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Hitchcock M, Xu J. Global Analyses of Multi-Locus Sequence Typing Data Reveal Geographic Differentiation, Hybridization, and Recombination in the Cryptococcus gattii Species Complex. J Fungi (Basel) 2023; 9:276. [PMID: 36836390 PMCID: PMC9967412 DOI: 10.3390/jof9020276] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2023] [Revised: 02/16/2023] [Accepted: 02/18/2023] [Indexed: 02/22/2023] Open
Abstract
Cryptococcus gattii species complex (CGSC) is a basidiomycete haploid yeast and globally distributed mammalian pathogen. CGSC is comprised of six distinct lineages (VGI, VGII, VGIII, VGIV, VGV, and VGVI); however, the geographical distribution and population structure of these lineages is incompletely described. In this study, we analyze published multi-locus sequence data at seven loci for 566 previously recorded sequence types (STs) encompassing four distinct lineages (VGI, VGII, VGIII, and VGIV) within the CGSC. We investigate indicators of both clonal dispersal and recombination. Population genetic analyses of the 375 STs representing 1202 isolates with geographic information and 188 STs representing 788 isolates with ecological source data suggested historically differentiated geographic populations with infrequent long-distance gene flow. Phylogenetic analyses of sequences at the individual locus and of the concatenated sequences at all seven loci among all 566 STs revealed distinct clusters largely congruent with four major distinct lineages. However, 23 of the 566 STs (4%) each contained alleles at the seven loci belonging to two or more lineages, consistent with their hybrid origins among lineages. Within each of the four major lineages, phylogenetic incompatibility analyses revealed evidence for recombination. However, linkage disequilibrium analyses rejected the hypothesis of random recombination across all samples. Together, our results suggest evidence for historical geographical differentiation, sexual recombination, hybridization, and both long-distance and localized clonal expansion in the global CGSC population.
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Affiliation(s)
| | - Jianping Xu
- Department of Biology, McMaster University, Hamilton, ON L8S 4K1, Canada
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van der Torre MH, Andrews RA, Hooker EL, Rankin A, Dodd S. Systematic review on Cryptococcus neoformans/Cryptococcus gattii species complex infections with recommendations for practice in health and care settings. CLINICAL INFECTION IN PRACTICE 2022. [DOI: 10.1016/j.clinpr.2022.100154] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/17/2022] Open
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Prevalence, Genetic Structure, and Antifungal Susceptibility of the Cryptococcus neoformans/C. gattii Species Complex Strains Collected from the Arboreal Niche in Poland. Pathogens 2021; 11:pathogens11010008. [PMID: 35055956 PMCID: PMC8780472 DOI: 10.3390/pathogens11010008] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/16/2021] [Revised: 12/17/2021] [Accepted: 12/19/2021] [Indexed: 11/30/2022] Open
Abstract
Fungi belonging to the Cryptococcus neoformans/C. gattii species complex (CNGSC) are etiological agents of serious and not infrequently fatal infections in both humans and animals. Trees are the main ecological niche and source of potential exposition concerning these pathogens. With regard to epidemiology of cryptococcosis, various surveys were performed worldwide, enabling the establishment of a map of distribution and genetic structure of the arboreal population of the CNGSC. However, there are regions, among them Central and Eastern Europe, in which the data are lacking. The present study shows the results of such an environmental study performed in Wrocław, Poland. The CNGSC strains were detected in 2.2% of the tested trees belonging to four genera. The obtained pathogen population consisted exclusively of C. neoformans, represented by both the major molecular type VNI and VNIV. Within the tested group of isolates, resistance to commonly used antimycotics was not found, except for 5-fluorocytosine, in which about 5% of the strains were classified as a non-wild type.
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Eucalyptus gunnii and Eucalyptus pulverulenta 'Baby Blue' Essential Oils as Potential Natural Herbicides. Molecules 2021; 26:molecules26216749. [PMID: 34771155 PMCID: PMC8587786 DOI: 10.3390/molecules26216749] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/04/2021] [Revised: 10/29/2021] [Accepted: 11/04/2021] [Indexed: 12/02/2022] Open
Abstract
The phytotoxicity and eco-compatibility of essential oils (EOs) from Eucalyptus gunnii (EG) and E. pulverulenta ‘Baby Blue’ (EP), cultivated in Italy for their cut foliage, were investigated. Leaf micromorphology, EOs phytochemical characterization, and phytotoxicity were analysed. EP revealed a significantly higher oil gland density and a higher EO yield with respect to EG. In both EOs, 1,8-cineole was the major compound (~75%), followed by α-pinene in EG (13.1%) and eugenol in EP (7.5%). EO phytotoxicity was tested on both weeds (Lolium multiflorum, Portulaca oleracea) and crops (Raphanus sativus, Lactuca sativa, Lepidium sativum, Solanum lycopersicum, Pisum sativum, Cucumis sativus). EG EO inhibited germination of P. oleracea, R. sativus, and S. lycopersicum seeds (ranging from 61.5 to 94.6% for the higher dose used), while affecting only radical elongation in S. lycopersicum (ranging from 66.7 to 82.6%). EP EO inhibited germination of P. oleracea and R. sativus (ranging from 41.3 to 74.7%) and affected radical elongation of L. sativum and L. multiflorum (ranging from 57.4 to 76.0%). None of the EOs affected the germination and radical growing of L. sativa, P. sativum, and C. sativus. Moreover, EP EO was more active than EG EO in inhibiting α-amylase, a key enzyme for seed growth regulation. Brine shrimp lethality assay showed that both EOs are safe for aquatic organisms, suggesting their high eco-compatibility. The data collected provide useful information for future applications of these EOs in agriculture as safe and selective bioherbicides.
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Ergin Ç, Şengül M, Aksoy L, Döğen A, Sun S, Averette AF, Cuomo CA, Seyedmousavi S, Heitman J, Ilkit M. Cryptococcus neoformans Recovered From Olive Trees ( Olea europaea) in Turkey Reveal Allopatry With African and South American Lineages. Front Cell Infect Microbiol 2019; 9:384. [PMID: 31788454 PMCID: PMC6856141 DOI: 10.3389/fcimb.2019.00384] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/07/2019] [Accepted: 10/25/2019] [Indexed: 11/13/2022] Open
Abstract
Cryptococcus species are life-threatening human fungal pathogens that cause cryptococcal meningoencephalitis in both immunocompromised and healthy hosts. The natural environmental niches of Cryptococcus include pigeon (Columba livia) guano, soil, and a variety of tree species such as Eucalyptus camaldulensis, Ceratonia siliqua, Platanus orientalis, and Pinus spp. Genetic and genomic studies of extensive sample collections have provided insights into the population distribution and composition of different Cryptococcus species in geographic regions around the world. However, few such studies examined Cryptococcus in Turkey. We sampled 388 Olea europaea (olive) and 132 E. camaldulensis trees from seven locations in coastal and inland areas of the Aegean region of Anatolian Turkey in September 2016 to investigate the distribution and genetic diversity present in the natural Cryptococcus population. We isolated 84 Cryptococcus neoformans strains (83 MATα and 1 MAT a) and 3 Cryptococcus deneoformans strains (all MATα) from 87 (22.4% of surveyed) O. europaea trees; a total of 32 C. neoformans strains were isolated from 32 (24.2%) of the E. camaldulensis trees, all of which were MATα. A statistically significant difference was observed in the frequency of C. neoformans isolation between coastal and inland areas (P < 0.05). Interestingly, the MAT a C. neoformans isolate was fertile in laboratory crosses with VNI and VNB MATα tester strains and produced robust hyphae, basidia, and basidiospores, thus suggesting potential sexual reproduction in the natural population. Sequencing analyses of the URA5 gene identified at least five different genotypes among the isolates. Population genetics and genomic analyses revealed that most of the isolates in Turkey belong to the VNBII lineage of C. neoformans, which is predominantly found in southern Africa; these isolates are part of a distinct minor clade within VNBII that includes several isolates from Zambia and Brazil. Our study provides insights into the geographic distribution of different C. neoformans lineages in the Mediterranean region and highlights the need for wider geographic sampling to gain a better understanding of the natural habitats, migration, epidemiology, and evolution of this important human fungal pathogen.
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Affiliation(s)
- Çağri Ergin
- Department of Microbiology, Faculty of Medicine, Pamukkale University, Denizli, Turkey
| | - Mustafa Şengül
- Department of Microbiology, Faculty of Medicine, Pamukkale University, Denizli, Turkey
| | - Levent Aksoy
- Department of Microbiology, Faculty of Medicine, Pamukkale University, Denizli, Turkey
| | - Aylin Döğen
- Department of Pharmaceutical Microbiology, Faculty of Pharmacy, University of Mersin, Mersin, Turkey
| | - Sheng Sun
- Department of Molecular Genetics and Microbiology, Duke University Medical Center, Durham, NC, United States
| | - Anna F Averette
- Department of Molecular Genetics and Microbiology, Duke University Medical Center, Durham, NC, United States
| | - Christina A Cuomo
- Infectious Disease and Microbiome Program, Broad Institute of MIT and Harvard, Cambridge, MA, United States
| | - Seyedmojtaba Seyedmousavi
- Microbiology Service, Department of Laboratory Medicine, Clinical Center, National Institutes of Health, Bethesda, MD, United States
| | - Joseph Heitman
- Department of Molecular Genetics and Microbiology, Duke University Medical Center, Durham, NC, United States
| | - Macit Ilkit
- Division of Mycology, Department of Microbiology, Faculty of Medicine, University of Çukurova, Adana, Turkey
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Prakash A, Randhawa HS, Khan ZU, Ahmad S, Hagen F, Meis JF, Chowdhary A. Environmental distribution of Cryptococcus species and some other yeast-like fungi in India. Mycoses 2018; 61:305-313. [PMID: 29280202 DOI: 10.1111/myc.12741] [Citation(s) in RCA: 20] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/18/2017] [Accepted: 12/18/2017] [Indexed: 11/30/2022]
Abstract
A study of environmental distribution revealed the occurrence of Cryptococcus neoformans and C. gattii in 9% and 3%, respectively, of 611 samples investigated. C. neoformans showed the highest isolation frequency from tree trunk hollows in Delhi (31%), whereas C. gattii occurred in 12% of the samples in Delhi and 5% in Rajasthan. In addition, Cryptococcus laurentii (=Papiliotrema laurentii), C. rajasthanensis (=Papiliotrema rajasthanensis), C. podzolicus (=Saitozyma podzolica) and C. flavescens (=Papiliotrema flavescens) occurred in 0.5% each. The recovery of C. flavescens and C. podzolicus was new findings for India. One more noteworthy finding was isolation of a new yeast, recently classified as Saitozyma cassiae sp. Novo. The previous strain of this yeast came from tree bark debris in South India. Our isolates came from decayed wood inside a trunk hollow of an Acacia tree in, Bharatpur Bird Sanctuary, Rajasthan. The isolations of novel strains of Cutaneotrichosporon moniliiforme from decayed wood of a Pinus tree was another significant finding. Phenotypically, they differed from T. moniliforme by being encapsulated cells, had melanin-like pigment production and were unable to assimilate d-manitol and d-melezitose. AFLP analysis showed a distinctive banding profile vis-a-vis the reference strains of T. moniliiforme and Cryptotrichosporon anacardii.
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Affiliation(s)
- Anupam Prakash
- Department of Medical Mycology, Vallabhbhai Patel Chest Institute, University of Delhi, Delhi, India
| | - Harbans S Randhawa
- Department of Medical Mycology, Vallabhbhai Patel Chest Institute, University of Delhi, Delhi, India
| | - Zia U Khan
- Department of Microbiology, Faculty of Medicine, Kuwait University, Safat, Kuwait
| | - Suhail Ahmad
- Department of Microbiology, Faculty of Medicine, Kuwait University, Safat, Kuwait
| | - Ferry Hagen
- Department of Medical Microbiology and Infectious Diseases, Canisius - Wilhelmina Hospital, Nijmegen, The Netherlands.,Department of Medical Mycology, Westerdijk Fungal Biodiversity Institute, Utrecht, The Netherlands
| | - Jacques F Meis
- Department of Medical Microbiology and Infectious Diseases, Canisius - Wilhelmina Hospital, Nijmegen, The Netherlands.,Center of Expertise in Mycology Radboudumc/CWZ, Utrecht, The Netherlands
| | - Anuradha Chowdhary
- Department of Medical Mycology, Vallabhbhai Patel Chest Institute, University of Delhi, Delhi, India
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Cogliati M, D'Amicis R, Zani A, Montagna MT, Caggiano G, De Giglio O, Balbino S, De Donno A, Serio F, Susever S, Ergin C, Velegraki A, Ellabib MS, Nardoni S, Macci C, Oliveri S, Trovato L, Dipineto L, Rickerts V, McCormick-Smith I, Akcaglar S, Tore O, Mlinaric-Missoni E, Bertout S, Mallié M, Martins MDL, Vencà ACF, Vieira ML, Sampaio AC, Pereira C, Criseo G, Romeo O, Ranque S, Al-Yasiri MHY, Kaya M, Cerikcioglu N, Marchese A, Vezzulli L, Ilkit M, Desnos-Ollivier M, Pasquale V, Korem M, Polacheck I, Scopa A, Meyer W, Ferreira-Paim K, Hagen F, Theelen B, Boekhout T, Lockhart SR, Tintelnot K, Tortorano AM, Dromer F, Varma A, Kwon-Chung KJ, Inácio J, Alonso B, Colom MF. Environmental distribution of Cryptococcus neoformans and C. gattii around the Mediterranean basin. FEMS Yeast Res 2016; 16:fow045. [PMID: 27188887 DOI: 10.1093/femsyr/fow045] [Citation(s) in RCA: 47] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 05/04/2016] [Indexed: 11/15/2022] Open
Abstract
In order to elucidate the distribution of Cryptococcus neoformans and C. gattii in the Mediterranean basin, an extensive environmental survey was carried out during 2012-2015. A total of 302 sites located in 12 countries were sampled, 6436 samples from 3765 trees were collected and 5% of trees were found to be colonized by cryptococcal yeasts. Cryptococcus neoformans was isolated from 177 trees and C. gattii from 13. Cryptococcus neoformans colonized 27% of Ceratonia, 10% of Olea, Platanus and Prunus trees and a lower percentage of other tree genera. The 13 C. gattii isolates were collected from five Eucalyptus, four Ceratonia, two Pinus and two Olea trees. Cryptococcus neoformans was distributed all around the Mediterranean basin, whereas C. gattii was isolated in Greece, Southern Italy and Spain, in agreement with previous findings from both clinical and environmental sources. Among C. neoformans isolates, VNI was the prevalent molecular type but VNII, VNIV and VNIII hybrid strains were also isolated. With the exception of a single VGIV isolate, all C. gattii isolates were VGI. The results confirmed the presence of both Cryptococcus species in the Mediterranean environment, and showed that both carob and olive trees represent an important niche for these yeasts.
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Affiliation(s)
- Massimo Cogliati
- Dip. Scienze Biomediche per la Salute, Università degli Studi di Milano, Via Pascal 36, 20133 Milano, Italy
| | - Roberta D'Amicis
- Dip. Scienze Biomediche per la Salute, Università degli Studi di Milano, Via Pascal 36, 20133 Milano, Italy
| | - Alberto Zani
- Dip. Scienze Biomediche per la Salute, Università degli Studi di Milano, Via Pascal 36, 20133 Milano, Italy
| | - Maria Teresa Montagna
- Dip. Scienze Biomediche ed Oncologia Umana, Università degli Studi di Bari 'Aldo Moro', Piazza Giulio Cesare 11, 70124 Bari, Italy
| | - Giuseppina Caggiano
- Dip. Scienze Biomediche ed Oncologia Umana, Università degli Studi di Bari 'Aldo Moro', Piazza Giulio Cesare 11, 70124 Bari, Italy
| | - Osvalda De Giglio
- Dip. Scienze Biomediche ed Oncologia Umana, Università degli Studi di Bari 'Aldo Moro', Piazza Giulio Cesare 11, 70124 Bari, Italy
| | - Stella Balbino
- Dip. Scienze Biomediche ed Oncologia Umana, Università degli Studi di Bari 'Aldo Moro', Piazza Giulio Cesare 11, 70124 Bari, Italy
| | - Antonella De Donno
- Dip. di Scienze e Tecnologie Biologiche ed Ambientali, Università del Salento, Via Monteroni, 73100 Lecce, Italy
| | - Francesca Serio
- Dip. di Scienze e Tecnologie Biologiche ed Ambientali, Università del Salento, Via Monteroni, 73100 Lecce, Italy
| | - Serdar Susever
- Dept. of Nutrition and Dietetics, Cyprus Near East University, Near East Boulevard, 99138 Nicosia, Cyprus
| | - Cagri Ergin
- Medical School, Pamukkale University, Kliniki Kampusu, 20160 Denizli, Turkey
| | - Aristea Velegraki
- Medical School National and Kapodistrian University of Athens, Mikras Asias 75, 11527 Athens, Greece
| | - Mohamed S Ellabib
- Medical College, University of Tripoli, Tripoli University Road, Tripoli, Libya
| | - Simona Nardoni
- Dip. Scienze Veterinarie, Università di Pisa, Via delle Piagge 2, 56124 Pisa, Italy
| | - Cristina Macci
- Istituto per lo Studio degli Ecosistemi (ISE), National Research Council (CNR), Via Moruzzi 1, 56124 Pisa, Italy
| | - Salvatore Oliveri
- Dip. di Scienze Microbiologiche e Scienze Ginecologiche, Università degli Studi di Catania, Via Androne 81, 95124 Catania, Italy
| | - Laura Trovato
- Dip. di Scienze Microbiologiche e Scienze Ginecologiche, Università degli Studi di Catania, Via Androne 81, 95124 Catania, Italy
| | - Ludovico Dipineto
- Dip. di Medicina Veterinaria e Produzioni Animali, University of Napoli Federico II, C.so Umberto I 40, 80138 Napoli, Italy
| | - Volker Rickerts
- Dept. of Infeciuos Diseases, Robert-Koch Institute, D-13302 Berlin, Germany
| | | | - Sevim Akcaglar
- School of Medicine, Uludag University, Gorukle Kampusu, 16059 Bursa, Turkey
| | - Okan Tore
- School of Medicine, Uludag University, Gorukle Kampusu, 16059 Bursa, Turkey
| | | | - Sebastien Bertout
- Unité Mixte Internationale 'Recherches Translationnelles sur l'infection à VIH et les Maladies Infectieuses', Université de Montpellier, 15 Avenue Charles Flahault, 34093 Montpellier, France
| | - Michele Mallié
- Unité Mixte Internationale 'Recherches Translationnelles sur l'infection à VIH et les Maladies Infectieuses', Université de Montpellier, 15 Avenue Charles Flahault, 34093 Montpellier, France
| | - Maria da Luz Martins
- Instituto de Higiene e Medicina Tropical, Rua da Junqueira 100, 1349-008 Lisbon, Portugal
| | - Ana C F Vencà
- Instituto de Higiene e Medicina Tropical, Rua da Junqueira 100, 1349-008 Lisbon, Portugal
| | - Maria L Vieira
- Instituto de Higiene e Medicina Tropical, Rua da Junqueira 100, 1349-008 Lisbon, Portugal
| | - Ana C Sampaio
- CITAB, Universidade de Trás-os-Montes e Alto Douro, Quinta dos Prados, 5000-801 Vila Real, Portugal
| | - Cheila Pereira
- CITAB, Universidade de Trás-os-Montes e Alto Douro, Quinta dos Prados, 5000-801 Vila Real, Portugal
| | - Giuseppe Criseo
- Department of Chemical, Biological, Pharmaceutical and Environmental Sciences, University of Messina, Piazza Pugliatti 1, 98122 Messina, Italy
| | - Orazio Romeo
- Department of Chemical, Biological, Pharmaceutical and Environmental Sciences, University of Messina, Piazza Pugliatti 1, 98122 Messina, Italy
| | - Stéphane Ranque
- IP-TPT Infections Parasitaires Transmission Pphysiopathologie et Therapeutiques, Aix-Marseille University, 27 Blv. Jean Moulin, 13005 Marseille, France
| | - Mohammed H Y Al-Yasiri
- IP-TPT Infections Parasitaires Transmission Pphysiopathologie et Therapeutiques, Aix-Marseille University, 27 Blv. Jean Moulin, 13005 Marseille, France
| | - Meltem Kaya
- School of Medicine, Marmara University, MÜ Göztepe Kampüsü, 34722 Istanbul, Turkey
| | - Nilgun Cerikcioglu
- School of Medicine, Marmara University, MÜ Göztepe Kampüsü, 34722 Istanbul, Turkey
| | - Anna Marchese
- Sezione di Microbiologia del DISC, Università di Genova-IRCCS San Martino IST Genova, Largo Benzi 10, 16132 Genova, Italy
| | - Luigi Vezzulli
- Dipartimento di Scienze della Terra, dell'Ambiente e della Vita (DISTAV), Università di Genova, C.so europa 26, 16132 Genova, Italy
| | - Macit Ilkit
- Dept. of Microbiology, University of Çukurova Sariçam, Çukurova Üniversitesi Rektörlüğü, 01330 Adana, Turkey
| | - Marie Desnos-Ollivier
- Institut Pasteur, CNRS, Unité de Mycologie Moléculaire, 25-28 Rue du Dr Roux, 75015 Paris, France
| | - Vincenzo Pasquale
- Dip. di Scienze e Tecnologie, Università degli Studi di Napoli Parthenope, Via Amm. F. Acton 38, 80133 Napoli, Italy
| | - Maya Korem
- Div. of Microbiology and Infectious Diseases, Hadassah-Hebrew University Medical Center, Ein Kerem, P.O. Box 12271 Jerusalem, Israel
| | - Itzhack Polacheck
- Div. of Microbiology and Infectious Diseases, Hadassah-Hebrew University Medical Center, Ein Kerem, P.O. Box 12271 Jerusalem, Israel
| | - Antonio Scopa
- Facoltà di Scienze Agrarie, Forestali e Ambientali, Università degli Studi della Basilicata, Via Nazario Sauro 85, 85100 Potenza, Italy
| | - Wieland Meyer
- Molecular Mycology Research Laboratory, CIDM, MBI, Sydney Medical School-Westmead Hospital, University of Sydney/Westmead Millennium Institute, 176 Hawkesbury Rd, NSW 2145 Westmead, NSW, Australia
| | - Kennio Ferreira-Paim
- Molecular Mycology Research Laboratory, CIDM, MBI, Sydney Medical School-Westmead Hospital, University of Sydney/Westmead Millennium Institute, 176 Hawkesbury Rd, NSW 2145 Westmead, NSW, Australia
| | - Ferry Hagen
- Canisius-Wilhelmina Hospital, Weg door Jonkerbos 100, 6532 SZ Nijmegen, The Netherlands
| | - Bart Theelen
- CBS-KNAW Fungal Biodiversity Centre, Uppsalalaan 8, 3584 CT Utrecht, The Netherlands
| | - Teun Boekhout
- CBS-KNAW Fungal Biodiversity Centre, Uppsalalaan 8, 3584 CT Utrecht, The Netherlands
| | - Shawn R Lockhart
- Centers for Disease Control and Prevention, 1600 Clifton Rd, Atlanta, GA 30333 Atlanta, USA
| | - Kathrin Tintelnot
- Dept. of Infeciuos Diseases, Robert-Koch Institute, D-13302 Berlin, Germany
| | - Anna Maria Tortorano
- Dip. Scienze Biomediche per la Salute, Università degli Studi di Milano, Via Pascal 36, 20133 Milano, Italy
| | - Françoise Dromer
- Institut Pasteur, CNRS, Unité de Mycologie Moléculaire, 25-28 Rue du Dr Roux, 75015 Paris, France
| | - Ashok Varma
- National Institute of Allergy and Infectious Diseases, 31 Center Dr, Bethesda, MD 20892 Bethesda, USA
| | - Kyung J Kwon-Chung
- National Institute of Allergy and Infectious Diseases, 31 Center Dr, Bethesda, MD 20892 Bethesda, USA
| | - Joäo Inácio
- School of Pharmacy and Biomolecular Sciences, University of Brighton, Lewes Road, BN2 4GJ Brighton, UK
| | - Beatriz Alonso
- School of Pharmacy and Biomolecular Sciences, University of Brighton, Lewes Road, BN2 4GJ Brighton, UK
| | - Maria F Colom
- Medical School, Universidad Miguel Hernández, Avenida de la Universidad, 03202 Alicante, Spain
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Abstract
Understanding of the taxonomy and phylogeny of Cryptococcus gattii has been advanced by modern molecular techniques. C. gattii probably diverged from Cryptococcus neoformans between 16 million and 160 million years ago, depending on the dating methods applied, and maintains diversity by recombining in nature. South America is the likely source of the virulent C. gattii VGII molecular types that have emerged in North America. C. gattii shares major virulence determinants with C. neoformans, although genomic and transcriptomic studies revealed that despite similar genomes, the VGIIa and VGIIb subtypes employ very different transcriptional circuits and manifest differences in virulence phenotypes. Preliminary evidence suggests that C. gattii VGII causes severe lung disease and death without dissemination, whereas C. neoformans disseminates readily to the central nervous system (CNS) and causes death from meningoencephalitis. Overall, currently available data indicate that the C. gattii VGI, VGII, and VGIII molecular types more commonly affect nonimmunocompromised hosts, in contrast to VGIV. New, rapid, cheap diagnostic tests and imaging modalities are assisting early diagnosis and enabling better outcomes of cerebral cryptococcosis. Complications of CNS infection include increased intracranial pressure, severe neurological sequelae, and development of immune reconstitution syndrome, although the mortality rate is low. C. gattii VGII isolates may exhibit higher fluconazole MICs than other genotypes. Optimal therapeutic regimens are yet to be determined; in most cases, initial therapy with amphotericin B and 5-flucytosine is recommended.
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Danesi P, Furnari C, Granato A, Schivo A, Otranto D, Capelli G, Cafarchia C. Molecular identity and prevalence of Cryptococcus spp. nasal carriage in asymptomatic feral cats in Italy. Med Mycol 2014; 52:667-73. [PMID: 25082953 DOI: 10.1093/mmy/myu030] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
Cryptococcosis is a life-threatening fungal disease that infects humans and animals worldwide. Inhalation of fungal particles from an environmental source can cause primary infection of the respiratory system. As animals can be considered a sentinel for human diseases, the aim of this study was to determine the prevalence and molecular identity of Cryptococcus spp. in the nasal cavity of feral cats. Cats from 162 urban and rural feral cat colonies were sampled over 3 years. Of 766 cats from which nasal swabs were obtained, Cryptococcus spp. were recovered from 95 (12.6%), including 37 C. magnus (4.8%), 16 C. albidus (2.0%), 15 C. carnescens (1.9%), 12 C. neoformans (1.6%), as well as C. oeirensis (n = 3), C. victoriae (n = 3), C. albidosimilis (n = 2), Filobasidium globisporum (n = 2), C. adeliensis (n = 1), C. flavescens (n = 1), C. dimnae (n = 1), C. saitoi (n = 1), and C. wieringae (n = 1) with prevalence <1%. Thirteen Cryptococcus species were identified by polymerase chain reaction and sequencing of internal transcribed spacer amplicons. Statistical analysis did not identify any predisposing factors that contributed to nasal colonization (eg, sex, age, season, or habitat). Results suggest that asymptomatic feral cats may carry C. neoformans and other Cryptococcus species in their sinonasal cavity. Genotyping of the specific cryptococcal isolates provides a better understanding of the epidemiology of these yeasts.
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Affiliation(s)
- Patrizia Danesi
- Istituto Zooprofilattico Sperimentale delle Venezie, Viale dell'Università 10, 35020, Legnaro, Padua, Italy Department of Veterinary Medicine, University of Bari, Str. prov.le per Casamassima Km, 3, 70010, Valenzano, Bari, Italy
| | - Carmelo Furnari
- Veterinary regional district service ULSS 20, Local Public Health and Social Authority of Veneto Region, Via di Campo Marzo 20, 37133, Verona, Italy
| | - Anna Granato
- Istituto Zooprofilattico Sperimentale delle Venezie, Viale dell'Università 10, 35020, Legnaro, Padua, Italy
| | - Alice Schivo
- Istituto Zooprofilattico Sperimentale delle Venezie, Viale dell'Università 10, 35020, Legnaro, Padua, Italy
| | - Domenico Otranto
- Department of Veterinary Medicine, University of Bari, Str. prov.le per Casamassima Km, 3, 70010, Valenzano, Bari, Italy
| | - Gioia Capelli
- Istituto Zooprofilattico Sperimentale delle Venezie, Viale dell'Università 10, 35020, Legnaro, Padua, Italy
| | - Claudia Cafarchia
- Department of Veterinary Medicine, University of Bari, Str. prov.le per Casamassima Km, 3, 70010, Valenzano, Bari, Italy
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10
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Danesi P, Firacative C, Cogliati M, Otranto D, Capelli G, Meyer W. Multilocus sequence typing (MLST) and M13 PCR fingerprinting revealed heterogeneity amongstCryptococcusspecies obtained from Italian veterinary isolates. FEMS Yeast Res 2014; 14:897-909. [DOI: 10.1111/1567-1364.12178] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/10/2014] [Revised: 06/16/2014] [Accepted: 06/26/2014] [Indexed: 11/29/2022] Open
Affiliation(s)
- Patrizia Danesi
- Istituto Zooprofilattico Sperimentale delle Venezie; Legnaro Italy
- Department of Veterinary Medicine; University of Bari; Bari Italy
| | - Carolina Firacative
- Molecular Mycology Research Laboratory; Centre for Infectious Diseases and Microbiology; Sydney Medical School - Westmead Hospital; Marie Bashir Institute for Infectious Diseases and Biosecurity; The University of Sydney; Westmead Millennium Institute; Sydney NSW Australia
- Grupo de Microbiología; Instituto Nacional de Salud; Bogotá Colombia
| | - Massimo Cogliati
- Laboratorio di Micologia Medica; Istituto di Igiene e Medicina Preventiva; University of Milan; Milan Italy
| | - Domenico Otranto
- Department of Veterinary Medicine; University of Bari; Bari Italy
| | - Gioia Capelli
- Istituto Zooprofilattico Sperimentale delle Venezie; Legnaro Italy
| | - Wieland Meyer
- Molecular Mycology Research Laboratory; Centre for Infectious Diseases and Microbiology; Sydney Medical School - Westmead Hospital; Marie Bashir Institute for Infectious Diseases and Biosecurity; The University of Sydney; Westmead Millennium Institute; Sydney NSW Australia
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11
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Susceptibility of intact germinating Arabidopsis thaliana to human fungal pathogens Cryptococcus neoformans and C. gattii. Appl Environ Microbiol 2013; 79:2979-88. [PMID: 23435895 DOI: 10.1128/aem.03697-12] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The fungus Cryptococcus contributes a large global burden of infectious death in both HIV-infected and healthy individuals. As Cryptococcus is an opportunistic pathogen, much of the evolutionary pressure shaping virulence occurs in environments in contact with plants and soil. The present studies investigated inoculation of intact seeds of the common weed Arabidopsis thaliana with fungal cells over a 21-day period. C. gattii was the more virulent plant pathogen, resulting in disrupted germination as well as increased stem lodging, fungal burden, and plant tissue colocalization. C. neoformans was a less virulent plant pathogen but exhibited prolonged tissue residence within the cuticle and vascular spaces. Arabidopsis mutants of the PRN1 gene, which is involved in abiotic and biotic signaling affecting phenylalanine-derived flavonoids, showed altered susceptibility to cryptoccocal infections, suggesting roles for this pathway in cryptococcal defense. The fungal virulence factor laccase was also implicated in plant pathogenesis, as a cryptococcal lac1Δ strain was less virulent than wild-type fungi and was unable to colonize seedlings. In conclusion, these studies expand knowledge concerning the ecological niche of Cryptococcus by demonstrating the pathogenic capacity of the anamorphic form of cryptococcal cells against healthy seedlings under physiologically relevant conditions. In addition, an important role of laccase in plant as well as human virulence may suggest mechanisms for laccase retention and optimization during evolution of this fungal pathogen.
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12
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Cogliati M. Global Molecular Epidemiology of Cryptococcus neoformans and Cryptococcus gattii: An Atlas of the Molecular Types. SCIENTIFICA 2013; 2013:675213. [PMID: 24278784 PMCID: PMC3820360 DOI: 10.1155/2013/675213] [Citation(s) in RCA: 164] [Impact Index Per Article: 14.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/08/2012] [Accepted: 12/11/2012] [Indexed: 05/08/2023]
Abstract
Cryptococcosis is a fungal disease affecting more than one million people per year worldwide. The main etiological agents of cryptococcosis are the two sibling species Cryptococcus neoformans and Cryptococcus gattii that present numerous differences in geographical distribution, ecological niches, epidemiology, pathobiology, clinical presentation and molecular characters. Genotyping of the two Cryptococcus species at subspecies level supplies relevant information to understand how this fungus has spread worldwide, the nature of its population structure, and how it evolved to be a deadly pathogen. At present, nine major molecular types have been recognized: VNI, VNII, VNB, VNIII, and VNIV among C. neoformans isolates, and VGI, VGII, VGIII, and VGIV among C. gattii isolates. In this paper all the information available in the literature concerning the isolation of the two Cryptococcus species has been collected and analyzed on the basis of their geographical origin, source of isolation, level of identification, species, and molecular type. A detailed analysis of the geographical distribution of the major molecular types in each continent has been described and represented on thematic maps. This study represents a useful tool to start new epidemiological surveys on the basis of the present knowledge.
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Affiliation(s)
- Massimo Cogliati
- Lab. Micologia Medica, Dipartimento di Scienze Biomediche per la Salute, Università degli Studi di Milano, Via Pascal 36, 20133 Milano, Italy
- *Massimo Cogliati:
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13
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Colom MF, Hagen F, Gonzalez A, Mellado A, Morera N, Linares C, García DF, Peñataro JS, Boekhout T, Sánchez M. Ceratonia siliqua(carob) trees as natural habitat and source of infection byCryptococcus gattiiin the Mediterranean environment. Med Mycol 2012; 50:67-73. [DOI: 10.3109/13693786.2011.574239] [Citation(s) in RCA: 58] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
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Abstract
Infections caused by the emerging pathogen Cryptococcus gattii are increasing in frequency in North America. During the past decade, interest in the pathogen has continued to grow, not only in North America but also in other areas of the world where infections have recently been documented. This review synthesizes existing data and raises issues that remain to be addressed.
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Affiliation(s)
- Julie Harris
- Mycotic Diseases Branch, Centers for Disease Control and Prevention, 1600 Clifton Rd NE, MS C-09, Atlanta, GA 30309 USA.
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15
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Environmental isolation of Cryptococcus gattii serotype B, VGI/MATα strains in southern Italy. Mycopathologia 2011; 171:423-30. [PMID: 21253853 DOI: 10.1007/s11046-010-9389-z] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/04/2010] [Accepted: 12/28/2010] [Indexed: 12/14/2022]
Abstract
Until recently, Cryptococcus gattii was believed to be endemic in tropical and subtropical regions. To date, it has unexpectedly emerged as primary pathogen in temperate climate indicating that it has evolved and adapted to new environmental conditions including those existing in the Mediterranean area. Earlier attempts to isolate C. gattii from our environment were unsuccessful but this time, 18 years after the last environmental screening for C. neoformans, we isolated C. gattii from Eucalyptus camaldulensis in Reggio Calabria, Italy. The strains were serotype B, mating type α and were assigned to the molecular type VGI. In this study, we reported the first real environmental isolation of C. gattii in southern Italy that emphasized the observed global expansion of this yeast.
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16
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Datta K, Bartlett KH, Baer R, Byrnes E, Galanis E, Heitman J, Hoang L, Leslie MJ, MacDougall L, Magill SS, Morshed MG, Marr KA. Spread of Cryptococcus gattii into Pacific Northwest region of the United States. Emerg Infect Dis 2009; 15:1185-91. [PMID: 19757550 PMCID: PMC2815957 DOI: 10.3201/eid1508.081384] [Citation(s) in RCA: 206] [Impact Index Per Article: 13.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/03/2022] Open
Abstract
This organism should be recognized as an emerging pathogen in the United States. Cryptococcus gattii has emerged as a human and animal pathogen in the Pacific Northwest. First recognized on Vancouver Island, British Columbia, Canada, it now involves mainland British Columbia, and Washington and Oregon in the United States. In Canada, the incidence of disease has been one of the highest worldwide. In the United States, lack of cryptococcal species identification and case surveillance limit our knowledge of C. gattii epidemiology. Infections in the Pacific Northwest are caused by multiple genotypes, but the major strain is genetically novel and may have emerged recently in association with unique mating or environmental changes. C. gattii disease affects immunocompromised and immunocompetent persons, causing substantial illness and death. Successful management requires an aggressive medical and surgical approach and consideration of potentially variable antifungal drug susceptibilities. We summarize the study results of a group of investigators and review current knowledge with the goal of increasing awareness and highlighting areas where further knowledge is required.
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Affiliation(s)
- Kausik Datta
- Johns Hopkins University School of Medicine, Baltimore, Maryland 21205, USA
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17
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Datta K, Bartlett KH, Marr KA. Cryptococcus gattii: Emergence in Western North America: Exploitation of a Novel Ecological Niche. Interdiscip Perspect Infect Dis 2009; 2009:176532. [PMID: 19266091 PMCID: PMC2648661 DOI: 10.1155/2009/176532] [Citation(s) in RCA: 44] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/10/2008] [Accepted: 11/17/2008] [Indexed: 12/15/2022] Open
Abstract
The relatively uncommon fungal pathogen Cryptococcus gattii recently emerged as a significant cause of cryptococcal disease in human and animals in the Pacific Northwest of North America. Although genetic studies indicated its possible presence in the Pacific Northwest for more than 30 years, C. gattii as an etiological agent was largely unknown in this region prior to 1999. The recent emergence may have been encouraged by changing conditions of climate or land use and/or host susceptibility, and predictive ecological niche modeling indicates a potentially wider spread. C. gattii can survive wide climatic variations and colonize the environment in tropical, subtropical, temperate, and dry climates. Long-term climate changes, such as the significantly elevated global temperature in the last 100 years, influence patterns of disease among plants and animals and create niche microclimates habitable by emerging pathogens. C. gattii may have exploited such a hitherto unrecognized but clement environment in the Pacific Northwest to provide a wider exposure and risk of infection to human and animal populations.
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Affiliation(s)
- Kausik Datta
- School of Medicine, Johns Hopkins University, 720 Rutland Avenue, Room 1064, Ross Building, Baltimore, MD 21205, USA
| | - Karen H. Bartlett
- School of Environmental Health, University of British Columbia, Vancouver, BC, Canada V6T 1Z3
| | - Kieren A. Marr
- School of Medicine, Johns Hopkins University, 720 Rutland Avenue, Room 1064, Ross Building, Baltimore, MD 21205, USA
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Xue C, Tada Y, Dong X, Heitman J. The human fungal pathogen Cryptococcus can complete its sexual cycle during a pathogenic association with plants. Cell Host Microbe 2007; 1:263-73. [PMID: 18005707 DOI: 10.1016/j.chom.2007.05.005] [Citation(s) in RCA: 131] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/27/2007] [Revised: 04/19/2007] [Accepted: 05/21/2007] [Indexed: 12/17/2022]
Abstract
Cryptococcus is a globally distributed human fungal pathogen that primarily afflicts immunocompromised individuals. How and why this human fungal pathogen associates with plants and how this environmental niche influences its life cycle remains a mystery. We established Cryptococcus-Arabidopsis and Cryptococcus-Eucalyptus systems and discovered that Cryptococcus proliferates and mates on plant surfaces. Mating efficiency of C. gattii was markedly enhanced on plants and myo-inositol and indole acetic acid were specific plant products that stimulated mating. On Arabidopsis, dwarfing and chlorosis were observed following infection with a fungal mixture of two opposite mating-type strains, but not with either mating-type alone. This infection process is countered by the plant jasmonate-mediated defense mechanism. These findings reveal that Cryptococcus can parasitically interact with plants to complete its sexual cycle, which may impact an understanding of the origin and evolution of both plant and animal fungal pathogens in nature.
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Affiliation(s)
- Chaoyang Xue
- Department of Molecular Genetics and Microbiology, Duke University, Durham, NC 27710, USA
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19
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Kidd SE, Chow Y, Mak S, Bach PJ, Chen H, Hingston AO, Kronstad JW, Bartlett KH. Characterization of environmental sources of the human and animal pathogen Cryptococcus gattii in British Columbia, Canada, and the Pacific Northwest of the United States. Appl Environ Microbiol 2006; 73:1433-43. [PMID: 17194837 PMCID: PMC1828779 DOI: 10.1128/aem.01330-06] [Citation(s) in RCA: 177] [Impact Index Per Article: 9.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022] Open
Abstract
Cryptococcus gattii has recently emerged as a primary pathogen of humans and wild and domesticated animals in British Columbia, particularly on Vancouver Island. C. gattii infections are typically infections of the pulmonary and/or the central nervous system, and the incidence of infection in British Columbia is currently the highest reported globally. Prior to this emergence, the environmental distribution of and the extent of colonization by C. gattii in British Columbia were unknown. We characterized the environmental sources and potential determinants of colonization in British Columbia. C. gattii was isolated from tree surfaces, soil, air, freshwater, and seawater, and no seasonal prevalence was observed. The C. gattii concentrations in air samples were significantly higher during the warm, dry summer months, although potentially infectious propagules (<3.3 microm in diameter) were present throughout the year. Positive samples were obtained from many different areas of British Columbia, and some locations were colonization "hot spots." C. gattii was generally isolated from acidic soil, and geographic differences in soil pH may influence the extent of colonization. C. gattii soil colonization also was associated with low moisture and low organic carbon contents. Most of the C. gattii isolates recovered belonged to the VGIIa genetic subtype; however, sympatric colonization by the VGIIb strain was observed at most locations. At one sampling site, VGIIa, VGIIb, VGI, and the Cryptococcus neoformans serotype AD hybrid all were coisolated. Our findings indicate extensive colonization by C. gattii within British Columbia and highlight an expansion of the ecological niche of this pathogen.
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Affiliation(s)
- Sarah E Kidd
- School of Occupational and Environmental Hygiene, 364-2206 East Mall, Vancouver, University of British Columbia V6T 1Z3, Canada
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20
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Colom MF, Frasés S, Ferrer C, Jover A, Andreu M, Reus S, Sánchez M, Torres-Rodríguez JM. First case of human cryptococcosis due to Cryptococcus neoformans var. gattii in Spain. J Clin Microbiol 2005; 43:3548-50. [PMID: 16000503 PMCID: PMC1169187 DOI: 10.1128/jcm.43.7.3548-3550.2005] [Citation(s) in RCA: 47] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
We report the first case of human cryptococcosis due to Cryptococcus neoformans var. gattii described in our country, which was presented as brain cryptococcoma in an immunocompetent patient. An extensive sampling of the patient's environment was carried out to find the source of infection.
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Affiliation(s)
- M Francisca Colom
- División de Microbiología, Facultad de Medicina, Universidad Miguel Hernández, Sant Joan d'Alacant, 03550 Alicante, Spain.
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21
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Giles SS, Batinic-Haberle I, Perfect JR, Cox GM. Cryptococcus neoformans mitochondrial superoxide dismutase: an essential link between antioxidant function and high-temperature growth. EUKARYOTIC CELL 2005; 4:46-54. [PMID: 15643059 PMCID: PMC544162 DOI: 10.1128/ec.4.1.46-54.2005] [Citation(s) in RCA: 70] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/17/2004] [Accepted: 10/13/2004] [Indexed: 11/20/2022]
Abstract
Manganese superoxide dismutase is an essential component of the mitochondrial antioxidant defense system of most eukaryotes. In the present study, we used a reverse-genetics approach to assess the contribution of the Cryptococcus neoformans manganese superoxide dismutase (Sod2) for antioxidant defense. Strains with mutations in the SOD2 gene exhibited increased susceptibility to oxidative stress as well as poor growth at elevated temperatures compared to isogenic wild-type strains. The sod2Delta mutants were also avirulent in a murine model of inhaled cryptococcosis. Reconstitution of a sod2Delta mutant restored Sod2 activity, eliminated the oxidative stress and temperature-sensitive (ts) phenotypes, and complemented the virulence phenotype. Characterization of the ts phenotype revealed a dependency between Sod2 antioxidant activity and the ability of C. neoformans cells to adapt to growth at elevated temperatures. The ts phenotype could be suppressed by the addition of either ascorbic acid (10 mM) or Mn salen (200 muM) at 30 degrees C, but not at 37 degrees C. Furthermore, sod2Delta mutant cells that were incubated for 24 h at 37 degrees C under anaerobic, but not aerobic, conditions were viable when shifted to the permissive conditions of 25 degrees C in the presence of air. These data suggest that the C. neoformans Sod2 is a major component of the antioxidant defense system in this human fungal pathogen and that adaptation to growth at elevated temperatures is also dependent on Sod2 activity.
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Affiliation(s)
- Steven S Giles
- Department of Medicine, Duke University Medical Center, Durham, NC 27710, USA.
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22
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McClelland EE, Adler FR, Granger DL, Potts WK. Major histocompatibility complex controls the trajectory but not host-specific adaptation during virulence evolution of the pathogenic fungus Cryptococcus neoformans. Proc Biol Sci 2004; 271:1557-64. [PMID: 15306300 PMCID: PMC1691764 DOI: 10.1098/rspb.2004.2736] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/17/2023] Open
Abstract
Genes of the major histocompatibility complex (MHC) play a critical role in immune recognition and are the most genetically diverse loci known. One hypothesis to explain this diversity postulates that pathogens adapt to common MHC haplotypes and thus favour selection of new or rare alleles. To determine whether the pathogenic yeast Cryptococcus neoformans adapts to MHC-dependent immune responses, it was serially passaged in two independent replicate lines of five B10 MHC-congenic strains and Balb/c mice. All passaged lines increased in virulence as measured by reduced host survival. MHC influenced the rate (trajectory) of virulence increase during passages as measured by significant differences in mortality rate (p < 0.001). However, when the post-passage strains were tested, no MHC differences in mortality rate remained and only minor differences in titres were observed. Also contrary to expectations, increased virulence in three lines passaged in B10 mice had a larger effect in Balb/c mice, and the evolution of virulence in lines passaged in alternating hosts was not retarded. To our knowledge, these data represent the first experimental test of MHC-specific adaptation in a non-viral pathogen. The failure to observe MHC effects despite dramatically increased virulence and host-genotype-specific adaptation to non-MHC genes suggests that escape of MHC-dependent immune recognition may be difficult for pathogens with unlimited epitopes or that other virulence factors can swamp MHC effects.
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Affiliation(s)
- Erin E McClelland
- Department of Biology, University of Utah, 257 South 1400 East, Salt Lake City, UT 84112, USA.
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