Trichophyton verrucosum

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Trichophyton verrucosum
Trichophyton verrucosum chlamydospores.jpg
Chlamydospores of T. verrucosum growing in chains at 37 C
Scientific classification OOjs UI icon edit-ltr.svg
Domain: Eukaryota
Kingdom: Fungi
Division: Ascomycota
Class: Eurotiomycetes
Order: Onygenales
Family: Arthrodermataceae
Genus: Trichophyton
Species:
T. verrucosum
Binomial name
Trichophyton verrucosum
E. Bodin (1902)
Synonyms
  • Ectotrichophyton verrucosum Castell. & Chalm. (1919)
  • Favotrichophyton verrucosum Neveu-Lem. (1921)
  • Trichophyton album Sabour (1908)
  • Trichophyton ochraceum Sabour(1908)
  • Trichophyton discoides Sabour(1910)

Trichophyton verrucosum, commonly known as the cattle ringworm fungus, is a dermatophyte largely responsible for fungal skin disease in cattle, but is also a common cause of ringworm in donkeys, dogs, goat, sheep, and horses. [1] It has a worldwide distribution, however human infection is more common in rural areas where contact with animals is more frequent, and can cause severe inflammation of the afflicted region. [2] [3] Trichophyton verrucosum was first described by Emile Bodin in 1902.

Contents

Growth and morphology

Trichophyton verrucosum is very slow-growing compared to other dermatophytes. [4] In culture, it is characterized by being flat, white/cream colour, having an occasional dome, with a glabrous texture, known as the variant album, however other variations are also found: T. verrucosum var. ochraceum has a flat, yellow, glabrous colony; T. verrucosum var. discoides has a gray-white, flat, and tomentose colony; and T. verrucosum var. autotrophicum is rarely seen and is associated with sheep. [5] [6] Under a microscope, macronidia are rare, and have a rat-tail or string bean shape, while micronidia are tear-shaped and have been only observed in laboratories when grown under enriched conditions. [7] It lacks a teleomorph (sexual) stage. [5] At 37 °C (the only dermatophyte with an optimum growth temperature this high), [7] chlamydospores become thick-walled and found in long chains. [6] Macronidia are more commonly produced on BCP-milk solids-yeast extract agar, and only on colonies over 7 days old. [5] Under refrigeration, it will die. [7] Regions infected with T. verrucosum will fluoresce under a blacklight in cattle, but not in humans. [6]

Epidemiology and pathology

Cow showing characteristic hairless lesions associated with T. verrucosum. Toplin des dieles tiesse vea.jpg
Cow showing characteristic hairless lesions associated with T. verrucosum.

Infections in cattle

Trichophyton verrucosum is thought to have evolved from a soil-dwelling ancestor that migrated to its contemporary cattle host, losing many features that it previously required for survival in soil habitats through genetic drift, including vitamin prototrophy, urease activity, and the ability to perforate hair. [8] Infection is characterized by 10–50 mm patches of hair loss, desquamation, and formation of thick crusts. [9] Trichophyton verrucosum is endemic in cattle, and almost exclusively the fungus that is isolated from cattle with ringworm, with younger cattle being more prone to infection due to their skin having higher pH, and having weaker immune systems. [4] [6] [10] [11]

The disease is important economically, as it can spoil milk, meat, and leather quality of cattle. Infection in cattle peaks in fall and winter in overcrowded and cramped cattle-housing. [12] Transmission can occur directly through contact between sick and healthy animals, and indirectly through fomites that can be viable for up to 4 years. [12] Rearing cattle together with other ruminants, such as sheep, may increase prevalence of infection due to ruminants being able to roam free, spreading the infection. [10] One study in Italy of 20 farms and 294 cattle found all farms contained infected cattle, with prevalence within farms ranging between 25-100%. [11] In contrast, immunization has eradicated T. verrucosum from herds in Eastern Germany [3] and by 2012 only two herds in Norway were affected. [13] The LTF-130 vaccine was developed in the early 1970s by a team led by Lyubov Yablochnik and A. K. Sarkisov at the All-Russian Scientific Research Institute of Experimental Veterinary Medicine. [14]

Infections in humans

While distribution is worldwide, T. verrucosum and other zoophilic dermatophytes are the most frequently isolated fungi from skin lesions in Southern Europe and the Middle East (T. rubrum, a dermatophyte that more commonly infects humans, is the most prevalent in other regions). [15] Infection to humans is largely zoonotic, and can be transmitted through direct contact or bites, but there have also been recorded cases of laboratory acquired infection, and needlestick injury during vaccination. [9] [16] Contact with horse blankets and cattle posts can also cause infection, and T. verrucosum has also been isolated from flies, although it is unknown whether flies can serve as vectors of transmission. [5] The majority of infections are occupational, and this includes agricultural workers, veterinarians, stockyard workers, and grain handlers (infection can also be transmitted human-to-human, thus family members of these workers are also at risk). [5] Infection of the hair is ectothrix, and can cause tinea capitis (with potential for kerions and irreversible scarring and alopecia), as well as tinea corporis, tinea manuum, tinea barbae, and tinea profunda. [3] [4] [9] It is the most common cause of tinea barbae in man. A vaccine exists for both cattle and humans, and combined with hygienic practices has led to a decline in cases. [11] It has also been observed that recurrent infections do not occur. [5] Treatment can include oral terbinafine, fluconazole, or griseofulvin; topical treatment is also possible, however it requires more time and may have lower rates of compliance, proving to be less effective. [17] [18]

Isolation and identification

Trichophyton verrucosum (L) and T. violaceum (R) grown for 7 d on Bromocresol purple milk solids glucose agar at 37 C. Trichophyton verrucosum BCP.jpg
Trichophyton verrucosum (L) and T. violaceum (R) grown for 7 d on Bromocresol purple milk solids glucose agar at 37 C.

In preparing samples for diagnosis, a scraping of the skin from the active border of infection is taken, and is inoculated directly onto the test medium. [1] Trichophyton verrucosum is auxotrophic for inositol and thiamine, and as such can be distinguished from other dermatophytes by observing strong growth on Trichophyton agar 3 (a medium rich in thiamine and inositol) and none to weak growth on Trichophyton agars 1 and 2 (deficient in these nutrients). [19] It will also grow on Sabouraud agar, but only with the addition of yeast extract (which provides the inositol and thiamine it requires). [1] In Bromocresol purple (BCP) milk solids glucose agar, a medium used to distinguish the dermatophytes from bacteria and other organisms by evaluating ammonium production during proteolysis, T. verrucosum produces a weakly alkaline result (faint purple) and clearing of milk solids with a characteristic halo on the periphery. Negative test results occur for the urease test, hair perforation test, and casamino acids erythritol albumin agar. [5] In conjunction to physiological tests, contact with cattle should also be used as a criterion due to the zoophilic and occupational nature of the disease. [20] Otherwise, misdiagnosis as pyoderma or bacterial folliculitis can occur, with the prescribed antibacterial treatment having no effect. [16] Indeed, one study found that people infected with T. verrucosum had to visit a physician on average of 2.5 times, with 25 days elapsing, before a proper diagnosis was obtained. [20] This may lead to an underestimation of the true number of cases, as many people will recover from the disease before obtaining a proper diagnosis. [16] Looking at the stratum corneum under a microscope may also aid in diagnosis, which is done by adding 10% KOH solution and a Periodic acid-Schiff stain. Swollen chlamydospores 5-10 μm in diameter will appear outside the hair shaft, while skin samples will have swollen spores mixed with dermatophyte filaments. [1] [2] [5]

Related Research Articles

<span class="mw-page-title-main">Athlete's foot</span> Skin infection caused by fungus

Athlete's foot, known medically as tinea pedis, is a common skin infection of the feet caused by a fungus. Signs and symptoms often include itching, scaling, cracking and redness. In rare cases the skin may blister. Athlete's foot fungus may infect any part of the foot, but most often grows between the toes. The next most common area is the bottom of the foot. The same fungus may also affect the nails or the hands. It is a member of the group of diseases known as tinea.

Dermatophyte is a common label for a group of fungus of Arthrodermataceae that commonly causes skin disease in animals and humans. Traditionally, these anamorphic mold genera are: Microsporum, Epidermophyton and Trichophyton. There are about 40 species in these three genera. Species capable of reproducing sexually belong in the teleomorphic genus Arthroderma, of the Ascomycota. As of 2019 a total of nine genera are identified and new phylogenetic taxonomy has been proposed.

<span class="mw-page-title-main">Tinea capitis</span> Cutaneous fungal infection of the scalp

Tinea capitis is a cutaneous fungal infection (dermatophytosis) of the scalp. The disease is primarily caused by dermatophytes in the genera Trichophyton and Microsporum that invade the hair shaft. The clinical presentation is typically single or multiple patches of hair loss, sometimes with a 'black dot' pattern, that may be accompanied by inflammation, scaling, pustules, and itching. Uncommon in adults, tinea capitis is predominantly seen in pre-pubertal children, more often boys than girls.

<span class="mw-page-title-main">Dermatophytosis</span> Fungal infection of the skin

Dermatophytosis, also known as ringworm, is a fungal infection of the skin. Typically it results in a red, itchy, scaly, circular rash. Hair loss may occur in the area affected. Symptoms begin four to fourteen days after exposure. Multiple areas can be affected at a given time.

<span class="mw-page-title-main">Kerion</span> Medical condition

Kerion or kerion celsi is an acute inflammatory process which is the result of the host's response to a fungal ringworm infection of the hair follicles of the scalp that can be accompanied by secondary bacterial infection(s). It usually appears as raised, spongy lesions, and typically occurs in children. This honeycomb is a painful inflammatory reaction with deep suppurative lesions on the scalp. Follicles may be seen discharging pus. There may be sinus formation and rarely mycetoma-like grains are produced. It is usually caused by dermatophytes such as Trichophyton verrucosum, T. mentagrophytes, and Microsporum canis. Treatment with oral griseofulvin common.

<span class="mw-page-title-main">Tinea manuum</span> Medical condition

Tinea manuum is a fungal infection of the hand, mostly a type of dermatophytosis, often part of two feet-one hand syndrome. There is diffuse scaling on the palms or back of usually one hand and the palmer creases appear more prominent. When both hands are affected, the rash looks different on each hand, with palmer creases appearing whitish if the infection has been present for a long time. It can be itchy and look slightly raised. Nails may also be affected.

<span class="mw-page-title-main">KOH test</span> Test to differentiate between skin fungi

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<i>Trichophyton rubrum</i> Species of fungus

Trichophyton rubrum is a dermatophytic fungus in the phylum Ascomycota. It is an exclusively clonal, anthropophilic saprotroph that colonizes the upper layers of dead skin, and is the most common cause of athlete's foot, fungal infection of nail, jock itch, and ringworm worldwide. Trichophyton rubrum was first described by Malmsten in 1845 and is currently considered to be a complex of species that comprises multiple, geographically patterned morphotypes, several of which have been formally described as distinct taxa, including T. raubitschekii, T. gourvilii, T. megninii and T. soudanense.

<i>Trichophyton</i> Genus of Fungi

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<i>Microsporum audouinii</i> Species of fungus

Microsporum audouinii is an anthropophilic fungus in the genus Microsporum. It is a type of dermatophyte that colonizes keratinized tissues causing infection. The fungus is characterized by its spindle-shaped macroconidia, clavate microconidia as well as its pitted or spiny external walls.

<i>Trichophyton tonsurans</i> Species of fungus

Trichophyton tonsurans is a fungus in the family Arthrodermataceae that causes ringworm infection of the scalp. It was first recognized by David Gruby in 1844. Isolates are characterized as the "–" or negative mating type of the Arthroderma vanbreuseghemii complex. This species is thought to be conspecific with T. equinum, although the latter represents the "+" mating strain of the same biological species Despite their biological conspecificity, clones of the two mating types appear to have undergone evolutionary divergence with isolates of the T. tonsurans-type consistently associated with Tinea capitis whereas the T. equinum-type, as its name implies, is associated with horses as a regular host. Phylogenetic relationships were established in isolates from Northern Brazil, through fingerprinting polymorphic RAPD and M13 markers. There seems to be lower genomic variability in the T. tonsurans species due to allopatric divergence. Any phenotypic density is likely due to environmental factors, not genetic characteristics of the fungus.

<i>Microsporum gypseum</i> Species of fungus

Microsporum gypseum is a soil-associated dermatophyte that occasionally is known to colonise and infect the upper dead layers of the skin of mammals. The name refers to an asexual "form-taxon" that has been associated with four related biological species of fungi: the pathogenic taxa Arthroderma incurvatum, A. gypsea, A. fulva and the non-pathogenic saprotroph A. corniculata. More recent studies have restricted M. gypseum to two teleomorphic species A. gypseum and A. incurvatum. The conidial states of A. fulva and A. corniculata have been assigned to M. fulvum and M. boullardii. Because the anamorphic states of these fungi are so similar, they can be identified reliably only by mating. Two mating strains have been discovered, "+" and "–". The classification of this species has been based on the characteristically rough-walled, blunt, club-shaped, multicelled macroconidia. Synonyms include Achorion gypseum, Microsporum flavescens, M. scorteum, and M. xanthodes. There has been past nomenclatural confusion in the usage of the generic names Microsporum and Microsporon.

<i>Trichophyton mentagrophytes</i> Species of fungus

Trichophyton mentagrophytes is a species in the fungal genus Trichophyton. It is one of three common fungi which cause ringworm in companion animals. It is also the second-most commonly isolated fungus causing tinea infections in humans, and the most common or one of the most common fungi that cause zoonotic skin disease. Trichophyton mentagrophytes is being frequently isolated from dogs, cats, rabbits, guinea pigs and other rodents, though at least some genetic variants possess the potential of human-to-human transmission, e.g. Type VII and Type VIII. Particular genetic variants of the fungus have distinct geographic ranges.

<i>Microsporum canis</i> Species of fungus

Microsporum canis is a pathogenic, asexual fungus in the phylum Ascomycota that infects the upper, dead layers of skin on domesticated cats, and occasionally dogs and humans. The species has a worldwide distribution.

Trichophyton concentricum is an anthropophilic dermatophyte believed to be an etiological agent of a type of skin mycosis in humans, evidenced by scaly cutaneous patches on the body known as tinea imbricata. This fungus has been found mainly in the Pacific Islands and South America.

Microsporum nanum is a pathogenic fungus in the family Arthrodermataceae. It is a type of dermatophyte that causes infection in dead keratinized tissues such as skin, hair, and nails. Microsporum nanum is found worldwide and is both zoophilic and geophilic. Animals such as pigs and sheep are the natural hosts for the fungus; however, infection of humans is also possible. Majority of the human cases reported are associated with pig farming. The fungus can invade the skin of the host; if it is scratched off by the infected animal, the fungus is still capable of reproducing in soil.

<i>Microsporum gallinae</i> Species of fungus

Microsporum gallinae is a fungus of the genus Microsporum that causes dermatophytosis, commonly known as ringworm. Chickens represent the host population of Microsporum gallinae but its opportunistic nature allows it to enter other populations of fowl, mice, squirrels, cats, dogs and monkeys. Human cases of M. gallinae are rare, and usually mild, non-life-threatening superficial infections.

<i>Epidermophyton floccosum</i> Species of fungus

Epidermophyton floccosum is a filamentous fungus that causes skin and nail infections in humans. This anthropophilic dermatophyte can lead to diseases such as tinea pedis, tinea cruris, tinea corporis and onychomycosis. Diagnostic approaches of the fungal infection include physical examination, culture testing, and molecular detection. Topical antifungal treatment, such as the use of terbinafine, itraconazole, voriconazole, and ketoconazole, is often effective.

<span class="mw-page-title-main">Lyubov Yablochnik</span> Russian microbiologist

Lyubov Yablochnik was a Soviet and Russian veterinary microbiologist.

References

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  3. 1 2 3 Havlickova, Blanka; Czaika, Viktor A.; Friedrich, Markus (September 2008). "Epidemiological trends in skin mycoses worldwide". Mycoses. 51: 2–15. doi:10.1111/j.1439-0507.2008.01606.x. PMID   18783559. S2CID   3398710.
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  5. 1 2 3 4 5 6 7 8 Kane, J., Summerbell, R., Sigler, L., Krajden, S., Land. G. (1997). Laboratory Handbook of Dermatophytes. California: Star. ISBN   0-89863-157-2.{{cite book}}: CS1 maint: multiple names: authors list (link)
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  8. ↑ Summerbell, R. (2000). Biology of dermatophytes and other keratinophilic fungi. Bilbao: Revista Iberoamericana de Micología. pp. 30–43. ISBN   84-607-0711-3.
  9. 1 2 3 Sayfarth, F., Roediger, C., Graser, Y., Erhard, M., Burmester, A., Elsner, P., Hipler, UC. (2011). "Case report: Trichophyton verrucosum infection after needlestick injury with an attenuated live vaccine against cattle ringworm". Mycoses. 54 (6): 870–876. doi:10.1111/j.1439-0507.2011.02015.x. PMID   21615536. S2CID   20736796.{{cite journal}}: CS1 maint: multiple names: authors list (link)
  10. 1 2 El-Tras, Wael F.; Tayel, Ahmed A.; Mohamed, Radi A.; El-Kordy, Doaa M.; El-Kady, Nevein N.; Samir, Ahmed (September 2015). "Mixed rearing correlates with the existence of Trichophyton verrucosum pathogens in humans". Dermatologica Sinica. 33 (3): 130–133. doi: 10.1016/j.dsi.2014.12.006 .
  11. 1 2 3 Papini, R., Nadoni, S., Fanelli, A., Mancianti, F. (March 2009). "High Infection Rate of Trichophyton verrucosum in Calves from Central Italy". Zoonoses and Public Health. 56 (2): 59–64. doi:10.1111/j.1863-2378.2008.01157.x. PMID   18705659. S2CID   6480150.{{cite journal}}: CS1 maint: multiple names: authors list (link)
  12. 1 2 Agnetti, F., Righi, C., Scoccia, E., Felici, A., Crotti, S., Moretta, I., Papini, M. (2014). "Trichophyton verrucosum infection in cattle farms of Umbria (Central Italy) and transmission to humans". Mycoses. 57 (7): 400–405. doi:10.1111/myc.12174. PMID   24621382. S2CID   25324021.{{cite journal}}: CS1 maint: multiple names: authors list (link)
  13. ↑ Rybnikář, A; Chumela, J; Vrzal, V; Krupka, V (1991). "Immunity in cattle vaccinated against ringworm". Mycoses. 34 (9–10): 433–436. doi:10.1111/j.1439-0507.1991.tb00809.x. PMID   1820524. S2CID   37335502.
  14. ↑ Sarkisov, A. K.; Petrovitch, S. V.; Nikiforov, L. I.; Yablochnik, L. M.; Koroleva, V. P. (1971). "Immunization of Cattle against Trichophytosis". J. Veterinary (In Russian). 2: 54–56.
  15. ↑ Seebacher, Claus; Bouchara, Jean-Philippe; Mignon, Bernard (14 May 2008). "Updates on the Epidemiology of Dermatophyte Infections". Mycopathologia. 166 (5–6): 335–352. doi:10.1007/s11046-008-9100-9. PMID   18478365. S2CID   24443131.
  16. 1 2 3 Baker, R.D. (1971). Human Infection with Fungi, Actinomycetes and Algae (1 ed.). Springer-Verlag Berlin Heidelberg. pp. 304–307. ISBN   978-3-662-12029-3.
  17. ↑ O'Gorman, S. M.; Britton, D.; Collins, P. (June 2015). "An uncommon dermatophyte infection: two cases of cutaneous infection with Trichophyton verrucosum". Clinical and Experimental Dermatology. 40 (4): 395–398. doi:10.1111/ced.12559. PMID   25511845. S2CID   22067675.
  18. ↑ Noble, SL; Forbes, RC; Stamm, PL (July 1998). "Diagnosis and management of common tinea infections". American Family Physician. 58 (1): 163–74, 177–8. PMID   9672436.
  19. ↑ "Fungi" (PDF). University of Alberta Microfungus Collection & Herbarium. Retrieved 13 October 2015.
  20. 1 2 Morrell, Jessica; Stratman, Erik (October 2011). "Primary Care and Specialty Care Delays in Diagnosing Infection Related to Cattle Exposure". Journal of Agromedicine. 16 (4): 244–250. doi:10.1080/1059924X.2011.605715. PMID   21958398. S2CID   24889774.
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