A new medium for the presumptive identification of dermatophytes.

A new medium, Dermatophyte Identification Medium (DIM) (trade mark pending), was specifically developed to eliminate problems of false-positive results associated with commercially marketed media, such as dermatophyte test medium (DTM). Previous investigations had demonstrated that DTM only partially suppressed growth of nondermatophytes and that several of these nondermatophytic fungi that were morphologically similar to dermatophytes caused false-positive results. Presumptive identification of an unknown isolate as a dermatophyte required only the transfer of a portion of the suspected colony recovered from the specimen to DIM. Positive results, evidenced by a change in the color of the medium, were observed within 24 to 48 h. In studies of over 500 isolates of dermatophytes and common nondermatophyte molds, as well as close to 600 yeast isolates, false-positive results were always associated with bacterial contamination of the mold isolates while false negatives were only observed with occasional isolates of Trichophyton verrucosum. DIM culture was an inexpensive, rapid, and accurate method for the presumptive identification of dermatophytes in the clinical mycology laboratory.

A U.S. epidemiologic survey of superficial fungal diseases.

BACKGROUND: Large-scale studies performed outside the United States have demonstrated that most cases of onychomycosis and tinea pedis are caused by dermatophytes, primarily Trichophyton rubrum. However, other studies have suggested that yeasts and nondermatophytic molds may play a role, particularly in onychomycosis. OBJECTIVE: This study was undertaken to determine the epidemiology of superficial fungal infections in a U.S. population. METHODS: Fungal cultures were performed on patients with clinically suspected tinea cruris, tinea corporis, tinea capitis, tinea pedis, and onychomycosis. RESULTS: Dermatophytes were the most commonly isolated fungi in each type of superficial fungal disease studied. T. rubrum was the most commonly isolated dermatophyte species, although Trichophyton tonsurans was more common in tinea capitis and equally common in tinea corporis/tinea cruris. In tinea pedis and onychomycosis, dermatophytes appeared in approximately 95% and 82% of isolates, respectively. Candida albicans and nondermatophyte molds played only a minor role in onychomycosis; C. albicans was isolated in 7% of nail cultures and nondermatophytic molds were isolated in 11%. CONCLUSION: These results are in general agreement with other major epidemiologic studies performed outside the United States. Dermatophyte fungi cause most superficial fungal infections.

Cokeromyces recurvatus, a mucoraceous zygomycete rarely isolated in clinical laboratories.

Cokeromyces recurvatus Poitras was isolated from an endocervical specimen obtained from a 37-year-old, insulin-dependent diabetic. The patient's diabetic condition had been well controlled for 10 years, and she had no other known medical problem. This is only the fourth time that this zygomycete has been recovered from a human source. While there was no evidence of tissue invasion in the present patient, the observation of fungus-like structures in two separate Papanicolaou-stained cervical smears prepared 1 year apart suggests that C. recurvatus may be capable of colonizing endocervical tissue.

Scedosporium inflatum osteomyelitis in a dog.

Scedosporium inflatum Malloch et Salkin was found to cause osteomyelitis in a 6-year-old spayed female beagle. The previously healthy dog suddenly developed right-forelimb lameness. Bony changes consisting of proliferation with some lysis were noted on radiographic examinations. Microscopic observations of stained sections of tissue obtained by biopsy of the distal humerus revealed the presence of septate branching hyphae. Cultures inoculated with tissue from a later biopsy yielded a mold subsequently identified as S. inflatum. Tissue sections stained with specific Scedosporium fluorescent-antibody conjugate were positive, further substantiating the diagnosis. Although the dog was treated with oral itraconazole, no improvement in the animal's condition was noted, and it was euthanized. Autopsy revealed dissemination of the etiologic agent to the lungs.

Normally saprobic cryptococci isolated from Cryptococcus neoformans infections.

We report two cases in which Cryptococcus laurentii was isolated from surgically resected pulmonary lesions but the cryptococcal cells is tissue reacted positively with a specific fluorescent antibody (FA) conjugate for Cryptococcus neoformans. Both patients had no apparent host defense defects. In both cases, multiple cryptococcal isolates were obtained from tissue, and yeastlike cells consistent with C. neoformans were seen in direct histology. The isolates were identified by assimilation patterns and standard procedures including phenoloxidase reactions. Since C. laurentii was consistently isolated by using stringent procedures, it was considered unlikely that the fungus represented surgical or laboratory contamination. Its presence may be the result of dual infection not detected by FA, but other possible explanations exist. The results show the value of the FA test in diagnostic mycology and call into question previous reports of cryptococci other than C. neoformans as agents of infection.

Isolation and characterization of Sporothrix schenckii from clinical and environmental sources associated with the largest U.S. epidemic of sporotrichosis.

The largest recorded epidemic of sporotrichosis in the United States occurred in 1988 and involved a total of 84 cases in 15 states. All cases were associated with Wisconsin-grown sphagnum moss. Twenty-one clinical isolates of Sporothrix schenckii and 69 environmental isolates of Sporothrix spp. from the epidemic were characterized and compared. The environmental isolates were recovered from 102 samples of sphagnum moss and other material by using direct plating techniques. Characteristics examined included macroscopic and microscopic morphology, conversion to a yeast phase, exoantigen reactions, and virulence in mice. On the basis of these studies, eight environmental isolates were identified as S. schenckii, five were identified as Ophiostoma stenoceras, and the remainder were identified as Sporothrix species. The environmental isolates of S. schenckii were recovered from moss samples from one Pennsylvania nursery and from three New York State Soil and Water Conservation districts, but none were recovered from moss directly from the bogs in Wisconsin.

Fatal encephalitis caused by Dactylaria constricta var. gallopava in a snowy owl chick (Nyctea scandiaca).

Dactylaria constricta var. gallopava (Cooke) Salkin et Dixon was found to cause fatal encephalitis in a 28-day-old, captivity-bred snowy owl chick (Nyctea scandiaca). The previously healthy bird suddenly developed ataxia, severe torticollis, and extensor rigidity of the legs. Since the animal did not improve with antibiotic or vitamin-mineral supplement therapy, the chick was euthanized 5 days after the onset of neurologic signs. At necropsy, all tissues except the brain were grossly normal. Cultures inoculated with blood from the brain and heart yielded a dematiaceous mould that subsequently proved to be D. constricta var. gallopava. This is the first report of natural central nervous system infection caused by D. constricta var. gallopava in a snowy owl.

First report of subcutaneous phaeohyphomycosis of the foot caused by Phoma minutella.

Phoma minutella, a dematiaceous hyphomycete, was isolated to the exclusion of all other fungi from a subcutaneous inflammatory process on the foot of a farmer undergoing corticosteroid therapy for myasthenia gravis. Isolation was achieved on several nutrient media. Examination of stained smears and sections revealed dematiaceous fungal elements consistent with the mold. This is the first reported association of P. minutella with a human infection and only the second reported case involving a Phoma sp. as the etiologic agent of a subcutaneous infection.

Opportunistic infection of the spleen caused by Aureobasidium pullulans.

The mold Aureobasidium pullulans was isolated on several nutrient media from a splenic abscess in a patient with disseminated lymphoma. Examination of stained smears and paraffin sections revealed fungal structures characteristic of this organism. This is the first reported association of A. pullulans with an opportunistic visceral infection.

Evaluation of human hair sources for the in vitro hair perforation test.

The in vitro hair perforation test for dermatophytes was evaluated with hair from males and females aged 6 months to 67 years, including hair of various natural colors and hair which had been bleached, tinted, curled, sprayed, or subjected to various combinations of these treatments. In contrast to published recommendations, the source of hair had no effect on this diagnostic procedure.

Evaluation of Abbott Quantum II yeast identification system.

The identity of each of 239 yeasts, encompassing 9 genera and 30 species, was determined with the Quantum II and API 20C identification systems. With API 20C results accepted as being correct, Quantum II proved to be 92% accurate in identification of common isolates, e.g., Candida albicans and Torulopsis glabrata, but only 73% effective with less frequently encountered yeasts, e.g., Trichosporon beigelii and Rhodotorula glutinis. Overall, Quantum II was 86% as accurate as API 20C for the yeast isolates tested. In addition, physical problems were encountered in inoculation of Quantum II cartridges and in the automated reading of some biochemical tests. We conclude that Quantum II is not yet suitable for routine identification of clinical yeast isolates.