Rubén López-Martínez

Candidosis, a new challenge.

Superficial candidosis is a common fungal infection that could become a gateway to systemic spread. Candida albicans is the most important Candida spp; recently, so-called emergent species, such as C dubliniensis, C famata, and C lipolytica have been isolated. This chapter describes the clinical manifestations and laboratory diagnostic techniques, including direct examination, smears, cultures, and physiologic tests. Topical antifungal drugs available for the treatment of superficial candidosis, including imidazoles, triazoles, allylamines, and nystatin, are also discussed. For granulomatous and invasive forms of candidosis, triazoles, allylamines (terbinafine), echinocandins (caspofungin), and amphotericin B are elective therapeutic choices. It is important to eliminate associated predisposing factors that contribute to infection and, if possible, all samples obtained should be evaluated for cases of resistance.

Fungal peritonitis in 15 patients on continuous ambulatory peritoneal dialysis (CAPD)

Peritonitis is a frequent complication in patients with chronic renal failure on continuous ambulatory peritoneal dialysis (CAPD) treatment. The aim of this study was to know the prevalence of fungal peritonitis on patients undergoing CAPD, and to determine the antifungal susceptibility pattern of the identified isolates. Samples of the peritoneal dialysis fluid from 165 patients on CAPD treatment with peritonitis manifestations were submitted to mycological study (direct microscopic examination, culture and antifungal susceptibility test). Ten Candida isolates were identified, being C. albicans and C. parapsilosis the most common species. From isolates obtained, three species (C. albicans, C. parapsilosis, and C. guilliermondii) presented itraconazole resistance while C. glabrata was resistant to both itraconazole and ketoconazole. Aspergillus fumigatus was associated to peritonitis in three cases and Acremonium sp. in two.

Isolation of Cryptococcus neoformans var. neoformans from bird droppings, fruits and vegetables in Mexico City

The presence ofCryptococcus neoformans in various natural sources, such as bird droppings, fruits and vegetables, was investigated. A total of 711 samples were analyzed;C. neoformans var.neoformans was isolated from seven out of 74 bird droppings (9.5%), with parrots as one of the most significant sources. Fruits were positive in 9.5% of the 169 samples studied, specially citrus fruits, particularly grapefruit, in which the highest frequency was found. From the 468 vegetable samples, only 20 were positive (4.2%). It is emphasized that five of the positive vegetables species are autochthonous to Mexico: avocado (Nectandra salicifolia), beet (Beta vulgaris var.quinopodiace), chayote (Sechium edule), stringbean (Cassia sp), and nopal (Opuntia ficus-indica).

Effectiveness of terbinafine in the eradication of Microsporum canis from laboratory cats

Summary. In this study, the coats of 20 cats with no dermatophytosis lesions were sampled for colonization by Microsporum canis, which was isolated in 45% of cases. All cats were treated with oral terbinafine for 3 weeks. The drug was administered orally at a daily dosage 8.25 mg kg−1. Mycologic status was assessed at the end of the treatment; and after follow‐up at 2 days, and 4 and 9 weeks. The final evaluation revealed a complete mycologic cure of all cats by obtaining negative cultures, thereby demonstrating that terbinafine is an effective method of eradication of dermatophyte colonization.

Dermatophytes isolated from laboratory animals

In order to determine the presence of dermatophytes in healthy skin, 200 animals from the animal house of Faculty of Medicine, U.N.A.M., were studied; these were 50 rats, 50 rabbits, 50 mice, and 50 guinea pigs. Out of these 200 animals, 29.5% had positive isolation of Trichophyton mentagrophytes, var. lacticolor. The frequency variation was: rats, 68%; rabbits, 36%; mice, 8%; and guinea pigs, 6%. Male rats and male rabbits, had the higher incidence of positives. The epidemiologic repercussion of these and the significance to use these animals in biomedical investigation is discussed.

Cryptococcus neoformàns var. gattii among patients with cryptococcal meningitis in Mexico. First observations

A retrospective study of 20 patients with cryptococcal meningitis and their isolated strains was performed. Cryptococcus neoformans var. neoformans was recovered from 14 (70%) cases, and var. gattii was recovered from six (30%) patients. Twelve patients had AIDS (all carrying var. neoformans), two had other diseases (one with var. neoformans and one var. gattii) and there was no identifiable underlying disease in six (one var. neoformans and five var. gattii). Fourteen patients (11 var. neoformans and three var. gattii) resided in the Mexico City area, where a temperate climate is prevalent, and there were six cases (three var. neoformans and three var. gattii) from states with a tropical/subtropical climate. Although there was no significant statistical difference between the two varieties, the fatal outcome was higher in patients with var. neoformans. The disease caused by var. gattii strains was characterized by a higher opening pressure, more inflamatory changes of CSF and a longer clinical course (delayed clinical and mycological cure). Cryptococcus neoformans var. gattii is a significant cause of cryptococcal meningitis in patients without underlying diseases in Mexico.

Dermatophytoses in Mexico City.

Summary. We analysed 2350 biological samples from patients with a clinical diagnosis of superficial mycoses who attended outpatient services over a 7‐year period. Samples of scales were processed by direct microscopic examination with 15% KOH and cultured on Sabouraud glucose agar with chloramphenicol and cycloheximide. Laboratory examination confirmed dermatophytosis in 860 (36.6%) cases, of which 80.9% were caused by Trichophyton rubrum. The most frequently observed dermatophytoses were tinea unguium (60%) and tinea pedis (25.6%). In agreement with previous observations, we demonstrate that T. rubrum continues to increase in Mexico.

Resistencia a compuestos azólicos de aislamientos clínicos de Trichophyton spp.

Resumen Ante el aumento de pacientes con dermatofitosis y mala respuesta terapeutica, se estudio la sensibilidad antifungica a itraconazol, ketoconazol y fluconazol por el metodo E-test, en 36 aislamientos clinicos de dermatofitos. Considerando los parametros del Clinical Laboratory Standards Institute, se encontro resistencia a uno o mas antifungicos en siete aislamientos (19,4%): tres de Trichophyton rubrum, tres de Trichophyton mentagrophytes y uno de Trichophyton tonsurans. Un aislamiento de T. rubrum mostro resistencia a los tres azoles y los seis restantes unicamente a fluconazol. Es importante establecer la sensibilidad antifungica como parte del protocolo de estudio de pacientes con dermatofitosis con mala respuesta terapeutica.

Nocardia brasiliensis: in vitro and in vivo growth response to steroid sex hormones

As actinomycetoma is more frequent in males than in females, the possibility that hormones might modify theNocardia brasiliensis growth and the course of experimental actinomycetoma was explored. FiveN. brasiliensis strains were grown on Sabouraud agar containing estradiol, progesterone or testosterone, in 3 different concentrations. Colony diameters were measured weekly for 7 weeks.N. brasiliensis strains were also grown in Sabouraud broth containing hormones. Glucose concentration was measured weekly for 6 weeks. Finally, experimental actinomycetoma was produced in male and female hormone-treated mice. Invasion rate, plantar pad diameter and positive retrocultures were assessed. In vitro experiments showed that progesterone and testosterone inhibitN. brasiliensis growth, manifested by lower colony diameters and greater glucose concentrations. In vivo experiments demonstrated that estradiol limits actinomycetoma development. Progesterone and testosterone induced greater diameters of inoculated plantar pads and greater invasion rates with greater positive culture numbers than estradiol. Results partially explain the resistance of females to actinomycetoma.

Levaduras causantes de onicomicosis en cuatro centros dermatológicos mexicanos y su sensibilidad antifúngica a compuestos azólicos

BACKGROUND Yeasts represent the second cause of nail fungal infection in the world, and Candida albicans and Candida parapsilosis are the two most common species. OBJECTIVES To determine the yeast species frequency and their in vitro antifungal susceptibility, obtained from patients with clinical features suggestive of onychomycosis. METHODS A prospective study was carried out in four dermatological care centers in Mexico from 2004 to 2007. Clinical diagnosis was corroborated by direct examination and culture. The yeast species was determined by morphological and biochemical tests. An antifungal susceptibility test to ketoconazole, itraconazole and fluconazole by the broth microdilution method was performed on each isolate (document M27-A2). RESULTS One hundred sixty-six yeast isolates were obtained; the most frequently found species were C. parapsilosis (31.9%), C. albicans (22.4%) and Candida guilliermondii (12.7%). Of all isolates, 51 showed resistance to one or several of the azole compounds: 33 to itraconazole, 12 to ketoconazole and 6 to fluconazole. It was remarkable that the four Candida glabrata isolates were resistant to the three azole compounds; C. guilliermondii and Candida famata were resistant to itraconazole in 42.9% and 54.5%, respectively. CONCLUSION The results obtained show the importance of identifying the aetiological agent and antifungal susceptibility testing in order to avoid therapeutic failures in onychomycosis.