Susceptibility Test for Fungi: Clinical and Laboratorial Correlations in Medical Mycology

Abstract

SUMMARYDuring recent decades, antifungal susceptibility testing has become standardized and nowadays has the same role of the antibacterial susceptibility testing in microbiology laboratories. American and European standards have been developed, as well as equivalent commercial systems which are more appropriate for clinical laboratories. The detection of resistant strains by means of these systems has allowed the study and understanding of the molecular basis and the mechanisms of resistance of fungal species to antifungal agents. In addition, many studies on the correlation of in vitro results with the outcome of patients have been performed, reaching the conclusion that infections caused by resistant strains have worse outcome than those caused by susceptible fungal isolates. These studies have allowed the development of interpretative breakpoints for Candida spp. and Aspergillus spp., the most frequent agents of fungal infections in the world. In summary, antifungal susceptibility tests have become essential tools to guide the treatment of fungal diseases, to know the local and global disease epidemiology, and to identify resistance to antifungals.

Investigating cross‐contamination by yeast strains from dental solid waste to waste‐handling workers by DNA sequencing

“…() published the first Brazilian report involving a clinical isolate of C. haemulonii nonsusceptible to this antifungal drug. Studies attested that antifungal resistance is becoming an emerging problem and secondary resistance to amphotericin B has been described for several yeast species, including C. haemulonii (Alastruey‐Izquierdo, Melhem, Bonfietti, & Rodriguez‐Tudela, ; Ramos et al., ). Following the parameters established by CLSI M27‐A3 (Santos et al., ), samples #5 and 8 (identified as C. guilliermondii by genotypic and automated methods, respectively) and sample #17 (identified as C. haemulonii by conventional and automated methods) were susceptible to caspofungin (MIC ≤ 1).…”

“…Antifungal susceptibility testing was performed according to the Clinical and Laboratory Standards Institute (CLSI, 2008) updated to CLSI 2012 parameters reported by some published papers (Alastruey-Izquierdo et al, 2015;Almeida et al, 2012;Nunes et al, 2013;Orasch et al, 2014;Ramos et al, 2015;Santos et al, 2014). The last edition of CLSI revised the azole and echinocandin clinical breakpoints against Candida species.…”

In vitro susceptibility of dematiaceous fungi to nine antifungal agents determined by two different methods

“…In recent years, several commercial antifungal test products have been introduced, among which YeastOne® method is widely used. This method has the advantages of shortening the test time, simplifying the procedure and facilitating the determination of endpoints . The YeastOne® method has already been applied in Candida , Aspergillus and Dermatophytes, but little is known about its application to black fungi …”

Biguanides enhance antifungal activity against Candida glabrata

“…Clinical strains of other Candida species were obtained from the MGH microbiology lab or Dr. Dimitrios Kontonyanis (MDAnderson Cancer Center). Drug resistant isolates included one dose-dependent fluconazole resistant strain (Strain FR-1), two fluconazole-resistant strains (FR-2, FR-3), three micafungin-resistant strains (MR-1, MR-2, MR-3), and one fluconazole-micafungin double-resistant strain (FR/MR), as determined by Clinical Laboratory and Standards Institute (CSLI) criteria [48]. Antifungal susceptibility testing was confirmed by the MGH microbiology lab using microplate dilution and summarized in Supplemental Table 1.…”

“…Biguanide drug testing was adopted from CLSI microdilution antifungal testing [48]. Candida strains were incubated in RPMI-MOPS media at an inoculum of 200 yeasts per 100µl of media, and the indicated concentration of test drug.…”