_ Study of Clinically Suspected
`- Onychomycosisin a Podiatric
`Population
`
`Maureen B. Jennings, DPM*
`Jeffrey M. Weinberg, MDt+
`Evelyn K. Koestenblatt, MSt
`Christine Lesczezynski§
`
`is a mycotic infection of the keratinized
`Onychomycosis, by definition,
`tissue of the nail plate. Although it is commonly considered to be caused
`by one of the dermatotropic fungi, a variety of other organisms have
`been implicated as etiologic agentsin the disease, including some bac-
`teria and yeasts. When it is caused by a fungus, any orall of three
`types of organisms can be involved: dermatophytes, yeasts, and non-
`dermatophyte organisms, The purposeof this Study was to identify the
`microorganisms found in fungal cultures of clinically suspected ony-
`chomycosis in the patient population of the Foot Clinics of New York in
`New York City, the largest foot clinic in the world. Of the 1,800 medical
`charls reviewed, 214 had culture results, of which 120 were positive.
`Trichophyton rubrum was the most prevalent pathogen, found in 67%
`of positive cultures. The most remarkable risk factor was age, with 80%
`of affected individuals older than 35 years. False-negatives may ac-
`count for the high percentage (44%) of negative cultures in this study.
`(J Am Podiatr Med Assoc 92(6): 327-330, 2002)
`TREEtNTETSNEARL
`
`|
`|
`
`Onychomycosis, by definition, is a mycotic infection
`of the keratinizedtissue of the nail plate.! Onychanry-
`cosis accounts for approximately 30%ofall fungal in-
`fections and is the most frequently encountered nail
`disease.* The US Health and Nutrition Examination
`Study of more than 20,000 subjects aged 1 to 74 years
`found a prevalenceof 2.2%for onychomycosis”
`Although onychomycosis is commonly considered
`to be caused by one ofthe dermatotropic fungi, a va-
`hety of other organisms have beenimplicatedas eti-
`dlogic agents in the disease, including some bacteria
` 5 “Assistant Dean for Research, New York College of Po-
`“attic
`Medicine, 1800 Park Ave, New York, NY 10038.
`“Director of Clinical Research, St. Luke's-Roosevell Hos-
`Bal Center, New York, NY,
`M * Tinical Assistant Professor, New York Medical College,
`Metropolitan Hospital Center, New York, NY.
`_ Clinical Research Associate, Department of Institutional
`Aeseareh, New York College af Podiatric Medicine, New
`York, NY,
`:
`
`and yeasts.*® When onychomycosis is caused by a
`fungus, any or all of three types of organisms can be
`involved: dermatophytes, yeasts, and nondermato-
`phyte organisms.’ The etiology of onychomycosis
`seems to differ by geographic location, The dermato-
`phytes, in particular Trickaphyton rubrum, are raost
`frequently seen in the United States,’ whereas Can-
`dida has been reported with high frequency in Bel-
`gium® and Spain.” Of 165 positive cultures examined
`in Hong Kong for single infections, 44.7%were 7
`rubrum and 26.3% were Canilida (other than Cand-
`da albicans). A Canadian study® of 131 patients
`with mycologically confirmed pedal onychomycosis
`found that the causative pathogens were predomi-
`nantly (92.9%) dermatophytes—68% 7 rubrum and
`20% Trichophyton mentagraphytes. Scytalidium, a
`nondermataphyte, is more frequent in tropical cli-
`mates.” In Britain, T rubrum was the most frequent
`pathologic agent, with T mentagrophyles and hpi-
`
`Journal of the American Podiatric Medical Association * Voi 92 * No 6 » June 2002
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`Page | of 4
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`327
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`EXHIBIT
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`220]
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`Kaken Exhibit 2201
`Acrux v. Kaken
`IPR2017-00190
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`dermophyton floccosum being less common.In
`eastern Saudi Arabia, one study" revealed Candida
`to be the pathogen in 204 of 248 cases of culturally
`positive onychomycosis.
`There are striking differences in the frequency
`with which each group of fungi is responsible for the
`mycotic infection.’ Distal and lateral subungual ony-
`chomycosis, which is an infection of the nail bed and
`plate, is often caused by T rubrum, but it may also
`be caused by T mentagrophytes and E floccosum.
`Distal and lateral subungual onychomycosis is the
`most frequent type of onychomycosis. Once the hy-
`ponychium is infected, the fungi advance to the nail
`bed epithelium. The fungi are sheltered by the nail
`plate, creating a moist and soft subungual environ-
`mentideal for fungus. Once the pathogen invades the
`matrix, the fungus is entrapped in the newly formed
`nail and infiltrates the entire nail plate.2 Proximal
`subungual onychomycosisis an infection of the prox-
`imal nail fold (the eponychium), with the infection
`extending distally under the nail plate. Trichophyton
`rubrum. is most frequently implicated in proximal
`subungual onychomycosis.' * Trichophyton meg-
`ninti, Trichophyton tonsurans, Trichophyton
`schoenleinii, T mentagrophytes, and E floccosum
`have also been reported to cause proximal subun-
`gual onychomycosis.' White superficial onychomyco-
`sis, which is found in toenails only, affects the nail
`plate and is usually caused by T mentagrophytes,
`which is better suited biochemically to invade the
`nail plate. White superficial onychomycosis can be
`caused by nondermatophyte molds such as As-
`pergillus species, Acremoniuin species, Fusarium
`oxysporum, and Scopulariopsis brevicaulis2:\¢
`Although onychomycosis is rare in children,its in-
`cidence increases with age? Studies? = have shown
`a higherprevalence in males thanin females.It is hy-
`pothesized that occupational factors may play a role
`in sex prevalence.” Psoriasis has been shown to in-
`crease the risk of developing onychomycosis.” The
`consensus is that there is probably not a higher
`prevalence of onychomycosis in the diabeticnail, but
`increased Candida infections of the nail andsur-
`rounding fissues can pose a serious risk in the dia-
`betic patient.
`The diagnosis of onychomycosis is made through
`clinical observation, direct microscopic examination
`with potassium hydroxide (KOH), fungal culture, and
`biopsy with histologic analysis. The clinical signs of
`tinea unguiuminclude thickening subungual debris,
`discoloration, and surface irregularity. Examination
`with KOHis a screening tool for the presence or ab-
`sence of fungus, butit does not identify the organism.
`Sabouraud’s dextrose agar, with the antibacterial
`
`agent chloramphenicol and the mold inhibitor cyclo.
`heximide, is usedto aidin the identification offungal
`pathogens. Histologic analysis evaluates the topo-
`graphic distribution, density, and nature of fungi. The
`histologic preparation can be used to confirm or
`negate the culture results.!®
`The purpose of this study was to identify the py.
`croorganisms found in fungal cultures of clinically
`suspected onychomycosis in the patient populationof
`the Foot Clinics of New York in New York City, the
`largest foot clinic in the world. This was a systematic,
`rétrospective, epidemiologic survey of onychomyco.
`sis based on laboratory data. To the authors’ know:
`edge, these data have not been collected in the past,
`Other data, such as KOHresults, patient demographic
`information, and incidence of other systemic dis.
`eases, were also collected.
`
`Materials and Methods
`
`Eighteen hundred medical charts frompatients atthe
`Foot Clinics of New York whohada clinical diagno
`sis of onychomycosis were randomly chosenandre
`viewed. Nail clippings, subungual debris, and scrap-
`ings were taken from patients clinically suspectedof
`having onychornycosis. The nail samples were care-
`fully transported to the laboratory. Nail portions were
`taken for clearing with 10% KOH and direct micro-
`scopic examination. Nail cultures were inoculatedat
`30°C and were examined weekly for 4 weeks. The
`laboratory used Sabouraud’s dextrose agar contai-
`ing cycloheximide(0.5 mg/mL) and chloramphenicol
`(0.05 mg/mL). Charts with a culture report hadpert
`nent data extracted. All data were documentedonthe
`case report forms, including patient demographic i-
`formation(age, race, and sex) and culture results.
`
`Results
`
`Table 1 lists the species of possible infective orga
`ismas frompositive cultures ofpatients with a clinical
`diagnosis of onychomycosis. Of the 1,800 charts re
`viewed, 214 had culture results, of which 120 were
`positive. Trichophyton rubriamn was the most pee
`lent pathogen (67%). Eighty percent of affected indi
`viduals were older than 35 years. Of 214patients, 208
`were younger than 35 years, 39% were agedd6 to»
`years, and 41%wereolderthan 55 years; 61% were fe
`male; and 14% were diabetic. Twenty-eight percett
`(59/214)ofthe patients clinically diagnosed as having
`onychomycosis had negative KOH results. Forty-fou
`percent(94/214) ofthe fungal cultures were negative
`Twenty-one percent of patients with onychomycosis
`(from whom a culture was taken) had concurel
`
`328
`
`June 2002 * Vol 92 * No 6 « Journal of the American Podiatric Medical Association
`
`Page 2 of 4
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`

`SSomenreeeTeoaHTEeeee
`et al found that T rubrum was the most common iso-
`Table 1. Fungal Organisms Foundin 120 Positive Cultures
`late among the dermatophytes. Ghannoum etal, how-
`from Patients with Onychomycosis
`ever, found Acremonitum to be the most common
`
`Organism Number(%)SereneEEEOeme
`
`nondermatophyte; the present study showed Penicil-
`Dermatophytes
`lium and Aspergillus to be the most common nonder-
`Trichophyton rubrum
`matophytes. In the study by Ghannoumet al, C parap-
`Trichophyton mentagrophytes
`stlosis represented 66.7% of the yeast species, whereas
`Yeasts
`the present study showed C parapsilosis at 38%, the
`Candida albicans
`same percentage as for Rkodotorula rubra.
`Candida parapsilosis
`In a similar study by Srinivas et al?! in 1993, nail
`Rhodotorula rubra
`Trichosporon beigelii
`scrapings and clippings were collected from 100 pa-
`Cryptococcus uniguttulatus
`tients. The culture positivity for molds was 22%, with
`Aspergillus species predominating. The criteria for
`Hyalohyphomycetes (nonpigmented fungi)
`Penicillium species
`reporting the mold as a pathogen were KOH positivi-
`Aspergillus species
`ty plus an isolation of the same fungus in culture on
`Scopulariopsis brevicaulis
`three consecutive occasions at intervals of at least 7
`Paecilomyces species
`days each and absence of systemic or local antifun-
`Fusarium species
`gal treatmentduring the period of investigation.
`Phaeohyphomycetes (pigmentedfungi)
`Aureobasidium pullulans
`Chaetomium species
`Cladosporium species
`
`80 (67)
`2 (2)
`
`2 (2)
`8 (7)
`8 (7)
`2 (2)
`10)
`
`3 (3)
`3 (3)
`1(1)°
`1(1)
`1 (1)
`
`2 (2)
`1(1)
`1(1}
`
`Discussion
`
`Onychomycosis, a fungal infection of the toenails
`Zygomycetes
`and fingernails, can affect standing, walking, and ex-
`Rhizopus species
`ercising, resulting in pain and discomfort. A definitive
`Mixed infection
`diagnosis is crucial for effective treatment because
`2 {2)
`T rubrum, C parapsilosis
`other dermatologic disorders mimic onychomycosis.
`T rubrum, Aspergillus niger 14)nnncnrnnnnnanacmmmrrrrrmnttenhieemnttATT
`
`The easiest and quickest way to confirm the diagno-
`sis is with KOH preparation, in which spores and fun-
`gal filaments are easily detected.? Mycologic culture
`is a generally accepted methodof confirming the di-
`agnosis.
`The yieldofpositive cultures can be disappointing,
`as indicated by this study, in which 56% (120/214) of
`the cultures were positive. Often, not enough speci-
`men is inoculated onto culture media. Therefore,it is
`important to curette into the “spongy” area to in-
`erease the chance of obtaining a positive culture.
`Wheninterpreting negative culture results, false-neg-
`atives are frequent, which may account for the high
`percentage (44%) of negative cultures in this study.
`Negative cultures are mostly causedbylack of living
`fungi in the collection of subungual debris. When a
`dermatophyte and a nondermatophyte are grown,
`the dermatophyte is considered the pathogen, al-
`though both may play a role in the clinical picture.
`Further studies warrant serial cultures and micro-
`scopicfindings for yeast cells as definitive proof that
`nondermatophyte molds and yeasts are causative
`pathogens ratherthan contaminants,
`Theresults ofthis study show the increasing num-
`bers of nondermatophyte molds and yeasts present.
`in nail infection (Aspergillus, 3%; C parapsilosis,
`7%). Candida albicansis usually secondary to chron-
`ic paronychia and is found more frequently in finger-
`
`4)
`
`tinea pedis. Twenty-nine percent (35/120) of the pa-
`tients with positive cultures had concurrent tinea
`pedis, whereas 11% (10/94) of the patients with nega-
`tive cultures had concurrent tinea pedis.
`Five types of molds were isolated from nine pa-
`tients: Fusariwm(n = 1), Aspergillus (n = 3), S brevi-
`coulis (n= 1), Paecilomyces (n = 1), and Penicillium
`(n = 3) (Table 1). As no serial cultures were avail-
`able, these nondermatophyte molds are listed for
`purposes of information and the reporting of organ-
`ism distribution. Without serial cultures, it cannot be
`determined whether they are pathogens or contami-
`nants.” Eight percent ofthe positive cultures showed
`Candida, with 80% (8/10) of those with Candida
`parapsilosis and 20% (2/10) with C albicans. Der-
`matophyte onychomycosis affected more male pa-
`tients, whereas all ten patients with Candida ony-
`chomycosis were female.
`A study by Ghannoumet al? of 253 onychomy-
`cotic nail samples showed dermatophytes as the
`most commonlyisolated fungi (59%), A specimen
`was considered positive if septate hyphae were seen
`on microscopic examination, culture, or both. Non-
`dermatophyte molds and yeasts represented approxi-
`Mately 20% each. As in the present study, Ghannoum
`
`Journal of the American Podiatric Medical Association
`
`* Vol 92 * No 6 » June 2002
`
`329
`
`Page 3 of 4
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`

`

`of onychomycosis in Cordoba, Spain: prevailing fungi
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`‘
`oes
`2
`z
`1
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`ei
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`:
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`| of the American Podiatric Medical Association
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