Has the era of individualised medicine arrived for antifungals? A review of antifungal pharmacogenomics.

Treatment or prophylaxis of invasive fungal infection in recipients of haemopoietic SCT (HSCT) may require management of coexistent malnutrition, organ dysfunction and GVHD, all of which create added potential for inter- and intra-patient variations in drug metabolism as well as drug interactions. Polymorphism is common in genes encoding pathway components of antifungal drug metabolism such as enzymes (cytochrome P450 (CYP450), glutathione S-transferase, N-acetyltransferase and uridine 5'-diphospho-glucuronosyltransferase), uptake transporters (organic cationic transporter, novel organic cationic transporter, organic anion transporter protein (OATP), organic anion transport (OAT), and peptide tranporter) and efflux transporters (breast cancer resistance protein, bile sale export pump (BSEP), multidrug and toxin extrusion type transporter, multidrug resistance protein (MRP), OAT, permeability glycoprotein (P-gp), and urate transporter). Specific polymorphisms may be generalised throughout a population or largely confined to ethnic groups. CYP450 enzymes, especially 2C9 and 2C19, exhibit extensive polymorphism and are central to the metabolism of azole antifungals and their interactions with other drugs including calcineurin inhibitors, cytotoxics and benzodiazepines. Polymorphism may ultimately affect drug efficacy: CYP2C19 variation leads to a fivefold variation in voriconazole levels between individuals. Anticipated routine provision of pharmacogenomic data in the future for new drugs, together with accumulating knowledge about established agents, challenge physicians to assimilate and apply that information to drug prescribing. Increasing availability of pharmacogenomic data may strengthen demand for rapid turn-around therapeutic drug monitoring of antifungal agents in HSCT recipients.

Histoplasmosis in Europe: report on an epidemiological survey from the European Confederation of Medical Mycology Working Group.

The purpose of this survey was to systematically collect data on individuals with histoplasmosis in Europe over a 5-year period (from January 1995 to December 1999). This included information on where and how the infection was acquired, the patient's risk factors, the causative organism, how the infection was diagnosed and what therapy the patients received. Data were sent on a standardized survey form via a national convenor to the coordinator. During the survey, 118 cases were reported, with 62 patients having disseminated disease, 31 acute pulmonary infection, chronic pulmonary infection in 6 and localized disease in 2 patients. For 17 patients, the diagnosis of histoplasmosis was incidental, usually secondary to investigations for lung cancer. Most patients had travelled to known endemic areas, but 8 patients (from Italy, Germany and Turkey) indicated that they had not been outside their countries of origin and hence these cases appear to be autochthonous. Notable observations during the survey were the reactivation of the disease up to 50 years after the initial infection in some patients and transmission of the infection by a transplanted liver. Itraconazole was the most commonly used therapy in both pulmonary and disseminated disease. The observation of autochthonous cases of disease suggests that the endemic area of histoplasmosis is wider than classically reported and supports continued surveillance of the disease throughout Europe.

Update on the genus Malassezia.

Malassezia yeasts are commensals of normal human skin, but also cause pityriasis versicolor, seborrhoeic dermatitis and evidence is accumulating that they play a significant role in atopic eczema/dermatitis syndrome (AEDS; formerly atopic dermatitis). The taxonomy of the genus has changed considerably and is likely to change more in the future. Our understanding of the interaction between Malassezia and the host demonstrates that it has the paradoxical ability to both stimulate and suppress the immune response directed against it and there is a fine balance in its existence at the interface between commensalism and pathogenicity.

Testing of antifungal combinations against yeasts and dermatophytes.

BACKGROUND: Fungal infections of the nail are a common and chronic problem. The main pathogens responsible for onychomycosis are dermatophytes, yeasts and moulds. Despite significant improvements, approximately 20% of patients with onychomycosis still fail on antifungal therapy. The successful exploitation of drug synergy may provide a useful approach to improve cure rates. METHODS: The minimum inhibitory concentrations (MIC(80)) were recorded for pathogens that are most frequently responsible for onychomycosis against combinations of several antifungal agents, namely, fluconazole, itraconazole, terbinafine and amorolfine. Fractional inhibitory concentrations (FICs) were then calculated from the MIC(80) results and the FIC values for each drug in the combinations added to determine the degree of synergy. A combined value of <1 was taken to suggest synergy; a value of 1-2 indicated an additive effect or indifference; and a combined FIC value of >2 was taken to suggest antagonism. RESULTS: Overall, 46% of amorolfine combinations showed results suggestive of synergy, with the most synergistic results seen against dermatophytes (54%) and moulds (52%). CONCLUSIONS: Some combinations of drugs may have synergistic activity in vitro; however, the importance of this in a clinical setting is yet to be established, and more studies are justified.

A two year global evaluation of the susceptibility of Candida species to fluconazole by disk diffusion.

The in-vitro activity of fluconazole against 46,831 yeast isolates collected over a two-year period from 57 laboratories in 33 countries worldwide was assessed using a disc diffusion method. Candida albicans was the organism isolated most frequently, accounting for 68.6% of the total number of isolates. C. glabrata, C. tropicalis, C parapsilosis and C. krusei and Cryptococcus neoformans represented 9.9, 4.7, 4.3, 1.9, and 1.4% of isolates respectively during the 2 year period and rates varied markedly between countries. In 1999 data blood isolates represented 4.9% of all isolates and intensive care unit isolates represented 9.9%. In both the 1998 and 1999 data, 99% of C. albicans were fully susceptible (S) to fluconazole, and 95.6% of all species of yeasts tested were S or susceptible-dose dependent (S-DD) to fluconazole. No emerging trends of resistance were noted with any of the Candida spp. tested as 96% of all isolates retained susceptibility (S or S-DD) to this agent.

An investigation into the pathogenesis of vulvo-vaginal candidosis.

OBJECTIVE: To monitor yeasts isolated from women during and between episodes of recurrent vulvo-vaginal candidosis (VVC) to determine whether vaginal relapse or re-infection occurred. METHODS: Women presenting at the genitourinary medicine clinic with signs and symptoms of VVC were recruited to the study (n = 121). A vaginal washing, high vaginal swab (HVS) and rectal swab were taken and the women treated with a single 500 mg clotrimazole pessary. Women were asked to re-attend after 1, 4, and 12 weeks, or when the VVC recurred, when vaginal washings and HVS were repeated. Candida isolates recovered were strain typed using the Ca3 probe and their similarity assessed. Antifungal susceptibility to fluconazole and clotrimazole were determined. RESULTS: Of the women recruited, 47 completed the study, either returning for four visits or suffering a recurrence during the study period. Of the 22 women who experienced recurrence, the same strain was responsible for the initial and recurrent episode in 17 women. For the remaining five women, four had strain replacement and one had a change of species. None of the isolates recovered from the women demonstrated resistance to either clotrimazole or fluconazole. CONCLUSIONS: Our findings support the theory of vaginal relapse and thus may support the use of more prolonged courses of antifungal therapy initially to increase the chances of eradication of the yeast.

Cell-mediated immunity to the mycelial phase of Malassezia spp. in patients with pityriasis versicolor and controls.

BACKGROUND: Malassezia is the aetiological agent of pityriasis versicolor. The mycelial phase of the organism predominates in lesions of pityriasis versicolor. OBJECTIVES: To evaluate the cell-mediated immune (CMI) response to the mycelial phase of Malassezia in patients with this disease, which has not previously been studied. METHODS: The CMI status of 12 patients with pityriasis versicolor and 12 age- and sex-matched controls to mycelial antigen(s) of the organism was examined. The responses to the mycelial form of three strains of the organism were assessed using lymphocyte transformation and leucocyte migration inhibition assays. RESULTS: The transformation responses of the lymphocytes from both patients and controls gave transformation indices < or = 3, although the responses of lymphocytes from patients with pityriasis versicolor to the mycelial form of Malassezia strains were generally higher than those of the controls. In the leucocyte migration inhibition assay, leucocytes from patients with pityriasis versicolor and controls responded to the mycelial antigens of three different Malassezia strains; however, there was no significant difference in leucocyte response between patients with pityriasis versicolor and controls. CONCLUSIONS: Patients with pityriasis versicolor do not therefore have a CMI deficiency to Malassezia mycelial antigens but fail to generate a protective CMI response to mycelial antigens over and above that of control individuals during active disease.

Production of the mycelial phase of Malassezia in vitro.

To study the pathogenicity of Malassezia, the agent of pityriasis versicolor, it is necessary to obtain the mycelial form in vitro. A range of different components and conditions were tested to induce yeast cells of the organism to produce mycelia in vitro using different culture media. A mycelial culture medium was developed that consisted of bacteriological peptone, glucose, yeast extract, ox bile, glycerol, glycerol monostearate, Tween 80, squalene, glycine, potassium nitrate, sodium chloride, ferrous sulphate and magnesium sulphate with or without agar. The liquid and solid medium had a pH of 5.6 and the temperature of incubation was 30 degrees C. Cultures were incubated in air. This medium was able to induce some strains of Malassezia to produce up to 40% mycelium in vitro. In total, 33 different strains of Malassezia obtained from the skin of the healthy individuals and patients with pityriasis versicolor were tested for mycelium production. The strains of Malassezia capable of producing mycelium in vitro all possessed the serovar A antigen.

Vaginal yeasts in the era of "over the counter" antifungals.

OBJECTIVE: To establish whether there has been any rise in the prevalence of non-albicans Candida species isolated from vaginal swabs since the introduction of "over the counter" antifungal treatments. METHOD: A retrospective review looking at all positive vaginal yeast isolates collected from women attending one genitourinary medicine clinic during the 6 year period from 1993 to 1998 inclusive. All positive vaginal yeast isolates were included, regardless of whether or not the patients were symptomatic. Isolates from HIV positive women were excluded from the analysis. RESULTS: No increase in non-albicans vaginal yeast isolates was shown during the period studied. The proportion of non-albicans yeasts remained constant at approximately 5% of the total yeasts isolated. The most common non-albicans yeast isolated was C glabrata. CONCLUSION: There is no evidence from this study to suggest that the increasing use of "over the counter" antifungal treatment has selected for atypical, possibly inherently azole resistant, strains of vaginal yeasts in HIV seronegative women.

The role of Malassezia species in the ecology of human skin and as pathogens.

The new taxonomic structure of the lipophilic genus Malassezia was presented with key characteristics for the seven described species. Among techniques used for epidemiological surveys, the pulsed field gel electrophoresis (PFGE) was found to be of little value in contrast to randomly amplified polymorphic DNA (RAPD). Immunological studies still yielded conflicting results but at least the immunomodulatory capacity of Malassezia yeasts appeared to be related to the cell wall lipids. A review of Malassezia infections together with the present consensus for their prevention and treatment was also made.

IgG subclasses specific to Staphylococcus epidermidis and Propionibacterium acnes in patients with acne vulgaris.

IgG subclasses specific to Staphylococcus epidermidis and Propionibacterium acnes were determined in sera from patients with mild, moderate or severe acne and from a control group. Titres specific to S. epidermidis were all within the same range and did not differ between groups. The titres of IgG subclasses to specific to P. acnes did vary between groups. IgG1 and IgG3 were significantly higher in severe acne patients compared with moderate acne patients, while IgG2 was significantly higher in moderate and severe patients compared with controls. Titres of IgG4 did not differ between groups. The pattern of titres observed suggests that, while the antibody response to S. epidermidis is relatively harmless, antibodies to P. acnes may be involved in the pathogenesis of acne vulgaris.

Humoral immunity to Malassezia furfur serovars A, B and C in patients with pityriasis versicolor, seborrheic dermatitis and controls.

This study examined the humoral immune responses to Malassezia furfur serovars A, B and C of 10 patients with pityriasis versicolor, 10 patients with seborrheic dermatitis and 20 age- and sex-matched controls. A transferable solid-phase ELISA was used to determine titres of total Igs, IgM, IgA and IgG specific to M. furfur serovars A, B and C. The results demonstrated that patients with seborrheic dermatitis had a significantly higher titre of total Igs to serovar A than patients with pityriasis versicolor; and that patients with seborrheic dermatitis had a significantly higher titre of IgA to serovar C than patients with pityriasis versicolor. The titres of total Igs for controls and patients with seborrheic dermatitis were significantly lower to serovar B than to serovar C. A modified TSP ELISA was used to determine the titres of the IgG subclasses. Titres of IgG1,3,4 to serovar B were significantly higher in seborrheic dermatitis patients than pityriasis versicolor patients and titres of IgG3 to serovar A were significantly higher in seborrheic dermatitis patients than pityriasis versicolor patients. However, despite the differences between the patient groups, none of these results was significantly different to those of controls. Thus, this study did not demonstrate any differences in humoral immunity of patients suffering from Malassezia-associated dermatoses when compared to normal controls. These results may suggest that the humoral immune response to M. furfur is not related to the pathogenesis of Malassezia-associated dermatoses, but simply to the carriage of M. furfur on the skin.

Cell-mediated immune responses to Malassezia furfur serovars A, B and C in patients with pityriasis versicolor, seborrheic dermatitis and controls.

It has been postulated that patients with Malassezia furfur-associated dermatoses have a deficient cell-mediated immune response to M. furfur. This study examined the cell-mediated immune responses to M. furfur serovars A, B and C of 10 patients with pityriasis versicolor and 10 age- and sex-matched controls; and 10 patients with seborrheic dermatitis and 10 age- and sex-matched controls. The responses to each serovar of M. furfur were assessed using the lymphocyte transformation assay and the leukocyte migration inhibition assay. The lymphocyte transformation responses of the patients with pityriasis versicolor to M. furfur serovars A, B and C (0/10, 6/10 and 5/10 respectively) were not significantly different from those of controls (0/10, 2/10 and 1/10). However, for patients with seborrheic dermatitis, significantly more patients' lymphocytes responded to serovars B and C (6/10 and 6/10 respectively) than those of controls (1/10 and 1/10). No patient or control responded to serovar A. In the leukocyte migration inhibition assay, the leukocytes from a greater proportion of patients with pityriasis versicolor (5/7) responded to serovar B than controls (2/10); and the leukocytes from a greater proportion of patients with seborrheic dermatitis (4/10) responded to serovar C than controls (0/9). Thus, this data did not indicate the presence of any cell-mediated immune deficiency to M. furfur in patients with pityriasis versicolor or seborrheic dermatitis, as measured by the lymphocyte transformation assay or the leukocyte migration inhibition assay. The greater responsiveness of T lymphocytes from patients may indicate that T lymphocytes might be involved in the pathogenesis of these diseases.

The carriage of Malassezia furfur serovars A, B and C in patients with pityriasis versicolor, seborrhoeic dermatitis and controls.

The aetiological role of Malassezia furfur in various dermatoses is controversial. The role of the three serovars of M. furfur in Malassezia-associated diseases has not been investigated. This study measured population densities of M. furfur serovars A, B and C, propionibacteria and Micrococcaceae on the chest, back, forehead, left and right cheeks of 10 patients with pityriasis versicolor, and 10 age- and sex-matched controls; and 10 patients with seborrhoeic dermatitis, and 10 age- and sex-matched controls. The population densities of M. furfur, propionibacteria and Micrococcaceae did not vary at a given site between patients and the corresponding control subjects. Malassezia furfur serovar A was found to be the predominant isolate on the chest and back of all four groups, but there was no difference in the distribution of serovars on the forehead and cheeks. No serovar was specifically associated with lesional skin in either disease. Thus, this data indicated that there was no difference in either the total population density of M. furfur or the distribution of serovars on lesional skin compared with control skin in either pityriasis versicolor or seborrhoeic dermatitis.