Search

Background The successful treatment of onychomycosis depends on accurate diagnosis. Conventional diagnostic methods, including direct microscopy and fungal culture, are non-specific, insensitive and time-consuming. Recently, PCR has shown promise in improving the diagnosis of onychomycosis. We aimed to evaluate a commercially available PCR kit for the in vitro detection of dermatophytes and specifically Trichophyton rubrum in nail specimens with suspected onychomycosis, and to compare the detection rates of PCR with conventional diagnostic methods. Methods Nail specimens were prospectively collected from patients with clinically suspected onychomycosis. All nail specimens were positive on direct microscopic examination. PCR and fungal cultures were administered, and the detection rates of dermatophytes were compared. Results In all, 107 nail specimens were analysed. The fungal culture was positive in 57 (53%) specimens (38 dermatophytes and 19 non-dermatophytes). PCR was positive in 77 (72%) specimens (63 T. rubrum and 14 pan-dermatophyte). A total of 37 specimens (35%) were positive for both fungal culture and PCR. PCR detected dermatophytes in 39 specimens that were missed by the fungal culture, increasing the diagnosis of dermatophyte-positive specimens by 37%. Five dermatophyte–culture-positive specimens were negative for PCR. Conclusions This study demonstrates that PCR increases the sensitivity of detection of dermatophytes in nail specimens. Despite its limitations, the use of PCR can complement direct microscopic examination and fungal cultures to aid clinicians in the diagnosis of suspected dermatophytic onychomycosis.

Superficial cutaneous fungal infection, principally dermatophytosis, is an extremely common skin disease. Various in vitro test systems have been developed in recent years to determine the antifungal activity of various drugs. The minimum inhibitory concentration (MIC) obtained may give an indication of the in vivo potency of the drugs.One hundred patients (69 men and 31 women) with a clinical diagnosis of dermatophytosis were entered into the study. Direct microscopy and culture were done on all patients. The MICS were determined using the broth dilution method.The age range was 1-76 years. The most common diagnosis was tinea corporis (36%), followed by tinea cruris (22%), and tinea pedis (19%). The most common fungus isolated was T. rubrum (58%), followed by E. floccosum (14%), and T. mentagrophytes (10%). The majority of the isolates was sensitive to the three drugs tested (griseofulvin, ketoconazole, and itraconazole). Of the isolates, 82% were sensitive to griseofulvin, 78% to ketoconazole, and 81% to itraconazole, all at a concentration of0.25 micrograms/mL. For T. rubrum, there were four isolates that had an MIC ofor = 64 micrograms/mL to griseofulvin, seven isolates and nine isolates with an MICor = 64 micrograms/mL to ketoconazole and itraconazole, respectively. T. interdigitale was relatively resistant to the three drugs in vitro with four of seven isolates having an MICor = 4 micrograms/mL with griseofulvin, one of seven isolate with an MICor = 64 micrograms/mL with ketoconazole, and three of seven isolates with an MICor = 32 micrograms/mL with itraconazole.The in vitro antifungal activity of griseofulvin, ketoconazole, and itraconazole are similar against dermatophytes in Singapore. Griseofulvin may be given as the first-line drug for treating such infections in Singapore.

Case no. 1 A 70-year-old Indian man had lateral onycholysis of his left big toe since 1989. Nail scrapings from the left big toenail were negative three times in 1989 and 1990. Fungal cultures from the left big toenail were negative for dermatophyte and nondermatophyte molds in 1990. The condition did not respond to topical itraconazole 1% lotion (prepared by our pharmacy from itraconazole capsules), ketoconazle cream, tolnaftate lotion and nonstaining Castellani paint as well as oral itraconazole 100 mg daily for 4 weeks. In 1993, there was distal onycholysis of the fingernails on the left thumb, left ring and index and right little fingers as well. Once again, the skin scrapings from the finger- and toenails were negative. The condition did not respond to topical tolnaftate lotion, clotrimazole 1% lotion, miconazole 1% lotion, thiabendazole 10% lotion and nonstaining Castellani paint. In September 1999, both big toenails had crumbling nail plates and ragged distal edges. Nail scrapings showed the presence of mycelium and the fungal culture result was reported Scytalidium dimidiatum and Fusarium species. The Fusarium was thought to be a nonpathogenic coloniser. He was treated with oral griseofulvin, thiabendazole 10% lotion and nonstaining Castellani paint without much improvement. He was last seen in January 2001. There was still destruction of the nail plate and separation of the nail plate from the nail bed. Case no. 2 A 45-year-old Chinese man who worked as a clerk in a cosmetic company was first seen in July 1994 for scaly hyperkeratotic rashes on both soles for 10 years. He had tried using miconazole cream but the problem persisted. Skin scrapings revealed the presence of mycelium and fungal culture result war reported as Hendersonula toruloidea. He was born in Singapore and had never lived overseas. The condition persisted despite 9 weeks of oral griseofulvin 250 mg twice daily and miconazole 2% cream, 3 months of 10% thiabendazole lotion, 2 weeks of oral thiabendazole 500 mg twice daily and ung Whitfield. He subsequently defaulted after the last visit in April 1995, when he was prescribed amorolfine cream. He was seen again in July 1998 for acne vulgaris. His soles were still hyperkeratotic but skin scrapings were not taken. He defaulted again after 3 visits. Case no. 3 A 33-year-old Indian man who had been working in a machine assembly line for 12 years presented with an itchy scaly rash on his feet for 3 years and on the hands for 1 year in November 1996. The rash was especially prominent on the toewebs and occasionally formed vesicles and became secondarily infected. He had been treated with antifungal creams, with the addition of oral antibiotics for episodes of secondary infection, but the skin condition deteriorated. He wore shoes at work and had been exposed to coolants for 3 years. There was no history of atopy or allergies. On examination, there was maceration and scaling between the right second and third toes. Scaling was seen in the toewebs and near the thumbs bilaterally. The nails and groin were normal. Skin scrapings were negative on the hands, but showed a few hyphae on the toewebs. Fungal cultures from the toewebs were negative but bacterial cultures of the toewebs grew Acinetobacter baumanii and Klebsiella species, both of which were sensitive to gentamicin. The diagnoses of secondarily infected tinea pedis and hand dermatitis were made. The infection settled with oral cloxacillin and topical gentamicin cream but the skin of the hands and feet remained dry and fissured. He was then treated as for hand and foot dermatitis with moderately potent topical corticosteroids with minimal improvement. Repeated skin scrapings were negative in January and May 1997. He defaulted in September 1998. He returned in March 2000 with an acute exacerbation of a dry itchy rash on his palms and soles. He was treated as for dermatitis with cephalexin and a tapering course of prednisolone with significant improvement. Due to the persistent rashs, a skin scraping of the feet was repeated in May 2000 and this showed the presence of mycelium. He was treated with a course of oral griseofulvin 250 mg twice daily for 4 weeks with no improvement. He was then treated empirically with oral terbinafine 250 mg daily for 3 weeks and miconazole 2% cream, as cultures were not available. In June 2000 he had an infected exacerbation of his rash, which required treatment with oral cephalexin followed by oral cotrimoxazole. The skin scraping of the toewebs was negative and a diagnosis of acute dermatitis was made. He was given a tapering course of prednisolone with improvement. A patch test was negative. In November 2000, he still had a rash on the palms and soles. The fungal culture result was reported as Scytalidum dimidiatum but fungal scrapes had not been done. He was treated with oral itraconazole 200 mg daily for 4 weeks, oral cloxacillin and miconazole 2% cream.

BackgroundCandidal infections of the skin/nails and vagina are very common worldwide. Various in vitro test systems are available to help to determine the antifungal activity of drugs. The minimum inhibitory concentration (MIC) is a standard measure of the in vitro potency of drugs against yeasts. MethodsVaginal smears and skin/nail scrapings of 50 consecutive patients with candidal vaginitis and 46 consecutive patients (28 women, 18 men) with cutaneous/nail candidosis were used in the study. Direct microscopy and culture from vaginal smears and skin scrapings were performed on all patients. The MICs were determined using the broth dilution method. ResultsFor vaginal candidosis, the mean age of the patients was 28.2 years (range, 9–49 years). Candida albicans accounted for 58% of the isolates, C. glabrata for 32%, C. tropicalis for 6%, and C. parasilosis for 4%. At the MIC of 4 mg/L, 65–95% of C. albicans, 66–94% of C. glabrata, 33–100% of C. tropicalis, and 0–50% of C. parasilosis were susceptible to the drugs tested (ketoconazole, itraconazole, nystatin, amorolfine, clotrimazole, and miconazole). For cutaneous/nail candidosis, the mean age of the patients was 45 years (range, 19–82 years). C. albicans made up 59% of the isolates, C. parasilosis 20%, C. krusei 13%, C. glabrata 4%, and C. tropicalis 4%. At the MIC of 4 mg/L, 59–96% of C. albicans, 100% of C. glabrata, 83–100% of C. krusei, 89–100% of C. parasilosis, and 100% of C. tropicalis were susceptible to the drugs tested (ketoconazole, itraconazole, nystatin, amorolfine, clotrimazole, and miconazole). Conclusions C. albicans is the most common Candida species causing cutaneous/nail and vaginal candidosis in Singapore. The in vitro antifungal activities of ketoconazole, itraconazole, nystatin, amorolfine, clotrimazole, and miconazole are similar against the various Candida species. C. parasilosis in vaginal candidosis appears to be less susceptible. Here, itraconazole and amorolfine may be more effective.