Invasive scedosporiosis in lung transplant recipients: A nine-year retrospective study in a tertiary care hospital.

BACKGROUND: Scedosporium species and Lomentospora prolificans (Sc/Lp) are emerging molds that cause invasive disease associated with a high mortality rate. After Aspergillus, these molds are the second filamentous fungi recovered in lung transplant (LT) recipients. AIMS: Our objective was to evaluate the incidence, risk factors and outcome of Sc/Lp infections in LT recipients at a tertiary care hospital with a national reference LT program. METHODS: A nine-year retrospective study was conducted. RESULTS: During this period, 395 LT were performed. Positive cultures for Sc/Lp were obtained from twenty-one LT recipients. Twelve patients (incidence 3.04%) developed invasive scedosporiosis (IS). In 66.7% of the patients with IS the invasive infection was defined as a breakthrough one. The main sites of infection were lungs and paranasal sinuses. Most of the patients received combination antifungal therapy. The IS crude mortality rate after 30 days was 16.7%, and 33.3% after a year. CONCLUSIONS: Our study highlights improved survival rates associated with combination antifungal therapy in LT recipients and underlines the risk of breakthrough infections in patients with allograft dysfunction on nebulized lipidic amphotericin B prophylaxis. In addition to pretransplant colonization, acute or chronic organ dysfunctions seem to be the main risk factors for IS.

In vitro activities of echinocandins against Candida krusei determined by three methods: MIC and minimal fungicidal concentration measurements and time-kill studies.

We evaluated the in vitro activities of anidulafungin, micafungin, and caspofungin against Candida krusei by determining MIC and minimum fungicidal concentration (MFC) measurements and by the time-kill method. The geometric mean (GM)-MIC/GM-MFC values were 0.1/0.34, 0.25/0.44, and 1/2.29, respectively. The mean times to reach 99.9% growth reduction were 19.1 +/- 18.2 h (mean +/- standard deviation) for 2 mg/liter anidulafungin, 37.4 +/- 8.8 h for 2 mg/liter caspofungin, and 30.7 +/- 12.2 h for 1 mg/liter micafungin. Anidulafungin exhibited the highest time-kill rate, followed by micafungin. The three echinocandins showed fungicidal activity at concentrations reached in serum.

Comparison of posaconazole and voriconazole in vitro killing against Candida krusei.

The in vitro activity of posaconazole and voriconazole was evaluated by MIC, minimum fungicidal concentration (MFC), and time-kill methods. MFCs were determined for 15 Candida krusei and time-killing curves for 5 of these isolates. MFCs were obtained transferring 100 microL from clear MIC wells onto Sabouraud dextrose agar. Time-kill studies were performed in RPMI 1640 medium (5 mL, inoculum approximately 10(5) colony-forming unit [CFU]/mL). Geometric mean (GM) MIC and GM-MFC were 0.2 and 0.72 mg/L for posaconazole and 0.4 and 2.64 mg/L for voriconazole. The killing rate was isolate and concentration dependent; reductions in CFUs start at >or=0.12 mg/L (posaconazole) and >or= 0.5 mg/L (voriconazole). The mean time to reach a 90% growth reduction was 41.5+/-14.2 h (8 mg/L posaconazole) and 48.7+/-61.3 h (32 mg/L voriconazole). By time kill, a 99% killing rate was not reached by either agent. Both methods demonstrated that posaconazole (more active and greater killing rate) and voriconazole have fungicidal activity against C. krusei.

[Activity of anidulafungin against Candida biofilms]. / Actividad de la anidulafungina sobre biopelículas de Candida.

Currently, no standardized method to study the in vitro activity of antifungal agents on biofilms is available, thus, the comparison among different authors is difficult. The studies discussed in this review use the XTT reduction to measure the activity of antifungals on biofilms of 24 h of maturation. To date, biofilm anidulafungin MICs of 47 isolates of Candida spp. (25 Candida albicans, 16 Candida tropicalis, 5 Candida dubliniensis and 1 Candida parapsilosis) have been published. The geometric mean MIC of anidulafungin on biofilms of Candida spp. is of 1.18 microg/ml. Against isolates of species with great capacity of biofilm formation, the geometric mean MIC is 0.325 (C. albicans), 2 (C. parapsilosis) and 0.5 microg/ml (C. dubliniensis). No echinocandin has activity on C. tropicalis biofilms. In addition, anidulafungin can be used for lock therapy of catheters since it is the echinocandin with the least in vitro paradoxical effect.

[In vitro activity of amphotericin B and anidulafungin against Candida spp. biofilms]. / Actividad in vitro de la anfotericina B y la anidulafungina sobre biopelículas de Candida albicans y Candida tropicalis.

Invasive infections caused by Candida spp. are increasing worldwide and are becoming an important cause of morbidity and mortality in immunocompromised patients. A large number of manifestations of candidiasis are associated with the formation of biofilms on inert or biological surfaces. Candida spp. biofilms are recalcitrant to treatment with conventional antifungal therapies. The aim of this study was dual 1) to determine the prevalence of biofilm producers among clinical isolates from catheter (16 C. albicans ) and blood culture (2 C. albicans and 30 C. tropicalis), and 2) to determine the activity of amphotericin B and anidulafungin against C. albicans and C. tropicalis biofilms of 24 and 48 hours of maturation. Biofilms were developed using a 96-well microtitre plate model and production and activity of antifungal agents against biofilms were determined by the tetrazolium (XTT) reduction assay. Of catheter and blood isolates, 62.5 and 56.25%, respectively, produced biofilms. By species, 68.42% of C. albicans and 53.33% of C. tropicalis were biofilm producers. C. albicans biofilms showed more resistance to amphotericin B and anidulafungin than their planktonic counterparts. Complete killing of biofilms was never achieved, even at the highest concentrations of the drugs tested. Anidulafungin displayed more activity than amphotericin B against C. albicans biofilms of 24 hours of maturation (GM MIC 0.354 vs. 0.686 microg/ml), but against C. tropicalis biofilms amphotericin B was more active (GM MIC 11.285 vs. 0.476 microg/ml). In contrast, against biofilms with 48 hours maturation, amphotericin B was more active against both species.

Activity of Amphotericin B and Anidulafungin Combined with Rifampicin, Clarithromycin, Ethylenediaminetetraacetic Acid, N-Acetylcysteine, and Farnesol against Candida tropicalis Biofilms.

We evaluated the activity of (1) amphotericin-B (AMB), combined with rifampicin (RIF), clarithromycin (CLA), N-acetylcysteine (NAC), ethylenediaminetetraacetic acid (EDTA), and farnesol (FAR) (1000, 1000, 1000, 4000, and 30,000 mg/L, and 300 µM, respectively), against Candida tropicalis biofilms formed on polytetrafluoroethylene (PTFE) and (2) anidulafungin (ANF) combined with the same compounds at 8, 10, 5, 40, and 30 mg/L, and 30 µM, respectively, against biofilms formed on titanium. Biofilm growth kinetics were performed in a CDC Biofilm Reactor (CBR). PTFE or titanium disks were removed from the CBR at 24, 48, 72, and 96 h to determine the Log10CFU/cm². Killing kinetics were performed by adding the drugs to 24-h-mature biofilms (time 0). Disks were removed after 24, 48, and 72 h of drug exposure to determine Log10CFU/cm². Viable cells in biofilms were 4.73 and 4.29 Log10CFU/cm² on PTFE and titanium, respectively. Maximum Log10 decreases in CFU/cm² depend on the combination and were: 3.53 (AMB + EDTA), 2.65 (AMB + RIF), 3.07 (AMB + NAC), 2.52 (AMB + CLA), 1.49 (AMB + FAR), 2.26 (ANF + EDTA), 2.45 (ANF + RIF), 2.47 (ANF + NAC), 1.52 (ANF + CLA), and 0.44 (ANF + FAR). In conclusion, EDTA, NAC, RIF, and CLA improve the activity of AMB and ANF against biofilms developed on both surfaces, which could be an effective strategy against C. tropicalis biofilm-related infections.

[Activity of amphotericin B and anidulafungin, alone and combined, against Candida tropicalis biofilms developed on Teflon® and titanium]. / Actividad de la anfotericina B y la anidulafungina, solas y combinadas, frente a biopelículas de Candida tropicalis formadas sobre Teflon® y titanio.

BACKGROUND: Current therapeutic strategies have a limited efficacy against Candida biofilms that form on the surfaces of biomedical devices. Few studies have evaluated the activity of antifungal agents against Candida tropicalis biofilms. OBJECTIVES: To evaluate the activity of amphotericin B (AMB) and anidulafungin (AND), alone and in combination, against C. tropicalis biofilms developed on polytetrafluoroethylene (teflon -PTFE) and titanium surfaces using time-kill assays. METHODS: Assays were performed using the CDC Biofilm Reactor equipped with PTFE and titanium disks with C. tropicalis biofilms after 24h of maturation. The concentrations assayed were 40mg/l for AMB and 8mg/l for AND, both alone and combined. After 24, 48 and 72h of exposure to the antifungals, the cfu/cm2 was determined by a vortexing-sonication procedure. RESULTS: AMB reduced biofilm viable cells attached to PTFE and titanium by ≥99% and AND by 89.3% on PTFE and 96.8% on titanium. The AMB+AND combination was less active than AMB alone, both on PTFE (decrease of cfu/cm2 3.09 Log10vs. 1.08 when combined) and titanium (4.51 vs. 1.53 when combined), being the interaction irrelevant on both surfaces. CONCLUSIONS: AMB is more active than AND against C. tropicalis biofilms. Yeast killing rates are higher on titanium than on PTFE surfaces. The combination of AMB plus AND is less effective than AMB alone on both surfaces.