Search Results
Abstract
Drug based treatment of superficial fungal infections, such as onychomycosis, is not the only defense. Sanitization of footwear such as shoes, socks/stockings, and other textiles is integral to the prevention of recurrence, and reduction of spread for superficial fungal mycoses. The goal of this review was to examine the available methods of sanitization for footwear and textiles against superficial fungal infections. A systematic literature search of various sanitization devices and methods that could be applied to footwear and textiles using PubMed, Scopus, and MEDLINE was performed. Fifty-four studies were found relevant to the different methodologies, devices, and techniques of sanitization as it pertains to superficial fungal infections of the feet. These included topics of basic sanitization, antifungal and antimicrobial materials, sanitization chemicals and powder, laundering, ultraviolet, ozone, non-thermal plasma, microwave radiation, essential oils, and natural plant extracts. In management of onychomycosis it is necessary to think beyond treatment of the nail, as infections enter through the skin. Those prone to onychomycosis should examine their environment, including surfaces, shoes, and socks, and ensure that proper sanitization is implemented.
The Diagnosis of Onychomycosis in a Geriatric Population
A Study of 450 Cases in South Florida
An investigative study was performed to determine the diagnosis of onychomycosis in a South Florida geriatric population. In this study, 450 cases of suspected onychomycosis involving men and women 65 years of age and older from a private practice office and two nursing home settings were used. Samples were taken from the hallux toenail and sent to a mycology laboratory for fluorescent potassium hydroxide (KOH) preparation and microscopic examination of a fungal culture. Of the 450 cases studied, 46.4% of the patients had a single fungal organism cultured, 30.4% had a mixed fungal infection cultured, and 23.1% had no fungal growth. Saprophytes were found in 59.9% of the 526 total fungal organisms cultured while dermatophytes were found in only 23.8%. The results of this investigation demonstrate that there may be a shift from isolated dermatophyte infection to mixed saprophyte infections in a geriatric population with onychomycosis. (J Am Podiatr Med Assoc 91(9): 456-464, 2001)
Background:
Onychomycosis and tinea pedis (athlete’s foot) are infections of the nails and skin caused by pathogenic fungi collectively known as dermatophytes. These infections are difficult to treat, and patients often relapse; it is thought that a patient’s footwear becomes infected with these fungal organisms and, thus, is an important reservoir for reinfection. Therefore, it is important to find an effective means for killing the dermatophytes that may have colonized the inner surface of the shoes of patients with superficial fungal infections. In this study, we developed an in vitro model for culturing dermatophytes in footwear and used this model to evaluate the effectiveness of a commercial ultraviolet shoe sanitizer in eradicating the fungal elements residing in shoes.
Methods:
Leather and athletic shoes (24 pairs) were inoculated with either Trichophyton rubrum or Trichophyton mentagrophytes (107 colony-forming units/mL) strains and were placed at 35°C for 4 to 5 days. Next, we compared the ability of swabbing versus scraping to collect microorganisms from infected shoes. Following the optimized method, shoes were infected and were irradiated with one to three cycles of radiation. The inner surfaces of the shoes were swabbed or scraped, and the specimens were cultured for dermatophyte colony-forming units.
Results:
Leather and canvas shoes were infected to the same extent. Moreover, scraping with a scalpel was overall more effective than was swabbing with a cotton-tipped applicator in recovering viable fungal elements. Irradiation of shoes with one, two, or three cycles resulted in reduction of fungal colonization to the same extent.
Conclusions:
The developed infected shoe model is useful for assessing the effectiveness of ultraviolet shoe sanitizers. Also, ultraviolet treatment of shoes with a commercial ultraviolet C sanitizing device was effective in reducing the fungal burden in shoes. These findings have implications regarding breaking foot infection cycles. (J Am Podiatr Med Assoc 102(4): 309–313, 2012)
Onychomycosis Infections
Do Polymerase Chain Reaction and Culture Reports Agree?
Background:
Mycological culture is the traditional method for identifying infecting agents of onychomycosis despite high false-negative results, slower processing, and complications surrounding nondermatophyte mold (NDM) infections. Molecular polymerase chain reaction (PCR) methods are faster and suited for ascertaining NDM infections.
Methods:
To measure agreement between culture and PCR methods for identification of infecting species of suspected onychomycosis, single toenail samples from 167 patients and repeated serial samples from 43 patients with suspected onychomycosis were processed by culture and PCR for identification of 16 dermatophytes and five NDMs. Agreement between methods was quantified using the kappa statistic (κ).
Results:
The methods exhibited fair agreement for the identification of all infecting organisms (single samples: κ = 0.32; repeated samples: κ = 0.38). For dermatophytes, agreement was moderate (single samples: κ = 0.44; repeated samples: κ = 0.42). For NDMs, agreement was poor with single samples (κ = 0.16) but fair with repeated samples (κ = 0.25). Excluding false-negative reports from analyses improved agreement between methods in all cases except the identification of NDMs from single samples.
Conclusions:
Culture was three or four times more likely to report a false-negative result compared with PCR. The increased agreement between methods observed by excluding false-negative reports statistically clarifies and highlights the major discord caused by false-negative cultures. The increased agreement of NDM identification from poor to fair with repeated sampling along with their poor agreement in the single samples, with and without false-negatives, affirms the complications of NDM identification and supports the recommendation that serial samples help confirm the diagnosis of NDM infections.
Background: A high rate of false-negative dermatophyte detection is observed when the most common laboratory methods are used. These methods include microscopic observation of potassium hydroxide–digested nail clippings and culture methods using agar-based media supplemented with cycloheximide, chloramphenicol, and gentamicin to isolate dermatophytes. Microscopic detection methods that use calcofluor white staining or periodic acid–Schiff staining may also be substituted for and have previously been reported to be more sensitive than potassium hydroxide–digested nail clippings.
Methods: Trichophyton rubrum infections were detected directly from nails in a double-round polymerase chain reaction assay that uses actin gene–based primers. This method was compared with detection of fungal hyphae by using calcofluor white fluorescence microscopy of nail samples collected from 83 patients with onychomycosis who were undergoing antifungal drug therapy.
Results: Twenty-six of 83 samples (31.3%) were found to be positive by calcofluor white fluorescence microscopy, and 21 of 83 samples (25.3%) yielded positive results for T rubrum when actin gene–based primers in a double-round polymerase chain reaction assay were used. When calcofluor white fluorescence microscopy and polymerase chain reaction assay were used, the combined detection was 46.9% compared with 31.3% when calcofluor microscopy and culture of nail samples on Sabouraud’s dextrose agar supplemented with cycloheximide, chloramphenicol, and gentamicin were used.
Conclusions: These results suggest that the use of a direct DNA protocol is an alternative method for detecting Trichophyton infections. When this protocol is used, the presence of T rubrum DNA is directly detected. However, the viability of the dermatophyte is not addressed, and further methods need to be developed for the detection of viable T rubrum directly from nail samples. (J Am Podiatr Med Assoc 98(3): 224–228, 2008)
Fungal Diversity and Onychomycosis
An Analysis of 8,816 Toenail Samples Using Quantitative PCR and Next-Generation Sequencing
Background:
Onychomycosis is a fungal infection of the nail that is often recalcitrant to treatment and prone to relapse. Traditional potassium hydroxide and culture diagnosis is costly and time-consuming. Therefore, molecular methods were investigated to demonstrate effectiveness in diagnosis and to quantify the microbial flora present that may be contributing to disease.
Methods:
A total of 8,816 clinically suspicious toenail samples were collected by podiatric physicians across the United States from patients aged 0 to 103 years and compared with a control population (N = 20). Next-generation sequencing and quantitative polymerase chain reaction were used to identify and quantify dermatophytes, nondermatophyte molds, and bacteria.
Results:
Approximately 50% of suspicious toenails contained both fungi and bacteria, with the dermatophyte Trichophyton rubrum contributing the highest relative abundance and presence in 40% of these samples. Of the remaining 50% of samples, 34% had bacterial species present and 16% had neither. Fungi only were present in less than 1% of samples. Nondermatophyte molds contributed to 11.0% of occurrences in fungus-positive samples. All of the control samples were negative for fungi, with commensal bacterial species composing most of the flora population.
Conclusions:
Molecular methods were successful in efficiently quantifying microbial and mycologic presence in the nail. Contributions from dermatophytes were lower than expected, whereas the opposite was true for nondermatophyte molds. The clinical significance of these results is currently unknown.
Onychomycosis is a common problem seen in clinical practice. Given the differential diagnosis of dystrophic nails, it is helpful to obtain a definitive diagnosis of dermatophyte infection before initiation of antifungal therapy. Potassium hydroxide preparation and fungal culture, which are typically used in the diagnosis of these infections, often yield false-negative results. Recent studies have suggested that nail plate biopsy with periodic acid–Schiff stain may be a very sensitive technique for the diagnosis of onychomycosis. In this article, we review the literature on the utility of histopathologic analysis in the evaluation of onychomycosis. Many of these studies indicate that biopsy with periodic acid–Schiff is the most sensitive method for diagnosing onychomycosis. We propose that histopathologic examination is indicated if the results of other methods are negative and clinical suspicion is high; therefore, it is a useful complementary technique in the diagnosis of onychomycosis. (J Am Podiatr Med Assoc 95(3): 258–263, 2005)
Background:
Onychomycosis is a chronic nail infection caused by dermatophytes, Candida, nondermatophyte molds, and Trichosporon. The purpose of this study was to identify the underlying pathogen in patients with onychomycosis in our region.
Methods:
A retrospective analysis of 225 cases with onychomycosis, diagnosed over a 27-month period at the Department of Dermatoveneorology, Bezmialem Vakif University, Istanbul, Turkey, and confirmed with culture, was performed.
Results:
Patient age ranged from 2 to 87 years (mean ± SD, 41.59 ± 17.61), and female patients were more commonly affected (120 cases, 53.3%) than male patients. Lateral and distal subungual onychomycosis was detected in 180 cases (80%). Etiologic agents were as follows: Trichophyton rubrum, 77 cases (34.2%); Trichophyton mentagrophytes, 30 cases (13.3%), Candida albicans, 28 cases (12.4%); Candida parapsilosis, 25 cases (11.1%); Acremonium species, one case (0.4%); Aspergillus species, two cases (0.9%); Fusarium species, four cases (1.3%); and Trichosporon species, three cases (1.3%).
Conclusions:
The most frequent isolated etiologic agents were T rubrum for toenails and C albicans for fingernails.
Onychomycosis, by definition, is a mycotic infection of the keratinized 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 agents in the disease, including some bacteria and yeasts. When it is caused by a fungus, any or all of three types of organisms can be involved: dermatophytes, yeasts, and nondermatophyte organisms. The purpose of this study was to identify the microorganisms found in fungal cultures of clinically suspected onychomycosis 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 charts 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 account for the high percentage (44%) of negative cultures in this study. (J Am Podiatr Med Assoc 92(6): 327-330, 2002)
