Acremonium sclerotigenum-Acremonium egyptiacum: a multi-resistant fungal pathogen complicating the course of aplastic anaemia

A patient with aplastic anaemia, successively treated with caspofungin then liposomal amphotericin, developed a disseminated infection due to Acremonium, further confirmed as resistant in vitro to these drugs. Successful treatment was achieved with voriconazole. Multiple antifungal treatments may expose to the risk of breakthrough of multi-resistant pathogens in haematology patients.

Mucormycosis after allogeneic haematopoietic stem cell transplantation: a French Multicentre Cohort Study (2003-2008)

We conducted a nationwide retrospective study to evaluate clinical characteristics and outcome of mucormycosis among allogeneic haematopoietic stem cell transplant recipients. Twenty-nine patients were diagnosed between 2003 and 2008. Mucormycosis occurred at a median of 225 days after allogeneic haematopoietic stem cell transplant, and as a breakthrough infection in 23 cases. Twenty-six patients were receiving steroids, mainly for graft-versus-host disease treatment, while ten had experienced a prior post-transplant invasive fungal infection. Twenty-six patients received an antifungal treatment; surgery was performed in 12. Overall survival was 34% at 3 months and 17% at 1 year.

Pneumocystosis: a network survey in the Paris area 2003-2008

The aims of this network group were to collect epidemiological data of PcP cases in 14 hospitals in the Paris area and to determine the Di-Hydro Pteroate Synthase (DHPS) genotypes, genetic markers for possible sulfamide resistance. From January 1, 2003 to December 31, 2008, 993 (mean 166/year) PcP cases have been reported. Sixty-five percent of patients were HIV-positive. The median count of CD4 lymphocytes was 32/mm(3) (30 in HIV-positive patients, 152 in HIV-negative patients). In HIV-positive patients, PcP revealed the HIV infection in 39%. Among 304 PcP occurring in HIV known infected patients, no prophylaxis was prescribed for 64%; cotrimoxazole prophylaxis had been prescribed to 47 patients but only one of them had the right compliance. In HIV-negative patients (264), corticosteroids were prescribed in 59% and cytotoxic chemotherapies in 34%; 78% did not receive prophylaxis. One hundred sixty nine tumoral pathologies and 116 transplantations were notified. The mortality rate was 16% at day 14 (13% in HIV-positive patients, 26% in HIV-negative patients). Mutations in DHPS genes were detected in 18.5% of samples; 12.5% of patients were infected with several strains. The total annual number of cases has been stable for five years but the proportion of HIV-negative patients increased from 25% to 43%.

Molecular tools for identification of Zygomycetes and the diagnosis of zygomycosis

The identification of Zygomycetes and diagnosis of zygomycosis are notoriously difficult. However, there have been recent advances, particularly in the availability and evaluation of new molecular approaches. Two main issues are of importance: the identification to species level of a strain isolated in culture, and the identification of a zygomycete in tissues. By using several molecular targets and by increasing the number of available DNA sequences in international databases, several studies have shown that accurate molecular identification of Zygomycetes to species level is feasible. The internal transcribed spacer (ITS) region may be used as a first-line molecular target for the identification of Zygomycetes in pure culture. However, cultures from infected tissues are often negative and the different Zygomycetes share similar morphology according to histopathology. Furthermore, differentiation of a zygomycete from another hyalohyphomycete can sometimes be difficult in histopathology. Thus, alternative methods for the diagnosis of zygomycosis and for species identification directly from tissues are needed. For this purpose, molecular methods have been recently evaluated, both on unfixed fresh/frozen material and on formalin-fixed, paraffin-embedded biopsies. This review discusses the molecular approaches currently available for the identification of Zygomycetes and the diagnosis of zygomycosis.

Voriconazole pharmacokinetic variability in cystic fibrosis lung transplant patients

BACKGROUND

Aspergillosis is a high-risk complication in cystic fibrosis (CF) lung transplant patients. Azole antifungal drugs inhibit CYP3A4, resulting in significant metabolic drug-drug interactions. Voriconazole (VRZ) was marketed without therapeutic drug monitoring (TDM) recommendations, consistent with favorable pharmacokinetics, but regular determinations of plasma VRZ concentration were introduced in our center to manage interactions with calcineurin inhibitors and to document the achievement of therapeutic levels.

METHODS

VRZ TDM data analysis for trough concentration (C0) and peak concentration (C2) was carried out, using validated liquid chromatography assay with ultraviolet detection, for 35 CF lung transplant patients (mean age 25 years, mean weight 47 kg, balanced sex ratio) since 2003. Therapeutic range (C0: 1.5 +/- 0.5 - C2 : 4.0 +/- 1.0 mg/L) was expressed relative to pivotal pharmacokinetic trial data.

RESULTS

The duration of VRZ treatment ranged from 9 days to 22 months. The recommended standard dose of VRZ (200 mg twice a day, following the loading dose) resulted in significant plasma concentrations (>0.5 mg/L) in 20% of CF lung transplant patients. Therapeutic concentrations were obtained using higher doses (average 570 +/- 160 mg/day, +43%, P<0.01). Despite adaptation, C0 remained <0.5 mg/L (11%), even when the drug was administered intravenously, highlighting the variability of VRZ pharmacokinetics, possibly enhanced by CYP2C19 polymorphism. The risk of inefficacy during periods of underdosage was overcome by treatment with antifungal drug combinations (caspofungin, n=10). The therapeutic index was limited by neurologic effects (14%) and hepatic abnormalities (30%). VRZ concentrations correlated significantly (P<0.01) with aspartate aminotransferase levels but not with bilirubin levels. VRZ acted as a metabolic inhibitor of tacrolimus (C0 to dose ratio 5.8 +/- 2.6, n=31/VRZ versus 1.7 +/- 0.9 alone, P<0.001). Large changes in azole concentration affected the magnitude of the drug-drug interactions and adjustment requirements.

CONCLUSIONS

TDM is required because VRZ levels are often undetectable in treated CF lung transplant patients, supporting the use of antifungal drug combinations until achievement of VRZ C0 at a steady state between 1 and 2 mg/L. Plasma VRZ concentrations should be determined for the quantitative, individualized management of drug-drug interactions in lung transplant patients, in particular immunosuppressant such as tacrolimus, considering VRZ to be both a target and an inhibitor of CYP3A4.

Multicentre determination of quality control strains and quality control ranges for antifungal susceptibility testing of yeasts and filamentous fungi using the methods of the Antifungal Susceptibility Testing Subcommittee of the European Committee on Antimicrobial Susceptibility Testing (AFST-EUCAST)

A multicentre study involving seven laboratories was performed using techniques recommended by the Antifungal Susceptibility Testing Subcommittee of the European Committee on Antimicrobial Susceptibility Testing (AFST-EUCAST) to evaluate and propose quality control ranges and strains for susceptibility testing of fermentative yeasts and filamentous fungi. Participating laboratories tested the susceptibilities of a panel of 12 encoded isolates to amphotericin B, flucytosine, fluconazole, itraconazole, voriconazole and posaconazole. In total, 15 lots of assay medium were tested, with one lot being common to all laboratories, and 18 144 MIC values were determined. Intra- and inter-laboratory agreements and intra-class correlation coefficients (ICCs) of the results for each drug/strain/lot combination were calculated. An average value of 85% agreement was selected for validation purposes. The average percentage of intra-laboratory agreement was 90-95%, with ICC values of 0.90-0.95 (p <0.01). Inter-laboratory reproducibility was also high, with 92% agreement and an ICC of 0.97 (p <0.01). The reproducibility was somewhat better with the common lot of assay medium (96% agreement) than with the different lots (91% agreement), but this difference was not significant. Two isolates that showed trailing growth had agreement percentages below the 85% limit selected for validation purposes and were therefore excluded from the panel of quality control strains. The recommended EUCAST methodologies were found to be highly reproducible and reliable for susceptibility testing of yeasts and filamentous fungi. Ten isolates are proposed for use as quality control strains with these EUCAST procedures.

Use of voriconazole in a patient with aspergilloma caused by an itraconazole-resistant strain of Aspergillus fumigatus

The case is reported of a patient with cavitary sarcoidosis complicated by an aspergilloma caused by an itraconazole-resistant strain of Aspergillus fumigatus, who was treated with voriconazole. The authors suggest that susceptibility testing of A. fumigatus strains is of value during long-term therapy with itraconazole, and that voriconazole may be a good option for treatment of patients infected with itraconazole-resistant strains of A. fumigatus.

Results obtained with various antifungal susceptibility testing methods do not predict early clinical outcome in patients with cryptococcosis

The in vitro susceptibilities of Cryptococcus neoformans isolates from consecutive human immunodeficiency virus-positive and -negative patients to the antifungal agents fluconazole, amphotericin B, and flucytosine were determined by different techniques, including the CLSI method, Etest, and broth microdilution in yeast nitrogen base (YNB) medium, during a multicenter prospective study in France. The relationship between the in vitro data and the clinical outcome 2 weeks after the initiation of antifungal therapy was assessed. In addition, the correlation between the strain serotype and the in vitro activities of the antifungals was determined, and the susceptibility results obtained with the different techniques were also compared. Thirty-seven patients received a combination of amphotericin B with flucytosine as first-line therapy, 22 were treated with amphotericin B alone, and 15 received fluconazole alone. Whatever the antifungal tested, there was no trend toward higher MICs for strains isolated from patients who failed to respond to a given therapy compared to those from patients who did not with either the CLSI method, Etest, or broth microdilution in YNB medium. The MICs obtained by the CLSI or Etest method were significantly lower for serotype D strains than for serotype A strains for both fluconazole and amphotericin B, while flucytosine MICs were not different according to serotype. These findings suggest that the in vitro antifungal susceptibility of C. neoformans, as determined with the techniques used, is not able to predict the early clinical outcome in patients with cryptococcosis.

Evaluation of different commercial ELISA methods for the serodiagnosis of systemic candidosis

Different commercial enzyme-linked immunsorbent assays (ELISA) were evaluated in a preliminary study for diagnosis of systemic candidosis: Biomerica and Virotech GmbH, which allowed immunoglobulin G detection, and Platelia, which associated total antibody to antigen detection. They were tested with a home-made ELISA and compared with the routine techniques used in the hospital laboratory: indirect immunofluorescence and counter-immunoelectrophoresis. Sera were obtained from patients with probable or proven systemic candidosis (groups 3 and 4, n=8 and n=14, respectively) and from patients without systemic candidosis who were divided into controls (n=10), those hospitalized without Candida isolation (group 1, n=10) and those hospitalized with Candida isolation in a peripheral site (group 2, n=18). The immunoglobulin G ELISAs showed a higher sensitivity associated with lower specificity compared to the indirect immunofluorescence, counter-immunoelectrophoresis and total immunoglobulin ELISAs. Mannan antigen detection showed the highest specificity (78.9%). Its association with the detection of total anti-Candida immunoglobulins was more sensitive than the association of indirect immunofluorescence with counter-immunoelectrophoresis (95.4% versus 59%, respectively) with a specificity of 52.6% (versus 55.2%). Interest in the use of commercial ELISAs, more particularly the Platelia tests, has to be confirmed in a prospective study with follow-up of the patients.

Effect of medium composition on static and cidal activity of amphotericin B, itraconazole, voriconazole, posaconazole and terbinafine against Aspergillus fumigatus: a multicenter study

The effect of the medium composition on the fungistatic (MIC) and fungicidal (MLC) activity of amphotericin B, itraconazole, voriconazole, posaconazole and terbinafine against four Aspergillus fumigatus strains has been investigated by four European laboratories. MICs were determined by broth microdilution, using RPMI 1640 and Antibiotic Medium 3 (AM3), three times in three independent determinations by the four laboratories. MLCs were determined for the three independent determinations by the four laboratories, subculturing 100 microl from each well showing no visible growth after 48 hours. Except for a 2-dilution difference observed in three cases, no differences were observed between MICs determined on the two media. In contrast, a 3- to 6-dilution discrepancy between the MLCs was observed for the azoles. Endpoints on RPMI were higher than those on AM3. A 1-2 dilution difference was noted between both the endpoints of amphotericin B and of terbinafine. The highest inter- and intra-laboratory agreements were reached on AM3. The azoles showed a medium-dependent fungicidal activity.