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Pathogenic fungus

February 15, 2024

Pathogenic fungi are fungi that cause disease in humans or other organisms. Although fungi are eukaryotic, many pathogenic fungi are microorganisms.[1] Approximately 300 fungi are known to be pathogenic to humans;[2] their study is called "medical mycology". Fungal infections are estimated to kill more people than either tuberculosis or malaria—about two million people per year.[3]

In 2022 the World Health Organization (WHO) published a list of fungal pathogens which should be a priority for public health action.[4]

Markedly more fungi are known to be pathogenic to plant life than those of the animal kingdom.[5] The study of fungi and other organisms pathogenic to plants is called plant pathology.

Pathogens of particular concern edit

According to the World Health Organization (WHO) in 2022 pathogens of particular concern are:[4]

Critical priority
Cryptococcus neoformans, Candida auris, Aspergillus fumigatus, Candida albicans.
High priority
Nakaseomyces glabrata (Candida glabrata), Histoplasma spp., eumycetoma causative agents, Mucorales, Fusarium spp., Candida tropicalis, Candida parapsilosis.
Medium priority
Scedosporium spp., Lomentospora prolificans, Coccidioides spp., Pichia kudriavzeveii (Candida krusei), Cryptococcus gattii, Talaromyces marneffei, Pneumocystis jirovecii, Paracoccidioides spp.

Candida edit

 
Candida. Pap test specimen. Pap stain.

Candida species cause infections in individuals with deficient immune systems. Candida species tend to be the culprit of most fungal infections and can cause both systemic and superficial infection.[6] Th1-type cell-mediated immunity (CMI) is required for clearance of a fungal infection. Candida albicans is a kind of diploid yeast that commonly occurs among the human gut microflora. C. albicans is an opportunistic pathogen in humans. Abnormal over-growth of this fungus can occur, particularly in immunocompromised individuals.[7] C. albicans has a parasexual cycle that appears to be stimulated by environmental stress.[8]

C. auris, first described in 2009, is resistant to many frontline antifungal drugs, disinfectants, and heat, which makes it extremely difficult to eradicate. Like many fungal pathogens it mostly affects immunocompromised people; if in the blood or other organs and tissues, mortality is about 50%.[3]

Other species of Candida may be pathogenic as well, including Candida stellatoidea, C. tropicalis, C. pseudotropicalis, C. krusei, C. parapsilosis, and C. guilliermondii.[9]

Aspergillus edit

 
Aspergillosis. H&E stain.

The most common pathogenic species are Aspergillus fumigatus and Aspergillus flavus. Aspergillus flavus produces aflatoxin which is both a toxin and a carcinogen and which can potentially contaminate foods such as nuts. Aspergillus fumigatus and Aspergillus clavatus can cause allergic disease. Some Aspergillus species cause disease on grain crops, especially maize, and synthesize mycotoxins including aflatoxin. Aspergillosis is the group of diseases caused by Aspergillus. The symptoms include fever, cough, chest pain or breathlessness. Usually, only patients with weakened immune systems or with other lung conditions are susceptible.[1]

The spores of Aspergillus fumigatus are ubiquitous in the atmosphere. A. fumigatus is an opportunistic pathogen. It can cause potentially lethal invasive infection in immunocompromised individuals.[10] A. fumigatus has a fully functional sexual cycle that produces cleistothecia and ascospores.[citation needed]

Cryptococcus edit

 
Cryptococcus. FNA specimen. Field stain.

Cryptococcus neoformans can cause a severe form of meningitis and meningo-encephalitis in patients with HIV infection and AIDS. The majority of Cryptococcus species live in the soil and do not cause disease in humans. Cryptococcus neoformans is the major human and animal pathogen. Papiliotrema laurentii and Naganishia albida, both formerly referred to Cryptococcus, have been known to occasionally cause moderate-to-severe disease in human patients with compromised immunity. Cryptococcus gattii is endemic to tropical parts of the continent of Africa and Australia and can cause disease in non-immunocompromised people.[1]

Infecting C. neoformans cells are usually phagocytosed by alveolar macrophages in the lung.[11] The invading C. neoformans cells may be killed by the release of oxidative and nitrosative molecules by these macrophages.[12] However some C. neoformans cells may survive within the macrophages.[11] The ability of the pathogen to survive within the macrophages probably determines latency of the disease, dissemination and resistance to antifungal agents. In order to survive in the hostile intracellular environment of the macrophage, one of the responses of C. neoformans is to upregulate genes employed in responses to oxidative stress.[11]

The haploid nuclei of C. neoformans can undergo nuclear fusion (karyogamy) to become diploid. These diploid nuclei may then undergo meiosis, including recombination, resulting in the formation of haploid basidiospores that are able to disperse.[13] Meiosis may facilitate repair of C. neoformans DNA in response to macrophage challenge.[13][14]

Histoplasma edit

 
Histoplasmosis. PASD stain.

Histoplasma capsulatum can cause histoplasmosis in humans, dogs and cats. The fungus is most prevalent in the Americas, India and southeastern Asia. It is endemic in certain areas of the United States. Infection is usually due to inhaling contaminated air.

Pneumocystis edit

Pneumocystis jirovecii (or Pneumocystis carinii) can cause a form of pneumonia in people with weakened immune systems, such as premature children,patients on immunosuppressive treatment, the elderly and AIDS patients.[15]

Stachybotrys edit

Stachybotrys chartarum or "black mold" can cause respiratory damage and severe headaches. It frequently occurs in houses and in regions that are chronically damp.[16]

Host defense mechanisms edit

Endothermy edit

Mammalian endothermy and homeothermy are potent nonspecific defenses against most fungi.[17] A comparative genomic study found that in opportunistic fungi there are few if any specialised virulence traits consistently linked to opportunistic pathogenicity of fungi in humans apart from the ability to grow at 37 °C.[18]

Barrier tissues edit

The skin, respiratory tract, gastrointestinal tract, and the genital-urinary tract induced inflammation[vague] are common bodily regions of fungal infection.

Immune response edit

Studies have shown that hosts with higher levels of immune response cells such as monocytes/macrophages, dendritic cells, and invariant natural killer (iNK) T-cells exhibited greater control of fungal growth and protection against systemic infection. Pattern recognition receptors (PRRs) play an important role in inducing an immune response by recognizing specific fungal pathogens and initiating an immune response. In the case of mucosal candidiasis, the cells that produce cytokine IL-17 are extremely important in maintaining innate immunity.[19]

Link to extremotolerance edit

A comprehensive comparison of distribution of opportunistic pathogens and stress-tolerant fungi in the fungal tree of life showed that polyextremotolerance and opportunistic pathogenicity consistently appear in the same fungal orders and that the co-occurrence of opportunism and extremotolerance (e.g. osmotolerance and psychrotolerance) is statistically significant. This suggests that some adaptations to stressful environments may also promote fungal survival during the infection.[18]

See also edit

References edit

  1. ^ a b c San-Blas G; Calderone RA, eds. (2008). Pathogenic Fungi: Insights in Molecular Biology. Caister Academic Press. ISBN 978-1-904455-32-5.
  2. ^ "Stop neglecting fungi". Nature Microbiology. 2 (8): 17120. 25 July 2017. doi:10.1038/nmicrobiol.2017.120. PMID 28741610.
  3. ^ a b Geddes, Linda (10 February 2023). "'A growing threat to human health': we are ill-equipped for the dangers of fungal infections". The Guardian.
  4. ^ a b WHO fungal priority pathogens list to guide research, development and public health action. World Health Organization. 2022. ISBN 978-92-4-006025-8.
  5. ^ English, Mary P. (1980). Medical Mycology. London: Edward Arnold Publishers Limited. p. 5. ISBN 0-7131-2795-3.
  6. ^ Turner, S. A.; Butler, G. (2014-09-01). "The Candida Pathogenic Species Complex". Cold Spring Harbor Perspectives in Medicine. 4 (9): a019778. doi:10.1101/cshperspect.a019778. ISSN 2157-1422. PMC 4143104. PMID 25183855.
  7. ^ Martins N, Ferreira IC, Barros L, Silva S, Henriques M (2014). "Candidiasis: predisposing factors, prevention, diagnosis and alternative treatment". Mycopathologia. 177 (5–6): 223–40. doi:10.1007/s11046-014-9749-1. hdl:1822/31482. PMID 24789109. S2CID 795450.
  8. ^ Bennett RJ (2015). "The parasexual lifestyle of Candida albicans". Curr. Opin. Microbiol. 28: 10–7. doi:10.1016/j.mib.2015.06.017. PMC 4688137. PMID 26210747.
  9. ^ Beneke, E. S. (1966). Medical Mycology: Laboratory Manual (2nd ed.). Minneapolis, MN: Burgess Publishing Company. p. 161.
  10. ^ O'Gorman CM, Fuller H, Dyer PS (2009). "Discovery of a sexual cycle in the opportunistic fungal pathogen Aspergillus fumigatus". Nature. 457 (7228): 471–4. Bibcode:2009Natur.457..471O. doi:10.1038/nature07528. PMID 19043401. S2CID 4371721.
  11. ^ a b c Fan W, Kraus PR, Boily MJ, Heitman J (2005). "Cryptococcus neoformans gene expression during murine macrophage infection". Eukaryotic Cell. 4 (8): 1420–33. doi:10.1128/EC.4.8.1420-1433.2005. PMC 1214536. PMID 16087747.
  12. ^ Alspaugh JA, Granger DL (1991). "Inhibition of Cryptococcus neoformans replication by nitrogen oxides supports the role of these molecules as effectors of macrophage-mediated cytostasis". Infect. Immun. 59 (7): 2291–6. doi:10.1128/IAI.59.7.2291-2296.1991. PMC 258009. PMID 2050398.
  13. ^ a b Lin X, Hull CM, Heitman J (2005). "Sexual reproduction between partners of the same mating type in Cryptococcus neoformans". Nature. 434 (7036): 1017–21. Bibcode:2005Natur.434.1017L. doi:10.1038/nature03448. PMID 15846346. S2CID 52857557.
  14. ^ Bernstein H, Bernstein C, Michod RE (2018). "Sex in microbial pathogens". Infection, Genetics and Evolution. 57: 8–25. doi:10.1016/j.meegid.2017.10.024. PMID 29111273.
  15. ^ Ryan KJ; Ray CG, eds. (2004). Sherris Medical Microbiology (4th ed.). McGraw Hill. ISBN 978-0-8385-8529-0.
  16. ^ Bitnun, Ari; Nosal, Robert M (1999). "Stachybotrys chartarum (atra) contamination of the indoor environment: Health implications". Paediatrics & Child Health. 4 (2): 125–129. doi:10.1093/pch/4.2.125. ISSN 1205-7088. PMC 2828207. PMID 20212975.
  17. ^ Robert, V. A.; Casadevall, A. (2009). "Vertebrate Endothermy Restricts Most Fungi as Potential Pathogens". The Journal of Infectious Diseases. 200 (10): 1623–1626. doi:10.1086/644642. PMID 19827944.
  18. ^ a b Gostinčar, Cene; Zajc, Janja; Lenassi, Metka; Plemenitaš, Ana; de Hoog, Sybren; Al-Hatmi, Abdullah M. S.; Gunde-Cimerman, Nina (2018-11-01). "Fungi between extremotolerance and opportunistic pathogenicity on humans". Fungal Diversity. 93 (1): 195–213. doi:10.1007/s13225-018-0414-8. ISSN 1878-9129.
  19. ^ Brown GD, Drummond RA, Gaffen SL, Hise AG (2015). "Innate Defense against Fungal Pathogens". Cold Spring Harb Perspect Med. 5 (6): a019620. doi:10.1101/cshperspect.a019620. PMC 4426252. PMID 25384766.

Further reading edit

  • Almeida F, Rodrigues ML, Coelho C (2019). "The Still Underestimated Problem of Fungal Diseases Worldwide". Front Microbiol. 10: 214. doi:10.3389/fmicb.2019.00214. PMC 6379264. PMID 30809213.

External links edit

  • Ecmm.eu: Official European Confederation of Medical Mycology website

February 15, 2024
pathogenic, fungus, pathogenic, fungi, fungi, that, cause, disease, humans, other, organisms, although, fungi, eukaryotic, many, pathogenic, fungi, microorganisms, approximately, fungi, known, pathogenic, humans, their, study, called, medical, mycology, fungal. Pathogenic fungi are fungi that cause disease in humans or other organisms Although fungi are eukaryotic many pathogenic fungi are microorganisms 1 Approximately 300 fungi are known to be pathogenic to humans 2 their study is called medical mycology Fungal infections are estimated to kill more people than either tuberculosis or malaria about two million people per year 3 In 2022 the World Health Organization WHO published a list of fungal pathogens which should be a priority for public health action 4 Markedly more fungi are known to be pathogenic to plant life than those of the animal kingdom 5 The study of fungi and other organisms pathogenic to plants is called plant pathology Contents 1 Pathogens of particular concern 2 Candida 3 Aspergillus 4 Cryptococcus 5 Histoplasma 6 Pneumocystis 7 Stachybotrys 8 Host defense mechanisms 8 1 Endothermy 8 2 Barrier tissues 8 3 Immune response 9 Link to extremotolerance 10 See also 11 References 12 Further reading 13 External linksPathogens of particular concern editAccording to the World Health Organization WHO in 2022 pathogens of particular concern are 4 Critical priority Cryptococcus neoformans Candida auris Aspergillus fumigatus Candida albicans High priority Nakaseomyces glabrata Candida glabrata Histoplasma spp eumycetoma causative agents Mucorales Fusarium spp Candida tropicalis Candida parapsilosis Medium priority Scedosporium spp Lomentospora prolificans Coccidioides spp Pichia kudriavzeveii Candida krusei Cryptococcus gattii Talaromyces marneffei Pneumocystis jirovecii Paracoccidioides spp Candida edit nbsp Candida Pap test specimen Pap stain Candida species cause infections in individuals with deficient immune systems Candida species tend to be the culprit of most fungal infections and can cause both systemic and superficial infection 6 Th1 type cell mediated immunity CMI is required for clearance of a fungal infection Candida albicans is a kind of diploid yeast that commonly occurs among the human gut microflora C albicans is an opportunistic pathogen in humans Abnormal over growth of this fungus can occur particularly in immunocompromised individuals 7 C albicans has a parasexual cycle that appears to be stimulated by environmental stress 8 C auris first described in 2009 is resistant to many frontline antifungal drugs disinfectants and heat which makes it extremely difficult to eradicate Like many fungal pathogens it mostly affects immunocompromised people if in the blood or other organs and tissues mortality is about 50 3 Other species of Candida may be pathogenic as well including Candida stellatoidea C tropicalis C pseudotropicalis C krusei C parapsilosis and C guilliermondii 9 Aspergillus edit nbsp Aspergillosis H amp E stain The most common pathogenic species are Aspergillus fumigatus and Aspergillus flavus Aspergillus flavus produces aflatoxin which is both a toxin and a carcinogen and which can potentially contaminate foods such as nuts Aspergillus fumigatus and Aspergillus clavatus can cause allergic disease Some Aspergillus species cause disease on grain crops especially maize and synthesize mycotoxins including aflatoxin Aspergillosis is the group of diseases caused by Aspergillus The symptoms include fever cough chest pain or breathlessness Usually only patients with weakened immune systems or with other lung conditions are susceptible 1 The spores of Aspergillus fumigatus are ubiquitous in the atmosphere A fumigatus is an opportunistic pathogen It can cause potentially lethal invasive infection in immunocompromised individuals 10 A fumigatus has a fully functional sexual cycle that produces cleistothecia and ascospores citation needed Cryptococcus edit nbsp Cryptococcus FNA specimen Field stain Cryptococcus neoformans can cause a severe form of meningitis and meningo encephalitis in patients with HIV infection and AIDS The majority of Cryptococcus species live in the soil and do not cause disease in humans Cryptococcus neoformans is the major human and animal pathogen Papiliotrema laurentii and Naganishia albida both formerly referred to Cryptococcus have been known to occasionally cause moderate to severe disease in human patients with compromised immunity Cryptococcus gattii is endemic to tropical parts of the continent of Africa and Australia and can cause disease in non immunocompromised people 1 Infecting C neoformans cells are usually phagocytosed by alveolar macrophages in the lung 11 The invading C neoformans cells may be killed by the release of oxidative and nitrosative molecules by these macrophages 12 However some C neoformans cells may survive within the macrophages 11 The ability of the pathogen to survive within the macrophages probably determines latency of the disease dissemination and resistance to antifungal agents In order to survive in the hostile intracellular environment of the macrophage one of the responses of C neoformans is to upregulate genes employed in responses to oxidative stress 11 The haploid nuclei of C neoformans can undergo nuclear fusion karyogamy to become diploid These diploid nuclei may then undergo meiosis including recombination resulting in the formation of haploid basidiospores that are able to disperse 13 Meiosis may facilitate repair of C neoformans DNA in response to macrophage challenge 13 14 Histoplasma edit nbsp Histoplasmosis PASD stain Histoplasma capsulatum can cause histoplasmosis in humans dogs and cats The fungus is most prevalent in the Americas India and southeastern Asia It is endemic in certain areas of the United States Infection is usually due to inhaling contaminated air Pneumocystis editPneumocystis jirovecii or Pneumocystis carinii can cause a form of pneumonia in people with weakened immune systems such as premature children patients on immunosuppressive treatment the elderly and AIDS patients 15 Stachybotrys editStachybotrys chartarum or black mold can cause respiratory damage and severe headaches It frequently occurs in houses and in regions that are chronically damp 16 Host defense mechanisms editEndothermy edit Mammalian endothermy and homeothermy are potent nonspecific defenses against most fungi 17 A comparative genomic study found that in opportunistic fungi there are few if any specialised virulence traits consistently linked to opportunistic pathogenicity of fungi in humans apart from the ability to grow at 37 C 18 Barrier tissues edit The skin respiratory tract gastrointestinal tract and the genital urinary tract induced inflammation vague are common bodily regions of fungal infection Immune response edit Studies have shown that hosts with higher levels of immune response cells such as monocytes macrophages dendritic cells and invariant natural killer iNK T cells exhibited greater control of fungal growth and protection against systemic infection Pattern recognition receptors PRRs play an important role in inducing an immune response by recognizing specific fungal pathogens and initiating an immune response In the case of mucosal candidiasis the cells that produce cytokine IL 17 are extremely important in maintaining innate immunity 19 Link to extremotolerance editA comprehensive comparison of distribution of opportunistic pathogens and stress tolerant fungi in the fungal tree of life showed that polyextremotolerance and opportunistic pathogenicity consistently appear in the same fungal orders and that the co occurrence of opportunism and extremotolerance e g osmotolerance and psychrotolerance is statistically significant This suggests that some adaptations to stressful environments may also promote fungal survival during the infection 18 See also edit nbsp Fungi portalList of human diseases associated with infectious pathogens Microbiology Microsporidia Mycology Plant pathology Plague Inc References edit a b c San Blas G Calderone RA eds 2008 Pathogenic Fungi Insights in Molecular Biology Caister Academic Press ISBN 978 1 904455 32 5 Stop neglecting fungi Nature Microbiology 2 8 17120 25 July 2017 doi 10 1038 nmicrobiol 2017 120 PMID 28741610 a b Geddes Linda 10 February 2023 A growing threat to human health we are ill equipped for the dangers of fungal infections The Guardian a b WHO fungal priority pathogens list to guide research development and public health action World Health Organization 2022 ISBN 978 92 4 006025 8 English Mary P 1980 Medical Mycology London Edward Arnold Publishers Limited p 5 ISBN 0 7131 2795 3 Turner S A Butler G 2014 09 01 The Candida Pathogenic Species Complex Cold Spring Harbor Perspectives in Medicine 4 9 a019778 doi 10 1101 cshperspect a019778 ISSN 2157 1422 PMC 4143104 PMID 25183855 Martins N Ferreira IC Barros L Silva S Henriques M 2014 Candidiasis predisposing factors prevention diagnosis and alternative treatment Mycopathologia 177 5 6 223 40 doi 10 1007 s11046 014 9749 1 hdl 1822 31482 PMID 24789109 S2CID 795450 Bennett RJ 2015 The parasexual lifestyle of Candida albicans Curr Opin Microbiol 28 10 7 doi 10 1016 j mib 2015 06 017 PMC 4688137 PMID 26210747 Beneke E S 1966 Medical Mycology Laboratory Manual 2nd ed Minneapolis MN Burgess Publishing Company p 161 O Gorman CM Fuller H Dyer PS 2009 Discovery of a sexual cycle in the opportunistic fungal pathogen Aspergillus fumigatus Nature 457 7228 471 4 Bibcode 2009Natur 457 471O doi 10 1038 nature07528 PMID 19043401 S2CID 4371721 a b c Fan W Kraus PR Boily MJ Heitman J 2005 Cryptococcus neoformans gene expression during murine macrophage infection Eukaryotic Cell 4 8 1420 33 doi 10 1128 EC 4 8 1420 1433 2005 PMC 1214536 PMID 16087747 Alspaugh JA Granger DL 1991 Inhibition of Cryptococcus neoformans replication by nitrogen oxides supports the role of these molecules as effectors of macrophage mediated cytostasis Infect Immun 59 7 2291 6 doi 10 1128 IAI 59 7 2291 2296 1991 PMC 258009 PMID 2050398 a b Lin X Hull CM Heitman J 2005 Sexual reproduction between partners of the same mating type in Cryptococcus neoformans Nature 434 7036 1017 21 Bibcode 2005Natur 434 1017L doi 10 1038 nature03448 PMID 15846346 S2CID 52857557 Bernstein H Bernstein C Michod RE 2018 Sex in microbial pathogens Infection Genetics and Evolution 57 8 25 doi 10 1016 j meegid 2017 10 024 PMID 29111273 Ryan KJ Ray CG eds 2004 Sherris Medical Microbiology 4th ed McGraw Hill ISBN 978 0 8385 8529 0 Bitnun Ari Nosal Robert M 1999 Stachybotrys chartarum atra contamination of the indoor environment Health implications Paediatrics amp Child Health 4 2 125 129 doi 10 1093 pch 4 2 125 ISSN 1205 7088 PMC 2828207 PMID 20212975 Robert V A Casadevall A 2009 Vertebrate Endothermy Restricts Most Fungi as Potential Pathogens The Journal of Infectious Diseases 200 10 1623 1626 doi 10 1086 644642 PMID 19827944 a b Gostincar Cene Zajc Janja Lenassi Metka Plemenitas Ana de Hoog Sybren Al Hatmi Abdullah M S Gunde Cimerman Nina 2018 11 01 Fungi between extremotolerance and opportunistic pathogenicity on humans Fungal Diversity 93 1 195 213 doi 10 1007 s13225 018 0414 8 ISSN 1878 9129 Brown GD Drummond RA Gaffen SL Hise AG 2015 Innate Defense against Fungal Pathogens Cold Spring Harb Perspect Med 5 6 a019620 doi 10 1101 cshperspect a019620 PMC 4426252 PMID 25384766 Further reading editAlmeida F Rodrigues ML Coelho C 2019 The Still Underestimated Problem of Fungal Diseases Worldwide Front Microbiol 10 214 doi 10 3389 fmicb 2019 00214 PMC 6379264 PMID 30809213 External links editEcmm eu Official European Confederation of Medical Mycology website Retrieved from https en wikipedia org w index php title Pathogenic fungus amp oldid 1205989863, wikipedia, wiki, book, books, library,

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