An Epidemiologic Update on Invasive Fungal Infections*

Aspergillus and Candida are the 2 major sources of invasive mycoses, and deaths due to these infections have been increasing overall during the past 2 decades. Antimicrobial resistance is an important concern, but the extent of resistance among fungi remains largely undefined. Assessing resistance patterns is essential to determine optimal treatment strategies. For invasive Candida infections, the echinocandins and broad-spectrum triazoles are more potent than fluconazole and amphotericin B against significant clinical isolates of Candida, including the increasing number of fluconazole-resistant isolates (ie, C glabrata and C krusei). For invasive aspergillosis, 2 new approaches have the potential to improve on the hitherto abysmal mortality figures. Voriconazole has potent activity against Aspergillus and appears to be fungicidal, at least in neutropenic rabbit models of invasive aspergillosis. Voriconazole is active against all Aspergillus species and has been shown to be superior to amphotericin B in clinical trials of invasive aspergillosis. Caspofungin treatment of Aspergillus results in decreased angioinvasion and decreased pulmonary infarcts in animal models of invasive aspergillosis. However, its use as a primary therapy or as combination therapy is an outstanding question that still remains to be answered. To correlate in vitro and in vivo data, we suggest the “90-60 rule”: (bacterial or fungal) infections due to susceptible isolates respond to appropriate therapy about 90% of the time, and infections due to resistant isolates or those treated with inappropriate antimicrobials respond about 60% of the time. Our recommendations involve a stepwise approach to using in vitro susceptibility data for selection of fungal therapy. (Adv Stud Med. 2004;4(4A):S269-S275)