Sophie Touratier

Use and Limits of (1-3)-β-d-Glucan Assay (Fungitell), Compared to Galactomannan Determination (Platelia Aspergillus), for Diagnosis of Invasive Aspergillosis

ABSTRACT This study was undertaken to examine the performance of the Fungitell β-glucan (BG) assay, to compare it with that of the galactomannan (GM) test for the diagnosis of invasive aspergillosis (IA) in patients with hematological malignancies, and to examine the rates of false-positive BG and GM test results due to β-lactam antibiotics among sera of patients with Gram-positive or Gram-negative bacteremia and selected sera with false-positive results from the GM test. Serum samples from 105 patients with proven (n = 14) or probable (n = 91) IA, 97 hematology patients at risk for invasive fungal infections, 50 healthy blood donors, and 60 patients with bacteremia were used to study the sensitivities and specificities of the assays. The GM test was more specific than the BG assay (97% versus 82%, respectively; P = 0.0001) and the BG assay was more sensitive than the GM test (81% versus 49%, respectively; P < 0.0001) for IA diagnosis. The study of 49 separate batches of β-lactam antibiotics showed high and very similar rates of false-positive results for the GM and BG assays (29 and 33%, respectively; P = 0.82) but with an almost complete lack of concordance between the 2 assays. For patients with bacteremia, the rate of false-positive results was much higher with the BG test than with the GM test (37% versus 2%, respectively; P < 0.0001), with no significant difference between Gram-positive and Gram-negative bacteremia. In conclusion, the BG test may be useful for the diagnosis of IA because of its high sensitivity in comparison with the GM test, but the overall benefit of this assay remains limited because of its inadequate specificity and its cost.

Reduction of fluoroquinolone use is associated with a decrease in methicillin-resistant Staphylococcus aureus and fluoroquinolone-resistant Pseudomonas aeruginosa isolation rates: a 10 year study

OBJECTIVES High rates of methicillin-resistant Staphylococcus aureus (MRSA) and fluoroquinolone-resistant Pseudomonas aeruginosa may be related, in part, to the overuse of fluoroquinolones. The objective was to analyse and correlate long-term surveillance data on MRSA and fluoroquinolone-resistant P. aeruginosa rates and antibiotic consumption after implementation of an institution-wide programme to reduce fluoroquinolone use. METHODS An interrupted time series/quasi-experimental study of monthly fluoroquinolone use and MRSA and fluoroquinolone-resistant P. aeruginosa isolation rates was carried out in a tertiary hospital during three periods: pre-intervention (January 2000-August 2005), intervention (September 2005-March 2006), and post-intervention (March 2006-March 2010). The effect of the intervention on the consumption of fluoroquinolones and bacterial resistance was assessed using segmented regression analyses. RESULTS Mean monthly fluoroquinolone consumption dropped by 29.1 defined daily doses per 1000 patient-days (DDD/1000 PD) (95% CI 13.1-45.9; P = 0.0005) from a mean of 148.2 to 119.1 DDD/1000 PD during the intervention period. A sustained and significant decrease in fluoroquinolone consumption of -0.95 DDD/1000 PD/month was also observed during the post-intervention period (P = 0.0002). During the post-intervention period the rate of fluoroquinolone-resistant P. aeruginosa continuously decreased, from a mean of 42% to 26%, with a constant relative change rate of -13%/year (95% CI -19 to -5, P = 0.001). A decrease in the MRSA rate was observed during the intervention period, from a mean resistance rate of 27% to 21% (P < 0.0001). CONCLUSIONS We showed the sustained impact of a fluoroquinolone control programme on the reduction of fluoroquinolone use with a significant decrease in fluoroquinolone-resistant P. aeruginosa and MRSA rates over 4 years.

Breakthrough invasive fungal disease in patients receiving posaconazole primary prophylaxis: a 4-year study

Posaconazole (PSC) is currently recommended as primary prophylaxis in neutropenic patients with acute myeloid leukaemia (AML) and in allogenic haematopoietic stem cell transplantation (AHSCT) recipients with graft-versus-host disease (GVHD). Studies focusing on breakthrough invasive fungal disease (IFD) upon PSC prophylaxis show disparate results. In order to evaluate the incidence of IFD in patients on PSC prophylaxis and identify IFD risk factors, we carried out a retrospective study of all consecutive patients on PP from January 2007 to December 2010 in our hospital. Breakthrough IFDs were identified from the database of the central pharmacy and the French administrative database (PMSI), registering final medical diagnoses of hospitalized patients. Medical data were reviewed to study proven or probable IFD, according to EORTC/MSG definition. PSC plasma concentrations (PPC) were also retrieved. Poisson models were used for statistical analysis. Two hundred and seventy-nine patients received PSC prophylaxis for a median duration of 1.4 months (range 0.2-17.9). Proven (n=6) or probable (n=3) IFDs were diagnosed in nine cases (3.2%). IFD incidence rate per 100 person-month was 1.65 (95% CI, 0.79-2.97). IFDs were candidaemia (Candida glabrata, n=2), pulmonary invasive aspergillosis (n=3), disseminated fusariosis (n=2) and pulmonary mucormycosis (n=2). Seven deaths were reported, directly related to IFD in three patients (33.3%). First dosage of PPC under 0.3 mg/L was the single significant risk factor for IFD (RR, 7.77; 95% CI, 1.30-46.5; p 0.025). Breakthrough IFD in patients receiving PSC prophylaxis is rare but associated with a poor outcome. Low PSC plasma concentrations are associated with an increased risk of IFD.

Azole Resistance of Aspergillus fumigatus in Immunocompromised Patients with Invasive Aspergillosis.

To the Editor: Alanio et al. comment that the prevalence of azole-resistant Aspergillus disease may differ, depending on location of the hospital where patients are admitted and the patients’ underlying disease (1). Determining local or regional epidemiology, especially in areas where azole-resistant isolates are found in the environment, is indeed important. These isolates commonly harbor the TR34/L98H or TR46/Y121F/T289A resistance mechanism. Patients may inhale azole-resistant spores in the air and subsequently develop azole-resistant disease, even when they have never been treated with azoles (2). Although risk for inhalation of azole-resistant Aspergillus spores arguably might be similar for all patients, surveillance of Aspergillus isolates in the Netherlands indicates that resistance rates vary among hospitals. When all A. fumigatus isolates cultured from patients were investigated for azole resistance, resistance rates in the Netherlands ranged from 4.3% to 19.2% in 2013 and 3.8% to 13.3% in 2014 (3). The highest and lowest resistance rates were found in hospitals only 39 km from each other, supporting the observation made by Alanio et al. about variations in prevalence of azole-resistant Aspergillus disease (1).

Fluconazole and Echinocandin Resistance of Candida glabrata Correlates Better with Antifungal Drug Exposure Rather than with MSH2 Mutator Genotype in a French Cohort of Patients Harboring Low Rates of Resistance

Candida glabrata is a major pathogenic yeast in humans that is known to rapidly acquire resistance to triazole and echinocandin antifungal drugs. A mutator genotype (MSH2 polymorphism) inducing a mismatch repair defect has been recently proposed to be responsible for resistance acquisition in C. glabrata clinical isolates. Our objectives were to evaluate the prevalence of antifungal resistance in a large cohort of patients in Saint-Louis hospital, Paris, France, some of whom were pre-exposed to antifungal drugs, as well as to determine whether MSH2 polymorphisms are associated with an increased rate of fluconazole or echinocandin resistance. We collected 268 isolates from 147 patients along with clinical data and previous antifungal exposure. Fluconazole and micafungin minimal inhibition concentrations (MICs) were tested, short tandem repeat genotyping was performed, and the MSH2 gene was sequenced. According to the European Committee on Antimicrobial Susceptibility breakpoints, 15.7% of isolates were resistant to fluconazole (MIC > 32 mg/L) and 0.7% were resistant to micafungin (MIC > 0.03 mg/L). A non-synonymous mutation within MSH2 occurred in 44% of the isolates, and 17% were fluconazole resistant. In comparison, fluconazole resistant isolates with no MSH2 mutation represented 15% (P = 0.65). MSH2 polymorphisms were associated with the short tandem repeat genotype. The rate of echinocandin resistance is low and correlates with prior exposure to echinocandin. The mutator genotype was not associated with enrichment in fluconazole resistance but instead corresponded to rare and specific genotypes.

New therapeutic strategies for invasive aspergillosis in the era of azole resistance: how should the prevalence of azole resistance be defined?

Given reports showing a high prevalence of azole resistance in Aspergillus fumigatus, alternatives to azole therapy are discussed when a threshold of 10% of azole-resistant environmental isolates is reached. This raises the issue of calculation of this threshold, either on the prevalence of azole-resistant isolates as a whole or on the prevalence of azole-resistant cases in populations at risk of invasive aspergillosis (IA). For isolate evaluation, there are high disparities in routine microbiological procedures for the isolation of A. fumigatus and azole resistance detection. There are also huge differences between the microbiological work-up for diagnosing IA. Some centres rely on galactomannan detection alone without actively trying to culture appropriate samples, which affects reliability of the figures on the prevalence of resistance and thus the threshold of resistance. Moreover, reports from the laboratory could mix up figures from completely different patient populations: frequent azole-resistant isolates from pneumology patients and rare azole-resistant isolates from haematology patients. Therefore, to sum isolates from different specimens and different wards can lead to erroneous calculations for the restricted populations at risk of developing IA. In conclusion, assessing the incidence of azole resistance in A. fumigatus should be based on harmonized consensual microbiological methods and reports should be restricted to IA episodes in identified populations at risk of IA when the issue is to define an operational threshold for modifying recommendations.

Circulating Aspergillus fumigatus DNA Is Quantitatively Correlated to Galactomannan in Serum

The performance of antigen galactomannan (GM) for diagnosing invasive aspergillosis (IA) is hampered by the occurrence of false-positive results. Quantitative PCR has been proposed to improve the diagnosis of IA. Therefore, we analyzed the value of performing a PCR test to the GM-positive serum sample. Using a quantitative PCR assay specific for Aspergillus fumigatus 28S ribosomal DNA, we retrospectively tested 422 GM-positive (Platelia Bio-Rad kit) serum samples collected over 1 year from 147 patients. The cases were classified based on EORTC criteria as “proven,” “probable,” and “no–IA” before availability of the PCR results. After exclusion of 65 samples for non-reproducibility of GM positivity (n = 62) or PCR inhibition (n = 3), 75 (21.0%) of the remaining 357 samples were PCR-positive. GM and fungal DNA showed a significantly positive correlation (p < 0.0001, R2 = 0.27, slope = 0.98 ± 0.19). At least one PCR-positive result was observed in 63.3% (31/49) of IA patients and in 13.2% (13/98) of non-IA patients (p < 0.0001). The PCR positivity was also associated with the presence of other microbiological criteria among the 44 patients with IA and complete mycological workup (p = 0.014), as well as a higher mortality rate at six months among the 135 patients with hematological conditions (p = 0.0198). Overall, we found a quantitative correlation between serum GM and circulating DNA with an increased likelihood of IA when both were positive. A PCR-positive result also supported a higher fungal load when GM was already positive. We advocate adding a PCR test for every confirmed GM-positive serum sample.

Primary antifungal prophylaxis with micafungin after allogeneic hematopoietic stem cell transplantation: a monocentric prospective study

Dear Editor, Invasive fungal diseases (IFDs) after allogeneic hematopoietic stem cell transplantation (alloHSCT) are mainly caused by Aspergillus and Candida. Primary antifungal prophylaxis (PAP) with fluconazole is recommended for 100-day postalloHSCT [1]. Candida infections have evolved epidemiologically as azole-resistant species have increased [2, 3] and fluconazole does not preventAspergillus infections.Micafungin is active against mostCandida and Aspergillus species, with similar or superior overall efficacy over fluconazole during the neutropenic phase in hematological patients [3–8]. Due to its larger antifungal spectrum and lower interactions with immunosuppressive agents compared with fluconazole, we tested micafungin as a PAP through a monocentric prospective study focusing on alloHSCT recipients at high risk of IFDs. From November 2013 to September 2014, we included 26 consecutive recipients of a first unrelated alloHSCT after myelo-ablative or sequential conditioning, and retrospectively compared them with a previous 36-patient cohort with identical inclusion/exclusion criteria receiving fluconazole PAP. The primary objective was the incidence of invasive candidiasis. The incidences and reasons for antifungal withdrawal were compared between both groups. Antifungal treatment was initiated at the beginning of the conditioning regimen (micafungin 50 mg/day) or at D + 1 (fluconazole 400 mg/day). IFDs were recorded from transplantation until antifungal withdrawal or D + 60. Prophylaxes were withdrawn for: neutrophil recovery; acute graft-versus-host disease treated with steroids necessitating anti-Aspergillus prophylaxis; diagnosis of proven/probable/ possible IFDs (EORTC/MSG criteria) [9]; and indication for empirical antifungal treatment (fluconazole group only). Blood galactomannan was performed biweekly. In cases of febrile neutropenia lasting > 72 h despite large-spectrum antibiotherapy, a sinus-thoraco-abdomino-pelvic CT scan was performed. If radiological exams were normal, micafungin was continued until engraftment. Fluconazole was withdrawn and replaced by an empirical antifungal treatment (caspofungin or liposomal amphotericin B). Inverse probability of treatment weighting was used to limit confounding bias in outcome comparisons. The study was conducted according to the Helsinki declaration.