Projects / Programmes
The role of environmental and host factors in development of Clostridium difficile infection
| Code |
Science |
Field |
Subfield |
| 3.01.00 |
Medical sciences |
Microbiology and immunology |
|
| Code |
Science |
Field |
| B230 |
Biomedical sciences |
Microbiology, bacteriology, virology, mycology |
| Code |
Science |
Field |
| 3.05 |
Medical and Health Sciences |
Other medical sciences |
Clostridium difficile, zoonoses, gut microbiota, pathogenesis, public health
Researchers (21)
Organisations (6)
Abstract
Clostridium difficile induces diarrhoea, colitis or pseudomembranous colitis in patients with compromised normal gut flora due to antibiotic usage and/or underlying disease condition. C. difficile infection (CDI) is currently the most frequently occurring nosocomial infection in many European hospitals, but human community-acquired and animal infections are also increasing. This shift in epidemiology suggest some changes in C. difficile biology that could involve i) spread of genotypes with increased virulence and ii) increased overlap between major possible reservoirs of the bacterium (humans, animals, environment). Part of the project will therefore address analysis of C. difficile genotypes in several different reservoirs in Slovenia. Strains will originate from hospitalized and community-associated cases, from pets and from animals on small farms with close contact with humans, rivers, soil and food. Cultivation and molecular techniques will be optimized to improve the detection limits. For genotyping molecular methods with different spectrum of discriminatory power will be used (toxinotyping, ribotyping, PFGE, MLVA and MLST) to address relatedness of genotypes in different reservoirs. The fitness of different genotypes will be compared in nonvertebrate animal model using Porcellio scaber that will be developed during the project.
While two main C. difficile virulence factors, toxins A and B, are well characterized, still little is known about additional virulence factors and host factors. Second part of research will deal with host factors (immune response and gut microbiota) important for development of CDI. In humans poor host antibody response to toxins and probably cell wall proteins is known to correlate with disease onset or recurrences. We will study the reactivity of human and animal sera on cell wall proteins and spore proteins. Additionally, we will study interactions of C. difficile vegetative cells and spores with macrophages by fluorescent labelling and multiphoton confocal microscopy. Disturbed intestinal microbiota is needed for colonization of C. difficile. We will use novel molecular approach (denaturing gradient high pressure liquid chromatography; DHPLC) for detection of changes in bacterial/archaeal/fungal microbiota in humans and animals during C. difficile colonization or disease. Protective groups detected will be isolated and their antagonistic activity against C. difficile will be tested. Expected results will be important for understanding of distribution and significance of C. difficile in given reservoir and possibilities of transmissions and for further understanding of interactions between host and pathogen.
Significance for science
Patients with C. difficile infection, asymptomatic carriers, animals and environment are potential sources of infection with C. difficile spores. Overlap of PCR ribotypes prevalent in these reservoirs can suggest their potential importance. Within this project we described analysis of a large collection of C. difficile strains isolated from humans, animals and environment in Slovenia, which was the first such comparison described for any country. Results have shown that 1) some PCR ribotypes are distributed (or prevalent) in many environments and hosts (e.g. 014/020) and 2) currently animals are more important potential source for infection that environment (water, soil). The main results about host factors describe the role of gut microbiota in association with C. difficile. Our study on changes in gut microbiota in C. difficile colonized poultry was the first report on this subject in animals. The study on gut microbiota in humans was the first to describe the association of microbiota signatures (patterns of microbial groups) and not just presence or absence on the level of individual groups. Additional value of both studies is also description of fungal and arcaeal microbiota in addition to bacterial populations.
Significance for the country
The results of this project have for the first time described epidemiological situation of C. difficile infections in Slovenia, as the strains were collected for four month period from all routine laboratories performing C. difficile testing. This information will serve as a baseline for further comparisons and for evaluation of CDI reporting to National institute of Public Health. The project has strengthened the collaboration between groups and institutions important in surveillance, control and research of C. difficile in Slovenia. PhD student, graduate students and college students were participating in the research which contributed to their education. Also a national educational meeting on C. difficile was organized and the topic was included in all major national meetings on microbiology and infectious diseases. The public was informed and educated about the results through participation of project members in different TV shows and publications in daily and weekly newspapers Results were published in international journals and some of them were already well cited (Janežič et al, 2012, BMC Micro; citations (TC): 34, without autocitations (CI): 24).
Most important scientific results
Annual report
2011,
2012,
2013,
final report,
complete report on dLib.si
Most important socioeconomically and culturally relevant results
Annual report
2011,
2012,
2013,
final report,
complete report on dLib.si
