Characterisation of an ABC transporter of a resistant Candida glabrata clinical isolate

BACKGROUND Candida glabrata ranks second in epidemiological surveillance studies, and is considered one of the main human yeast pathogens. Treatment of Candida infections represents a contemporary public health problem due to the limited availability of an antifungal arsenal, toxicity effects and increasing cases of resistance. C. glabrata presents intrinsic fluconazole resistance and is a significant concern in clinical practice and in hospital environments. OBJECTIVE The aim of this study was to characterise the azole resistance mechanism presented by a C. glabrata clinical isolate from a Brazilian university hospital. METHODS Azole susceptibility assays, chemosensitisation, flow cytometry and mass spectrometry were performed. FINDINGS Our study demonstrated extremely high resistance to all azoles tested: fluconazole, voriconazole, posaconazole and itraconazole. This isolate was chemosensitised by FK506, a classical inhibitor of ABC transporters related to azole resistance, and Rhodamine 6G extrusion was observed. A mass spectrometry assay confirmed the ABC protein identification suggesting the probable role of efflux pumps in this resistance phenotype. MAIN CONCLUSIONS This study emphasizes the importance of ABC proteins and their relation to the resistance mechanism in hospital environments and they may be an important target for the development of compounds able to unsettle drug extrusion.

Antifungal pharmacodynamics: Latin America's perspective

Abstract The current increment of invasive fungal infections and the availability of new broad-spectrum antifungal agents has increased the use of these agents by non-expert practitioners, without an impact on mortality. To improve efficacy while minimizing prescription errors and to reduce the high monetary cost to the health systems, the principles of pharmacokinetics (PK) and pharmacodynamics (PD) are necessary. A systematic review of the PD of antifungals agents was performed aiming at the practicing physician without expertise in this field. The initial section of this review focuses on the general concepts of antimicrobial PD. In vitro studies, fungal susceptibility and antifungal serum concentrations are related with different doses and dosing schedules, determining the PD indices and the magnitude required to obtain a specific outcome. Herein the PD of the most used antifungal drug classes in Latin America (polyenes, azoles, and echinocandins) is discussed.

Extracellular phospholipase production of oral Candida albicans isolates from smokers, diabetics, asthmatics, denture wearers and healthy individuals following brief exposure to polyene, echinocandin and azole antimycotics

Abstract Objective Candida albicans is the primary causative agent of oral candidosis, and one of its key virulent attributes is considered to be its ability to produce extracellular phospholipases that facilitate cellular invasion. Oral candidosis can be treated with polyenes, and azoles, and the more recently introduced echinocandins. However, once administered, the intraoral concentration of these drugs tend to be sub-therapeutic and rather transient due to factors such as the diluent effect of saliva and cleansing effect of the oral musculature. Hence, intra-orally, the pathogenic yeasts may undergo a brief exposure to antifungal drugs. We, therefore, evaluated the phospholipase production of oral C. albicans isolates following brief exposure to sub-therapeutic concentrations of the foregoing antifungals. Materials and methods Fifty C. albicans oral isolates obtained from smokers, diabetics, asthmatics using steroid inhalers, partial denture wearers and healthy individuals were exposed to sub-therapeutic concentrations of nystatin, amphotericin B, caspofungin, ketoconazole and fluconazole for one hour. Thereafter the drugs were removed and the phospholipase production was determined by a plate assay using an egg yolk-agar medium. Results The phospholipase production of these isolates was significantly suppressed with a percentage reduction of 10.65, 12.14, 11.45 and 6.40% following exposure to nystatin, amphotericin B, caspofungin and ketoconazole, respectively. This suppression was not significant following exposure to fluconazole. Conclusions Despite the sub-therapeutic, intra oral, bioavailability of polyenes, echinocandins and ketoconazole, they are likely to produce a persistent antifungal effect by suppressing phospholipase production, which is a key virulent attribute of this common pathogenic yeast.

Paracoccidioidomycosis treatment / Tratamento da paracoccidioidomicose

SUMMARYConsidered to be an emerging endemic mycosis in Latin America, paracoccidioidomycosis is characterized by a chronic course and involvement of multiple organs in immunocompromised hosts. Infection sequelae are mainly related to pulmonary and adrenal insufficiency. The host-parasite interaction results in different expressions of the immune response depending on parasite pathogenicity, fungal load and genetic characteristics of the host. A few controlled and case series reports have shown that azoles and fast-acting sulfa derivatives are useful treatment alternatives in milder forms of the disease. For moderate/severe cases, more prolonged treatments or even parenteral routes are required especially when there is involvement of the digestive tract mucosa, resulting in poor drug absorption. Although comparative studies have reported that shorter treatment regimens with itraconazole are able to induce cure in chronically-infected patients, there are still treatment challenges such as the need for more controlled studies involving acute cases, the search for new drugs and combinations, and the search for compounds capable of modulating the immune response in severe cases as well as the paradoxical reactions.

RESUMOConsiderada micose endêmica emergente na América Latina, a paracoccidioidomicose é caracterizada por uma evolução crônica e envolvimento de múltiplos órgãos em pacientes com comprometimento imunológico. Sequelas da infecção estão relacionadas principalmente à insuficiência pulmonar e adrenal. A interação hospedeiro-parasito resulta em diferentes expressões da resposta imune dependendo da patogenicidade do parasito, carga fúngica e características genéticas do hospedeiro. Alguns estudos controlados e séries de casos têm demonstrado que azóis de ação rápida e derivados de sulfa constituem alternativas terapêuticas úteis nas formas mais leves da doença. Para casos moderados/graves, tratamentos mais prolongados ou mesmo por via parenteral são necessários especialmente quando há envolvimento de mucosa do trato digestivo, resultando em absorção deficiente de drogas. Embora estudos comparativos tenham relatado que esquemas terapêuticos mais curtos com itraconazol sejam capazes de induzir cura em pacientes cronicamente infectados, ainda existem desafios no tratamento, tais como a necessidade de maior número de estudos controlados envolvendo casos agudos, busca por novas drogas e combinações, compostos capazes de modular a resposta imune nos casos graves, e reações paradoxais.

Antifúngicos em infecções oculares: drogas e vias de administração / Antifungals in eye infections: drugs and routes of administration

O tratamento das infecções oculares por fungos representa um desafio à prática oftalmológica. Para obtermos resposta terapêutica adequada, além do uso da droga correta, é necessária a administração desta de forma eficaz. Este manuscrito reúne informações a respeito das principais drogas antifúngicas utilizadas em infecções oculares, suas concentrações e principais vias de administração.

Treatment of fungal eye infections represents a challenge to the ophthalmology practice. For an adequate therapeutic response, besides correct drug choice, it is necessary an effectively administration. This script gathers information about the major antifungal drugs used in eye infections, their concentrations and main administration routes.

Criptococosis meníngea asociada al SIDA. Análisis de los pacientes varones HIV (+) con criptococosis meníngea internados en la Sala 11 del Hospital Francisco J Muñiz / Meningeal cryptococcosis associated with AIDS. Analysis of male HIV (+) patients with internal meningeal cryptococcosis in Room 11 of Francisco J Muñiz Hospital

La criptococosis es una micosis sistémica oportunista con distribución universal causada por una levadura capsulada. El Cryptococcus neoformans (C. neoformans). C. neoformans infecta al hombre y a animales susceptibles por vía inhalatoria, provocando en huéspedes inmunocompetentes una primoinfección asintomática. Crece preferentemente en ambientes ricos con componentes nitrogenados, principalmente a partir de las excretas desecadas de las palomas que son ricas en nitrógeno y creatinina, con alto contenido en sales y pH alcalino, cualidades que facilitan la supervivencia del hongo. La diseminación hematógena del agente causal provoca múltiples localizaciones, las cuales se hacen clínicamente evidentes en pacientes con deterioro de la inmunidad mediada por células. A partir de la eclosión del SIDA se produjo un aumento significativo del número de casos, transformándose esta última condición en la causa predisponente más importante de esta micosis. La mayoría de los pacientes con SIDA y criptococosis del SNC presentan signos y síntomas de meningitis o meningoencefalitis subagudas como cefalea, fiebre, parálisis de nervios craneales, letargo, coma o amnesia de varias semanas de evolución. La anfotericina B es el pilar terapéutico del tratamiento. En nuestro estudio analizamos las características demográficas, epidemiológicas, clínicas, el líquido cefalorraquídeo, el diagnóstico micológico y el tratamiento empleado en los pacientes hospitalizados en Sala 11 con diagnóstico de criptococosis meníngea. En la criptococosis meníngea asociada al SIDA, el diagnóstico puede realizarse por el análisis de distintos tipos de especímenes biológicos, siendo los principales el examen microscópico directo del LCR con tinción de tinta china y el cultivo.

Cryptococcosis is a fungal opportunistic infection systemic who has universal distribution, caused by capsulated yeast, Cryptococcus neoformans. C. neoformans infects humans and susceptible animals by inhalation, causing an asymptomatic primary infection in immunocompetent hosts. It grows preterentially in rich environments with nitrogen components, mainly from dried excreta of pigeons that are rich in nitrogen and creatinine, with a high salt content and alkaline pH, qualities which facilitate the survival of the fungus. Haematogenous dissemination of the causative agent leads to multiple locations, which are clinically evident in patients with impairment of cell-mediated immunity. Since the emergence of AIDS, it was a significant in crease in the number of cases, who becomes in the most important predisposing cause of this mycosis. Most patients with AIDS and CNS cryptococcosis have signs and symptoms of subacute meningitis or meningoencephalitis as headache, fever, cranial nerve palsy, lethargy, coma or amnesia of several weeks of evolution. Amphotericin B therapy is the mainstay of treatment. We analyzed the demographic, epidemiological, clinical, cerebrospinal fluid, mycological diagnosis and treatment used for hospitalized patients in the unit 11 of the Infectious Disease Hospital Muñiz with the diagnosis of meningeal cryptococcosis. In meningeal cryptococcosis associated with AIDS, the diagnosis can be performed by the analysis of different types of biological specimens, mainly direct microscopic examination of CSF with India ink staining and culture.

New Antifungal Agents in Pediatric Practice.

Clinical needs for new antifungal agents have steadily increased with the rise and alteration in spectrum of invasive mycoses in children and neonates having AIDS, malignancies and undergoing immunosuppressive therapies. Several new options are now available for management of serious fungal infections. The aim of this review is to summarize the key features of the new antifungal agents and novel targets being investigated for the treatment of fungal infections, with special reference to its use in the treatment of pediatric fungal infections. New triazoles have broad spectrum of activity with voriconazole presently being the drug of choice against invasive aspergillosis, and posaconazole is the possible first substitute of amphotericin B against zygomycosis. Echinocandins with new mode of action of inhibition of fungal cell wall polysaccharide synthesis are effective in treating candidemia and invasive candidiasis. Some of these agents are however, still awaiting FDA approval for their use in pediatric practice.

Antifungal susceptibility testing of yeast isolated from corneal infections

PURPOSE: To report the antifungal susceptibility profile of yeast isolates obtained from cases of keratitis. METHODS: Susceptibility testing of 15 yeast strains isolated from corneal infections to amphotericin B, fluconazole, itraconazole and ketoconazole was performed using the NCCLS broth microdilution assay. RESULTS: Most episodes of eye infections were caused by Candida albicans. The antifungal drugs tested showed the following minimal inhibitory concentration values against yeast isolates: 0.125-0.5 µg/ml for amphotericin B; 0.125->64.0 µg/ml for fluconazole; 0.015-1.0 µg/ml for itraconazole and 0.015-0.125 µg/ml for ketoconazole. Despite the fact that all Candida isolates were judged to be susceptible to azoles, one isolate showed a minimal inhibitory concentration value significantly higher than a 90 percent minimal inhibitory concentration of all tested isolates. Rhodotorula rubra was resistant to fluconazole and itraconazole. CONCLUSIONS: Despite the fact that most yeast isolates from corneal infections are usually susceptible to amphotericin B and azoles, they exhibit a wide range of minimal inhibitory concentration values for antifungal drugs. The identification of strains at species level and their susceptibility pattern to antifungal drugs should be considered before determining the concentration to be used in topical antifungal formulations in order to optimize therapeutic response in eye infections.

Aetiology of vaginal infections in pregnant and non-pregnant women in Barbados

The aetiology of vaginal discharge was studied in 175 Barbadian women. Pregnant women accounted for 52 percent (91) of the population studied. Candida albicans was detected in 45 percent of the women, bacterial vaginosis in 28 percent and Trichomonas vaginalis in 8.6 percent. Bacterial vaginosis was more common in non-pregnant women (33 percent vs 23 per cent) whereas C. albicans was more common in pregnant women. Mixed infections were found in 10 women and an aetiological agent was detected in 75 percent of the women studied. These data emphasize the need for laboratory investigation of vaginal discharge since each of these infections can be treated effectively with specific agents