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Commensal animal- and food-related Gram-positive bacteria as reservoir of re-sistance determinants for Staphylococcus aureus
Project
Project code: BfR-BIOS-08-1329-557
Contract period: 01.12.2016
- 30.11.2018
Purpose of research: Applied research
Methicillin-resistant Staphylococcus aureus (MRSA) represent a significant problem in hospitals but also the occurrence of MRSA in livestock environment and food items came into focus within the last years. These socalled livestock-associated (LA) MRSA clonal lineages (especially clonal complex (CC) 398) emerged in pigs, poultry and cattle as well as in the production and processing of animal-derived food products (raw meat, etc.). It was found that S. aureus / MRSA of animal origin represent a reservoir for (novel) antibiotic resistances. Of particular importance was furthermore the discovery of a novel beta-lactam / methicillin resistance marker in MRSA. Instead of the gene mecA, which was previously known as the sole gene in S. aureus mediating methicillin resistance, these MRSA harbor the gene mecC, which is located on a so far unknown SCCmec element of type XI. The mecC gene has a homology of only 70% compared to the previously known mecA gene. So far, little is known about the origin of mecC and SCCmec XI from S. aureus. The gene mecC (and related allotypes) was not only restricted to S. aureus, since it was detected also in other staphylococcal species. It is discussed whether this unusual SCCmec element originated from coagulase-negative staphylococci (CoNS). This project should consider the development and change of beta-lactam resistance determinants and a possible transfer between staphylococci and closely related species, like macrococci. Staphylococci carrying the mecC gene are widespread among livestock animals, companion and wildlife animals. This raises the question whether these habitats may serve as a reservoir for methicillin-resistant staphylococci by carrying respective resistance-encoding elements or their precursors. This question will be addressed within the project. Furthermore, macrococci (especially Macrococcus caseolyticus) shall be isolated from animal sources (food products and animals isolates) and analyzed for the presence of phenotypic and genotypic beta-lactam/methicillin-resistance. The aim is to pursue the question whether genetic structures of resistance determinants share similarities to those found in S. aureus / MRSA and whether a transfer of genetic material and thereby antibiotic resistances might occur. Briefly, the aim is to analyze resistances among different Gram-positive bacteria from food and animal sources which are closely related to S. aureus. Between closely related bacterial species genetic material might frequently be transferred by horizontal gene transfer. With this, genetic determinants encoding uncommon/novel antibiotic resistances might be trans-ferred to S. aureus. This is of concern especially for zoonotic MRSA since a change of MRSA clones might possibly occur in case of an uptake of additional antibiotic resistances. Within this project we aim to evaluate whether livestock and wild animals might represent a reservoir of uncommon/novel antibiotic resistances; finally being able to assess whether bacteria from the food chain carry resistances, which might be transferred to S. aureus / MRSA.
Section overview
Subjects
- Animal health
- Biotechnology
- Toxicology
