A study of fungal infections in Malta

Abstract

A two year research study into fungal infections in Malta and Gozo was commenced in January 1995. In the initial stage, a postal questionnaire was sent to 200 medical practitioners, randomly selected. Of the 32% (n = 64) who responded, 82.8 % (n = 53) were family doctors and 17.2 % (n = 11) were specialists. They reported diagnosing less than 10 cases of fungal infections each per month. The summer months are usually associated with the highest incidence of fungal infections, mostly affecting exposed skin. Females were judged to be more prone than males but in both sexes, the age group with the highest incidence of fimgal infections is the 21 to 40 years group. With regards to antifungal agents, topical miconazole and clotrimazole are the most commonly prescribed whereas ketoconazole and griseofulvin are used to a lesser extent. The second part of the study involved setting up the diagnostic techniques and means to perform the laboratory isolation and identification of fungal species. Following this, between 2nd May 1995 till 30th April 1997, a total of 272 dermatological specimens from 259 patients were investigated. Female patients (50.2%) were slightly more numerous than male patients (49.8%). 43.4% of specimens were positive when cultured. The fungi cultivated (n = 139) included dermatophytes (n = 61), yeasts (n = 65), Aspergillus niger (n = 7), Aspergillus species (n = 1), Fusarium oxysporum (n = 2) and other Fusarium species (n = 3). C. parapsilosis was the most commonly isolated yeast, followed by C. albicans and C. tropicalis. The dermatophytes cultivated (in order of frequency) included M canis, T rubrum, T mentagrophytes, M gypseum, E. floccosum and T tonsurans. Cases of tinea capitis yielded predominantly M canis and just one isolate of T tonsurans var. sulphureum. T mentagrophytes was the principal agent causing tinea pedis. Antifungal susceptibility tests were then carried out on 60 dermatophyte and 5 Fusarium isolates. The antifungal drugs used were griseofulvin, terbinafine, amorolfine, itraconazole; ketoconazole and miconazole. With a few XVI exceptions, low MIC values for the majority of the dermatophytes were obtained, especially for amorolfine and terbinafine. There was one isolate of M canis with a high MIC value (:::: 64 mgIL) for amorolfine and griseofulvin. There was also another isolate of T rubrum with an MIC value for griseofulvin of 16 mgIL. The MIC values for the five Fusarium species tested were much higher than for the dermatophytes, especially for griseofulvin (>/ 64 mgIL). Both terbinafine and amorolfine showed good activity against the dermatophytes tested, with terbinafine being marginally more effective than amorolfine (non-statistically significant). The azole drugs were fungicidal at much higher concentrations with itraconazole showing higher fungicidal activity than either ketoconazole or miconazole (p < 0.001). Part of the research into dermatophytes touched on the molecular biology aspects of mycological identification. Dermatophyte DNA from M fulvum and E. jloccosum was successfully extracted and amplified by using a specific fungal primer system TR1 and TR2 in the polymerase chain reaction. In a study parallel to the one on dermatophytes, between 2nd May 1995 till 31 st July 1996, other clinical specimens were investigated for both yeasts and filamentous fungi. A total of 547 clinical (other than skin, hair and nail and excluding stool specimens) specimens were submitted from 452 patients. Most patients (n = 269, 59.5%) were over 60 years of age. Risk factors for fungal infections were ranked by analysing the medical records of the patients included in this study. Antibacterial therapy (86.9%), old age (64.1%) and intravascular catheterization (48.4%) posed the highest risks. Various yeasts were isolated, with C. albicans being the predominant yeast cultivated (n = 227, 46%), followed by C. tropicalis, C. glabrata and C. parapsilosis in that order. Filamentous fungi that were cultivated in this study included A. niger, A. jlavus and Acremonium species. Antifungal susceptibility tests showed that the majority of the yeasts were sensitive - however some resistance was present to amphotericin B, nystatin, 5-fluorocytosine, miconazole, ketoconazole and econazole. Positive feedback on the mycology services offered during this study, was given by the clinicians who participated by providing samples for analysis from their patients.