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Biomedical subjects

G Midgley

Publications and source records attributed to G Midgley.

At least 19 recordsLinked to original sources

IgE-reactivity to seven Malassezia species.

BACKGROUND: Malassezia yeasts play a role in the pathogenesis of atopic eczema/dermatitis syndrome (AEDS). The revised genus Malassezia includes several species which all are natural habitants of the human skin. In this study, we evaluated the presence of immunoglobulin E (IgE) antibodies to different Malassezia spp. in AEDS patients to allow optimization of the characterization of the IgE antibody profile of IgE-associated AEDS. METHODS: Ninety-six adult patients, with a clinical diagnosis of AEDS, were included in the study. Seventeen of the patients had IgE antibodies to M. sympodialis, ATCC 42132 (m70 ImmunoCAP, Pharmacia, Diagnostic AB, Uppsala, Sweden). The IgE antibodies to seven Malassezia spp. were measured and inhibition immunoblotting was performed to investigate whether M. sympodialis contains all the allergen components present in the other Malassezia spp. RESULTS: Twenty per cent of 79 AEDS patients with a negative m70 ImmunoCAP test had IgE antibodies to at least one of the other six Malassezia spp. tested. Our inhibition studies indicated that Malassezia spp. to a great extent, share allergenic determinants. However, Malassezia species also contained species-specific allergens. CONCLUSION: The use of only one species of Malassezia is not sufficient to detect all patients IgE sensitized to Malassezia. To obtain an optimal allergen preparation both common allergenic components as well as species-specific allergens have to be considered.

Adolescent↗

Scalp ringworm in south-east London and an analysis of a cohort of patients from a paediatric dermatology department.

BACKGROUND: Scalp ringworm or tinea capitis has become an increasingly important public health issue in the past decade in Great Britain. Recently, certain dermatology departments in London have seen a large increase in tinea capitis in all its forms. OBJECTIVES: The aim of this paper is to present the detailed analysis of a cohort of 277 patients with tinea capitis seen during a 2-year period together with the latest local figures of tinea capitis cases from an inner city paediatric dermatology service. Methods Demographic, clinical and laboratory data were collected prospectively over 2 years from all cases of ringworm in patients seen in a paediatric clinic specially set up for scalp problems. RESULTS: Sixty-two per cent of 277 cases of scalp ringworm were caused by Trichophyton tonsurans, occurring mainly (91%) in patients with Afro-Caribbean hair type, more often in boys (68%), and in the 3-8 year olds (70%). Only 7% of the patients had received appropriate treatment with oral griseofulvin. An additional 156 cases from the general paediatric dermatology clinic showed 91%T. tonsurans infections. CONCLUSIONS: The prevalence of scalp ringworm appears to be reaching epidemic proportions in certain areas that include south-east London. The clinical problem is not yet well recognized by local general practitioners.

Age Distribution↗

New chromogenic agar medium for the identification of Candida spp.

A new chromogenic agar medium (Candida diagnostic agar [CDA]) for differentiation of Candida spp. is described. This medium is based on Sabouraud dextrose agar (Oxoid CM41) and contains (per liter) 40.0 g of glucose, 10.0 g of mycological peptone, and 15.0 g of agar along with a novel chromogenic glucosaminidase substrate, ammonium 4-(2-[4-(2-acetamido-2-deoxy-beta-D-glucopyranosyloxy)-3-methoxyphenyl]-vinyl)-1-(propan-3-yl-oate)-quinolium bromide (0.32 g liter(-1)). The glucosaminidase substrate in CDA was hydrolyzed by Candida albicans and Candida dubliniensis, yielding white colonies with deep-red spots on a yellow transparent background after 24 to 48 h of incubation at 37 degrees C. Colonies of Candida tropicalis and Candida kefyr were uniformly pink, and colonies of other Candida spp., including Candida glabrata and Candida parapsilosis, were white. CDA was evaluated by using 115 test strains of Candida spp. and other clinically important yeasts and was compared with two commercially available chromogenic agars (Candida ID agar [bioMerieux] and CHROMagar Candida [CHROMagar Company Ltd.]). On all three agars, colonies of C. albicans were not distinguished from colonies of C. dubliniensis. However, for the group containing C. albicans plus C. dubliniensis, both the sensitivity and the specificity of detection when CDA was used were 100%, compared with values of 97.6 and 100%, respectively, with CHROMagar Candida and 100 and 96.8%, respectively, with Candida ID agar. In addition, for the group containing C. tropicalis plus C. kefyr, the sensitivity and specificity of detection when CDA was used were also 100%, compared with 72.7 and 98.1%, respectively, with CHROMagar Candida. Candida ID agar did not differentiate C. tropicalis and C. kefyr strains but did differentiate members of a broader group (C. tropicalis, C. kefyr, Candida lusitaniae plus Candida guilliermondii); the sensitivity and specificity of detection for members of this group were 94.7 and 93.8%, respectively. In addition to the increased sensitivity and/or specificity of Candida detection when CDA was used, differentiation of colony types on CDA (red spotted, pink, or no color) was unambiguous and did not require precise assessment of colony color.

Agar↗

A randomized comparison of 4 weeks of terbinafine vs. 8 weeks of griseofulvin for the treatment of tinea capitis.

BACKGROUND: Tinea capitis is a common childhood infection that has recently become more frequent in urban areas in Europe and the U.S.A. The current licensed treatment in children is griseofulvin 10 mg kg(-1) daily, which is usually given for 6--8 weeks. OBJECTIVES: To compare this treatment with a 4-week course of oral terbinafine. METHODS: Terbinafine was given at the following doses: in children weighing < 20 kg, 62.5 mg daily; 20--40 kg, 125 mg daily; > 40 kg, 250 mg daily. Two hundred and ten children aged 2--16 years, with mycologically confirmed tinea capitis, were randomized to 4 weeks treatment with terbinafine or 8 weeks with griseofulvin, and followed for a total of 24 weeks to determine the difference between treatments with respect to short- and long-term efficacy and tolerability. RESULTS: One hundred and forty-seven patients were evaluable (terbinafine 77, griseofulvin 70). Although the 4-week course of terbinafine resulted in a trend to more rapid clearance of tinea capitis, there were no statistically significant differences between the two drugs in terms of overall outcome or tolerability, apart from in a subgroup of patients with Trichophyton infections, and weighing > 20 kg, who responded better to terbinafine than to griseofulvin at 4 weeks. By contrast, there was a better response to griseofulvin than to terbinafine in patients with Microsporum audouinii infections. CONCLUSIONS: Overall, the study showed that 4 weeks of treatment with oral terbinafine has similar efficacy to 8 weeks of treatment with griseofulvin for the management of tinea capitis in children.

Adolescent↗

Tinea capitis in Europe: new perspective on an old problem.

A survey of tinea capitis conducted under the auspices of the European Confederation of Medical Mycology showed that laboratories contributing to a voluntary scheme for reporting have recently been seeing a different pattern of scalp ringworm. The survey was conducted among 92 medical mycology laboratories across 19 European countries by postal questionnaire comparing the years 1987 with 1997. The survey shows an overall increase in the numbers of cases caused by anthropophilic infections, which, in 1997, were the dominant causes of scalp infection; the greatest increase was seen in laboratories covering urban populations and in African Caribbean children living in Europe. While the commonest infection remains Microsporum canis, the largest overall increase has been in Trichophyton tonsurans, which in 1997 was the second commonest cause of infection overall and the commonest in urban populations. The pattern of change is not uniform in Europe and while some cities have reported large increases in T. tonsurans others, e.g. in France, have seen more cases of infection due to T. soudanense and M. audouinii. While these figures do not necessarily reflect changes in the underlying prevalence of infection, the trends are important to recognize as the control measures for anthropophilic tinea capitis differ from those used in zoophilic infections. In particular there is a need for an increased level of surveillance and more advice on control given to primary care physicians, dermatologists and school health authorities.

Data Collection↗

The lipophilic yeasts: state of the art and prospects.

Malassezia yeasts (lipophilic yeasts), have been classified to include seven species. Although molecular methods such as sequencing of RNA and karyotyping were used to determine the species, traditional techniques are also being explored for their identification. These include studies of morphology and the utilization of individual lipids. Reports now show the predominance of individual species recovered from normal skin and from patients with diseases such as pityriasis versicolor and seborrhoeic dermatitis. The majority of systemic infections reported have been in the bloodstream of premature neonates. Clusters of cases have occurred and molecular techniques employed to study the epidemiology. With the development of discriminatory methods to determine individual species and strains present in disease and in nature, our understanding of the pathogenicity and the epidemiology of this genus can be advanced.

Animals↗

An epidemic of Malassezia pachydermatis in an intensive care nursery associated with colonization of health care workers' pet dogs.

BACKGROUND: Malassezia species are lipophilic yeasts that are emerging as nosocomial pathogens, particularly in low-birth-weight neonates who receive lipid emulsions. When a cluster of patients with Malassezia pachydermatis infection was identified in an intensive care nursery, we initiated an investigation. METHODS: A case patient was defined as any infant in the intensive care nursery who had a positive culture for M. pachydermatis between October 17, 1993, and January 18, 1995. We conducted a cohort study to identify risk factors for colonization and infection with M. pachydermatis. We collected cultures from the infants and the health care workers and from the health care workers' pets, since this organism has been associated with otitis externa in dogs. RESULTS: Fifteen infants met the case definition: eight with bloodstream infections, two with urinary tract infections, one with meningitis, and four with asymptomatic colonization. The case patients were significantly more likely than the other infants to weigh 1300 g or less (15 of 65 vs. 0 of 419, P<0.001). In a multivariate analysis of infants weighing 1300 g or less, the independent risk factors for colonization or infection with M. pachydermatis were a greater severity of concomitant illness (odds ratio, 19.7; P=0.001), arterial catheterization for nine or more days (odds ratio, 29.5; P=0.027), and exposure to Nurse A (odds ratio, 74.7; P=0.004). In a point-prevalence survey, 9 additional infants, 1 health care worker, and 12 of the health care workers' pet dogs had positive cultures for M. pachydermatis. The isolates from all 15 case patients, the 9 additional colonized infants, 1 health care worker, and 3 of the 12 dogs had identical patterns of restriction-fragment-length polymorphisms. CONCLUSIONS: In this outbreak, it is likely that M. pachydermatis was introduced into the intensive care nursery on health care workers' hands after being colonized from pet dogs at home. The organism persisted in the nursery through patient-to-patient transmission.

Animals↗

Pityriasis versicolor with a unique clinical appearance.

We experienced an atypical case of pityriasis versicolor with a unique clinical appearance and undescribed mycological features. Although Malassezia sp. was cultured from the keratotic material, the fungal elements observed in the material were not readily identified as Malassezia. The diagnosis was established with the aid of immunohistochemical and ultrastructural studies with the aetiological agent being identified as M. globosa.

Diagnosis, Differential↗

Polymerase chain reaction and restriction fragment length polymorphism mediated detection and speciation of Candida spp causing intraocular infection.

PURPOSE: To determine the usefulness of polymerase chain reaction (PCR) and restriction fragment length polymorphism (RFLP) analysis in the identification and speciation of Candida spp that causes ocular infection. METHODS: Oligonucleotide primers based on the cytochrome P450 L1 A1 demethylase gene were used to successfully amplify by PCR a single 1.0-kb and a single 500-bp DNA fragment from C. albicans, C. tropicalis, C. krusei, C. glabrata, C. parapsilosis, and C. pelliculosa genomic DNA. RFLPs within the PCR product were identified after restriction enzyme digestion. RESULTS: The sensitivity of the amplification reaction after two rounds of PCR was 10 fg genomic C. albicans DNA or one copy of the gene. No amplification product was obtained when DNA from C. guilliermondii, Aspergillus fumigatus, Fusarium solani, human leukocytes, or 10 species of bacteria was used as a template. Experiments with spiked normal vitreous demonstrated equal sensitivity as long as the volume of vitreous did not exceed 20% of the total PCR volume. RFLP analysis of the PCR product generated from each species obtained from the first- and second-round amplification products enabled species identification after digestion with specific endonucleases. Application of the technique to four clinical samples was successful. CONCLUSIONS: It is expected that the simplicity of the DNA extraction technique allied with the broad specificity of the outer primers for all ophthalmically relevant Candida spp and the sensitivity of the second-round PCR will aid in the detection of fungal DNA in small intraocular samples. PCR-RFLP analysis has great potential in the rapid detection and identification of Candida spp and in the provision of a useful laboratory tool for the future.

Aqueous Humor↗

The genus Malassezia with description of four new species.

The genus Malassezia has been revised using morphology, ultrastructure, physiology and molecular biology. As a result the genus has been enlarged to include seven species comprising the three former taxa M. furfur, M. pachydermatis and M. sympodialis, and four new taxa M. globosa, M. obtusa, M. restricta and M. slooffiae. The descriptions of all the species include morphology of the colonies and of the cells, together with ultrastructural details. The physiological properties studied were the presence of catalase, the tolerance of 37 degrees C and the ability to utilize certain concentrations of Tween 20, 40, 60 and 80 as a source of lipid in a simple medium. Information is given for each of the taxa on mole% GC and also the rRNA sequence from the comparison previously described for the genus.

Catalase↗

Nail infections.

The increasing prevalence of onychomycoses, along with the wider range of organisms now recognized as potential pathogens, necessitates the accurate laboratory identification of the specific fungus involved. Although the majority of infections still are caused by dermatophyte and Candida species, many other nondermatophyte molds, such as Scytalidium dimidiatum, have been shown to be common agents of disease in certain geographic areas. It is well recognized that infections by nondermatophytes such as Scopulariopsis, Acremonium, and Aspergillus species occur worldwide. The availability of a range of new antifungal agents with various spectra of activity means that the exact identification of the pathogen is necessary to select the optimum treatment.

Fungi↗

Tinea capitis in south-east London--a new pattern of infection with public health implications.

Recent observations on tinea capitis cases in London suggest that there has been a change in the pattern of infection with a recent and significant rise in the incidence of infections due to anthropophilic fungi. The purpose of this study was to investigate the prevalence and identity of tinea capitis in schools in south-east London and factors which might affect the spread of infection. This was achieved by carrying out a survey of all children, with parental consent for scalp examination, in 14 nursery, infant or junior schools in Lambeth. In addition, the accuracy of clinical diagnosis was compared with mycological findings. There were 1057 children from 4 to 14 years of age in the study. The infection rate in different schools ranged from 0 to 12% with a mean of 2.5%. A further 4.9% of children were scalp carriers of dermatophytes (range in classes 0-47%). A striking feature was that all infections were caused by anthropophilic fungi, mainly Trichophyton tonsurans or Microsporum rivalieri, and there was a correlation between the presence of two or more carriers within a class and the infection in the other children. There was a poor correlation between ability of trained observers to predict infection on clinical grounds and mycological results. This investigation shows variable but significant levels of scalp ringworm in schools and that the dominant organisms are anthropophilic. It provides support for the observation that there has been a shift in the pattern of tinea capitis in London and, possibly, other U.K. centres, with a trend towards more infections transmissible among children, with T, tonsurans being the commonest organism. The implications for control, which involve screening in schools, where appropriate, and guidance to general practitioners on treatment, are discussed.

Carrier State↗

Adherence of Malassezia isolates to human keratinocytes in vitro--a study of HIV-positive patients with seborrhoeic dermatitis.

Adherence of Malassezia yeast cells to human keratinocytes was assessed by a novel technique using double-sided Sellotape. Although adherence using double-sided Sellotape is still merely a model for in vivo adherence, it approximates to the conditions found on the skin surface. There were no differences in adhesive properties to human keratinocytes between Malassezia strains originating from HIV-positive and HIV-negative patients with seborrhoeic dermatitis, nor was there a relationship between the severity of seborrhoeic dermatitis and in vitro adherence to human keratinocytes.

Adult↗

HIV disease and Malassezia yeasts: a quantitative study of patients presenting with seborrhoeic dermatitis.

Seborrhoeic dermatitis (SD) is a disease that affects 1-3% of the general population, 3-5% of young adults and 20-83% of patients with AIDS. Malassezia yeasts have been associated with the pathogenesis of this condition. The association between the Malassezia yeasts and HIV-related SD is still a controversial subject. The objective of our study was to investigate the role of Malassezia yeasts in the pathogenesis of SD in the HIV population comparing the number of yeasts' cells with the severity of the disease and degree of immunosuppression. We used two quantitative counting methods: direct counting with Sellotape-stripped skin and recovery of the yeasts in culture using contact plates. This investigation has demonstrated that there is a trend between numbers of yeasts present on lesional skin, severity of SD and CD4-positive T lymphocytes count in HIV-positive patients. No quantitative differences were observed between HIV-related and non-HIV related SD.

Adult↗

Mycology of nail disorders.

Cases of onychomycosis represent up to 30% of diagnosed superficial fungal infections and are caused by three groups of fungi: dermatophytes, yeasts, and nondermatophytic molds. The majority of toenail infections are caused by dermatophytes; Trichophyton rubrum is isolated with the greatest frequency. In infections of fingernails, Candida species can be isolated as frequently as the dermatophytes. Of the molds, Scytalidium species can infect both fingernails and toenails, as well as adjacent skin, and represent 3% of the nail infections in a temperate country such as the United Kingdom but a much higher proportion in tropical countries. Other molds such as Scopulariopsis, Acremonium, and Aspergillus species can infect damaged nails. The isolation of a dermatophyte is always considered indicative of infection, but the presence of other molds, which may be aerial contaminants, must be interpreted with care.

Arthrodermataceae↗