Nosocomial infections are an increasing problem in every countries. To prevent their occurrence, we need to understand their epidemiology, especially their source and mode of transmission. For that particular purpose, the use of molecular typing methods is required.
Our laboratory is involved in the development of new typing methods, their evaluation for epidemiological investigation and their application to specific topics.
The widespread occurrence of MRSA in hospitals is recognized as a major challenge. Successful prevention depends on effective programs of infection control, including detection of transmission events and effective strategies for their containment and prevention. A thorough understanding of the processes underlying the local emergence and spread of MRSA may help in the design of new strategies to counteract this evolution. Knowledge of how MRSA spreads throughout a hospital can be greatly improved by inferring transmission pathways on the basis of genetic relatedness.
Traditional typing methodologies suffer from poor levels of discrimination for localized epidemiology, where many cases of infection may be caused by a single outbreak strain. Next generation sequencing (NGS) addresses this by providing the capacity to detect single-nucleotide polymorphisms (SNPs) across the whole genome for a large number of outbreak isolates. The ability to identify the minutiae of genetic changes occurring within a single strain over very short time-scales allows the reconstruction of the phylogeny of a single outbreak, and the potential to identify the original source. In parallel, the sequence data can also potentially reveal clinically relevant phenotypes of the outbreak strain, such as resistance and virulence properties.
In this project, we propose to sequence c.a. 500 MRSA isolates from the clone ST-228 recovered from two University Swiss hospitals in Lausanne and Geneva, as well as over its global international distribution. These data will be analyzed in an epidemiological and evolutionary framework in order to investigate the short-term epidemiological evolutionary dynamics during a local outbreak. Data from these investigations will allow us to answer practical epidemiological questions regarding the sources and transmission dynamics of MRSA. This study will thus inform on the development of new and more sustained strategies to manage the spread of MRSA outbreaks, and will simultaneously address more fundamental questions concerning the short-term evolutionary dynamics of MRSA.