Severe kerion Celsi caused by Trichophyton quinckeanum: Severe kerion Celsi due to Trichophyton quinckeanum

We report a severe case of kerion Celsi of the scalp in a previously healthy 13-year-old girl due to Trichophyton quinckeanum, an emerging dermatophyte species in Europe. The species was definitely identified by DNA sequencing and the patient was successfully treated by oral terbinafine for 6 weeks. Kerion Celsi is a severe inflammatory form of tinea capitis, which is characterised by a purulent discharge and alopecia [1]. It typically occurs in children infected with zoophilic dermatophytes, such as Trichophyton mentagrophytes, and an increasing number of cases caused by other Trichophyton species has recently been reported [2]. Herein we report a severe case of kerion Celsi of the scalp caused by the emerging species Trichophyton quinckeanum, which was successfully treated by oral antifungal.

Rapamycin and caspofungin show synergistic antifungal effects in caspofungin-susceptible and caspofungin-resistant Candida strains in vitro

OBJECTIVES

Caspofungin is an echinocandin antifungal agent that inhibits synthesis of glucan required for the fungal cell wall. Resistance is mediated by mutation of Fks1 glucan synthase, among which S645P is the most common resistance-associated polymorphism. Rapamycin is a macrolide that inhibits the mechanistic target of rapamycin (mTOR) protein kinase activity. This study investigated the interaction between rapamycin and caspofungin in inhibiting the growth of WT Candida albicans and Fks1 S645P mutant clinical isolate, and WT Candida lusitaniae and genetically engineered isogenic strain with Fks1 S645P mutation at equivalent position.

METHODS

Interactions between caspofungin and rapamycin were evaluated using the microdilution chequerboard method in liquid medium. The results were analysed using the Loewe additivity model (FIC index, FICI) and the Bliss independence model (response surface, RS, analysis).

RESULTS

Synergy between rapamycin and caspofungin was shown for C. albicans and C. lusitaniae strains by RS analysis of the chequerboard tests. Synergy was observed in strains susceptible and resistant to caspofungin. Weak subinhibitory concentrations of rapamycin were sufficient to restore caspofungin susceptibility.

CONCLUSIONS

We report here, for the first time, synergy between caspofungin and rapamycin in Candida species. Synergy was shown for strains susceptible and resistant to caspofungin. This study highlights the possible implication of the TOR pathway in sensing antifungal-mediated cell wall stress and in modulating the cellular response to echinocandins in Candida yeasts.

Pneumocystis in the era of prophylaxis: do the guidelines have to change?

PURPOSE

In the era of effective prophylaxis, the objective of this study was to describe pneumocystis pneumonia (PCP) patients' profile and evaluate the consistency of clinical situations encountered with the recommended indications for prophylaxis.

METHODS

This was a single-centre, retrospective study. All adults (> 18 years) with a definitive diagnosis of PCP were included. Data were collected from patients' electronic medical files.

RESULTS

The study examined the medical files of 225 patients diagnosed with PCP and treated between 1 January, 2015, and 30 June, 2020. More than 95% of the patients were not on anti-PCP prophylaxis at the time of PCP diagnosis. There were 32 (14%) deaths before the end of PCP treatment, mainly in auto-immune disease (30%) and solid tumours (38%) groups unlike the solid-organ transplants group, among whom deaths were infrequent. Indeed, 48% of our cohort (n = 107) had both corticosteroid (CS) therapy, immunosuppressive or immunomodulatory treatment, and lymphopaenia and could have been considered at high risk for PCP. Trimethoprim/sulfamethoxazole was administered as first-line PCP curative treatment in 95% of the patients. Toxicities of this drug led to treatment interruption in 25% of the patients (except death).

CONCLUSIONS

This study found a high number of PCP cases over 5 years. Unsurprisingly, most of the patients were immunosuppressed, with risk factors for PCP already described in the literature. This large number of PCP cases should be avoidable and, consequently, questions arise. Faced with these data, prophylaxis should be common sense for immunocompromised patients with risk factors, even if formalised recommendations do not exist.

Identification of Predictive Markers and Outcomes of Late-onset Pneumocystis jirovecii Pneumonia in Kidney Transplant Recipients

Background

In the era of prophylaxis, Pneumocystis pneumonia (PCP) has become a late-onset opportunistic infection requiring indications for prolonged prophylaxis to be defined. The primary objective of our study was therefore to evaluate risk factors associated with late-onset PCP. The secondary objective was to assess the impact of this infection on graft and patient survival.

Methods

We conducted a French case-control study in Bordeaux and Toulouse center by matching 1 case to 1–2 controls from the same center based on the transplant date and the type of induction treatment.

Results

Seventy cases and 134 controls were included. PCP occurred at a median of 3 years after transplantation. The total lymphocyte count and CD4+ and CD8+ T-lymphocyte values were lower in the cases than in their matched controls on the day of infection and annually up to 4 years earlier. The covariables independently associated with PCP were the total lymphocyte count 1 year before Pneumocystis, mTOR inhibitors used as maintenance immunosuppressive drugs, and the administration of corticosteroid boluses used in acute rejection. A total lymphocyte count threshold <1000/µL offered the best predictive value for infection occurrence. PCP was associated with high incidence of graft loss and patient death (30% and 17% respectively, 3 years after PCP).

Conclusions

Pneumocystis pneumonia has dramatic consequences in kidney transplant recipients; a targeted prophylaxis based on simple criteria, such as chronic lymphopenia and/or history of corticosteroid boluses, could be useful to avoid life-threatening complications.

Challenging SNP impact on caspofungin resistance by full-length FKS1 allele replacement in Candida lusitaniae

OBJECTIVES

A strain of the opportunistic pathogenic yeast Candida lusitaniae was genetically engineered for full-length replacement of the FKS1 gene encoding the target of echinocandin antifungals in order to assess the impact of FKS mutations on echinocandin resistance and reduced echinocandin susceptibility (RES).

METHODS

FKS1 allelic exchange was achieved by transforming C. lusitaniae with two DNA fragments covering the entire FKS1 ORF. Both fragments overlap a 40 bp region where SNPs or small indels of interest were inserted. To target integration at the FKS1 locus, each DNA fragment was fused with split auxotrophic markers of which complementary truncated parts were previously inserted into the chromosomal regions flanking FKS1, allowing selection on minimal medium.

RESULTS

Three SNPs described in the FKS1 hotspot (HS) regions HS1 or HS2 of clinical isolates of Candida albicans were expressed at an equivalent position in C. lusitaniae and were confirmed to confer either reduced susceptibility (F641V) or full resistance (S645P and R1361G) to caspofungin. The F659 deletion reported in an FKS2 allele of Candida glabrata and the naturally occurring P660A substitution in FKS1 of Candida parapsilosis were shown to confer a 256-fold and 6-fold increase in caspofungin MIC, respectively, when introduced into an FKS1 allele of C. lusitaniae.

CONCLUSIONS

We have successfully developed a C. lusitaniae strain for the expression of full-length FKS1 alleles harbouring known mutations contributing to reduced susceptibility or resistance to caspofungin, thus opening the way for the screening of other FKS1/FKS2 mutations potentially involved in RES.

Pneumocystis Infection Outbreaks in Organ Transplantation Units in France: A Nation-Wide Survey

The burden of nosocomial Pneumocystis infections in transplantation units in France was evaluated through a retrospective survey. Over 12 years, 16 outbreaks occurred, including 13 among renal transplant recipients (RTRs). We performed Pneumocystis jirovecii genotyping in 5 outbreaks, which suggested that specific strains may have been selected by RTRs.

Toxoplasmosis in Transplant Recipients, Europe, 2010-2014

Transplantation activity is increasing, leading to a growing number of patients at risk for toxoplasmosis. We reviewed toxoplasmosis prevention practices, prevalence, and outcomes for hematopoietic stem cell transplant (HSCT) and solid organ transplant (SOT; heart, kidney, or liver) patients in Europe. We collected electronic data on the transplant population and prevention guidelines/regulations and clinical data on toxoplasmosis cases diagnosed during 2010–2014. Serologic pretransplant screening of allo-hematopoietic stem cell donors was performed in 80% of countries, screening of organ donors in 100%. SOT recipients were systematically screened in 6 countries. Targeted anti-Toxoplasma chemoprophylaxis was heterogeneous. A total of 87 toxoplasmosis cases were recorded (58 allo-HSCTs, 29 SOTs). The 6-month survival rate was lower among Toxoplasma-seropositive recipients and among allo-hematopoietic stem cell and liver recipients. Chemoprophylaxis improved outcomes for SOT recipients. Toxoplasmosis remains associated with high mortality rates among transplant recipients. Guidelines are urgently needed to standardize prophylactic regimens and optimize patient management.

AFM combined to ATR-FTIR reveals Candida cell wall changes under caspofungin treatment

Fungal pathogens from Candida genus are responsible for severe life-threatening infections and the antifungal arsenal is still limited. Caspofungin, an antifungal drug used for human therapy, acts as a blocking agent of the cell wall synthesis by inhibiting the β-1,3-glucan-synthase encoded by FKS genes. Despite its efficiency, the number of genetic mutants that are resistant to caspofungin is increasing. An important challenge to improve antifungal therapy is to understand cellular phenomenon that are associated with drug resistance. Here we used atomic force microscopy (AFM) combined to Fourier transform infrared spectroscopy in attenuated total reflection mode (ATR-FTIR) to decipher the effect of low and high drug concentration on the morphology, mechanics and cell wall composition of two Candida strains, one susceptible and one resistant to caspofungin. Our results confirm that caspofungin induces a dramatic cell wall remodelling via activation of stress responses, even at high drug concentration. Additionally, we highlighted unexpected changes related to drug resistance, suggesting that caspofungin resistance associated with FKS gene mutations comes from a combination of effects: (i) an overall remodelling of yeast cell wall composition; and (ii) cell wall stiffening through chitin synthesis. This work demonstrates that AFM combined to ATR-FTIR is a valuable approach to understand at the molecular scale the biological mechanisms associated with drug resistance.

Trichosporon faecale invasive infection in a patient with severe aplastic anemia: Efficacy of voriconazole and liposomal amphotericin B before neutrophil recovery

We report a case of a 51-year old man with a severe aplastic anemia who developed an invasive trichosporonosis to Trichosporon faecale with fungemia and skin lesions during severe neutropenia. The treatment was successful before neutrophil recovery with a combination of voriconazole and liposomal amphotericin B.

A Fox2-dependent fatty acid ß-oxidation pathway coexists both in peroxisomes and mitochondria of the ascomycete yeast Candida lusitaniae

It is generally admitted that the ascomycete yeasts of the subphylum Saccharomycotina possess a single fatty acid ß-oxidation pathway located exclusively in peroxisomes, and that they lost mitochondrial ß-oxidation early during evolution. In this work, we showed that mutants of the opportunistic pathogenic yeast Candida lusitaniae which lack the multifunctional enzyme Fox2p, a key enzyme of the ß-oxidation pathway, were still able to grow on fatty acids as the sole carbon source, suggesting that C. lusitaniae harbored an alternative pathway for fatty acid catabolism. By assaying 14Cα-palmitoyl-CoA consumption, we demonstrated that fatty acid catabolism takes place in both peroxisomal and mitochondrial subcellular fractions. We then observed that a fox2Δ null mutant was unable to catabolize fatty acids in the mitochondrial fraction, thus indicating that the mitochondrial pathway was Fox2p-dependent. This finding was confirmed by the immunodetection of Fox2p in protein extracts obtained from purified peroxisomal and mitochondrial fractions. Finally, immunoelectron microscopy provided evidence that Fox2p was localized in both peroxisomes and mitochondria. This work constitutes the first demonstration of the existence of a Fox2p-dependent mitochondrial β-oxidation pathway in an ascomycetous yeast, C. lusitaniae. It also points to the existence of an alternative fatty acid catabolism pathway, probably located in peroxisomes, and functioning in a Fox2p-independent manner.

Two missense mutations, E123Q and K151E, identified in the ERG11 allele of an azole-resistant isolate of Candida kefyr recovered from a stem cell transplant patient for acute myeloid leukemia

We report on the first cloning and nucleotide sequencing of an ERG11 allele from a clinical isolate of Candida kefyr cross-resistant to azole antifungals. It was recovered from a stem cell transplant patient, in an oncohematology unit exhibiting unexpected high prevalence of C. kefyr. Two amino acid substitutions were identified: K151E, whose role in fluconazole resistance was already demonstrated in Candida albicans, and E123Q, a new substitution never described so far in azole-resistant Candida yeast.

A disseminated infection with the antifungal-multiresistant teleomorphic fungus Neocosmospora vasinfecta in a patient with acute B-lymphoblastic leukemia

We report on a fatal invasive infection due to the ascomycetous fungus Neocosmospora vasinfecta, in a 20-year-old European patient suffering from an acute lymphoblastic leukemia. The infection could not be controlled by a bitherapy combining liposomal amphotericin B and voriconazole. This is the second case of disseminated infection reported with this unusual fungus, which develops under its teleomorphic state, is fully resistant to all systemic antifungals, and which is known to live in tropical countries.

Reverse line blot hybridisation screening of Pseudallescheria/Scedosporium species in patients with cystic fibrosis

The PCR-RLB (reverse line blot hybridisation) was applied as a molecular technique for the detection of members of Pseudallescheria and Scedosporium from sputum of patients with cystic fibrosis (CF). Fifty-nine sputum samples were collected from 52 CF patients, which were analysed by culture and PCR-RLB. Conventional and semi-selective culture yielded five positive samples, but the PCR-RLB hybridisation assay permitted the detection of members of Pseudallescheria/Scedosporium in 32 out of 52 patients (61.5%). In total, PCR-RLB yielded 47 positives. Pseudallescheria apiosperma was detected in 20 samples, while Pseudallescheria boydii and Pseudallescheria aurantiacum were detected in 17 and eight samples, respectively. Six samples gave a positive reaction with two distinct species-specific probes and one sample with three probes. In conclusion, the PCR-RLB assay described in this study allows the detection of Scedosporium spp. in CF sputum samples and the identification of Pseudallescheria apiosperma, P. boydii, S. aurantiacum, Scedosporium prolificans and Pseudallescheria minutispora.

Lindnera (Pichia) fabianii blood infection after mesenteric ischemia

Lindnera (Pichia) fabianii (teleomorph of Candida fabianii) is a yeast species rarely involved in human infections. This report describes the first known human case of a Lindnera fabianii blood infection after mesenteric ischemia. The 53-year-old patient was hospitalized in the intensive care unit after a suicide attempt and was suffering from a mesenteric ischemia and acute renal failure. Lindnera fabianii was recovered from an oropharyngeal swab, then isolated from stool and urine samples before the diagnosis of the blood infection. Caspofungin intravenous treatment was associated with a successful outcome. Final unequivocal identification of the strain was done by sequencing the internal transcribed spacer (ITS) region, and regions of 18S rDNA gene and of the translation elongation factor-1α gene. Until our work, the genomic databases did not contain the complete ITS region of L. fabianii as a single nucleotide sequence (encompassing ITS1, the 5.8S rDNA and ITS2), and misidentification with other yeast species, e.g., Lindnera (Pichia) mississippiensis, could have occurred. Our work demonstrates that the usual DNA barcoding method based on sequencing of the ITS region may fail to provide the correct identification of some taxa, and that partial sequencing of the EF1α gene may be much more effective for the accurate delineation and molecular identification of new emerging opportunistic yeast pathogens.

New highly divergent rRNA sequence among biodiverse genotypes of Enterocytozoon bieneusi strains isolated from humans in Gabon and Cameroon

Intestinal microsporidiosis due to Enterocytozoon bieneusi is a leading cause of chronic diarrhea in severely immunocompromised human immunodeficiency virus (HIV)-positive patients. It may be a public health problem in Africa due to the magnitude of the HIV pandemic and to poor sanitary conditions. We designed two prevalence studies of E. bieneusi in Central Africa, the first with HIV-positive patients from an urban setting in Gabon and the second with a nonselected rural population in Cameroon. Stool samples were analyzed by an immunofluorescence antibody test and PCR. Twenty-five out of 822 HIV-positive patients from Gabon and 22 out of 758 villagers from Cameroon were found to be positive for E. bieneusi. The prevalence rates of the two studies were surprisingly similar (3.0% and 2.9%). Genotypic analysis of the internal transcribed spacer region of the rRNA gene showed a high degree of diversity in samples from both countries. In Gabon, 15 isolates showed seven different genotypes: the previously reported genotypes A, D, and K along with four new genotypes, referred to as CAF1, CAF2, CAF3, and CAF4. In Cameroon, five genotypes were found in 20 isolates: the known genotypes A, B, D, and K and the new genotype CAF4. Genotypes A and CAF4 predominated in Cameroon, whereas K, CAF4, and CAF1 were more frequent in Gabon, suggesting that different genotypes present differing risks of infection associated with immune status and living conditions. Phylogenetic analysis of the new genotype CAF4, identified in both HIV-negative and HIV-positive subjects, indicates that it represents a highly divergent strain.

Oral histoplasmosis after radiation therapy for laryngeal squamous cell carcinoma

Histoplasmosis is a usually asymptomatic deep fungal infection of tropical origin with respiratory entry and possible oral, pharyngeal, or metastatic localization. The condition represents an important imported systemic mycosis with oral involvement. We report the case of a patient who developed an oropharyngeal reactivation of a latent Histoplasma infection after receiving local antitumoral radiation therapy of the neck. H capsulatum was shown to be present in the lesion by both histopathology and staining, and was deduced to be the causative organism of the disease.

[Antifungals cellular targets and mechanisms of resistance]

Antifungals of systemic use for the treatment of invasive fungal infections belong to four main chemical families which have globally three cellular targets in fungal cells: fluorinated pyrimidines act on deoxyribonucleic acid (DNA) replication and protein synthesis; polyenes and azoles are toxic for ergosterol and its biosynthetic pathway; lipopeptides inhibit the synthesis of cell wall beta glucans. The resistance mechanisms that are developed by some fungi begin to be well understood particularly in Candida yeasts. The underlying bases of these mechanisms are either mutations that modify the antifungal target, or that block access to the target, and, on the other hand, the overexpression of genes encoding the target, or some membrane proteins involved in the active efflux of antifungal drugs.

Development of an immunomagnetic separation-polymerase chain reaction (IMS-PCR) assay specific for Enterocytozoon bieneusi in water samples

AIMS

Microsporidia have become widely recognized as important human pathogens. Among Microsporidia, Enterocytozoon bieneusi is responsible for severe gastrointestinal disease. To date, no current therapy has been proven effective. Their mode of transmission and environmental occurrence are poorly documented because of the lack of detection methods that are both species-specific and sensitive. In this study, we developed a sensitive and specific molecular method to detect E. bieneusi spores in water samples.

METHODS AND RESULTS

The molecular assay combined immunomagnetic separation (IMS) and polymerase chain reaction (PCR) amplification to detect E. bieneusi spores. A comparison was made of IMS magnetic beads coated with two different monoclonal antibodies, one specific for the Encephalitozoon genus that cross-reacts with E. bieneusi and the other specific only for the E. bieneusi species itself.

CONCLUSIONS

Immunotech beads coated with the antibody specific for E. bieneusi were found to be the most effective combination.

SIGNIFICANCE AND IMPACT OF THE STUDY

The highly specific IMS-PCR assay developed in this study provides a rapid and sensitive means of screening water samples for the presence of E. bieneusi spores.

Evaluation of an immunofluorescent-antibody test using monoclonal antibodies directed against Enterocytozoon bieneusi and Encephalitozoon intestinalis for diagnosis of intestinal microsporidiosis in Bamako (Mali)

A 2-month study was carried out in Mali to evaluate an immunofluorescent-antibody test (IFAT) using monoclonal probes specific for Enterocytozoon bieneusi or Encephalitozoon intestinalis. Sixty-one human immunodeficiency virus (HIV)-seropositive adult patients and 71 immunocompetent children were enrolled. Microsporidia were detected in stools from 8 of 61 patients (13.1%) seropositive for HIV. A single species, E. bieneusi, was identified. All the children were negative for microsporidia. The sensitivity and specificity of IFAT were 100% compared with those of PCR, which was used as the "gold standard." Moreover, species identification by IFAT was more rapid and less expensive than that by PCR. These results show the suitability of IFAT for detection of microsporidia in developing countries.

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.

OBJECTIVE

To investigate the responsibility of dermatophytes in interdigital lesions of the feet in European marathon runners and to identify associated risk factors.

SUBJECTS AND METHODS

Runners of the 14th Médoc Marathon (n = 147) were interviewed on risk factors for tinea pedis and underwent physical and mycological examinations.

RESULTS

Interdigital lesions of the feet were found in 66 runners (45%). A dermatophyte was isolated in 45 runners (31%), 12 of whom were asymptomatic. Trichophyton interdigitale and T. rubrum accounted for 49% and 35.5%, respectively, of the cases of tinea pedis. Thirty-three (22%) of the 102 runners free of dermatophyte infection had lesions resembling those of tinea pedis. Increasing age and use of communal bathing facilities were predictive of T. rubrum culture.

CONCLUSIONS

Marathon runners are at high risk for tinea pedis, but dermatophytes are responsible for only half of the foot lesions found in runners. The existence of asymptomatic carriers calls for prophylactic measures.

One-step purification of Enterocytozoon bieneusi spores from human stools by immunoaffinity expanded-bed adsorption

An original, reliable, and reproducible method for the purification of Enterocytozoon bieneusi spores from human stools is described. We recently reported the production of a species-specific monoclonal antibody (MAb) 6E52D9 immunoglobulin G2a (IgG2a) raised against the exospore of E. bieneusi spore walls. The MAb was used as a ligand to develop an immunoaffinity matrix. The mouse IgG2a MAb was bound directly to a Streamline rProtein A adsorbent, used for expanded-bed adsorption of immunoglobulins, for optimal spatial orientation of the antibody and maximum binding efficiency of the antigen. The complex was then cross-linked covalently using dimethyl pimelimidate dihydrochloride. After incubation of the immunoaffinity matrix with filtered stool samples containing numerous E. bieneusi spores and before elution with 6 M guanidine HCl, the expansion of the adsorbent bed eliminated all the fecal contaminants. The presence of spores in the elution fractions was determined by an indirect immunofluorescence antibody test (IFAT). E. bieneusi spores were found in the elution fraction in all four experiments and were still highly antigenic as indicated by IFAT. Smears examined by light microscopy contained very clean spores with no fecal debris or background bacterial and fungal contaminants. However, spore recovery rates were relatively low: an average of 10(7) spores were purified per run. This technique for isolating E. bieneusi spores directly from human stool samples with a high degree of purity opens up new approaches for studying this parasite.

Production of monoclonal antibodies directed against the microsporidium Enterocytozoon bieneusi

Several hybridomas producing antibodies detected by indirect immunofluorescence antibody test (IFAT) were established by fusion of mouse myeloma SP2/O with spleen cells from BALB/c mice immunized against whole spores (protocol 1) or chitinase-treated spores (protocol 2) of Enterocytozoon bieneusi and were cloned twice by limiting dilutions. Two monoclonal antibodies (MAbs), 3B82H2 from protocol 1, isotyped as immunoglobulin M (IgM), and 6E52D9 from protocol 2, isotyped as IgG, were expanded in both ascites and culture. IFAT with the MAbs showed that both MAbs reacted exclusively with the walls of the spores of E. bieneusi, strongly staining the surface of mature spores, and produced titers of greater than 4,096. Immunogold electron microscopy confirmed the specific reactivities of both antibodies. No cross-reaction, either with the spores of the other intestinal microsporidium species Encephalitozoon intestinalis or with yeast cells, bacteria, or any other intestinal parasites, was observed. The MAbs were used to identify E. bieneusi spores in fecal specimens from patients suspected of having intestinal microsporidiosis. The IFAT was validated against standard staining methods (Chromotrope 2R and Uvitex 2B) and PCR. We report here the first description and characterization of two MAbs specific for the spore wall of E. bieneusi. These MAbs have great potential for the demonstration and species determination of E. bieneusi, and their application in immunofluorescence identification of E. bieneusi in stool samples could offer a new diagnostic tool for clinical laboratories.