Search

ABSTRACTAspergillusspp. are among the most common causes of opportunistic invasive fungal infections in tertiary care hospitals. Little is known about the prevalence and in vitrosusceptibility of Aspergillusspecies in Latin America, because there are few medical centers able to perform accurate identification at the species level. The purpose of this study was to analyze the distribution of cryptic and rare Aspergillusspecies among clinical samples from 133 patients with suspected aspergillosis admitted in 12 medical centers in Brazil and to analyze the in vitroactivity of different antifungal drugs. The identification of Aspergillusspecies was performed based on a polyphasic approach, as well as sequencing analysis of the internal transcribed spacer (ITS) region, calmodulin, and ß-tubulin genes and phylogenetic analysis when necessary. The in vitrosusceptibility tests with voriconazole, posaconazole, and itraconazole were performed according to the CLSI M38-A2 document (2008). We demonstrated a high prevalence of cryptic species causing human infection. Only three isolates, representing the species Aspergillus thermomutatus, A. ochraceus, and A. calidoustus, showed less in vitrosusceptibility to at least one of the triazoles tested. Accurate identifications of Aspergillusat the species level and with in vitrosusceptibility tests are important because some species may present unique resistance patterns against specific antifungal drugs.

Although the Sensititre Yeast-One (SYO) and Etest methods are widely utilized, interpretive criteria are not available for triazole susceptibility testing of Candidaor Aspergillusspecies. We collected fluconazole, itraconazole, posaconazole, and voriconazole SYO and Etest MICs from 39 laboratories representing all continents for (method/agent-dependent) 11,171 Candida albicans, 215 C. dubliniensis, 4,418 C. glabrataspecies complex, 157 C.guilliermondii(Meyerozyma guilliermondii), 676 C. krusei(Pichia kudriavzevii), 298 C.lusitaniae(Clavispora lusitaniae), 911 C.parapsilosissensu stricto, 3,691 C.parapsilosisspecies complex, 36 C.metapsilosis, 110 C.orthopsilosis, 1,854 C.tropicalis, 244 Saccharomyces cerevisiae, 1,409 Aspergillus fumigatus, 389 A.flavus, 130 A.nidulans, 233 A.niger, and 302 A.terreuscomplex isolates.

ABSTRACTEstimating epidemiological cutoff endpoints (ECVs/ECOFFS) may be hindered by the overlap of MICs for mutant and nonmutant strains (strains harboring or not harboring mutations, respectively). Posaconazole MIC distributions for the Aspergillus fumigatusspecies complex were collected from 26 laboratories (in Australia, Canada, Europe, India, South and North America, and Taiwan) and published studies. Distributions that fulfilled CLSI criteria were pooled and ECVs were estimated. The sensitivity of three ECV analytical techniques (the ECOFFinder, normalized resistance interpretation [NRI], derivatization methods) to the inclusion of MICs for mutants was examined for three susceptibility testing methods (the CLSI, EUCAST, and Etest methods). The totals of posaconazole MICs for nonmutant isolates (isolates with no known cyp51Amutations) and mutant A. fumigatusisolates were as follows: by the CLSI method, 2,223 and 274, respectively; by the EUCAST method, 556 and 52, respectively; and by Etest, 1,365 and 29, respectively. MICs for 381 isolates with unknown mutational status were also evaluated with the Sensititre YeastOne system (SYO). We observed an overlap in posaconazole MICs among nonmutants and cyp51Amutants. At the commonly chosen percentage of the modeled wild-type population (97.5%), almost all ECVs remained the same when the MICs for nonmutant and mutant distributions were merged: ECOFFinder ECVs, 0.5 μg/ml for the CLSI method and 0.25 μg/ml for the EUCAST method and Etest; NRI ECVs, 0.5 μg/ml for all three methods. However, the ECOFFinder ECV for 95% of the nonmutant population by the CLSI method was 0.25 μg/ml. The tentative ECOFFinder ECV with SYO was 0.06 μg/ml (data from 3/8 laboratories). Derivatization ECVs with or without mutant inclusion were either 0.25 μg/ml (CLSI, EUCAST, Etest) or 0.06 μg/ml (SYO). It appears that ECV analytical techniques may not be vulnerable to overlap between presumptive wild-type isolates and cyp51Amutants when up to 11.6% of the estimated wild-type population includes mutants.