Antifungal susceptibility of invasive yeast isolates in Italy: the GISIA3 study in critically ill patients

Abstract

BackgroundYeasts are a common cause of invasive fungal infections in critically ill patients. Antifungal susceptibility testing results of clinically significant fungal strains are of interest to physicians, enabling them to adopt appropriate strategies for empiric and prophylactic therapies. We investigated the antifungal susceptibility of yeasts isolated over a 2-year period from hospitalised patients with invasive yeast infections.Methods638 yeasts were isolated from the blood, central venous catheters and sterile fluids of 578 patients on general and surgical intensive care units and surgical wards. Etest strips and Sensititre panels were used to test the susceptibility of the isolates to amphotericin B, anidulafungin, caspofungin, fluconazole, itraconazole, posaconazole and voriconazole in 13 laboratories centres (LC) and two co-ordinating centres (CC). The Clinical and Laboratory Standards Institute (CLSI) reference broth microdilution method was used at the CCs for comparison.ResultsEtest and Sensititre (LC/CC) MIC90 values were, respectively: amphotericin B 0.5/0.38, 1/1 mg/L; anidulafungin 2/1.5 and 1/1 mg/L; caspofungin 1/0.75 and 0.5/0.5 mg/L; fluconazole 12/8 and 16/16 mg/L; itraconazole 1/1.5, 0.5/0.5 mg/L; posaconazole 0.5 mg/L and voriconazole 0.25 mg/L for all. The overall MIC90 values were influenced by the reduced susceptibility of Candida parapsilosis isolates to echinocandins and a reduced or lack of susceptibility of Candida glabrata and Candida krusei to azoles, in particular fluconazole and itraconazole. Comparison of the LC and CC results showed good Essential Agreement (90.3% for Etest and 92.9% for Sensititre), and even higher Categorical Agreement (93.9% for Etest and 96% for Sensititre); differences were observed according to the species, method, and antifungal drug. No cross-resistance between echinocandins and triazoles was detected.ConclusionsOur data confirm the different antifungal susceptibility patterns among species, and highlight the need to perform antifungal susceptibility testing of clinically relevant yeasts. With the exception of a few species (e.g. C. glabrata for azoles and C. parapsilosis for echinocandins), the findings of our study suggest that two of the most widely used commercial methods (Etest and Sensititre) provide valid and reproducible results.

Correlation Between Candida Albicans Biofilm Formation and Invasion of the Invertebrate Host Galleria Mellonella

“…Twenty out of 142 clinical isolates of C. albicans collected during an Italian National survey on invasive fungal infection in ICU [16] were used to assess whether biofilm production can be a hallmark of virulence in vivo. The 20 strains were selected for further experiments based on their high reproducibility or constant incapacity to form biofilm in vitro.…”

“…The primary aim of this work was to assess the pathogenic role of filamentation and biofilm formation in a subset of C. albicans isolates collected from cases of invasive infections in patients hospitalized in medical or surgical ICU [16]. To simulate invasive infections, the virulence potential of biofilm was determined in the G. mellonella model comparing biofilm producer (BP) and nonproducer (NP) invasive C. albicans strains.…”

Epidemiology and Changes in Patient-Related Factors from 1997 to 2009 in Clinical Yeast Isolates Related to Dermatology, Gynaecology, and Paediatrics

“…Nevertheless, in the DGP wards, the increase in NCA strains followed those found in the other medical specialities [15, 16, 20, 21, 26, 29, 34, 54, 55, 61, 64, 66]. A summary of the distribution of Candida species in epidemiological surveys of the last decades was given in [66–68].…”

Antifungal resistance does not necessarily affectCandida glabratafitness

“…2,27 This therapeutic choice could have been made because of the previous exposure of the patient to azoles, and because two of the three available echinocandins were still having MIC values compatible with the proposed MIC interpretive breakpoints for susceptibility at that time. 28,29 We have to consider that often physicians initiate antifungal treatment without regard to in vitro data, which arrive too late and when the patient starts to improve. 2,11 In a retrospective study, Shields and co-workers suggested that the FKS genotype is a better indicator of echinocandin therapeutic failure than MIC alone.…”