Guillaume Desoubeaux

Colonization with the enteric protozoa Blastocystis is associated with increased diversity of human gut bacterial microbiota

Alterations in the composition of commensal bacterial populations, a phenomenon known as dysbiosis, are linked to multiple gastrointestinal disorders, such as inflammatory bowel disease and irritable bowel syndrome, or to infections by diverse enteric pathogens. Blastocystis is one of the most common single-celled eukaryotes detected in human faecal samples. However, the clinical significance of this widespread colonization remains unclear, and its pathogenic potential is controversial. To address the issue of Blastocystis pathogenicity, we investigated the impact of colonization by this protist on the composition of the human gut microbiota. For that purpose, we conducted a cross-sectional study including 48 Blastocystis-colonized patients and 48 Blastocystis-free subjects and performed an Ion Torrent 16S rDNA gene sequencing to decipher the Blastocystis-associated gut microbiota. Here, we report a higher bacterial diversity in faecal microbiota of Blastocystis colonized patients, a higher abundance of Clostridia as well as a lower abundance of Enterobacteriaceae. Our results contribute to suggesting that Blastocystis colonization is usually associated with a healthy gut microbiota, rather than with gut dysbiosis generally observed in metabolic or infectious inflammatory diseases of the lower gastrointestinal tract.

Molecular identification of Pentatrichomonas hominis in two patients with gastrointestinal symptoms

The trichomonad species Pentatrichomonas hominis colonises the gastrointestinal tract and is generally considered as a commensal organism in humans. However, some studies have recognised an association between diarrhoea and P hominis infection in dogs and cats.1 2 In the present report, we have identified this species using molecular tools in two patients with gastrointestinal troubles. Our data suggest that P hominis is a possible zoonotic species with a significant potential of transmission by water and could be the causative agent of intestinal symptoms in children. An adult (case 1) was followed up for different pathologies including irritable bowel syndrome (IBS). Diarrhoeic stools of the patient were examined and were negative for intestinal parasites. Filter paper/slant culture technique for the recovery of Strongyloides stercoralis larval-stage nematodes from fresh faeces was performed. After 5 days, microscopic examination of the stool culture using merthiolate-iodine-formalin and RAL555 stains did not detect larval nematodes but numerous flagellates, provisionally identified as trichomonads (figure 1A,B). Although no treatment against trichomonads was administered to the patient, the stool examinations performed afterwards did not reveal trichomonads or other parasites. Figure 1 Cytological appearance of trichomonad cells in stool culture (case 1). (A) Merthiolate-iodine-formalin- and (B) RAL555-stained smears showing numerous trichomonad cells (arrows). Note the round shape of the micro-organisms. Typical microtubular cytoskeletal structures of trichomonads including flagella and axostyle–pelta complex are not visible. Bar=15 μm. A young child (case 2) presented with abdominal pain and loose stools without fever. A stool sample was examined by direct light …

Diagnosis of invasive pulmonary aspergillosis: updates and recommendations.

Invasive pulmonary aspergillosis is an opportunistic mycosis, difficult to diagnose, due to the environmental fungi of the genus Aspergillus. The diagnostic tools, even if more are available, are still limited in number and effectiveness. The current recommendations issued by the EORTC/MSG (European Organization of Research and Treatment of Cancer/Mycoses Study Group) and the ECIL (European Conference for Infection in Leukemia) suggest collecting epidemiological, radio-clinical, and biological data to support the diagnosis of aspergillosis with a strong presumption. Thus, medical imaging and serum galactomannan antigen currently constitute the basis of the screening approach, although they both have some limitations in specificity. (1→3)-β-D-glucans are pan-fungal serum markers with a very good negative predictive value. Real-time PCR lacks standardization, and fungal culture from respiratory specimens is sometimes not sensitive enough. Histology allows proving the diagnosis of aspergillosis, but biopsy is not always possible in immunodepressed patients. We present the various arguments for the diagnosis of invasive aspergillosis, with a particular emphasis on recent exploration techniques.

Epidemiological Outbreaks of Pneumocystis jirovecii Pneumonia Are Not Limited to Kidney Transplant Recipients: Genotyping Confirms Common Source of Transmission in a Liver Transplantation Unit

ABSTRACT Over a 5-month period, four liver transplant patients at a single hospital were diagnosed with Pneumocystis jirovecii pneumonia (PCP). This unusually high incidence was investigated using molecular genotyping. Bronchoalveolar lavage fluids (BALF) obtained from the four liver recipients diagnosed with PCP were processed for multilocus sequence typing (MLST) at three loci (SOD, mt26s, and CYB). Twenty-four other BALF samples, which were positive for P. jirovecii and collected from 24 epidemiologically unrelated patients with clinical signs of PCP, were studied in parallel by use of the same method. Pneumocystis jirovecii isolates from the four liver recipients all had the same genotype, which was different from those of the isolates from all the epidemiologically unrelated individuals studied. These findings supported the hypothesis of a common source of contamination or even cross-transmission of a single P. jirovecii clone between the four liver recipients. Hospitalization mapping showed several possible encounters between these four patients, including outpatient consultations on one particular date when they all possibly met. This study demonstrates the value of molecular genotyping of P. jirovecii isolated from clinical samples for epidemiological investigation of PCP outbreaks. It is also the first description of a common source of exposure to a single P. jirovecii clone between liver transplant recipients and highlights the importance of prophylaxis in such a population.

Two cases of opportunistic parasite infections in patients receiving alemtuzumab

Two cases are reported of rare digestive opportunistic parasites in patients being treated with alemtuzumab for lymphoid haematological malignancies. In both patients, classical biological examinations were insufficient to reach the diagnosis. Only specific parasitological techniques enabled diagnoses of cryptosporidiosis and microsporidiosis, respectively. In both cases, cellular immune reconstitution was sufficient to eradicate these opportunistic infections. In this context, parasitological diagnosis is often underestimated by medical practitioners, so immunologists and oncohaematologists need to be aware of this kind of opportunistic pathogen.

Is real-time PCR-based diagnosis similar in performance to routine parasitological examination for the identification of Giardia intestinalis, Cryptosporidium parvum/Cryptosporidium hominis and Entamoeba histolytica from stool samples? Evaluation of a new commercial multiplex PCR assay and literature review

Microscopy is the reference standard for routine laboratory diagnosis in faecal parasitology but there is growing interest in alternative methods to overcome the limitations of microscopic examination, which is time-consuming and highly dependent on an operators skills and expertise. Compared with microscopy, DNA detection by PCR is simple and can offer a better turnaround time. However, PCR performances remain difficult to assess as most studies have been conducted on a limited number of positive clinical samples and used in-house PCR methods. Our aim was to evaluate a new multiplex PCR assay (G-DiaParaTrio; Diagenode Diagnostics), targeting Giardia intestinalis, Cryptosporidium parvum/Cryptosporidium hominis and Entamoeba histolytica. To minimize the turnaround time, PCR was coupled with automated DNA extraction (QiaSymphony; Qiagen). The PCR assay was evaluated using a reference panel of 185 samples established by routine microscopic examination using a standardized protocol including Ziehl-Neelsen staining and adhesin detection by ELISA (E. histolytica II; TechLab). This panel, collected from 12 French parasitology laboratories, included 135 positive samples for G. intestinalis (n = 38), C. parvum/C. hominis (n = 26), E. histolytica (n = 5), 21 other gastrointestinal parasites, together with 50 negative samples. In all, the G-DiaParaTrio multiplex PCR assay identified 38 G. intestinalis, 25 C. parvum/C. hominis and five E. histolytica leading to sensitivity/specificity of 92%/100%, 96%/100% and 100%/100% for G. intestinalis, C. parvum/C. hominis and E. histolytica, respectively. This new multiplex PCR assay offers fast and reliable results, similar to microscopy-driven diagnosis for the detection of these gastrointestinal protozoa, allowing its implementation in routine clinical practice.

Successful treatment with fumagillin of the first pediatric case of digestive microsporidiosis in a liver-kidney transplant

We report the first successful use, to our knowledge, of fumagillin alone in a pediatric patient to cure intestinal microsporidiosis in a liver‐kidney transplanted child. Detection of Enterocytozoon bieneusi in stool became negative from the first post‐therapeutic control, while digestive symptoms disappeared in 4 days. During a 9‐month follow‐up, polymerase chain reaction and direct examinations remained negative for microsporidia in her feces. No major undesirable effects were noted during the anti‐microsporidial therapy.

Therapeutic antibodies and infectious diseases, Tours, France, November 20−22, 2012

The Therapeutic Antibodies and Infectious Diseases international congress was held in Tours, France on November 20−22, 2012. The first session was devoted to the development of antibodies directed against bacterial toxins or viruses that could be used in a potential bioterrorist threat situation. The second session dealt with the effector functions of anti-microbial antibodies, while the third was oriented toward anti-viral antibodies, with a special emphasis on antibodies directed against the human immunodeficiency and hepatitis C viruses. After a lecture by a speaker from the US Food and Drug Administration on antibody cocktails, the second day ended with a special session dedicated to discussions regarding the involvement of French biotechnology industries in the field. On the last day, the congress concluded with talks about current antibody treatments for infectious diseases, with a particular focus on their adverse events. Participants enjoyed this very stimulating and convivial meeting, which gathered scientists from various countries who had different scientific research interests.

A Nebulized Intra-tracheal Rat Model of Invasive Pulmonary Aspergillosis

Animal models are particularly useful for the study of many infectious diseases, including those caused by fungi. Invasive pulmonary aspergillosis is most frequently studied in mouse models. We present here an animal model of this disease based on undernourished immunocompromised rats infected with Aspergillus fumigatus spores by intra-tracheal nebulisation.

Rodent Models of Invasive Aspergillosis due to Aspergillus fumigatus: Still a Long Path toward Standardization

Invasive aspergillosis has been studied in laboratory by the means of plethora of distinct animal models. They were developed to address pathophysiology, therapy, diagnosis, or miscellaneous other concerns associated. However, there are great discrepancies regarding all the experimental variables of animal models, and a thorough focus on them is needed. This systematic review completed a comprehensive bibliographic analysis specifically-based on the technical features of rodent models infected with Aspergillus fumigatus. Out the 800 articles reviewed, it was shown that mice remained the preferred model (85.8% of the referenced reports), above rats (10.8%), and guinea pigs (3.8%). Three quarters of the models involved immunocompromised status, mainly by steroids (44.4%) and/or alkylating drugs (42.9%), but only 27.7% were reported to receive antibiotic prophylaxis to prevent from bacterial infection. Injection of spores (30.0%) and inhalation/deposition into respiratory airways (66.9%) were the most used routes for experimental inoculation. Overall, more than 230 distinct A. fumigatus strains were used in models. Of all the published studies, 18.4% did not mention usage of any diagnostic tool, like histopathology or mycological culture, to control correct implementation of the disease and to measure outcome. In light of these findings, a consensus discussion should be engaged to establish a minimum standardization, although this may not be consistently suitable for addressing all the specific aspects of invasive aspergillosis.