Epidemiology, risk factor, species distribution, antifungal resistance and outcome of Candidemia at a single French hospital: a 7-year study.

Candidemia remains a major cause of disease worldwide and is associated with a high mortality rate. We conducted a retrospective study of candidemia at Nantes Hospital, France, between 2004 and 2010. A total of 191 episodes (n = 188 patients) were reviewed. Incidence, demographics, risk factors, antifungal management, species identification, in vitro susceptibility and 12 weeks survival were analysed. Global incidence of candidemia was 0.37‰ admissions. Higher incidences were observed in haematology (6.65‰) and intensive care units (2‰). Central venous catheter and antibiotic exposure were the most frequent risk factors (77% and 76% respectively). Candida albicans was the predominant species (51.8%) followed by C. parapsilosis (14.5%), C. glabrata (9.8%), C. tropicalis (9.8%) and C. krusei (4.1%). However, species distribution differed significantly between medical units with frequency of C. tropicalis being higher in haematology compared to other medical units. Fluconazole and caspofungin were the main antifungals given as first-line therapy. Although not significant, 12 weeks mortality rate was 30.9%, being higher for C. tropicalis (44.4%) than for C. parapsilosis (16%). Acquired azole or echinocandin resistance was noted in some isolates, underlining the need for systematic antifungal susceptibility testing in patients with candidemia. These epidemiological findings will be of interest for antifungal stewardship at our hospital.

Deciphering azole resistance mechanisms with a focus on transcription factor-encoding genes TAC1, MRR1 and UPC2 in a set of fluconazole-resistant clinical isolates of Candida albicans.

Several and often combined mechanisms can lead to acquired azole resistance in Candida albicans and subsequent therapeutic failure. The aim of this study was to provide a complete overview of the molecular basis of azole resistance in a set of six C. albicans clinical isolates recovered from patients who failed azole therapy. For this purpose, expression levels of CDR1, MDR1 and ERG11 were investigated by reverse transcription PCR (RT-PCR) together with amplification and sequencing of the genes encoding their transcription factors TAC1, MRR1 and UPC2. In all, the data underline that azole resistance in this set of clinical isolates results from distinct, often combined, mechanisms, being mostly driven by CDR1 and/or MDR1 active efflux. We show that gain-of-function (GOF) mutations in the transcription-factor-encoding genes TAC1, MRR1 and UPC2 are a common event in azole-resistant C. albicans clinical isolates. In addition, together with the finding that these genes are highly permissive to nucleotide changes, we describe several novel mutations that could act as putative GOF mutations involved in fluconazole resistance.

Multilocus sequence typing of Pneumocystis jirovecii from clinical samples: how many and which loci should be used?

Pneumocystis jirovecii pneumonia (PCP) is an opportunistic infection with airborne transmission and remains a major cause of respiratory illness among immunocompromised individuals. In recent years, several outbreaks of PCP, occurring mostly in kidney transplant recipients, have been reported. Currently, multilocus sequence typing (MLST) performed on clinical samples is considered to be the gold standard for epidemiological investigations of nosocomial clusters of PCP. However, until now, no MLST consensus scheme has emerged. The aim of this study was to evaluate the discriminatory power of eight distinct loci previously used for the molecular typing of P. jirovecii (internal transcribed spacer 1 [ITS1], cytochrome b [CYB], mitochondrial rRNA gene [mt26S], large subunit of the rRNA gene [26S], superoxide dismutase [SOD], ß-tubulin [ß-TUB], dihydropteroate synthase [DHPS], and dihydrofolate reductase [DHFR]) using a cohort of 33 epidemiologically unrelated patients having respiratory samples that were positive for P. jirovecii and who were admitted to our hospital between 2006 and 2011. Our results highlight that the choice of loci for MLST is crucial, as the discriminatory power of the method was highly variable from locus to locus. In all, the eight-locus-based scheme we used displayed a high discriminatory power (Hunter [H] index, 0.996). Based on our findings, a simple and alternative MLST scheme relying on three loci only (mt26S, CYB, and SOD) provides enough discriminatory power (H-index, 0.987) to be used for preliminary investigations of nosocomial clusters of PCP.

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.

High prevalence of triazole resistance in Aspergillus fumigatus, especially mediated by TR/L98H, in a French cohort of patients with cystic fibrosis.

OBJECTIVES: Triazole resistance in Aspergillus fumigatus due to a single azole resistance mechanism (TR/L98H) is increasingly reported in European countries. Data from patients with cystic fibrosis (CF) are limited. Our study aimed to investigate the prevalence and molecular mechanisms of azole resistance in A. fumigatus in a cohort of patients with CF. METHODS: Eighty-five A. fumigatus isolates from 50 CF patients, collected between January 2010 and April 2011, were retrospectively analysed for azole resistance using agar plates containing 4 mg/L itraconazole. MICs of itraconazole, voriconazole and posaconazole were determined according to EUCAST methodology for each isolate able to grow on this medium. Species identification was performed by sequencing of the ß-tubulin gene. Sequencing analysis of the cyp51A gene and its promoter region was conducted. RESULTS: Nine isolates (four patients, 8% prevalence) were able to grow on itraconazole-containing agar plates. Itraconazole resistance was confirmed by EUCAST methodology (MICs >2 mg/L). All isolates had mutations in the cyp51A gene at residues previously involved in azole resistance: L98H (n = 5), M220T (n = 4) and G54R (n = 1). One patient had three genetically distinct azole-resistant isolates identified during the study. The isolates with L98H that were recovered from three patients (6% prevalence) also had the 34 bp tandem repeat in the promoter region of cyp51A (TR/L98H) and displayed multiazole resistance. CONCLUSIONS: We report an 8% prevalence of itraconazole resistance in CF patients in our centre, mostly driven by TR/L98H (6%). Our data confirm that TR/L98H occurs in France and can be highly prevalent in CF patients.

A new and highly divergent Enterocytozoon bieneusi genotype isolated from a renal transplant recipient.

A 49-year-old renal transplant recipient was admitted to our hospital due to abundant liquid diarrhea and dehydration. Parasitological investigations, including genotyping, led to the diagnosis of intestinal microsporidiosis due to a new and highly divergent internal transcribed spacer (ITS) genotype of Enterocytozoon bieneusi. The potential route of transmission through horse stools is discussed.

Phaeohyphomycosis due to Alternaria infectoria: a single-center experience with utility of PCR for diagnosis and species identification.

The term phaeohyphomycosis refers to a rare group of fungal infections characterized by the presence of dark-walled hyphae or yeast-like cells in affected tissues. Herein, we report on the clinical and epidemiological characteristics of six cases of phaeohyphomycosis due to Alternaria spp. that occurred in our hospital over a 30-month period (from January 2008 to June 2010). Interestingly, whereas histopathological examinations were positive and fungal cultures yielded molds in all cases, mycological identification using conventional phenotypic methods was never possible despite prolonged incubation of the isolates. Identification of Alternaria infectoria species complex was obtained for each isolate by amplification and sequencing of the internal transcribed spacer of the ribosomal DNA (ITS rDNA). All patients had favourable outcomes following the introduction of azole-based antifungal therapy. This case series describes the clinical course of these six patients and highlights the utility of molecular identification to help in the identification of the etiologic agent when classical mycological methods have failed.

Trichomonads in pleural effusion: case report, literature review and utility of PCR for species identification.

Trichomonas tenax is a flagellated protozoan commonly found in the human oral cavity but of unusual occurrence in pulmonary infections. We describe a case of a 67-year-old patient with glioblastoma who presented with severe pleurisy in the post-operative period while she was receiving high-dose corticotherapy. Several motile flagellated protozoa were identified in the pleural fluid. Trichomonas tenax was identified by molecular methods. Pulmonary infections with Trichomonads might be underestimated because of diagnostic difficulties. The utility of molecular biology for species identification is underlined and the pathogenicity of Trichomonad parasites in human lungs is discussed in light of previously reported cases.

Invasive Myceliophthora thermophila infection mimicking invasive aspergillosis in a neutropenic patient: a new cause of cross-reactivity with the Aspergillus galactomannan serum antigen assay.

Myceliophthora thermophila is a thermophilic mould widely found in the environment but rarely responsible for human infections. We describe a case of invasive Myceliophthora thermophila infection mimicking invasive aspergillosis in a neutropenic patient with haematological malignancy. Cross-reactivity with Aspergillus galactomannan assay (GM) was demonstrated by repeated positive results and confirmed by cross-reaction between the fungal isolate and the GM assay. The patient was successfully treated with voriconazole. Potential GM cross-reactivity must be considered in future studies including patients categorized as having probable invasive aspergillosis using the GM as the only mycological criterion.

Fatal invasive infection with fungemia due to Microascus cirrosus after heart and lung transplantation in a patient with cystic fibrosis.

Scopulariopsis species are rarely but increasingly recognized as opportunistic pathogens in immunocompromised patients. We report on a patient suffering from cystic fibrosis who developed disseminated fungal infection due to a rare Scopulariopsis species, Microascus cirrosus, after heart and lung transplantation. Despite antifungal combination therapy with voriconazole and caspofungin, the patient died 4 weeks after transplantation. Diagnostic difficulties and optimal management of disseminated Scopulariopsis/Microascus infections are discussed.

Disseminated Scedosporium/Pseudallescheria infection after double-lung transplantation in patients with cystic fibrosis.

We report a case of disseminated Scedosporium/Pseudallescheria infection due to Pseudallescheria boydii sensu stricto after lung transplantation in a patient with cystic fibrosis. Dissemination occurred under voriconazole. Despite surgery and combination therapy with voriconazole, caspofungin, and terbinafine, the patient died 8 months after transplantation. Previously reported cases are reviewed.

Aspergillus fumigatus endocarditis of the mitral valve in a heart transplant recipient: a case report.

Aspergillus endocarditis is a rare event after heart transplantation. We report a case of Aspergillus fumigatus endocarditis after orthotopic heart transplantation. The patient was treated with a combination of voriconazole and caspofungin without valve replacement and survived for 168 days after the diagnosis. Previously reported cases are reviewed.

Molecular study of microsporidiosis due to Enterocytozoon bieneusi and Encephalitozoon intestinalis among human immunodeficiency virus-infected patients from two geographical areas: Niamey, Niger, and Hanoi, Vietnam.

Microsporidiosis cases due to Enterocytozoon bieneusi and Encephalitozoon intestinalis are emerging opportunistic infections associated with a wide range of clinical syndromes in humans. The aim of this study was to specify microsporidial epidemiology in two different geographical areas. From November 2004 to August 2005, 228 and 42 stool samples were collected in Niamey, Niger, and Hanoi, Vietnam, respectively. Screening for microsporidia was performed using UV-light microscopy. Detection was confirmed by molecular biology using two methods specific for E. bieneusi and E. intestinalis. All samples positive for E. bieneusi were subjected to genotyping. In this study, we found high prevalences of microsporidiosis among human immunodeficiency virus-infected patients, 10.5% and 9.5%, respectively, in Niamey and Hanoi. These levels of prevalence are similar to those recorded in European countries before highly active antiretroviral therapy was introduced. In the samples positive for E. bieneusi, we found seven distinct genotypes, including two genotypes not previously described. The E. bieneusi genotype distributions in the two geographical areas suggest different routes of infection transmission, person-to-person in Niger and zoonotic in Vietnam.