Cross-resistance among antifungal agents
Cross-resistance among azoles is expected as the target of action on fungi is similar. In HIV- positive patients a high level of cross- resistance to itraconazole was observed in fluconazole–resistant C. glabrata and C. tropicalis compared with C. albicans and C. krusei isolates28. Cross-resistance in
C. glabrata strains was
expression of CgCDR1, CgCDR2 genes and CDR efflux pumps. Though voriconazole also has cross-resistance with other azoles, the rate is low, and after performing in vitro susceptibility testing it may be used in patients who have previously been exposed to fluconazole or itraconazole6. However, in a study conducted in India, high cross-resistance to fluconazole, itraconazole and voriconazole was reported in C. albicans and C. tropicalis blood isolates, though the mechanism of resistance was not studied.14 Cross-resistance has been observed among the three echinocandins.17, 18 Cross-resistance should not be expected between the echinocandin class of drugs and either the polyene or azoles, as the sites of action are different.
due to increased