Relationship between Fungal Colonisation of the Respiratory Tract in Lung Transplant Recipients and Fungal Contamination of the Hospital Environment

International audienceBackgroundAspergillus colonisation is frequently reported after lung transplantation. The question of whether aspergillus colonisation is related to the hospital environment is crucial to prevention.MethodTo elucidate this question, a prospective study of aspergillus colonisation after lung transplantation, along with a mycological survey of the patient environment, was performed.ResultsForty-four consecutive patients were included from the day of lung transplantation and then examined weekly for aspergillus colonisation until hospital discharge. Environmental fungal contamination of each patient was followed weekly via air and surface sampling. Twelve patients (27%) had transient aspergillus colonisation, occurring 1–13 weeks after lung transplantation, without associated manifestation of aspergillosis. Responsible Aspergillus species were A. fumigatus (6), A. niger (3), A. sydowii (1), A. calidoustus (1) and Aspergillus sp. (1). In the environment, contamination by Penicillium and Aspergillus was predominant. Multivariate analysis showed a significant association between occurrence of aspergillus colonisation and fungal contamination of the patient’s room, either by Aspergillus spp. in the air or by A.fumigatus on the floor. Related clinical and environmental isolates were genotyped in 9 cases of aspergillus colonisation. For A. fumigatus (4 cases), two identical microsatellite profiles were found between clinical and environmental isolates collected on distant dates or locations. For other Aspergillus species, isolates were different in 2 cases; in 3 cases of aspergillus colonisation by A. sydowii, A. niger and A. calidoustus, similarity between clinical and environmental internal transcribed spacer and tubulin sequences was >99%.ConclusionTaken together, these results support the hypothesis of environmental risk of hospital acquisition of aspergillus colonisation in lung transplant recipients

A2 gene of Old World cutaneous Leishmania is a single highly conserved functional gene

BACKGROUND: Leishmaniases are among the most proteiform parasitic infections in humans ranging from unapparent to cutaneous, mucocutaneous or visceral diseases. The various clinical issues depend on complex and still poorly understood mechanisms where both host and parasite factors are interacting. Among the candidate factors of parasite virulence are the A2 genes, a family of multiple genes that are developmentally expressed in species of the Leishmania donovani group responsible for visceral diseases (VL). By contrast, in L. major determining cutaneous infections (CL) we showed that A2 genes are present in a truncated form only. Furthermore, the A2 genomic sequences of L. major were considered subsequently to represent non-expressed pseudogenes [1]. Consequently, it was suggested that the structural and functional properties of A2 genes could play a role in the differential tropism of CL and VL leishmanias. On this basis, it was of importance to determine whether the observed structural/functional particularities of the L. major A2 genes were shared by other CL Leishmania, therefore representing a proper characteristic of CL A2 genes as opposed to those of VL isolates. METHODS: In the present study we amplified by PCR and sequenced the A2 genes from genomic DNA and from clonal libraries of the four Old World CL species comparatively to a clonal population of L. infantum VL parasites. Using RT-PCR we also amplified and sequenced A2 mRNA transcripts from L. major. RESULTS: A unique A2 sequence was identified in Old World cutaneous Leishmania by sequencing. The shared sequence was highly conserved among the various CL strains and species analysed, showing a single polymorphism C/G at position 58. The CL A2 gene was found to be functionally transcribed at both parasite stages. CONCLUSION: The present study shows that cutaneous strains of leishmania share a conserved functional A2 gene. As opposed to the multiple A2 genes described in VL isolates, the CL A2 gene is unique, lacking most of the nucleotide repeats that constitute the variable region at the 5'end of the VL A2 sequences. As the variable region of the VL A2 gene has been shown to correspond to a portion of the protein which is highly immunogenic, the present results support the hypothesis of a possible role of the A2 gene in the differential tropism of CL and VL leishmania parasites

Accumulation and transport of microbial-size particles in a pressure protected model burn unit: CFD simulations and experimental evidence

<p>Abstract</p> <p>Background</p> <p>Controlling airborne contamination is of major importance in burn units because of the high susceptibility of burned patients to infections and the unique environmental conditions that can accentuate the infection risk. In particular the required elevated temperatures in the patient room can create thermal convection flows which can transport airborne contaminates throughout the unit. In order to estimate this risk and optimize the design of an intensive care room intended to host severely burned patients, we have relied on a computational fluid dynamic methodology (CFD).</p> <p>Methods</p> <p>The study was carried out in 4 steps: i) patient room design, ii) CFD simulations of patient room design to model air flows throughout the patient room, adjacent anterooms and the corridor, iii) construction of a prototype room and subsequent experimental studies to characterize its performance iv) qualitative comparison of the tendencies between CFD prediction and experimental results. The Electricité De France (EDF) open-source software <it>Code_Saturne</it>^®(<url>http://www.code-saturne.org</url>) was used and CFD simulations were conducted with an hexahedral mesh containing about 300 000 computational cells. The computational domain included the treatment room and two anterooms including equipment, staff and patient. Experiments with inert aerosol particles followed by time-resolved particle counting were conducted in the prototype room for comparison with the CFD observations.</p> <p>Results</p> <p>We found that thermal convection can create contaminated zones near the ceiling of the room, which can subsequently lead to contaminate transfer in adjacent rooms. Experimental confirmation of these phenomena agreed well with CFD predictions and showed that particles greater than one micron (i.e. bacterial or fungal spore sizes) can be influenced by these thermally induced flows. When the temperature difference between rooms was 7°C, a significant contamination transfer was observed to enter into the positive pressure room when the access door was opened, while 2°C had little effect. Based on these findings the constructed burn unit was outfitted with supplemental air exhaust ducts over the doors to compensate for the thermal convective flows.</p> <p>Conclusions</p> <p>CFD simulations proved to be a particularly useful tool for the design and optimization of a burn unit treatment room. Our results, which have been confirmed qualitatively by experimental investigation, stressed that airborne transfer of microbial size particles via thermal convection flows are able to bypass the protective overpressure in the patient room, which can represent a potential risk of cross contamination between rooms in protected environments.</p

Modele experimental d'etude de la croissance de toxoplasma Gondii en culture cellulaire : applications biologiques et pharmacologiques

SIGLECNRS T Bordereau / INIST-CNRS - Institut de l'Information Scientifique et TechniqueFRFranc

Evaluation du risque lié à l'exposition aérienne à Aspergillus fumigatus

Aspergillus fumigatus est un champignon filamenteux pathogène responsable de différentes formes d infections pulmonaires allergiques sur les sujets immunocompétents et d infections invasives chez les patients neutropéniques. L inhalation de spores est le mode habituel de contamination suggérant un rôle majeur de l environnement dans l épidémiologie de l aspergillose. Cependant, la relation entre les concentrations d Aspergillus dans l air et la probabilité d infections ne sont pas connues. Dans cette étude, trois approches complémentaires ont été proposées pour analyser cette relation. In vitro, nous avons utilisé un dispositif de culture en interface air-liquide pour analyser les conséquences de l exposition de cellules pulmonaires A549 à différentes concentrations de spores d Aspergillus fumigatus. Aucun effet significatif sur la production de cytokines pro-inflammatoires n'a été retrouvé suite à cette exposition, même lorsque cette exposition aspergillaire était combinée avec une exposition au formaldéhyde. In vivo, la relation entre l exposition à des spores d Aspergillus et la survenue d une infection a été étudiée dans un modèle murin d aspergillose invasive en utilisant la souche de référence Af293 d Aspergillus fumigatus. Dans une approche bayésienne la relation dose-infection entre probabilité d infection et exposition aux spores a été estimée en utilisant le modèle exponentiel et le modèle plus flexible bêta-Poisson. Ceci a permis d estimer la dose infectieuse 50 à 1,8-1,9.104 spores inhalées viables. Secondairement, ce modèle a été utilisé pour mettre au point un nouveau modèle de réactivation d aspergillose et étudier l efficacité de l amphotéricine B liposomale dans la prophylaxie de l aspergillose invasive. Chez l homme, nous avons tenté d estimer la relation entre l exposition environnementale aux spores fongiques et l incidence de la colonisation ou de l infection aspergillaire chez 44 transplantés pulmonaires étudiée de façon consécutive. A l'aide d'un modèle de régression par GEE, nous avons trouvé une relation significative entre la contamination des surfaces par Aspergillus et l incidence de la colonisation. De plus, nous avons montré des identités génotypiques entre les isolats cliniques et environnementaux d Aspergillus, ce qui confirme les risques d acquisition d Aspergillus dans le cadre hospitalier. Globalement, ces résultats apportent des données nouvelles sur la relation entre la contamination environnementale et la probabilité d aspergillose chez les patients immunodéprimésAspergillus fumigatus is an opportunistic fungal pathogen responsible for various respiratory diseases in normal hosts and severe invasive infections in neutropenic patients. Spore inhalation is the usual route of Aspergillus infection, suggesting a determining role of environmental contamination in the epidemiology of aspergillosis. However the relationship between Aspergillus concentration in the air and probability of infection is not quantitatively known. In this study, three different approaches were proposed to analyse this relationship. In vitro we used an air-liquid interface module to expose pulmonary A549 cells to high concentrations of A. fumigatus spores, but found not effect of exposure on the production of pro-inflammatory cytokines, even when exposure was combined with exposure to formaldehyde. In vivo, the relationship between spore exposure and infection was examined in a murine model of invasive aspergillosis, using the reference Af293 strain of A. fumigatus. In a bayesian approach, the dose-response relationship between the probability of infection and spore exposure was approximated using the exponential model and the more flexible beta-Poisson model. It allowed estimating the median infective dose at 1.8-1.9x104 inhaled viable spores. Further, this model was used to develop a unique model of reactivating aspergillosis and then to examine the efficacy of liposomal amphotericin B on prophylaxis of aspergillosis. In human, we attempted to estimate the relationship between environmental exposure to fungal spores and the incidence of Aspergillus colonization or infection in 44 consecutive lung transplant recipients. In a GEE multivariate analysis, we found a significant relationship between surface contamination by Aspergillus and the incidence of colonization. Furthermore, we found genotypic similarities between clinical and environmental isolates of Aspergillus, which confirm the risk of acquisition of Aspergillus in the hospital setting. Altogether, this result provides new insights into the relationship between airborne exposure and probability of aspergillosis in immunocompromised hostsPARIS-BIUSJ-Biologie recherche (751052107) / SudocSudocFranceF

Etude expérimentale de l'effet des probiotiques sur l'infection par Cryptosporidium parvum

PARIS-BIUP (751062107) / SudocSudocFranceF

Applications des techniques de biologie moléculaire à l' étude de la contamination environnementale par des parasites d' intérêt médical et vétérinaire (valorisation industrielle)

PARIS-BIUSJ-Thèses (751052125) / SudocPARIS-BIUSJ-Physique recherche (751052113) / SudocSudocFranceF

VALEUR DE L'ANTIGENEMIE ASPERGILLAIRE DANS LE DIAGNOSTIC ET LE SUIVI THERAPEUTIQUE DE L'ASPERGILLOSE INVASIVE (DES BIOL. MED.)

PARIS6-Bibl. St Antoine CHU (751122104) / SudocPARIS-BIUM (751062103) / SudocSudocFranceF

Airborne contamination by Pneumocystis (contribution to the characterization of the environmental risk)

PARIS7-Bibliothèque centrale (751132105) / SudocSudocFranceF