Time to intestinal clearance of carbapenemase-producing Enterobacterales in hospital patients: a longitudinal retrospective observational cohort study.

BACKGROUND: Intestinal clearance of carbapenemase-producing Enterobacterales (CPE-IC) is a cornerstone to discontinue isolation precautions for CPE patients in hospitals. This study aimed to evaluate the time to spontaneous CPE-IC and identify its potential associated risk factors. METHODS: This retrospective cohort study was carried out between January 2018 and September 2020 on all patients in a 3200-bed teaching referral hospital with confirmed CPE intestinal carriage. CPE-IC was defined as at least three consecutive CPE-negative rectal swab cultures without a subsequent positive result. A survival analysis was performed to determine the median time to CPE-IC. A multivariate Cox model was implemented to explore the factors associated with CPE-IC. RESULTS: A total of 110 patients were positives for CPE, of whom 27 (24.5%) achieved CPE-IC. Median time to CPE-IC was 698 days. Univariate analysis showed that female sex (P=0.046), multiple CPE-species in index cultures (P=0.005), Escherichia coli or Klebsiella spp. (P=0.001 and P=0.028, respectively) were significantly associated with the time to CPE-IC. Multivariate analysis highlighted that identification of E. coli carbapenemase-producing or CPEs harbouring ESBL genes in index culture extended the median time to CPE-IC, respectively (adjusted hazard ratio (aHR) = 0.13 (95% confidence interval: 0.04-0.45]; P=0.001 and aHR = 0.34 (95% confidence interval: 0.12-0.90); P=0.031). CONCLUSION: Intestinal decolonization of CPE can take several months to years to occur. Carbapenemase-producing E. coli are likely to play a key role in delaying intestinal decolonization, probably through horizontal gene transfer between species. Therefore, discontinuation of isolation precautions in CPE-patients should be considered with caution.

Interlaboratory evaluation of Mucorales PCR assays for testing serum specimens: A study by the fungal PCR Initiative and the Modimucor study group.

Interlaboratory evaluations of Mucorales qPCR assays were developed to assess the reproducibility and performance of methods currently used. The participants comprised 12 laboratories from French university hospitals (nine of them participating in the Modimucor study) and 11 laboratories participating in the Fungal PCR Initiative. For panel 1, three sera were each spiked with DNA from three different species (Rhizomucor pusillus, Lichtheimia corymbifera, Rhizopus oryzae). For panel 2, six sera with three concentrations of R. pusillus and L. corymbifera (1, 10, and 100 genomes/ml) were prepared. Each panel included a blind negative-control serum. A form was distributed with each panel to collect results and required technical information, including DNA extraction method, sample volume used, DNA elution volume, qPCR method, qPCR template input volume, qPCR total reaction volume, qPCR platform, and qPCR reagents used. For panel 1, assessing 18 different protocols, qualitative results (positive or negative) were correct in 97% of cases (70/72). A very low interlaboratory variability in Cq values (SD = 1.89 cycles) were observed. For panel 2 assessing 26 different protocols, the detection rates were high (77-100%) for 5/6 of spiked serum. There was a significant association between the qPCR platform and performance. However, certain technical steps and optimal combinations of factors may also impact performance. The good reproducibility and performance demonstrated in this study support the use of Mucorales qPCR as part of the diagnostic strategy for mucormycosis.

Invasive rhino-orbital-cerebral aspergillosis in an immunocompetent patient.

INTRODUCTION: Rhino-orbital-aspergillosis (ROA) is a rare but serious disease in immunocompetent patients. Diagnosis is often delayed due to the absence of specific clinical symptoms. We describe the case of a patient who presented initially with ROA which spread progressively to the right ethmoid-sphenoid sinuses and then to the brain. OBSERVATION: A 61-year-old patient with a history of well-controlled diabetes presented with a sudden severe decrease in right visual acuity. Cerebral MRI showed the presence of an infiltrate in the right orbital apex extending to the homolateral cavernous sinus without any cerebral involvement. A diagnosis of right orbital myositis was made and corticosteroid therapy was started. His symptoms worsened progressively leading to quasi-blindness. A new MRI showed the development of right sphenoid-ethmoid osteolytic lesions. A fungal aetiology was suspected and tests for fungal biomarkers found a ß-(1-3)-D-glucan level of 99pg/ml but negative galactomannan. An ethmoid biopsy was performed for histological and mycological investigations, including the detection of Aspergillus DNA by qPCR. qPCR was positive and culture resulted in the isolation of multi-sensitive Aspergillus fumigatus. Treatment was initiated with voriconazole. Due to persistence of blindness and the appearance of a lesion extending to the right frontal lobe, surgical excision was performed followed by antifungal treatment for a total duration of 1year. The patient is currently stable, but has persistence of blindness in the right eye. CONCLUSION: Invasive ROA is a rare but serious disease in immunocompetent patients which should be evoked in the differential diagnosis of a tumour or vasculitis. Early diagnosis is essential for optimal management.

Antifungal susceptibility testing practices in mycology laboratories in France, 2018.

A survey of mycology laboratories for antifungal susceptibility testing (AFST) was undertaken in France in 2018, to better understand the difference in practices between the participating centers and to identify the difficulties they may encounter as well as eventual gaps with published standards and guidelines. The survey captured information from 45 mycology laboratories in France on how they perform AFST (number of strains tested, preferred method, technical and quality aspects, interpretation of the MIC values, reading and interpretation difficulties). Results indicated that 86% of respondents used Etest as AFST method, with a combination of one to seven antifungal agents tested. Most of the participating laboratories used similar technical parameters to perform their AFST method and a large majority used, as recommended, internal and external quality assessments. Almost all the participating mycology laboratories (98%) reported difficulties to interpret the MIC values, especially when no clinical breakpoints are available. The survey highlighted that the current AFST practices in France need homogenization, particularly for MIC reading and interpretation.

Emergence of Aspergillus fumigatus azole resistance in azole-naïve patients with chronic obstructive pulmonary disease and their homes.

Azole-resistant Aspergillus fumigatus (ARAF) has been reported in patients with chronic obstructive pulmonary disease (COPD) but has not been specifically assessed so far. Here, we evaluated ARAF prevalence in azole-naïve COPD patients and their homes, and assessed whether CYP51A mutations were similar in clinical and environmental reservoirs. Sixty respiratory samples from 41 COPD patients with acute exacerbation and environmental samples from 36 of these patient's homes were prospectively collected. A. fumigatus was detected in respiratory samples from 11 of 41 patients (27%) and in 15 of 36 domiciles (42%). Cyp51A sequencing and selection on itraconazole medium of clinical (n = 68) and environmental (n = 48) isolates yielded ARAF detection in 1 of 11 A. fumigatus colonized patients with COPD (9%) and 2 of 15 A. fumigatus-positive patient's homes (13%). The clinical isolate had no CYP51A mutation. Two environmental isolates from two patients harbored TR34 /L98H mutation, and one had an H285Y mutation. Coexistence of different cyp51A genotypes and/or azole resistance profiles was detected in 3 of 8 respiratory and 2 of 10 environmental samples with more than one isolate, confirming the need for a systematic screening of all clinically relevant isolates. The high prevalence of ARAF in patients with COPD and their homes supports the need for further studies to assess the prevalence of azole resistance in patients with Aspergillus diseases in Northern France.

Bacteriome and Mycobiome Interactions Underscore Microbial Dysbiosis in Familial Crohn's Disease.

UNLABELLED: Crohn's disease (CD) results from a complex interplay between host genetic factors and endogenous microbial communities. In the current study, we used Ion Torrent sequencing to characterize the gut bacterial microbiota (bacteriome) and fungal community (mycobiome) in patients with CD and their nondiseased first-degree relatives (NCDR) in 9 familial clusters living in northern France-Belgium and in healthy individuals from 4 families living in the same area (non-CD unrelated [NCDU]). Principal component, diversity, and abundance analyses were conducted, and CD-associated inter- and intrakingdom microbial correlations were determined. Significant microbial interactions were identified and validated using single- and mixed-species biofilms. CD and NCDR groups clustered together in the mycobiome but not in the bacteriome. Microbiotas of familial (CD and NCDR) samples were distinct from those of nonfamilial (NCDU) samples. The abundance of Serratia marcescens and Escherichia coli was elevated in CD patients, while that of beneficial bacteria was decreased. The abundance of the fungus Candida tropicalis was significantly higher in CD than in NCDR (P = 0.003) samples and positively correlated with levels of anti-Saccharomyces cerevisiae antibodies (ASCA). The abundance of C. tropicalis was positively correlated with S. marcescens and E. coli, suggesting that these organisms interact in the gut. The mass and thickness of triple-species (C. tropicalis plus S. marcescens plus E. coli) biofilm were significantly greater than those of single- and double-species biofilms. C. tropicalis biofilms comprised blastospores, while double- and triple-species biofilms were enriched in hyphae. S. marcescens used fimbriae to coaggregate or attach with C. tropicalis/E. coli, while E. coli was closely apposed with C. tropicalis Specific interkingdom microbial interactions may be key determinants in CD. IMPORTANCE: Here, we characterized the gut bacterial microbiota (bacteriome) and fungal community (mycobiome) in multiplex families with CD and healthy relatives and defined the microbial interactions leading to dysbiosis in CD. We identified fungal (Candida tropicalis) and bacterial (Serratia marcescens and Escherichia coli) species that are associated with CD dysbiosis. Additionally, we found that the level of anti-Saccharomyces cerevisiae antibodies (ASCA; a known CD biomarker) was associated with the abundance of C. tropicalis We also identified positive interkingdom correlations between C. tropicalis, E. coli, and S. marcescens in CD patients and validated these correlations using in vitro biofilms. These results provide insight into the roles of bacteria and fungi in CD and may lead to the development of novel treatment approaches and diagnostic assays.

Multicenter Comparison of the Etest and EUCAST Methods for Antifungal Susceptibility Testing of Candida Isolates to Micafungin.

In vitro susceptibility of 933 Candida isolates, from 16 French hospitals, to micafungin was determined using the Etest in each center. All isolates were then sent to a single center for determination of MICs by the EUCAST reference method. Overall essential agreement between the two tests was 98.5% at ±2 log2 dilutions and 90.2% at ±1 log2 dilutions. Categorical agreement was 98.2%. The Etest is a valuable alternative to EUCAST for the routine determination of micafungin MICs in medical mycology laboratories.

Role of mannose-binding lectin in intestinal homeostasis and fungal elimination.

Mannose-binding lectin (MBL) is a soluble lectin of the innate immune system that is produced by the liver and secreted into the circulation where it activates the lectin complement pathway, enhances phagocytosis of microorganisms by leukocytes, and modulates inflammation. MBL can recognize patterns on the surface of different pathogens, including Candida albicans. Our aims were to investigate whether MBL is expressed in the gut epithelium and to examine its effect on the modulation of intestinal inflammation and C. albicans elimination. Using reverse transcriptase-PCR, MBL transcripts were highly expressed in different parts of the mouse gut. MBL expression was also detected by immunoblotting and immunolocalization in response to C. albicans colonization of the gut; the highest expression of MBL was detected in the stomach. Blocking MBL by administering mannans to mice increased C. albicans colonization. MBL-deficient mice had a higher level of colonization than wild-type mice. Dextran sodium sulfate-induced colitis promoted C. albicans dissemination to the kidneys and lungs of MBL-deficient mice. MBL-deficient mice exhibited elevated expression of interleukin (IL)-17, IL-23, dectin-1, and Toll-like receptor-4. This study shows that MBL expression is induced in the gut in response to C. albicans sensing and is required for intestinal homeostasis and host defense against C. albicans.

Assessment of microscopic and molecular tools for the diagnosis and follow-up of cryptosporidiosis in patients at risk.

Cryptosporidiosis is an important though underreported public health concern. Molecular tools might be helpful in improving its diagnosis. In this study, ZR Fecal DNA MiniPrep™ Kit (ZR) and NucliSens® easyMAG® (EM) were compared using four Cryptosporidium-seeded feces and 29 Cryptosporidium-positive stools. Thereafter, ZR was selected for prospective evaluation of Cryptosporidium detection by 18S rDNA and LAXER quantitative PCR (qPCR) in 69 stools from 56 patients after Cryptosporidium detection by glycerin, modified Ziehl-Neelsen (ZN) and auramine-phenol (AP) stainings. The combination of any of the two extraction methods with 18S qPCR yielded adequate detection of Cryptosporidium in seeded stools, but the ZR kit showed the best performance. All 29 Cryptosporidium-positive samples were positive with 18S qPCR, after both ZR and EM extraction. However, false-negative results were found with LAXER qPCR or nested PCR. Cryptosporidiosis was diagnosed in 7/56 patients. All the microscopic methods enabled the initial diagnosis, but Cryptosporidium was detected in 12, 13, and 14 samples from these seven patients after glycerin, ZN, and AP staining respectively. Among these samples, 14 and 12 were positive with 18S and LAXER qPCR respectively. In two patients, Cryptosporidium DNA loads were found to be correlated with clinical evolution. Although little known, glycerin is a sensitive method for the initial detection of Cryptosporidium. When combined with 18S qPCR, ZR extraction, which had not been evaluated so far for Cryptosporidium, was an accurate tool for detecting Cryptosporidium and estimating the oocyst shedding in the course of infection.

Invasive Candida infections in surgical patients in intensive care units: a prospective, multicentre survey initiated by the European Confederation of Medical Mycology (ECMM) (2006-2008).

A prospective, observational, multicentre study of invasive candidosis (IC) in surgical patients in intensive care units (ICUs) was conducted from 2006 to 2008 in 72 ICUs in 14 European countries. A total of 779 patients (62.5% males, median age 63 years) with IC were included. The median rate of candidaemia was 9 per 1000 admissions. In 10.8% the infection was already present at the time of admission to ICU. Candida albicans accounted for 54% of the isolates, followed by Candida parapsilosis 18.5%, Candida glabrata 13.8%, Candida tropicalis 6%, Candida krusei 2.5%, and other species 5.3%. Infections due to C. krusei (57.9%) and C. glabrata (43.6%) had the highest crude mortality rate. The most common preceding surgery was abdominal (51.5%), followed by thoracic (20%) and neurosurgery (8.2%). Candida glabrata was more often isolated after abdominal surgery in patients ≥60 years, and C. parapsilosis was more often isolated in neurosurgery and multiple trauma patients as well as children ≤1 year of age. The most common first-line treatment was fluconazole (60%), followed by caspofungin (18.7%), liposomal amphotericin B (13%), voriconazole (4.8%) and other drugs (3.5%). Mortality in surgical patients with IC in ICU was 38.8%. Multivariate analysis showed that factors independently associated with mortality were: patient age ≥60 years (hazard ratio (HR) 1.9, p 0.001), central venous catheter (HR 1.8, p 0.05), corticosteroids (HR 1.5, p 0.03), not receiving systemic antifungal treatment for IC (HR 2.8, p <0.0001), and not removing intravascular lines (HR 1.6, p 0.02).

Preliminary evidence for a serum disaccharide signature of invasive Candida albicans infection detected by MALDI Mass Spectrometry.

The diagnosis of systemic Candida infections is a recognized challenge. We developed a mass spectrometry strategy to detect signals from Candida molecules in patients' sera. Pre-analytical procedures were designed to extract oligosaccharides from serum. A peak m/z of at 365 was specifically revealed in sera from patients with candidaemia with regard to healthy controls. This biomarker was identified as a disaccharide, its presence did not correlate with mannanaemia or glucanaemia. Mouse models of Candida albicans colonization and infection showed that the signal was specifically associated with tissue invasion, suggesting that clinical evaluation of its usefulness in discriminating colonized and infected patients would be worthwhile.

Evaluation of two matrix-assisted laser desorption ionization-time of flight mass spectrometry (MALDI-TOF MS) systems for the identification of Candida species.

Candida spp. are responsible for severe infections in immunocompromised patients and those undergoing invasive procedures. The accurate identification of Candida species is important because emerging species can be associated with various antifungal susceptibility spectra. Conventional methods have been developed to identify the most common pathogens, but have often failed to identify uncommon species. Several studies have reported the efficiency of matrix-assisted laser desorption ionization-time of flight mass spectrometry (MALDI-TOF MS) for the identification of clinically relevant Candida species. In this study, we evaluated two commercially available MALDI-TOF systems, Andromas™ and Bruker Biotyper™, for Candida identification in routine diagnosis. For this purpose, we investigated 1383 Candida isolates prospectively collected in eight hospital laboratories during routine practice. MALDI-TOF MS results were compared with those obtained using conventional phenotypic methods. Analysis of rDNA gene sequences with internal transcribed regions or D1-D2 regions is considered the reference standard for identification. Both MALDI-TOF MS systems could accurately identify 98.3% of the isolates at the species level (1359/1383 for Andromas™; 1360/1383 for Bruker Biotyper™) vs. 96.5% for conventional techniques. Furthermore, whereas conventional methods failed to identify rare or emerging species, these were correctly identified by MALDI-TOF MS. Both MALDI-TOF MS systems are accurate and cost-effective alternatives to conventional methods for mycological identification of clinically relevant Candida species and should improve the diagnosis of fungal infections as well as patient management.

[Singular, systemic, self-reactive IgG patterns related to age: relationship with cerebral malaria susceptibility in exposed subjects residing in an endemic area in Abidjan, Côte-d'Ivoire]. / Singularité des profils d'autoréactivité systémique en fonction de l'âge: relations avec la susceptibilité au neuropaludisme chez les sujets exposés en région endémique à Abidjan, Côte-d'Ivoire.

The impact of autoimmunity on malaria-infection evolution reported by various works has led us to compare reactive patterns of self-dependent systemic IgG from 54 patients aged less than 15 years old to those from 46 subjects older than 15 years. These subjects were divided into 34 Plasmodium falciparum asymptomatic carriers (ACs), 30 cases of uncomplicated malaria (UM), and 36 patients suffering from cerebral malaria (CM) living in the same endemic area. The reactivity of the plasma antibodies against human brain tissue extract was assessed by western blotting. Comparative analysis of reactive bands (linear discriminant analysis, LDA) revealed the existence of patterns that distinguish, among the more susceptible subjects aged less than 15 years old, the different clinical forms. In contrast, in less susceptible subjects aged more than 15 years old, the patterns are homogenous and do not allow the separation of these clinical forms. This self-reactive repertoire might be witnessed as an imprint of the clinical tolerance acquired during the years of living in endemic areas. The singularity of this profile under the age of 15 years might have a prognostic value.

Diagnosis, management and outcome of Candida endocarditis.

Limited data exist on Candida endocarditis (CE) outcome in the era of new antifungals. As early diagnosis of CE remains difficult, non-culture-based tools need to be evaluated. Through the French prospective MYCENDO study (2005-2007), the overall characteristics and risk factors for death from CE were analysed. The contribution of antigen detection (mannan/anti-mannan antibodies and (1,3)-ß-d-glucans) and molecular tools was evaluated. Among 30 CE cases, 19 were caused by non-albicans species. Sixteen patients (53%) had a predisposing cardiac disease, which was a valvular prosthesis in ten (33%). Nine patients (30%) were intravenous drug users; none of them had right-sided CE. Among the 21 patients who were not intravenous drug users, 18 (86%) had healthcare-associated CE. Initial therapy consisted of a combination of antifungals in 12 of 30 patients (40%). Thirteen patients (43%) underwent valve replacement. The median follow-up was 1 year after discharge from hospital (range, 5 months to 4 years) and hospital mortality was 37%. On univariate analysis, patients aged ≥60 years had a higher mortality risk (OR 11, 95% CI 1.2-103.9; p 0.024), whereas intravenous drug use was associated with a lower risk of death (OR 0.12, 95% CI 0.02-0.7; p 0.03). Among 18 patients screened for both serum mannan/anti-mannan antibodies and (1,3)-ß-d-glucans, all had a positive result with at least one of either test at CE diagnosis. Real-time PCR was performed on blood (SeptiFast) in 12 of 18, and this confirmed the blood culture results. In conclusion, CE prognosis remains poor, with a better outcome among younger patients and intravenous drug users. Detection of serum antigens and molecular tools may contribute to earlier CE diagnosis.

Evaluation of a recombinant antigen-based enzyme immunoassay for the diagnosis of noninvasive aspergillosis.

Antibody detection is a key diagnostic tool for noninvasive aspergillosis (NIA) such as allergic bronchopulmonary aspergillosis and chronic pulmonary aspergillosis. Specific immunoprecipitin detection (IPD) is considered as the reference but lacks standardization and is time-consuming. To evaluate the performance of a new anti-Aspergillus fumigatus IgG enzyme immunoassay (EIA) kit using a recombinant A. fumigatus antigen (Bio-Rad), a retrospective study was performed on 551 sera collected from patients with a definite diagnosis of NIA (group 1; n = 64), bronchial Aspergillus colonization (group 2; n = 26), and probable aerial Aspergillus contamination (group 3; n = 44); from patients suspected of NIA with negative serological and mycological investigations (group 4; n = 49); and from a group of 222 patients not suspected of NIA (group 5). The EIA exhibited excellent reproducibility with coefficients of variation below 10%. Agreement with IPD was calculated between 62.5 and 84.4% according to the group of patients with Cohen's kappa coefficient at 0.6196 ± 0.077. Taking as reference a composite status including clinical, radiological, mycological, and serological data, sensitivity (group 1) and specificity (other groups) were calculated between 90.2 and 93.8% and 54.3 and 100%, respectively. Lower specificity was observed for patients with Aspergillus colonization. However, Yule Q coefficients estimating the correlation between EIA result and the definite diagnosis of NIA were calculated between 0.97 and 0.98. The method is a highly useful screening tool for the diagnosis of NIA, reducing the need for confirmatory IPD tests.

Invasive fungal infections: epidemiology and analysis of antifungal prescriptions in onco-haematology.

WHAT IS KNOWN AND OBJECTIVE: Invasive fungal infections (IFI) are associated with high rates of morbidity and mortality, particularly in onco-haematology patients. We aimed to study the epidemiology of IFI in neutropenic patients and estimate the economic impact of treatment of those infections. METHODS: All patients hospitalized in onco-haematology, and treated with antifungal agents, in 2005 were investigated. Four features were studied: the diagnosis for each patient, the antifungal drugs used, the thoracic densitometry reports and the sero-mycological data. Infectious episodes were stratified according to the EORTC 2008 classification criteria (10). RESULTS AND DISCUSSION: Of the 1130 patients surveyed, 192 patients received systemic antifungal agents. Of these 46% had acute leukaemia, 29% bone-marrow allografts, 7% lymphoma and 18% other malignant haemopathies. Using the EORTC 2008 criteria (10), there were 8 proved IFI (3 aspergillosis, 3 candidosis and 2 other IFI), 17 probable IFI (11 aspergillosis, 6 candidosis) and 16 possible aspergillosis. The incidence of IFI was 2·1%. Eighty patients (41·7%) had received prophylaxis: 56 with fluconazole and 24 with voriconazole. Treatment was most often empirical (n = 127, 66·1%). Combination of two antifungals was used in 17 cases. The mean duration of prophylactic, empirical, proved/probable aspergillosis-directed, candidaemia-directed and combination treatment was 19, 19, 46, 32 and 27 days, respectively. The cost of antifungal treatment in 2005 reached almost 2,000,000 €, including 427,000 € for documented infections (proved and probable), 1,246,000 € for empirical treatment and 58,300 € for prophylaxis. WHAT IS NEW AND CONCLUSION: The incidence of IFI is low but the pharmacoeconomic impact is extremely high. Improved strategies are required to reduce the frequency and duration of empirical treatment without compromising beneficial outcome.

Preliminary clinical study using a multiplex real-time PCR test for the detection of bacterial and fungal DNA directly in blood.

Early diagnosis of sepsis, rapid identification of the causative pathogen(s) and prompt initiation of appropriate antibiotic treatment have a combined impact on mortality due to sepsis. In this observational study, a new DNA-based system (LightCycler SeptiFast (LC-SF) test; Roche Diagnostics) allowing detection of 16 pathogens at the species level and four groups of pathogens at the genus level has been evaluated and compared with conventional blood cultures (BCs). One hundred BC and LC-SF results were obtained for 72 patients admitted to the intensive-care unit over a 6-month period for suspected sepsis. Microbiological data were compared with other biological parameters and with clinical data. The positivity rate of BCs for bacteraemia/fungaemia was 10%, whereas the LC-SF test allowed detection of DNA in 15% of cases. The LC-SF performance, based on its clinical relevance, was as follows: sensitivity, 78%; specificity, 99%; positive predictive value, 93%; and negative predictive value, 95%. Management was changed for four of eight (50%) of the patients because organisms were detected by the LC-SF test but not by BC. LC-SF results were obtained in 7-15 h, in contrast to the 24-72 h required for BC. According to the LC-SF results, initial therapy was inadequate in eight patients, and antibiotic treatment was changed. Our results suggest that the LC-SF test may be a valuable complementary tool in the management of patients with clinically suspected sepsis.

Antibodies against glucan, chitin, and Saccharomyces cerevisiae mannan as new biomarkers of Candida albicans infection that complement tests based on C. albicans mannan.

Antibodies against Saccharomyces cerevisiae mannan (ASCA) and antibodies against synthetic disaccharide fragments of glucans (ALCA) and chitin (ACCA) are biomarkers of Crohn's disease (CD). We previously showed that Candida albicans infection generates ASCA. Here, we explored ALCA and ACCA as possible biomarkers of invasive C. albicans infection (ICI). ASCA, ALCA, ACCA, and Candida mannan antigen and antibody detection tests were performed on 69 sera obtained sequentially from 18 patients with ICIs proven by blood culture, 59 sera from CD patients, 47 sera from hospitalized subjects colonized by Candida species (CZ), and 131 sera from healthy controls (HC). ASCA, ALCA, and ACCA levels in CD and ICI patients were significantly different from those in CZ and HC subjects (P<0.0001). In ICI patients, these levels increased as infection developed. Using ASCA, ALCA, ACCA, and Platelia Candida tests, 100% of ICIs were detected, with the kinetics of the antibody response depending on the patient during the time course of infection. A large number of sera presented with more than three positive tests. This is the first evidence that the detection of antibodies against chitin and glucans has diagnostic value in fungal infections and that these tests can complement more specific tests. Future trials are necessary to assess the value of these tests in multiparametric analysis, as well as their pathophysiological relevance.

Multilocus sequence typing reveals intrafamilial transmission and microevolutions of Candida albicans isolates from the human digestive tract.

Candida albicans is a human commensal that is also responsible for superficial and systemic infections. Little is known about the carriage of C. albicans in the digestive tract and the genome dynamics that occur during commensalisms of this diploid species. The aim of this study was to evaluate the prevalence, diversity, and genetic relationships among C. albicans isolates recovered during natural colonization of the digestive tract of humans, with emphasis on Crohn's disease patients who produce anti-yeast antibodies and may have altered Candida sp. carriage. Candida sp. isolates were recovered from 234 subjects within 25 families with multiple cases of Crohn's disease and 10 control families, sampled at the oral and fecal sites. Prevalences of Candida sp. and C. albicans carriage were 53.4% and 46.5%, respectively, indicating frequent commensal carriage. No differences in prevalence of carriage could be observed between Crohn's disease patients and healthy subjects. Multilocus sequence typing (MLST) of C. albicans isolates revealed frequent colonization of a subject or several members of the same family by genetically indistinguishable or genetically close isolates. These latter isolates differed by loss-of-heterozygosity events at one or several of the MLST loci. These loss-of-heterozygosity events could be due to either chromosome loss followed by duplication or large mitotic recombination events between complementary chromosomes. This study was the first to jointly assess commensal carriage of C. albicans, intrafamilial transmission, and microevolution. The high frequency of each of these events suggests that the digestive tract provides an important and natural niche for microevolutions of diploid C. albicans through the loss of heterozygosity.