The dermatophytes Fungi that stalk you and your loved ones as their petri plate

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1 The dermatophytes Fungi that stalk you and your loved ones as their petri plate Dr. Richard Summerbell Dalla Lana School of Public Health, University of Toronto Geraldine Kaminski Medical Mycology Library Bacteria Purple bacteria Cyanobacteria Gram positives Clostridium Mycoplasma Archaebacteria Methanobacterium Methanococcus Pyrococcus Archaeglobus Eukarya Animals Slime moulds Fungi Plants Pyrobaculum Borrelia Thermologa Deinococcus Green nonsulfur bacteria Aquifex Flagellates Trichomonads Microsporidia Image courtesy of the late Dr. Julius Kane Source: Oak Ridge National Laboratory 1

2 Chytridiomycota (water moulds) Zygomycota (sweet rots) Basidiomycota (mushrooms, rusts, smuts) Ascomycota (sac fungi, true moulds, yeasts) 300 MYA 600 MYA after Purves et al, 1998 Talaromyces = Penicillium sexual stage called: teleomorph asexual stage called: anamorph 2

3 Character evolution and speciation in dermatophytes Mating Dikaryotization Meiosis Mitosis Onygena cervina Jan Zavrel ˆ 3

4 Soil association characters Morphology conidial abundance and variety formation of perforating organs in dissociated i dhair arthropod antipredation or dispersal features conidial ornamentation rigid peridial "wireframe" peridial spirals, hooks and spines Physiology osmotolerance vitamin and amino acid autotrophy constitutive protease and urease activity Genetics intact heterothallic mating system conspicuous teleomorph Dikaryotization Mitosis Mitosis Mating Meiosis Mitosis Characters associated with non-soil associated animals Morphology attenutated conidiation, trend to monomorphic to aconidial strains l f h i f i loss of hair perforating organs loss of arthropod antipredation or dispersal features smooth conidia loss of teleomorph structures including peridial appendages, coils, etc. Physiology osmosensitive vitamin and amino acid auxotrophy i d d t ti it ( t b lit i ) induced protease activity (catabolite repression) attenuated urease activity Genetics heterothallic mating system dismantled loss of teleomorph and related structures 4

5 What are the dermatophytes? anamorph (asexual genera) Trichophyton, Microsporum and Epidermophyton both Trichophyton and Microsporum also contain some nonpathogenic species (not defined as dermatophytes = skin plants, ergo called dermatophytoids = look like dermatophytes. ) teleomorphs, formed only in some species, all in genus Arthroderma Tinea (dermatophytosis) dermatophytosis different tinea disease types for scalp, beard area, glabrous skin (face, trunk, leg, arm), groin, foot skin, nails (finger or toe). Main categories scalp dermatophytes mostly affecting children, but often converting some adults to cryptic carriers, e.g., Trichophyton tonsurans glabrous skin dermatophytes acquired from animals, e.g., Microsporum canis from cats human-associated dermatophytes mainly of feet, hands and groin, e.g., Trichophyton rubrum Ecological categories host/substrate Anthropophilic typically growing on humans Zoophilic have animal population hosts, but occasional human infections occur Geophilic associated with keratinous habitats in soil, e.g., decomposing hair and feathers 5

6 Dermatophyte eco-morphological types Soil-associated dermatophytes (and dermatophytoids = nonpathogenic members of Trichophyton and Microsporum) ) full slate of soil association characters listed in previous slide geophiles, zoophiles of burrowing and denning animals Non-soil-associated dermatophytes genetic drift for unselected characters allows fixation of mutations leading to loss of soil-association characters; usually at least two of the items listed are altered, e.g., in typical Trichophyton rubrum, urease and hair perforation lost, sexuality lost along with one mating type, growth rate moderate not fast, osmotolerance lost, macroconidia very sparsely formed if at all. anthropophiles, zoophiles of ungulates (cows, sheep) and horses Mating type determination Mat genes now amplified in dermatophytes Mating type can often be identified in classical genetics by crossing members of most species with testers of Arthroderma simii. Partial mating reaction with formation of non-maturing ascomata seen in pairings of opposite mating type Dermatophytosis: body site specificities here tinea barbae, infection of beard area from Emedicine website Tinea capitis mainly in children adult carriers, usually an older woman in the family may cause y school and other outbreaks 6

7 Tinea corporis (T. verrucosum on finger) Tinea manuum usually caused by zoophilic species usually caused by T. rubrum T. rubrum may also cause it, esp. the afroasiatic form Tinea pedis (severe) Foot dermatophytosis (severe) anthropophilic species involved: mostly T. rubrum, T. interdigitale 7

8 Tinea pedis (moccasin foot) Nail dermatophytosis (tinea unguium, a subcategory of onychomycosis) mostly same species as cause tinea pedis T. rubrum attacks nails from below (moist); T. interdigitale from above (dry) fungus typically grows in tinea pedis for 20+ years, then gradually moves in to colonize nails Dermatophytosis: hair invasion in vivo for species causing t. capitis Ectothrix: M. canis coating hair surface with substrate-arthroconidia endothrix: Trichophyton tonsurans, T. violaceum, T. soudanense ectothrix: M. canis, M. audouinii, M. ferrugineum ( small-spored ), T. verrucosum, T. megninii ( large-spored ) favic: air channels and large hyphae in hair, seen only in T. schoenleinii infection 8

9 Endothrix: T. tonsurans filling hair shaft with substrate-arthroconidia Favic hair invasion: T. schoenleinii Zoophilic infections: Dog with severe M. canis infection Microsporum canis on cat 9

10 Microsporum canis on cat: fluorescence Population host vs. occasional host M. canis populations maintain themselves perpetually petua on cats, Trichophyton (mentagrophytes complex) state of Arthroderma benhamiae on rabbits and cavies, T. (m. complex) state of A. vanbreuseghemii on rats and squirrels, etc Such species can all cause occasional infections in atypical hosts, e.g., in humans, deer, horses, seals, dogs, etc. They are not chronically carried in populations of these occasional hosts and there is minimal effect of this host cross-over on the population genetics of the fungal species. Taxonomy problems I species now mainly based on phylogenetic study traditional taxonomy distinguished species distinguished by profound changes occurring in switch from soil-associated to non-soil-associated niches: strong morphological change (slower growth, few conidia, etc.) often also physiological change (e.g., gain of a vitamin requirement, loss of hair perforation ability) population-host jump (to human, cow, sheep, camel or horse) loss of sexuality and generally also of one mating type many of these transformed niche-jumpers are now found to be very phylogenetically close to the soil-associated ancestral species, leading to controversy about whether they should retain their separate names or not, e.g., chicken dermatophyte Microsporum gallinae, derived from geophilic Arthroderma grubyi/microsporum vanbreuseghemii Taxonomy problems II Some traditional species were long known to be species-complexes p composed of organisms distinguishable only by mating, e.g., T. mentagrophytes complex (A. benhamiae, A. vanbreuseghemii) and M. gypseum complex (A. gypseum, A. incurvatum, A. fulvum). There is now a trend to name these species individually (e.g, T. interdigitale for anamorphs related to A. vanbreuseghemii) even though they can only be reliably identified using molecular techniques (still too expensive for routine diagnostic work) 10

11 Dendrogram Identification: traditional characters Trichophyton dermatophytes, M. canis complex and E. floccosum main Microsporum group mostly nonpathogenic Trichophyton dermatophytoids macroconidia alone, smooth-walled (Epidermophyton) h t with microconidia, rough-walled (Microsporum) with microconidia, smooth walled (Trichophyton) problem is that macroconidia are often not seen at all. Also, microconidia may be absent, and are essentially always absent in some species. Identification: BCP (bromcresyl purple) milk solids glucose agar The BCP indicator detects: acid production by many bacteria and nondermatophytic fungi (and then turns yellow) alkaline ammonium ion production by dermatophytes (and some nonpathogens) utilizing amino acids from protein as a sole carbon source The milk solids show: peptonization (clearing) showing the presence of proteases cleaving proteins into short segments Some other common physiological identification techniques Christensen urea broth or agar indicates urease enzyme Vitamin and other growth factor requirement tests series of 7 Trichophyton agars, but usually only 3 4 are regularly used hair perforation in vitro Sabouraud + 3% or 5% salt 11

12 BCP MSG reactions of common fast-growing dermatophytes T. rubrum vs. T. mentagrophytes complex on BCP MSG + reactions T. rubrum ( ) common Microsporum spp.: ( ) reactions Trichophyton mentagrophytes complex on BCP MSG and urea broth Trichophyton rubrum on BCP MSG, Christensen urea broth at 7 d 12

13 Bacterially contaminated Trichophyton rubrum on BCP MSG, Christensen urea broth at 7 d Hair perforation antibiotic-polyresistant bacteria carried over into urease test may cause false + reactions. The BCP MSG medium is used antibiotic-free so that it, in various ways, will reveal this cryptic bacterial contamination Here the bacteria are evidenced by the atypical yellowish colour of the T. rubrum colony Trichophyton violaceum (pale form), vitamin test Dendrogram Trichophyton dermatophytes, M. canis complex and E. floccosum main Microsporum group mostly nonpathogenic Trichophyton dermatophytoids 13

14 Microsporum canis, the cat ringworm fungus (also infects humans, especially children, who handle cats) from Univ. of Alberta dermatophytes website teleomorph A. otae Image courtesy of Dr. Joe Kowalski Microsporum canis colony Image courtesy of Dr. E. Pierard 14

15 Microsporum canis colony reverse Sabouraud Microsporum audouinii colony on Sabouraud anthropophile, infects mostly scalp of patients < 19 yr old now mainly restricted to central and west Africa, but may arrive on travellers, immigrants Microsporum audouinii beaked macroconidium Microsporum audouinii microconidia 15

16 Microsporum audouinii on diagnostic media Microsporum audouinii on rice Microsporum ferrugineum An anthropophilic fungus causing epidemic juvenile tinea capitis in humans. The clinical features are similar to those of infections caused by M. audouinii. Invaded hairs show an ectothrix infection and fluoresce a greenish-yellow under Wood's ultra-violet light. Distribution: Central Asia, central Africa, possibly still rarely present in Korea and Romania (historical endemic strongholds). Key Features: Culture characteristics and distinctive "bamboo" hyphae

17 Microsporum gallinae colony considered a synonym of M. vanbreuseghemii by Gräser et al. Microsporum gallinae asexual species, typically on glabrous skin of fowl 17

18 Microsporum vanbreuseghemii macroconidia anamorph of A. grubyi, geophilic Microsporum gypseum colony geo- philic, but may infect humans and animals infections often selflimiting but inflammatory Microsporum gypseum macroconidia Microsporum cookei colony teleomorph A. cajetani nonpathogen, subject of a few very weak case reports, probably all in error 18

19 Microsporum cookei colony reverse Microsporum cookei conidia Microsporum persicolor colony Microsporum persicolor macroconidium teleomorph A. persicolor may be a zoophile associated with voles and bats (pipistrelle) or possibly a geophile may infect people, e.g., gardeners; also not uncommon from dogs noses hard to distinguish from T. mentagrophytes complex, thus under-reported in many areas 19

20 Microsporum persicolor microconidia Microsporum persicolor microconidia and spiral appendages Microsporum nanum colony Microsporum nanum colony reverse teleomorph A. obtusum zoophile with swine population host 20

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22 Epidermophyton floccosum colonies on Sabouraud and Sab - 3% salt Epidermophyton floccosum conidia anthropophile mainly associated with tinea cruris, but some t. corporis, t. pedis and t. unguium now becoming very uncommon in developed world 22

23 Epidermophyton floccosum conidia T. mentagrophytes complex zoophilic Arthroderma vanbreuseghemii and very closely related anthropophilic Trichophyton interdigitale. The former is mainly from rats and causes inflammatory tinea corporis in humans, while the latter is the most common fungus in this complex in human infection and mainly causes tinea pedis and t. unguium zoophilic Arthroderma benhamiae, mainly from rabbits and cavies; some typical humanassociated strains in North America and eastern Europe also mate with this species T. mentagrophytes sensu stricto, zoophilic, associated with mice, causing inflammatory tinea corporis, a single mating type mating with A. benhamiae T. erinacei, the hedgehog dermatophyte, a single mating type mating with A. benhamiae Dendrogram again / T. equinum Trichophyton dermatophytes, M. canis complex and E. floccosum main Microsporum group mostly nonpathogenic Trichophyton dermatophytoids University of Iowa, Dept of Dermatology 23

24 Foot dermatophytosis (severe) Trichophyton mentagrophytes complex vs. yellow T. rubrum on BCP MSG Trichophyton mentagrophytes complex on BCP MSG and urea broth Anamorph of Arthroderma vanbreuseghemii (genetically Trichophyton interdigitale) 24

25 Trichophyton mentagrophytes complex (T. interdigitale?) velvety form Trichophyton interdigitale (cottony) Trichophyton mentagrophytes complex: spiral appendage Trichophyton mentagrophytes complex: macroconidia 25

26 Arthoderma simii mating cross Trichophyton simii conidia and Arthoderma simii ascospores Trichophyton verrucosum colony zoophile with cattle population host mainly infects handlers of animals or their fomites inflammatory tinea corporis, capitis, barbae 26

27 Geraldine Kaminski Medical Mycology Library Image courtesy of the late Dr. Libero Ajello Trichophyton verrucosum primary outgrowth Trichophyton verrucosum vitamins: inos + thiam (#3), thiam alone (#4), vit-free (#1) 27

28 Trichophyton verrucosum chlamydospores Trichophyton verrucosum chlamydospores Trichophyton verrucosum macroconidia Trichophyton concentricum causal agent of tinea imbricata endemic to Pacific Islands and to southeast Asian indigenous hill tribe peoples, as well as a few groups of South American indigenous people susceptibility inherited as a recessive allele often a chronic lifelong infection affecting much of the body surface 28

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30 198 T. mentagrophytes ss. str. / T. schoenleinii / T. sarkisovii complex T. mentagrophytes, after molecular study, was strictly redefined with a taxonomic Neotype to include only the mouse dermatophyte, the former T. m. var. quinckeanum, and isolate types that could not be separated from it genetically (most notably the Bactrian camel dermatophyte, T. sarkisovii). very closely related is the anthropophilic T. schoenleinii, agent of favus. Dendrogram / T. equinum Trichophyton mentagrophytes var. quinckeanum Trichophyton dermatophytes, M. canis complex and E. floccosum main Microsporum group mostly nonpathogenic Trichophyton dermatophytoids A zoophilic form of T. mentagrophytes and the cause of "mouse favus" seen on mice as thick saucer-shapedshaped yellow crusted lesions called scutula. Infections in humans are usually inflammatory and sometimes produce scutula. Invaded hairs are rarely seen but they may show either ectothrix or endothrix infection. Infected human hairs do not fluoresce under Wood's ultra-violet light, but very occasional hairs from experimental lesions in guinea pigs may show a pale yellow fluorescence. Distribution: Difficult to establish but probably world-wide. Often associated with mice plagues in the Australian Wheat Belt. Key Features: Culture characteristics, microscopic morphology, contact with mice, odour and rapid urease test. 30

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33 249 Trichophyton schoenleinii primary outgrowth anthropophile, causal agent of favus and severe scarring alopecia now extirpated except in central Africa, central Asia Trichophyton schoenleinii colony 33

34 Dendrogram / T. equinum Trichophyton dermatophytes, M. canis complex and E. floccosum main Microsporum group mostly nonpathogenic Trichophyton dermatophytoids 34

35 Trichophyton tonsurans colony (striate morphology) anthropophile, main agent of endothrix childhood tinea capitis in most of the world increasingly predominant, especially in urban areas with minority communities living in relative poverty most common dermatophyte in some parts of USA Trichophyton tonsurans Trichophyton tonsurans mahogany red form, reverse 35

36 Trichophyton tonsurans sulfureum form, reverse Trichophyton tonsurans thiamine stimulation Trichophyton tonsurans conidia Trichophyton tonsurans caterpillar forms 36

37 Trichophyton equinum colony zoophile with horse population host Triochophyton equinum colony reverse closely related to anthropophile T. tonsurans is + mating type while T. tonsurans is Triochophyton equinum vitamin test (nicotinic acid required)

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39 208 Trichophyton erinacei European type long known: yellow colony reverse, urease negative, population host is European hedgehog Erinaceus europaeus Trichophyton erinacei African type often urease positive; forms teleomorph newly described d by Japanese researchers, occurs on African hedgehog Atelerix albiventris Trichophyton erinacei European type: yellow colony reverse, urease negative 39

40 Trichophyton rubrum vs. T. mentagrophytes complex on BCP MSG Trichophyton rubrum: emerging as the most common dermatophyte in most parts of the world anthropophilic, mostly causing tinea pedis, t. unguium, t. cruris, t. manuum and t. corporis microsatellite typing shows two types, the afro-asiatic type (synonymous name T. raubitschekii still used informally), mainly involved in inflammatory, chronic tinea corporis and t. cruris in south Asia and central Africa, is type A, while the typical T. rubrum, predominantly from non-inflammatory tinea pedis and t. unguium (also other sites) is type B Dendrogram T. rubrum /T. violaceum complex / T. equinum / T. yaoundei / T. soudanense / T. gourvilii / T. megninii Trichophyton dermatophytes, M. canis complex and E. floccosum main Microsporum group mostly nonpathogenic Trichophyton dermatophytoids Image courtesy of the late Dr. Julius Kane 40

41 Nail dermatophytosis (onychomycosis) Trichophyton rubrum colony Trichophyton rubrum colony reverse Trichophyton rubrum microconidia 41

42 Trichophyton rubrum on BCP MSG, PDA, CEA, SAB at 7 d Trichophyton rubrum melanoid form Trichophyton rubrum melanoid form Trichophyton rubrum rodhainii form 42

43 Trichophyton rubrum yellow form Trichophyton rubrum yellow form on SAB and plain casamino acids agar (reverse) Trichophyton rubrum microsatellite genotype A ( T. raubitschekii ) colonies Trichophyton rubrum microsatellite genotype A ( T. raubitschekii ) colony reverse 43

44 Trichophyton rubrum microsatellite genotype A ( T. raubitschekii ) conidia Trichophyton rubrum microsatellite genotype A ( T. raubitschekii ) colonies Trichophyton rubrum microsatellite genotype A ( T. raubitschekii ) conidia Trichophyton rubrum microsatellite genotype A ( T. raubitschekii ) on BCP and Christensen urea broth 44

45 Trichophyton rubrum microsatellite genotype A ( T. raubitschekii ) distribution Trichophyton rubrum microsatellite genotype A ( T. raubitschekii ) Trichophyton megninii colony reverse Trichophyton megninii colony similar but not identical to T. rubrum in ITS sequence, considered a synonym by some authors causes tinea corporis, t. capitis and dt. barbae b mainly in Portugal mating type + whereas T. rubrum is 45

46 Trichophyton rubrum vs. T. megninii on BCP MSG Trichophyton violaceum colony T. megninii requires exogenous L-histidine histidine, and thus grows on test medium Trichophyton agar # 7 but not the histidine-free # 6. urease positive, but may be slow and is better seen in an indole-urea broth test. anthropophile mainly causing tinea capitis (endothrix) in children endemic to middle east and north and east Africa Trichophyton violaceum on three media Trichophyton violaceum asymmetrical chlamydospores 46

47 Trichophyton violaceum microconidia (from pleomorphic colony) Trichophyton violaceum (pale form) on BCP MSG Trichophyton soudanense on BCP MSG anthrophophile: endothrix tinea capitis agent endemic to sub-saharan Africa recently proposed as synonymous with T. rubrum, which does not cause endothrix tinea capitis and is strongly morphologically different, but is only consistently different in common sequence types at a relatively low level nonetheless, clinically and in the diagnostic lab, can only be handled as a distinct entity Trichophyton soudanense Sabouraud and BCP MSG 47

48 Trichophyton soudanense on Sabouraud Trichophyton soudanense microconidia Trichophyton soudanense red variant Trichophyton soudanense red variant with yellow colour restored on SAB-3% salt 48

49 Trichophyton soudanense red variant Trichophyton soudanense reflexive branch Trichophyton soudanense reflexive branch Trichophyton soudanense reflexive branch 49

50 Further development T1 Microsatellites in T. rubrum lineage Microsatellite types in T. rubrum lineage members (Ohst et al. taxonomy) T. violaceum (violaceum) C T. violaceum (yaoundei) D T. rubrum T. violaceum T. rubrum (soudanense!) T. rubrum (raubitschekii) A A T. rubrum (megninii) A T. rubrum (common rubrum) B Ohst T et al J Clin Microbiol 42: T1 microsatellite patterns Ohst et al. (2004) JCM 42: Trichophyton rubrum microsatellite studies Traditional species name T1 type T. violaceum C T. yaoundei D T. gourvilii A T. soudanense A T. megninii A T. rubrum granular / T. raubitschekii tropical torso/groin dermatophyte T. rubrum cottony cosmopolitan foot and hand dermatophyte, sometimes infecting torso/groin A B Asterisks indicate isolates with reflexive branching 50

51 Trichophyton ajelloi colonies Trichophyton ajelloi conidia non- pathogenic geophile subject of some dubious case reports teleomorph A. uncinatum Trichophyton terrestre complex: colony species complex of nonpathogenic geophiles no growth at 37 degrees in vitro regular object of false case reports due to common isolation as a contaminant from T. rubrum etc. lesions Trichophyton terrestre complex: conidia distinguishing morphological feature: range of conidial sizes intergrading from micro- to macro- 51

52 Trichophyton terrestre complex: colony Arthoderma quadrifidum ascoma most common teleomorph in T. terrestre complex Arthroderma quadrifidum appendages 52