Araceli Monzón

Head-to-Head Comparison of the Activities of Currently Available Antifungal Agents against 3,378 Spanish Clinical Isolates of Yeasts and Filamentous Fungi

ABSTRACT We have compared the activities of posaconazole and other currently available antifungal agents against a collection of 3,378 clinical isolates of yeasts and filamentous fungi. A total of 1,997 clinical isolates of Candida spp., 359 of other yeast species, 697 strains of Aspergillus spp., and 325 nondermatophyte non-Aspergillus spp. were included. The average geometric means of the MICs of agents that were tested against Candida spp. were 0.23 μg/ml for amphotericin B, 0.29 μg/ml for flucytosine, 0.97 μg/ml for fluconazole, 0.07 μg/ml for itraconazole, 0.04 μg/ml for voriconazole, 0.15 μg/ml for caspofungin, and 0.03 μg/ml for posaconazole. Voriconazole and posaconazole were active in vitro against the majority of isolates, with resistance to fluconazole and itraconazole, and against Cryptococcus neoformans and other Basidiomycota yeasts. Posaconazole was the most active of antifungal agents tested against Aspergillus spp., with an average geometric mean of 0.10 μg/ml. It was active against Paecilomyces spp., Penicillium spp., Scedosporium apiospermum, and some black fungi, such as Alternaria spp. Multiresistant filamentous fungi, such as Scedosporium prolificans, Scopulariopsis brevicaulis, and Fusarium solani, were also resistant to voriconazole, caspofungin, and posaconazole. Amphotericin B and posaconazole were found to be active against most of the Mucorales strains tested. Posaconazole and currently available antifungal agents exhibit a potent activity in vitro against the majority of pathogenic fungal species.

Epidemiological Cutoffs and Cross-Resistance to Azole Drugs in Aspergillus fumigatus

ABSTRACT Antifungal susceptibility testing of molds has been standardized in Europe and in the United States. Aspergillus fumigatus strains with resistance to azole drugs have recently been detected and the underlying molecular mechanisms of resistance characterized. Three hundred and ninety-three isolates, including 32 itraconazole-resistant strains, were used to define wild-type populations, epidemiological cutoffs, and cross-resistance between azole drugs. The epidemiological cutoff for itraconazole, voriconazole, and ravuconazole for the wild-type populations of A. fumigatus was ≤1 mg/liter. For posaconazole, the epidemiological cutoff was ≤0.25 mg/liter. Up till now, isolates susceptible to itraconazole have not yet displayed resistance to other azole drugs. Cross-resistance between azole drugs depends on specific mutations in cyp51A. Thus, a substitution of glycine in position 54 of Cyp51A confers cross-resistance between itraconazole and posaconazole. A substitution of methionine at position 220 or a duplication in tandem of a 34-bp fragment in the cyp51A promoter combined with a substitution of leucine at position 98 for histidine confers cross-resistance to all azole drugs tested. The results obtained in this study will help to develop clinical breakpoints for azole drugs and A. fumigatus.

Antifungal susceptibility profile of clinical Fusarium spp. isolates identified by molecular methods

OBJECTIVES To analyse the susceptibility pattern of a collection of Fusarium clinical isolates. METHODS The antifungal susceptibility pattern of 67 isolates of Fusarium was analysed. Strains were identified by morphological and molecular methods by means of sequencing elongation factor alpha. RESULTS AND CONCLUSIONS Six different species were identified. Fusarium solani was the most frequently isolated, followed by Fusarium oxysporum, Fusarium proliferatum and Fusarium verticilloides. Amphotericin B was the only drug with in vitro activity (range: 0.015-32 mg/L). The rest of the antifungals tested (itraconazole, voriconazole, ravuconazole, posaconazole and terbinafine) showed very poor activity against Fusarium, confirming the multiresistant nature of this genus.

In Vitro Activities of Three Licensed Antifungal Agents against Spanish Clinical Isolates of Aspergillus spp.

ABSTRACT The aim of the present study was to identify retrospectively trends in the species distributions and the susceptibility patterns of Aspergillus species causing fungal infections in Spanish medical centers from 2000 to 2002. The susceptibilities of 338 isolates to amphotericin B, itraconazole, and voriconazole were tested. Aspergillus fumigatus was the most common species (54.7%), followed by Aspergillus terreus (14.8%) and Aspergillus flavus (13.9%). Non-A. fumigatus species were encountered in 45.3% of the samples studied. The majority of Aspergillus isolates were obtained from respiratory tract specimens, followed by ear and skin samples. The geometric mean (GM) MIC of amphotericin B was 0.56 μg/ml, and the amphotericin B MIC was >2 μg/ml for 16 isolates (4.7%). Nine of them were A. terreus. The GM MIC of itraconazole was 0.37, and the itraconazole MIC was >4 μg/ml for 12 (3.5%) isolates. The voriconazole MICs were also high for 8 of the 12 strains for which itraconazole MICs were high (voriconazole MIC range, 2 to 8 μg/ml).

Scopulariopsis brevicaulis, a Fungal Pathogen Resistant to Broad-Spectrum Antifungal Agents

ABSTRACT The antifungal susceptibility results for 32 clinical isolates of Scopulariopsis brevicaulis are presented. Flucytosine and itraconazole were inactive in vitro, and MICs of amphotericin B, voriconazole, and terbinafine for all isolates were high, with geometric means of 13, 25.8, and 14.4 μg/ml, respectively.

Molecular epidemiology and antifungal susceptibility patterns of Sporothrix schenckii isolates from a cat-transmitted epidemic of sporotrichosis in Rio de Janeiro, Brazil

Since 1998 a cat-transmitted epidemic of sporotrichosis has been observed in Rio de Janeiro (RJ), Brazil. Besides the lymphocutaneous and fixed forms, other presentations, such as disseminated cutaneous and mucosal involvement, as well as for the first time, erythema nodosum and erythema multiforme have been reported associated with sporotrichosis. This study investigates the phenotypes and genotypes of Sporothrix schenckii isolates recovered from different clinical forms of the disease noted as part of this epidemic. A total of 88 isolates recovered from 59 cases associated with the epidemic and 29 controls (from cases in other Brazilian regions and Spain) were included in this study. In vitro susceptibility testing was conducted as part of the phenotypic analysis, while the genotypic analysis involved a DNA fingerprinting method with primer M13 and ribosomal DNA sequencing of the internal transcribed spacer (ITS). MIC values of amphotericin B, itraconazole, posaconazole, ravuconazole, and terbinafine were found to be significantly lower (P<0.01) for isolates associated with the epidemic than for control strains. No differences in MIC values were observed related to clinical forms of the infection. Fingerprinting analysis showed that RJ epidemic strains were genetically related. Although nine subtypes were found, they were not associated with specific clinical forms. Similar results were obtained with the ITS sequence analysis. These data suggest that the strains isolated from the epidemic cases of sporotrichosis in RJ all originated from a common source.

Activity of Posaconazole and Other Antifungal Agents against Mucorales Strains Identified by Sequencing of Internal Transcribed Spacers

ABSTRACT The antifungal susceptibility profiles of 77 clinical strains of Mucorales species, identified by internal transcribed spacer sequencing, were analyzed. MICs obtained at 24 and 48 h were compared. Amphotericin B was the most active agent against all isolates, except for Cunninghamella and Apophysomyces isolates. Posaconazole also showed good activity for all species but Cunninghamella bertholletiae. Voriconazole had no activity against any of the fungi tested. Terbinafine showed good activity, except for Rhizopus oryzae, Mucor circinelloides, and Rhizomucor variabilis isolates.

In vitro activity of antifungals against Zygomycetes

To date, no reference standard for therapy for zygomycosis has been established because there are insufficient clinical data with which to make such a judgement. Knowledge of the species responsible for the infection and its antifungal susceptibility profile has become increasingly important in the management of patients. Amphotericin B is the most active drug against all the species involved, followed by posaconazole, whereas voriconazole has no activity. Echinocandins are completely inactive in vitro, but may be an interesting option when used in combination with other drugs.

Prevalence and Susceptibility Testing of New Species of Pseudallescheria and Scedosporium in a Collection of Clinical Mold Isolates

ABSTRACT The prevalence of new species of Pseudallescheria and Scedosporium in a collection of 46 clinical isolates was analyzed. Strain identification was done by morphological and molecular methods. Four Scedosporium aurantiacum isolates were detected among the panel of clinical strains. The susceptibility profile of S. aurantiacum was similar to that of Scedosporium apiospermum.

Comparative in vitro activity of voriconazole and itraconazole against fluconazole-susceptible and fluconazole-resistant clinical isolates of Candida species from Spain.

Abstract The in vitro activity of voriconazole was compared with that of itraconazole against 299 fluconazole-susceptible (MIC≤8 μg/ml) and 130 fluconazole-resistant (MIC≥16 μg/ml) clinical isolates of Candida spp. An adaptation of the National Committee for Clinical Laboratory Standards reference method was employed for determination of MICs. Voriconazole showed more potent activity than either fluconazole and itraconazole, even against some Candidaalbicans, Candidaglabrata, and Candidakrusei isolates resistant to fluconazole. However, for fluconazole-resistant isolates, the MICs of itraconazole and voriconazole were proportionally higher than for fluconazole-susceptible isolates. These data may indicate cross-resistance.