Claire Lacroix

Value of antigen detection using an enzyme immunoassay in the diagnosis and prediction of invasive aspergillosis in two adult and pediatric hematology units during a 4-year prospective study

Invasive aspergillosis (IA) is a well recognized, life‐threatening infection in neutropenic patients and stem cell transplantation recipients. Early diagnosis is important to achieve the best outcome for these patients; however, definite proof often is difficult to obtain due to counterindicated invasive procedures.

Matrix-assisted laser desorption ionization time-of-flight mass spectrometry for fast and accurate identification of clinically relevant Aspergillus species

New Aspergillus species have recently been described with the use of multilocus sequencing in refractory cases of invasive aspergillosis. The classical phenotypic identification methods routinely used in clinical laboratories failed to identify them adequately. Some of these Aspergillus species have specific patterns of susceptibility to antifungal agents, and misidentification may lead to inappropriate therapy. We developed a matrix-assisted laser desorption ionization time-of-flight (MALDI-TOF) mass spectrometry (MS)-based strategy to adequately identify Aspergillus species to the species level. A database including the reference spectra of 28 clinically relevant species from seven Aspergillus sections (five common and 23 unusual species) was engineered. The profiles of young and mature colonies were analysed for each reference strain, and species-specific spectral fingerprints were identified. The performance of the database was then tested on 124 clinical and 16 environmental isolates previously characterized by partial sequencing of the β-tubulin and calmodulin genes. One hundred and thirty-eight isolates of 140 (98.6%) were correctly identified. Two atypical isolates could not be identified, but no isolate was misidentified (specificity: 100%). The database, including species-specific spectral fingerprints of young and mature colonies of the reference strains, allowed identification regardless of the maturity of the clinical isolate. These results indicate that MALDI-TOF MS is a powerful tool for rapid and accurate identification of both common and unusual species of Aspergillus. It can give better results than morphological identification in clinical laboratories.

International Retrospective Analysis of 73 Cases of Invasive Fusariosis Treated with Voriconazole

ABSTRACT The outcomes for 73 invasive fusariosis patients treated with voriconazole were investigated. Patients with proven (n = 67) or probable (n = 6) infections were identified from the voriconazole clinical database (n = 39) and the French National Reference Center for Mycoses and Antifungals database (n = 34). Investigator-determined success was a complete or partial response. Survival was determined from day 1 of voriconazole therapy to the last day known alive. Patients were 2 to 79 years old (median, 43 years), and 66% were male. Identified Fusarium species (62%) were F. solani, F. moniliforme, F. proliferatum, and F. oxysporum. Underlying conditions analyzed included hematopoietic stem cell transplant (HSCT; 18%), hematologic malignancy (HM; 60%), chronic immunosuppression (CI; 12%), or other condition (OC; 10%). Infection sites were brain (5%), disseminated excluding brain (67%), lungs/sinus (15%), and other (12%). Most patients (64%) were or had recently been neutropenic (<500 cells/mm3). Therapy duration was 1 to 480 days (median, 57 days), with a 47% success rate. Baseline neutropenia impacted success adversely (P ≤ 0.03). Success varied by underlying condition (HSCT, 38%; HM, 45%; CI, 44%; OC, 71%) and infection site (brain, 0%; disseminated, 45%; other, 56%; lung/sinus, 64%) (P > 0.05). Combination therapy (13 patients) was no better than treatment with voriconazole alone. Overall, 59% of the patients died (49% died of fusariosis), and 90-day survival was 42%. Site of infection influenced survival (P = 0.02). Median survival (in days) by species was as follows: F. solani, 213; F. oxysporum, 112; Fusarium spp., 101; F. proliferatum, 84; F. moniliforme, 76. We conclude that voriconazole is a therapeutic option for invasive fusariosis.

Acquisition of Flucytosine, Azole, and Caspofungin Resistance in Candida glabrata Bloodstream Isolates Serially Obtained from a Hematopoietic Stem Cell Transplant Recipient

ABSTRACT We describe the acquisition of flucytosine, azole, and caspofungin resistance in sequential Candida glabrata bloodstream isolates collected from a bone marrow transplant patient with clinical failure. Point mutations in C. glabrata FUR1 (CgFUR1) and CgFKS2 and overexpression of CgCDR1 and CgCDR2 were observed in resistant isolates.

Breakthrough Disseminated Aspergillus ustus Infection in Allogeneic Hematopoietic Stem Cell Transplant Recipients Receiving Voriconazole or Caspofungin Prophylaxis

ABSTRACT Aspergillus ustus is an uncommon clinical species which is poorly susceptible to antifungals. We report two cases of A. ustus infections that occurred in allogeneic stem cell transplant recipients while they were receiving either voriconazole or caspofungin. Prolonged use of these new antifungal agents may increase the risk of the emergence of resistant organisms.

The strategy for the diagnosis of invasive pulmonary aspergillosis should depend on both the underlying condition and the leukocyte count of patients with hematologic malignancies.

The identification of the causative organism in invasive pulmonary aspergillosis (IPA) is recommended. We investigated whether a mycologic diagnostic strategy could be optimized based on patient characteristics. Fifty-five patients were enrolled in a prospective study. The presence of Aspergillus in respiratory samples occurred more frequently in non-acute leukemia (AL) patients than in AL patients (P = .0003), and in patients with leukocyte counts more than 100/mm(3) (P = .002). In a logistic regression model, these 2 factors appeared to be independent, with an adjusted odds ratio of 7.14 (95% confidence interval, 1.40-36.5) for non-AL patients and an adjusted odds ratio of 6.97 (95% confidence interval, 1.33-36.5) for patients with leukocyte counts more than 100/mm(3). A positive mycologic result was also more frequent among patients with lung CT scan signs of airway-invasive disease than among other patients (P = .043). Airway-invasive signs were more frequent among non-AL patients (P = .049), whereas angioinvasive disease was more frequent among both AL patients (P = .01) and patients with leukocyte counts less than 100/mm(3) (P = .001). A concomitant pulmonary infection was identified more frequently among non-AL patients (P = .005 vs allogeneic hematopoietic stem cell transplant and P = .048 vs others). Our results suggest that different strategies for diagnosing IPA should be considered based on the underlying condition.

Contribution of Galactomannan Antigen Detection in BAL to the Diagnosis of Invasive Pulmonary Aspergillosis in Patients With Hematologic Malignancies

BACKGROUND Invasive pulmonary aspergillosis (IPA) is difficult to diagnose. The detection of galactomannan (GM) in serum samples is useful for diagnosing IPA. A positive test for GM antigen in BAL has also been proposed as a criterion of IPA, although it has not been fully validated. The aim of our study was to evaluate the contribution of GM antigen detection in BAL to the diagnosis of IPA in hematologic patients. METHODS One hundred one consecutive patients treated for hematologic malignancy were explored by bronchoscopy and BAL for new pulmonary infiltrates. Both BAL fluid and serum samples were evaluated for GM using an enzyme-linked immunosorbent assay test, with an optical density index >or= 0.5 considered positive. Respiratory samples were also examined for the presence of fungi. RESULTS IPA was diagnosed in 33 patients according to European Organization for Research and Treatment of Cancer and Mycoses Study Group consensus group criteria (six proven, 23 probable, four possible). Nineteen of these 33 patients had a positive BAL GM test, whereas three patients without IPA had false-positive results. GM detection in BAL had a sensitivity of 57.6% (95% CI, 40.8%-72.8%) and a specificity of 95.6% (95% CI, 87.8%-98.5%). Among the 19 patients with IPA whose BAL was positive for GM, 15 also had a positive serum GM test. In 11 of these 19 patients, Aspergillus was identified in the respiratory samples. CONCLUSION Detection of GM in BAL is complementary of serum GM testing and mycologic evaluation of the respiratory samples for the diagnosis of IPA. Positive GM BAL was the sole microbiologic criterion in two of 33 patients studied.

Tinea pedis in European marathon runners

Background Epidemiological studies suggest that 15% of the population in industrial countries suffer from tinea pedis (athlete’s foot) and that persons who do sports are a high‐risk population.

Amino acid substitutions in the Candida albicans sterol Δ5,6-desaturase (Erg3p) confer azole resistance: characterization of two novel mutants with impaired virulence

OBJECTIVES To determine the mechanisms responsible for fluconazole resistance in two Candida albicans isolates (CAAL2 and CAAL76) recovered from two hospitalized patients after fluconazole prophylaxis. METHODS MICs of fluconazole and voriconazole were determined by the broth microdilution method (CLSI M27-A3), and by Etest(®) for amphotericin B. RNA expression levels of CDR1, MDR1 and ERG11 were determined by RT-PCR. Mutations in ERG11 and ERG3 were investigated by amplification and sequencing. Sterol membrane profiles were determined by gas chromatography-mass spectrometry (GC-MS). In vivo virulence was determined in a murine model of invasive candidiasis. RESULTS Both isolates displayed azole cross-resistance and reduced susceptibility to amphotericin B, and are novel Δ(5,6)-desaturase (Erg3p) mutants. CAAL2 harbours a new amino acid substitution (L193R), whereas a 13 bp deletion leading to a truncated Erg3p (Δ366-378) was found in CAAL76. Both genetic alterations impaired Erg3p function as shown by GC-MS in these isolates (ergosterol content below 10%, and accumulation of ergosta-7,22-dienol above 40%). In vivo, in a murine model of invasive candidiasis, both CAAL2 and CAAL76 exhibited a significant trend toward reduced virulence, which seems to be linked to a reduced capacity for hyphal growth. CONCLUSIONS These findings demonstrate the critical role of residue 193 in Erg3p function and azole resistance. We suggest that this attenuated in vivo virulence phenotype could be linked to lower potential for hyphal growth. Taken together, our findings highlight the fact that erg3 mutants must be considered in future studies aiming at investigating azole antifungal drug resistance.

Breakthrough C. parapsilosis and C. guilliermondii blood stream infections in allogeneic hematopoietic stem cell transplant recipients receiving long-term caspofungin therapy

Since 2004, when caspofungin became available at our institution for empirical treatment of fever, we have been faced with the occurrence of candidemia due to unusual species, i.e. C. parapsilosis and C. guilliermondii , which have been reported to exhibit decreased susceptibility to echinocandins