the management of this challenging form of keratitis.
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Affiliation(s)
- Pratima Vishwakarma
- The Ramoji Foundation Centre for Ocular Infections and the Cornea Institute, L V Prasad Eye Institute, Hyderabad, India
| | - Bhupesh Bagga
- The Ramoji Foundation Centre for Ocular Infections and the Cornea Institute, L V Prasad Eye Institute, Hyderabad, India
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Aggarwal D, Mitra S, Kalra P, Bagga B, Mishra D, Takkar B. Case Report: Poor Outcome Despite Aggressive Management in Pythium insidiosum Endophthalmitis. Am J Trop Med Hyg 2023; 108:27-30. [PMID: 36509056 PMCID: PMC9833092 DOI: 10.4269/ajtmh.22-0441] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/07/2022] [Accepted: 09/27/2022] [Indexed: 12/15/2022] Open
Abstract
Pythium insidiosum is a parasitic oomycete that can cause keratitis and closely resembles fungus, both clinically and morphologically. It requires a trained microbiologist for its differentiation from fungal filaments and has poor response to antifungal therapy. We present a case of primary isolation of the organism from the vitreous cavity in a case of endophthalmitis. The infection spread quickly and involved all the ocular tissues. The eye had poor visual outcome despite a sequence of rapidly completed retinal and corneal surgeries along with initiation of anti-Pythium therapy.
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Affiliation(s)
- David Aggarwal
- Anant Bajaj Retina Institute, L V Prasad Eye Institute (LVPEI), Hyderabad, India
| | | | | | | | - Dilip Mishra
- Department of Ophthalmic Pathology Laboratory, LVPEI, Hyderabad, India
| | - Brijesh Takkar
- Anant Bajaj Retina Institute, L V Prasad Eye Institute (LVPEI), Hyderabad, India
- Indian Health Outcomes, Public Health, and Economics Research Centre, LVPEI, Hyderabad, India
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Severe skin and soft tissue pythiosis acquired in a hot sp. Travel Med Infect Dis 2022; 48:102349. [DOI: 10.1016/j.tmaid.2022.102349] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/08/2021] [Revised: 03/25/2022] [Accepted: 04/25/2022] [Indexed: 12/14/2022]
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Thongsuk P, Plongla R, Thammahong A, Tiewsurin J, Worasilchai N, Chindamporn A, Suankratay C. Vascular pythiosis caused by Pythium aphanidermatum: the first case report in Asia. Eur J Med Res 2021; 26:132. [PMID: 34775999 PMCID: PMC8591800 DOI: 10.1186/s40001-021-00603-w] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/04/2021] [Accepted: 11/03/2021] [Indexed: 11/29/2022] Open
Abstract
BACKGROUND Pythium, soil-borne plant pathogens, are in the class Oomycetes. They are not true fungi, but are related to diatom and algae. There are two human pathogens including P. insidiosum and P. aphanidermatum. To date, only one case of pythiosis caused by P. aphanidermatum has been reported. We present herein the first case of P. aphanidermatum vascular pythiosis in Asia. CASE PRESENTATION A 47-year-old Thai woman, living in North Thailand, with ß thalassemia/hemoglobin E presented with acute recurrent arterial insufficiency of both legs. Emergent embolectomy with clot removal was performed. The pathology of the clot exhibited noncaseous granulomatous inflammation with many fungal hyphal elements. PCR identified P. aphanidermatum with 100% identity. Final diagnosis is vascular pythiosis. Unfortunately, the patient eventually expired after treatment with itraconazole, terbinafine, azithromycin, and doxycycline. CONCLUSIONS To date, only one case of pythiosis caused by P. aphanidermatum has been reported. We present herein the first case of P. aphanidermatum vascular pythiosis in Asia.
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Affiliation(s)
- Pannaporn Thongsuk
- Division of Infectious Diseases, Department of Medicine, Faculty of Medicine, Chulalongkorn University, Bangkok, 10330, Thailand
| | - Rongpong Plongla
- Division of Infectious Diseases, Department of Medicine, Faculty of Medicine, Chulalongkorn University, Bangkok, 10330, Thailand
| | - Arsa Thammahong
- Department of Microbiology, Faculty of Medicine, Chulalongkorn University, Bangkok, 10330, Thailand
| | - Jaruwan Tiewsurin
- Division of Infectious Diseases, Department of Medicine, Buddhachinaraj Hospital, Phitsanulok, 65000, Thailand
| | - Navaporn Worasilchai
- Department of Microbiology, Faculty of Medicine, Chulalongkorn University, Bangkok, 10330, Thailand
| | - Ariya Chindamporn
- Department of Microbiology, Faculty of Medicine, Chulalongkorn University, Bangkok, 10330, Thailand
| | - Chusana Suankratay
- Division of Infectious Diseases, Department of Medicine, Faculty of Medicine, Chulalongkorn University, Bangkok, 10330, Thailand.
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Câmara PEAS, Convey P, Rangel SB, Konrath M, Barreto CC, Pinto OHB, Silva MC, Henriques DK, de Oliveira HC, Rosa LH. The largest moss carpet transplant in Antarctica and its bryosphere cryptic biodiversity. Extremophiles 2021; 25:369-384. [PMID: 34117569 DOI: 10.1007/s00792-021-01235-y] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/21/2021] [Accepted: 06/01/2021] [Indexed: 01/16/2023]
Abstract
As part of the reconstruction of the Brazilian Antarctic Station on King George Island, three areas of moss carpet were transplanted to minimize the impact of the new facilities on the local biodiversity. A total of 650 m2 of moss carpet was transplanted to neighboring but previously uncolonized locations and has subsequently survived for the last 3 years. Antarctic moss carpets typically comprise low moss species diversity and are often monospecific. We investigated the cryptic biodiversity that was transplanted along with the carpets using a metabarcoding approach through high throughput sequencing. We targeted 16S rRNA for Bacteria and Archaea, ITS for Fungi and Viridiplantae and Cox1 for Metazoa. We detected DNA representing 263 taxa from five Kingdoms (Chromista, Fungi, Metazoa, Protista and Viridiplantae), two Domains (Archaea and Bacteria) and 33 Phyla associated with the carpet. This diversity included one Archaea, 189 Bacteria, 24 Chromista, 19 Fungi, eight Metazoa, seven Protista and 16 Viridiplantae. Bacteria was the most abundant, rich and diverse group, with Chromista second in diversity and richness. Metazoa was less diverse but second highest in dominance. This is the first study to attempt transplanting a significant area of moss carpet to minimize anthropogenic environmental damage in Antarctica and to use metabarcoding as a proxy to assess diversity associated with Antarctic moss carpets, further highlighting the importance of such habitats for other organisms and their importance for conservation.
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Affiliation(s)
| | | | - Sandro B Rangel
- Instituto Brasileiro Do Meio Ambiente, IBAMA, Brasilia, Brazil
| | - Marcelo Konrath
- China National Electronics Import and Export Corporation, CEIEC, Beijing, China
| | | | - Otavio H B Pinto
- Departamento de Biologia Molecular, Universidade de Brasília, Brasilia, Brazil
| | | | | | | | - Luiz H Rosa
- Departamento de Microbiologia, Universidade Federal de Minas Gerais, Belo Horizonte, Brazil
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Vishwakarma P, Mohanty A, Kaur A, Das S, Priyadarshini SR, Mitra S, Mittal R, Sahu SK. Pythium keratitis: Clinical profile, laboratory diagnosis, treatment, and histopathology features post-treatment at a tertiary eye care center in Eastern India. Indian J Ophthalmol 2021; 69:1544-1552. [PMID: 34011738 PMCID: PMC8302330 DOI: 10.4103/ijo.ijo_2356_20] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023] Open
Abstract
Purpose: The aim of this work was to study demography, clinical profile, laboratory diagnosis, and management of Pythium keratitis at a tertiary eye care center in Eastern India. Methods: Eighteen patients with culture-positive Pythium keratitis managed at our center between January 2016 and December 2018 were included in this retrospective study. Clinical features, laboratory investigations, treatment, and outcomes were analysed. Results: Pythium keratitis commonly affects middle-aged males with low socioeconomic profile and history of trauma. Samples stained with Gomori methenamine silver showed 93.8% positivity and Iodine-potassium iodide-sulfuric acid showed 100% positivity. Periodic acid-Schiff's showed negative staining in 62.5% and weak in 37.5%. Kirby-Bauer disc diffusion method showed zone of inhibition as 30.25 ± 4.61 mm for Linezolid and 23.56 ± 6.86 mm for Azithromycin. Medical management included topical/oral linezolid and azithromycin. Therapeutic penetrating keratoplasty (TPK) was done in 15 eyes (83.3%), repeat TPK in 4 eyes, and evisceration in 3 eyes (16.7%). One patient required only medical treatment. Globe salvation was obtained in 15 (83.3%) eyes, and good visual outcome in 7 eyes (38. 9%). There was graft failure in six eyes (40%) and two (11.1%) eyes went into phthisis. Patients were divided into early and late presenters. Late presenters had more complications and worse final visual outcome. Conclusion: Pythium keratitis can be differentiated from fungal keratitis by its characteristic appearance on slit-lamp examination, smear, culture, and histopathology. Early presentation, detection, and treatment with antibacterial drugs like linezolid and azithromycin results in a better prognosis. Early full-thickness corneal transplant should be considered for Pythium keratitis not responding to treatment.
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Affiliation(s)
- Pratima Vishwakarma
- Cornea & Anterior Segment Service, L V Prasad Eye Institute, Mithu Tulsi Chanrai Campus, Bhubaneswar, India
| | - Amrita Mohanty
- Cornea & Anterior Segment Service, L V Prasad Eye Institute, Mithu Tulsi Chanrai Campus, Bhubaneswar, India
| | - Amanjot Kaur
- Cornea & Anterior Segment Service, L V Prasad Eye Institute, Mithu Tulsi Chanrai Campus, Bhubaneswar, India
| | - Sujata Das
- Cornea & Anterior Segment Service, L V Prasad Eye Institute, Mithu Tulsi Chanrai Campus, Bhubaneswar, India
| | - Smruti Rekha Priyadarshini
- Cornea & Anterior Segment Service, L V Prasad Eye Institute, Mithu Tulsi Chanrai Campus, Bhubaneswar, India
| | - Sanchita Mitra
- Ocular Microbiology Service, L V Prasad Eye Institute, Mithu Tulsi Chanrai Campus, Bhubaneswar, India
| | - Ruchi Mittal
- Kanupriya Dalmia Ophthalmic Pathology Laboratory, L V Prasad Eye Institute, Mithu Tulsi Chanrai Campus, Bhubaneswar; Department of Pathology, Kalinga Institute of Medical Sciences, Bhubaneswar, Odisha, India
| | - Srikant K Sahu
- Cornea & Anterior Segment Service, L V Prasad Eye Institute, Mithu Tulsi Chanrai Campus, Bhubaneswar, India
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Predisposing Factors, Clinical Presentations, and Outcomes of Contact Lens-Related Pythium Keratitis. Cornea 2021; 40:1413-1419. [PMID: 33470674 DOI: 10.1097/ico.0000000000002651] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2020] [Accepted: 11/24/2020] [Indexed: 11/26/2022]
Abstract
PURPOSE To describe predisposing factors, clinical presentations, and treatment outcomes of contact lens (CL)-related Pythium keratitis. METHODS This was an 11-year retrospective study of CL-related Pythium keratitis conducted from 2009 to 2019. Six eyes of 6 patients were identified. Demographics, predisposing factors, CL history, clinical presentation, diagnostic tests, treatments, and outcomes were reviewed. RESULTS Mean age of the patients was 34 years (SD 16.3 years) with equal proportion between male and female patients. Five of 6 patients (83.3%) used soft CL, whereas 1 patient used rigid gas permeable lens. All patients had a history of water contamination (tap water and water from river and sea). Mean duration from the onset was 7.8 days (range 4-14 days). Mean size of the corneal lesion was 3.33 mm (SD 1.31 mm) in width. The typical feature of tentacle-like lesions radiating in a reticular pattern was observed in all patients. Feathery edge (1 eye), satellite lesions (2 eyes), and radial keratoneuritis (2 eyes) were also found. Every patient received therapeutic penetrating keratoplasty because of failed medical treatments. One patient subsequently underwent enucleation. Globe salvage was achieved in 5 patients (83.33%). CONCLUSIONS Awareness of the history of water contamination, recognition of specific clinical features of Pythium keratitis, and performing surgical treatment are key for achieving globe salvage in patients with CL-related Pythium keratitis.
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Shmalberg J, Moyle PS, Craft WF, Walton SA. Severe meningoencephalitis secondary to calvarial invasion of Lagenidium giganteum forma caninum in a dog. Open Vet J 2020; 10:31-38. [PMID: 32426254 PMCID: PMC7193878 DOI: 10.4314/ovj.v10i1.6] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/29/2019] [Accepted: 01/14/2020] [Indexed: 11/17/2022] Open
Abstract
Background: The oomycete Lagenidiumgiganteum forma caninum is an uncommon cause of severe dermal and subcutaneous infections in dogs with possible vascular invasion and other fatal sequelae. Infection within the central nervous system of affected dogs has not been previously reported. Case Description: A 6-year-old spayed female mixed-breed dog was evaluated at a referral institution with a 2-month history of suspected fungal infection in the region of the right mandibular lymph node that was refractory to surgical resection and empiric medical therapy. Physical examination identified a 6-cm fluctuant subcutaneous mass caudoventral to the ramus of the right mandible and a second firm mass in the region of the right caudal maxilla. Lesional punch biopsies were submitted for fungal culture and polymerase chain reaction (PCR), which subsequently identified L. giganteum forma caninum infection. Initial treatment consisted of anti-inflammatory doses of prednisone and hyperbaric oxygen therapy. Four weeks following initial evaluation, the patient was presented with progressive neurological signs consistent with a forebrain lesion. Magnetic resonance imaging revealed soft-tissue, contrast-enhancing lesions ventral to the calvarium adjacent to the site of original surgical resection and throughout the brain. Humane euthanasia was elected, and postmortem examination was consistent with the extension of local disease from the right masseter muscle into the right ventral calvarium. Postmortem DNA sequencing confirmed the identity of the organism as L. giganteum forma caninum. Conclusion: This is the first reported case of intracranial lagenidiosis in the dog. PCR distinguished this species from other Lagenidium species and from oomycetes of other genera, such as Pythiuminsidiosum and Paralagenidium karlingii. Regional extension of cutaneous lagenidiosis should therefore be considered in cases with concurrent or spontaneous neurologic disease.
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Affiliation(s)
- Justin Shmalberg
- Department of Comparative, Diagnostic and Population Medicine, College of Veterinary Medicine, University of Florida, Gainesville, FL 32611-0880, USA
| | - Patrick S Moyle
- Department of Small Animal Clinical Sciences, College of Veterinary Medicine, University of Florida, Gainesville, FL 32611-0880, USA
| | - William F Craft
- Department of Comparative, Diagnostic and Population Medicine, College of Veterinary Medicine, University of Florida, Gainesville, FL 32611-0880, USA
| | - Stuart A Walton
- Department of Small Animal Clinical Sciences, College of Veterinary Medicine, University of Florida, Gainesville, FL 32611-0880, USA
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Chitasombat MN, Jongkhajornpong P, Lekhanont K, Krajaejun T. Recent update in diagnosis and treatment of human pythiosis. PeerJ 2020; 8:e8555. [PMID: 32117626 PMCID: PMC7036273 DOI: 10.7717/peerj.8555] [Citation(s) in RCA: 46] [Impact Index Per Article: 11.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/11/2019] [Accepted: 01/13/2020] [Indexed: 12/20/2022] Open
Abstract
Human pythiosis is an infectious condition with high morbidity and mortality. The causative agent is the oomycete microorganism Pythium insidiosum. The pathogen inhabits ubiquitously in a wet environment, and direct exposure to the pathogen initiates the infection. Most patients with pythiosis require surgical removal of the affected organ, and many patients die from the disease. Awareness of pythiosis among healthcare personnel is increasing. In this review, we summarized and updated information on the diagnosis and treatment of human pythiosis. Vascular and ocular pythiosis are common clinical manifestations. Recognition of the typical clinical features of pythiosis is essential for early diagnosis. The definitive diagnosis of the disease requires laboratory testing, such as microbiological, serological, molecular, and proteomic assays. In vascular pythiosis, surgical intervention to achieve the organism-free margin of the affected tissue, in combination with the use of antifungal drugs and P. insidiosum immunotherapy, remains the recommended treatment. Ocular pythiosis is a serious condition and earliest therapeutic penetrating keratoplasty with wide surgical margin is the mainstay treatment. Thorough clinical assessment is essential in all patients to evaluate the treatment response and detect an early sign of the disease recurrence. In conclusion, early diagnosis and proper management are the keys to an optimal outcome of the patients with pythiosis.
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Affiliation(s)
- Maria Nina Chitasombat
- Division of Infectious Disease, Department of Medicine, Faculty of Medicine, Ramathibodi Hospital, Mahidol University, Bangkok, Thailand
| | - Passara Jongkhajornpong
- Department of Ophthalmology, Faculty of Medicine, Ramathibodi Hospital, Mahidol University, Bangkok, Thailand
| | - Kaevalin Lekhanont
- Department of Ophthalmology, Faculty of Medicine, Ramathibodi Hospital, Mahidol University, Bangkok, Thailand
| | - Theerapong Krajaejun
- Department of Pathology, Faculty of Medicine, Ramathibodi Hospital, Mahidol University, Bangkok, Thailand
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Rujirawat T, Patumcharoenpol P, Kittichotirat W, Krajaejun T. Oomycete Gene Table: an online database for comparative genomic analyses of the oomycete microorganisms. DATABASE-THE JOURNAL OF BIOLOGICAL DATABASES AND CURATION 2020; 2019:5525202. [PMID: 31260041 PMCID: PMC6601393 DOI: 10.1093/database/baz082] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 09/07/2018] [Revised: 05/01/2019] [Accepted: 05/29/2019] [Indexed: 11/14/2022]
Abstract
Oomycetes form a unique group of the fungal-like, aquatic, eukaryotic microorganisms. Lifestyle and pathogenicity of the oomycetes are diverse. Many pathogenic oomycetes affect a broad range of plants and cause enormous economic loss annually. Some pathogenic oomycetes cause destructive and deadly diseases in a variety of animals, including humans. No effective antimicrobial agent against the oomycetes is available. Genomic data of many oomycetes are currently available. Comparative analyses of the oomycete genomes must be performed to better understand the oomycete biology and virulence, as well as to identify conserved and biologically important proteins that are potential diagnostic and therapeutic targets of these organisms. However, a tool that facilitates comparative genomic studies of the oomycetes is lacking. Here, we described in detail the Oomycete Gene Table, which is an online user-friendly bioinformatic tool, designed to search, analyze, compare and visualize gene contents of 20 oomycetes in a customizable table. Genomic contents of other oomycete species, when available, can be added to the existing database. Some of the applications of the Oomycete Gene Table include investigations of phylogenomic relationships, as well as identifications of biologically important and pathogenesis-related genes of oomycetes. In summary, the Oomycete Gene Table is a simple and useful tool for comparative genomic analyses of oomycetes.
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Affiliation(s)
- Thidarat Rujirawat
- Department of Pathology, Faculty of Medicine, Ramathibodi Hospital, Mahidol University, Rama 6 Road, Ratchathewi District, Bangkok 10400, Thailand.,Research Center, Faculty of Medicine, Ramathibodi Hospital, Mahidol University, Rama 6 Road, Ratchathewi District, Bangkok 10400, Thailand.,Molecular Medicine Program, Multidisciplinary Unit, Faculty of Science, Mahidol University, Rama 6 Road, Ratchathewi District, Bangkok 10400, Thailand
| | - Preecha Patumcharoenpol
- Interdisciplinary Graduate Program in Bioscience, Faculty of Science, Kasetsart University, Ngamwongwan Road, Jatujak District, Bangkok 10900, Thailand
| | - Weerayuth Kittichotirat
- Systems Biology and Bioinformatics Research Group, Pilot Plant Development and Training Institute, King Mongkut's University of Technology Thonburi, Bang Khun Thian Chai Thale Road, Bang Khun Thian District, Bangkok 10150, Thailand.,Bioinformatics and Systems Biology Program, School of Bioresources and Technology and School of Information Technology, King Mongkut's University of Technology Thonburi, Bang Khun Thian Chai Thale Road, Bang Khun Thian District Bangkok 10150, Thailand
| | - Theerapong Krajaejun
- Department of Pathology, Faculty of Medicine, Ramathibodi Hospital, Mahidol University, Rama 6 Road, Ratchathewi District, Bangkok 10400, Thailand
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Human Pythiosis: Emergence of Fungal-Like Organism. Mycopathologia 2019; 185:801-812. [PMID: 31845178 DOI: 10.1007/s11046-019-00412-0] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/20/2019] [Accepted: 11/28/2019] [Indexed: 01/10/2023]
Abstract
Pythiosis is an emerging infectious disease caused by the aquatic oomycete Pythium insidiosum, a fungal-like organism. It is believed that P. insidiosum's zoospores, its infected form, play major role in pathogenesis. Vascular and ocular infections are the most common clinical manifestation in humans. It is difficult to establish the diagnosis given its relatively rarity and difficulty to distinguish P. insidiosum from other molds. Delay in diagnosis and treatment has been associated with poor outcomes. High index of suspicion is the key, particularly in thalassemia patients with arterial insufficiency and patients with fungal keratitis/endophthalmitis without improvement on antifungal therapy. Tissue culture and zoospore induction remain gold standard for diagnosis; however, DNA-based method should be performed simultaneously. The combination of radical surgery, antifungal agents, and immunotherapy has been recommended. It was previously believed that surgery with negative surgical margins was the essential to survive in vascular pythiosis; however, it was recently found that patients could have residual disease despite documented negative surgical margins as infected clot may be dislodged to proximal arterial sites prior to surgery. Serum β-D-glucan (BG) has been used to monitor disease response after treatment initiation in vascular pythiosis. A significant decrease in BG levels within 2 weeks after surgery is indicative of the absence of residual infection. Unfortunately, monitoring tools for ocular pythiosis are not yet available. Itraconazole plus terbinafine have generally been used in P. insidiosum-infected patients; however, antibacterial agents, including azithromycin and linezolid, have also been used with favorable outcomes in ocular disease. Recently, azithromycin or clarithromycin plus doxycyclin were used in two relapsed vascular pythiosis patients with good outcomes.
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16
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Rujirawat T, Patumcharoenpol P, Lohnoo T, Yingyong W, Kumsang Y, Payattikul P, Tangphatsornruang S, Suriyaphol P, Reamtong O, Garg G, Kittichotirat W, Krajaejun T. Probing the Phylogenomics and Putative Pathogenicity Genes of Pythium insidiosum by Oomycete Genome Analyses. Sci Rep 2018. [PMID: 29515152 PMCID: PMC5841299 DOI: 10.1038/s41598-018-22540-1] [Citation(s) in RCA: 34] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022] Open
Abstract
Pythium insidiosum is a human-pathogenic oomycete. Many patients infected with it lose organs or die. Toward the goal of developing improved treatment options, we want to understand how Py. insidiosum has evolved to become a successful human pathogen. Our approach here involved the use of comparative genomic and other analyses to identify genes with possible functions in the pathogenicity of Py. insidiosum. We generated an Oomycete Gene Table and used it to explore the genome contents and phylogenomic relationships of Py. insidiosum and 19 other oomycetes. Initial sequence analyses showed that Py. insidiosum is closely related to Pythium species that are not pathogenic to humans. Our analyses also indicated that the organism harbours secreted and adhesin-like proteins, which are absent from related species. Putative virulence proteins were identified by comparison to a set of known virulence genes. Among them is the urease Ure1, which is absent from humans and thus a potential diagnostic and therapeutic target. We used mass spectrometric data to successfully validate the expression of 30% of 14,962 predicted proteins and identify 15 body temperature (37 °C)-dependent proteins of Py. insidiosum. This work begins to unravel the determinants of pathogenicity of Py. insidiosum.
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Affiliation(s)
- Thidarat Rujirawat
- Department of Pathology, Faculty of Medicine, Ramathibodi Hospital, Mahidol University, Bangkok, Thailand.,Research Center, Faculty of Medicine, Ramathibodi Hospital, Mahidol University, Bangkok, Thailand.,Molecular Medicine Program, Multidisciplinary Unit, Faculty of Science, Mahidol University, Bangkok, Thailand
| | - Preecha Patumcharoenpol
- Department of Biomedical Informatics, University of Arkansas for Medical Sciences, Little Rock, Arkansas, 72205, USA.,Systems Biology and Bioinformatics Research Group, Pilot Plant Development and Training Institute, King Mongkut's University of Technology Thonburi, Bangkok, Thailand
| | - Tassanee Lohnoo
- Research Center, Faculty of Medicine, Ramathibodi Hospital, Mahidol University, Bangkok, Thailand
| | - Wanta Yingyong
- Research Center, Faculty of Medicine, Ramathibodi Hospital, Mahidol University, Bangkok, Thailand
| | - Yothin Kumsang
- Research Center, Faculty of Medicine, Ramathibodi Hospital, Mahidol University, Bangkok, Thailand
| | - Penpan Payattikul
- Research Center, Faculty of Medicine, Ramathibodi Hospital, Mahidol University, Bangkok, Thailand
| | - Sithichoke Tangphatsornruang
- Genomic Research Laboratory, National Center for Genetic Engineering and Biotechnology, National Science and Technology Development Agency, Pathumthani, Thailand
| | - Prapat Suriyaphol
- Bioinformatics and Data Management for Research, Office for Research and Development, Faculty of Medicine, Siriraj Hospital, Mahidol University, Bangkok, Thailand
| | - Onrapak Reamtong
- Department of Molecular Tropical Medicine and Genetics, Faculty of Tropical Medicine, Mahidol University, Bangkok, Thailand
| | - Gagan Garg
- CSIRO Agriculture and Food, Centre for Environment and Life Sciences, Floreat, WA, Australia
| | - Weerayuth Kittichotirat
- Systems Biology and Bioinformatics Research Group, Pilot Plant Development and Training Institute, King Mongkut's University of Technology Thonburi, Bangkok, Thailand.
| | - Theerapong Krajaejun
- Department of Pathology, Faculty of Medicine, Ramathibodi Hospital, Mahidol University, Bangkok, Thailand.
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He H, Liu H, Chen X, Wu J, He M, Zhong X. Diagnosis and Treatment of Pythium Insidiosum Corneal Ulcer in a Chinese Child: A Case Report and Literature Review. AMERICAN JOURNAL OF CASE REPORTS 2016; 17:982-988. [PMID: 28025573 PMCID: PMC5207016 DOI: 10.12659/ajcr.901158] [Citation(s) in RCA: 28] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/04/2022]
Abstract
Patient: Male, 7 Final Diagnosis: Pythium insidiosum Symptoms: Painful vision loss • red eye Medication:— Clinical Procedure: Application of multiple antifungal medicines followed by the penetrating keratoplasty Specialty: Ophthalmology
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Affiliation(s)
- Hong He
- Hainan Eye Hospital and Key Laboratory of Ophthalmology, Zhongshan Ophthalmic Center, Sun Yat-sen University, Haikou, Hainan, China (mainland)
| | - Hongshan Liu
- Hainan Eye Hospital and Key Laboratory of Ophthalmology, Zhongshan Ophthalmic Center, Sun Yat-sen University, Haikou, Hainan, China (mainland)
| | - Xiaolian Chen
- Hainan Eye Hospital and Key Laboratory of Ophthalmology, Zhongshan Ophthalmic Center, Sun Yat-sen University, Haikou, Hainan, China (mainland)
| | - Jiaochan Wu
- Hainan Eye Hospital and Key Laboratory of Ophthalmology, Zhongshan Ophthalmic Center, Sun Yat-sen University, Haikou, Hainan, China (mainland)
| | - Miao He
- Zhongshan Ophthalmic Center and State Key Laboratory of Ophthalmology, Sun Yat-sen Universityq, Guangzhou, Guangdong, China (mainland)
| | - Xingwu Zhong
- Hainan Eye Hospital and Key Laboratory of Ophthalmology, Zhongshan Ophthalmic Center, Sun Yat-sen University, Haikou, Hainan, China (mainland).,Zhongshan Ophthalmic Center and State Key Laboratory of Ophthalmology, Sun Yat-sen Universityq, Guangzhou, Guangdong, China (mainland)
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Spies CFJ, Grooters AM, Lévesque CA, Rintoul TL, Redhead SA, Glockling SL, Chen CY, de Cock AWAM. Molecular phylogeny and taxonomy of Lagenidium-like oomycetes pathogenic to mammals. Fungal Biol 2016; 120:931-947. [PMID: 27521626 DOI: 10.1016/j.funbio.2016.05.005] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/06/2016] [Revised: 05/03/2016] [Accepted: 05/09/2016] [Indexed: 10/21/2022]
Abstract
Over the past twenty years, infections caused by previously unrecognised oomycete pathogens with morphological and molecular similarities to known Lagenidium species have been observed with increasing frequency, primarily in dogs but also in cats and humans. Three of these pathogens were formally described as Lagenidium giganteum forma caninum, Lagenidium deciduum, and Paralagenidium karlingii in advance of published phylogenetic verification. Due to the complex nature of Lagenidium taxonomy alongside recent reports of mammalian pathogenic species, these taxa needed to be verified with due consideration of the available data for Lagenidium and its allied genera. This study does so through morphologic characterisation of the mammalian pathogenic species, and phylogenetic analyses. The six-gene phylogeny generally supports the most recent comprehensive classification of Lagenidium with a well-supported Lagenidium clade that includes the mammalian pathogens L. giganteum f. caninum and L. deciduum, and well-supported clades for which the names Myzocytiopsis and Salilagenidium can be applied. The genus Paralagenidium is phylogenetically unrelated to any of the main clades within the class Peronosporomycetes. Close relationships between pathogens of mammals and those of insects or nematodes were revealed. Further characterisation of Lagenidium-like taxa is needed to establish the risk of mammalian infection by pathogens of insects and nematodes.
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Affiliation(s)
- Christoffel F J Spies
- Agriculture and Agri-Food Canada, Ottawa Research and Development Centre, Ottawa, K1A 0C6, Ontario, Canada.
| | - Amy M Grooters
- Department of Veterinary Clinical Sciences, School of Veterinary Medicine, Louisiana State University, Baton Rouge, LA 70803, USA
| | - C André Lévesque
- Agriculture and Agri-Food Canada, Ottawa Research and Development Centre, Ottawa, K1A 0C6, Ontario, Canada
| | - Tara L Rintoul
- Agriculture and Agri-Food Canada, Ottawa Research and Development Centre, Ottawa, K1A 0C6, Ontario, Canada
| | - Scott A Redhead
- Agriculture and Agri-Food Canada, Ottawa Research and Development Centre, Ottawa, K1A 0C6, Ontario, Canada
| | | | - Chi-Yu Chen
- Department of Plant Pathology, National Chung Hsing University, 250 Kuo Kuang Road, Taichung 402, Taiwan
| | - Arthur W A M de Cock
- CBS-KNAW Fungal Biodiversity Centre, Uppsalalaan 8, 3584 CT Utrecht, The Netherlands
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Description of three novel Lagenidium (Oomycota) species causing infection in mammals. Rev Iberoam Micol 2016; 33:83-91. [PMID: 26924580 DOI: 10.1016/j.riam.2015.07.005] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/16/2015] [Revised: 07/09/2015] [Accepted: 07/17/2015] [Indexed: 11/21/2022] Open
Abstract
BACKGROUND Recent molecular phylogenetic analysis of Lagenidium strains recovered from subcutaneous lesions in cats, dogs, and a human with lagenidiosis resolved into four clades; one of them was Lagenidium giganteum, but three others were novel. AIMS Due to the recent increase in L. giganteum infections from mammals, we studied 21 Lagenidium strains isolated from dogs and a human available in our collection. METHODS Molecular phylogenetic studies and phenotypic characteristics were used to characterize the strains. RESULTS We report the finding of three novel species, herein designated as Lagenidium ajelloi, sp. nov., Lagenidium albertoi sp. nov, and Lagenidium vilelae sp. nov. Their morphological and growth features are also presented. CONCLUSIONS Our study revealed the presence of three novel Lagenidium species infecting mammals.
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Abstract
Strains pathogenic to mammals share phylogenetic and phenotypic features with strains approved for mosquito control. Infections of mammals by species in the phylum Oomycota taxonomically and molecularly similar to known Lagenidium giganteum strains have increased. During 2013–2014, we conducted a phylogenetic study of 21 mammalian Lagenidium isolates; we found that 11 cannot be differentiated from L. giganteum strains that the US Environmental Protection Agency approved for biological control of mosquitoes; these strains were later unregistered and are no longer available. L. giganteum strains pathogenic to mammals formed a strongly supported clade with the biological control isolates, and both types experimentally infected mosquito larvae. However, the strains from mammals grew well at 25°C and 37°C, whereas the biological control strains developed normally at 25°C but poorly at higher temperatures. The emergence of heat-tolerant strains of L. giganteum pathogenic to lower animals and humans is of environmental and public health concern.
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Pythium insidiosum keratitis: clinical profile and role of DNA sequencing and zoospore formation in diagnosis. Cornea 2015; 34:438-42. [PMID: 25738236 DOI: 10.1097/ico.0000000000000349] [Citation(s) in RCA: 55] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
PURPOSE To report the molecular and microbiological diagnosis and clinical profile of 13 patients with Pythium insidiosum keratitis. METHODS Phase 1 of the study consisted of DNA sequencing of the ITS region of the rDNA of 162 stocked morphologically unidentified nonconsecutive fungal isolates from corneal scraping of patients with keratitis (2010-2012). Blast and phylogenetic analyses of the sequences showed 9 to be P. insidiosum. A retrospective review of archived photographs of colony and direct microscopy of corneal scrapings and clinical records of the cases were performed. Phase 2 began in 2014, in which a simple method of zoospore formation was used for fungal colonies resembling those of P. insidiosum followed by DNA sequencing. RESULTS The prevalence of P. insidiosum among unidentified fungal isolates from keratitis was 9/162 (5.5%) in phase 1. In phase 2, 4/102 cases (3.9%) of fungal keratitis were identified as P. insidiosum (January-February, 2014). Phylogenetic analysis of all 13 fungal isolates confirmed the identification of P. insidiosum. Corneal infiltrates exhibited hyphate edges, tentacle-like extensions, and dot-like infiltrates surrounding the main infiltrate. Response to topical 5% natamycin eye drops with or without oral antifungals was poor (penetrating keratoplasty: 9 and evisceration: 2) with a mean follow-up period of 82 days. CONCLUSIONS P. insidiosum keratitis needs to be considered in the differential diagnosis of severe fungal keratitis. It can be identified using the zoospore formation method and confirmed by ITS DNA sequencing. Lack of response to currently used antifungal drugs calls for evaluation of newer drugs for medical therapy and consideration for early penetrating keratoplasty.
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Vilela R, Viswanathan P, Mendoza LA. A biochemical screening approach to putatively differentiate mammalian pathogenic Oomycota species in the clinical laboratory. J Med Microbiol 2015; 64:862-868. [PMID: 26293112 DOI: 10.1099/jmm.0.000111] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
The report of four novel mammalian pathogenic species of the genus Lagenidium prompted us to study the use of biochemical assays to differentiate the Oomycota mammalian pathogens Pythium insidiosum and Lagenidium spp. We investigated the reaction of 23 Lagenidium and eight Pythium species in various biochemical assays. Because the morphological features of the Oomycota species are similar to those of species in the Entomophthoramycota and Mucormycota, five fungal species with coenocytic hyphae were also included. We found that mammalian and plant isolates of Pythium spp. all hydrolysed sucrose, but Lagenidium species and the fungal strains did not. In addition, both Pythium spp. and Lagenidium spp. were found to be maltose-positive, whereas fungal strains did not hydrolyse this sugar. The fungal species and thermo-sensitive Lagenidium giganteum and Lagenidium humanum were urease-negative, but the mammalian Lagenidium spp. and Pythium spp. hydrolysed urea within 24 h. These findings suggest these assays can be used for the presumptive differentiation of mammalian Oomycota species in the laboratory.
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Affiliation(s)
- Raquel Vilela
- Biomedical Laboratory Diagnostics, Michigan State University, East Lansing, MI 48824, USA.,Superior Institute of Medicine, Belo Horizonte, Brazil.,Faculty of Pharmacy, Universidade Federal of Minas Gerais, Belo Horizonte, Brazil
| | - Poorna Viswanathan
- Microbiology and Molecular Genetics, Michigan State University, East Lansing, MI 48824, USA
| | - Leonel A Mendoza
- Biomedical Laboratory Diagnostics, Michigan State University, East Lansing, MI 48824, USA.,Microbiology and Molecular Genetics, Michigan State University, East Lansing, MI 48824, USA
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Kredics L, Narendran V, Shobana CS, Vágvölgyi C, Manikandan P. Filamentous fungal infections of the cornea: a global overview of epidemiology and drug sensitivity. Mycoses 2015; 58:243-60. [PMID: 25728367 DOI: 10.1111/myc.12306] [Citation(s) in RCA: 90] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2014] [Revised: 01/27/2015] [Accepted: 02/13/2015] [Indexed: 11/30/2022]
Abstract
Fungal keratitis is a serious suppurative, usually ulcerative corneal infection which may result in blindness or reduced vision. Epidemiological studies indicate that the occurrence of fungal keratitis is higher in warm, humid regions with agricultural economy. The most frequent filamentous fungal genera among the causal agents are Fusarium, Aspergillus and Curvularia. A more successful therapy of fungal keratitis relies on precise identification of the pathogen to the species level using molecular tools. As the sequence analysis of the internal transcribed spacer (ITS) region of the ribosomal RNA gene cluster (rDNA) is not discriminative enough to reveal a species-level diagnosis for several filamentous fungal species highly relevant in keratitis infections, analysis of other loci is also required for an exact diagnosis. Molecular identifications may also reveal the involvement of fungal species which were not previously reported from corneal infections. The routinely applied chemotherapy of fungal keratitis is based on the topical and systemic administration of polyenes and azole compounds. Antifungal susceptibility testing of the causal agents is of special importance due to the emergence and spread of resistance. Testing the applicability of further available antifungals and screening for new, potential compounds for the therapy of fungal keratitis are of highlighted interest.
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Affiliation(s)
- László Kredics
- Department of Microbiology, Faculty of Science and Informatics, University of Szeged, Szeged, Hungary
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Transcriptome analysis of the entomopathogenic oomycete Lagenidium giganteum reveals putative virulence factors. Appl Environ Microbiol 2014; 80:6427-36. [PMID: 25107973 DOI: 10.1128/aem.02060-14] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
A combination of 454 pyrosequencing and Sanger sequencing was used to sample and characterize the transcriptome of the entomopathogenic oomycete Lagenidium giganteum. More than 50,000 high-throughput reads were annotated through homology searches. Several selected reads served as seeds for the amplification and sequencing of full-length transcripts. Phylogenetic analyses inferred from full-length cellulose synthase alignments revealed that L giganteum is nested within the peronosporalean galaxy and as such appears to have evolved from a phytopathogenic ancestor. In agreement with the phylogeny reconstructions, full-length L. giganteum oomycete effector orthologs, corresponding to the cellulose-binding elicitor lectin (CBEL), crinkler (CRN), and elicitin proteins, were characterized by domain organizations similar to those of pathogenicity factors of plant-pathogenic oomycetes. Importantly, the L. giganteum effectors provide a basis for detailing the roles of canonical CRN, CBEL, and elicitin proteins in the infectious process of an oomycete known principally as an animal pathogen. Finally, phylogenetic analyses and genome mining identified members of glycoside hydrolase family 5 subfamily 27 (GH5_27) as putative virulence factors active on the host insect cuticle, based in part on the fact that GH5_27 genes are shared by entomopathogenic oomycetes and fungi but are underrepresented in nonentomopathogenic genomes. The genomic resources gathered from the L. giganteum transcriptome analysis strongly suggest that filamentous entomopathogens (oomycetes and fungi) exhibit convergent evolution: they have evolved independently from plant-associated microbes, have retained genes indicative of plant associations, and may share similar cores of virulence factors, such as GH5_27 enzymes, that are absent from the genomes of their plant-pathogenic relatives.
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