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Updated: Aug 21, 2026
Isolation and Identification of Waterborne Antibiotic-Resistant Bacteria and Molecular Characterization of their Antibiotic Resistance Genes
Published on: March 3, 2023
International dissemination of antibiotic resistant strains of bacterial pathogens
1Robert Koch Institute, Wernigerode Branch, Burgstr. 37, D-383855 Wernigerode, Germany. wittew@rki.de
Abstract:
The increasing incidence of methicillin and multiple resistant Staphylococcus aureus (MRSA) in nosocomial infections is mainly associated with a wide, international dissemination of well defined clonal lineages (epidemic MRSA) which are clearly different from community acquired MRSA by molecular typing patterns and structure of the staphylococcal cassette chromosome containing the mecA gene. Although belonging to a definite subpopulation within the species Enterococcus faecium, hospital associated vancomycin resistant isolates also containing the esp gene have very likely evolved by acquisition of glycopeptide resistance gene clusters at different occasions and at different times by a susceptible already disseminated clonal lineage. There is obviously a continuous selection of new types of extended spectrum beta-lactamases in enterobacteriaceae and also horizontal spread of bla-genes. Intrahospital dissemination of particular strains has often been observed, however, an international dissemination until now has been described only for Salmonella enterica serovar Typhimurium producing the CTX-M-3 enzyme. Multiresistant isolates of Salmonella enterica serovar Typhimurium phage type DT104 harbour a multiresistant gene cluster with resistance genes from taxonomically more unrelated species (tetG, floR, bla(PSE1)). Although in vitro transduction has been demonstrated, this gene cluster has only rarely been reported from isolates exhibiting other phage patterns of the same serovar or from other serovars of S. enterica.
Insights
The study examines the international spread of antibiotic-resistant bacteria, including methicillin-resistant Staphylococcus aureus (MRSA) and vancomycin-resistant Enterococcus faecium. It highlights the evolution and dissemination of resistance genes in nosocomial infections.
Area of Science:
- Microbiology
- Infectious Diseases
- Genetics
Background:
- Rising incidence of nosocomial infections caused by antibiotic-resistant bacteria.
- Dissemination of specific clonal lineages of methicillin-resistant Staphylococcus aureus (MRSA).
- Evolution of vancomycin resistance in Enterococcus faecium and extended-spectrum beta-lactamases in Enterobacteriaceae.
Purpose of the Study:
- To investigate the molecular mechanisms and dissemination patterns of antibiotic resistance in hospital-acquired infections.
- To differentiate between epidemic MRSA and community-acquired MRSA.
- To understand the evolution and spread of resistance genes in key bacterial pathogens.
Main Methods:
- Molecular typing to identify clonal lineages of MRSA.
- Analysis of staphylococcal cassette chromosome structures.
- Investigation of glycopeptide resistance gene clusters in Enterococcus faecium.
- Tracking the spread of extended-spectrum beta-lactamases and bla-genes in Enterobacteriaceae.
- Phage typing and genetic analysis of Salmonella enterica serovar Typhimurium DT104.
Main Results:
- Epidemic MRSA strains are distinct from community-acquired MRSA due to specific molecular patterns and SCCmec structures.
- Hospital-associated vancomycin-resistant Enterococcus faecium likely evolved through multiple acquisitions of resistance genes by a disseminated susceptible lineage.
- Continuous selection and horizontal spread of extended-spectrum beta-lactamases in Enterobacteriaceae.
- International dissemination of Salmonella enterica serovar Typhimurium producing CTX-M-3 enzyme.
- Multiresistant Salmonella enterica serovar Typhimurium DT104 harbors a complex gene cluster with genes from diverse species.
Conclusions:
- Specific clonal lineages and genetic elements drive the international spread of antibiotic resistance in nosocomial pathogens.
- Understanding resistance evolution and dissemination is crucial for controlling hospital-acquired infections.
- Further research is needed to elucidate the full extent of horizontal gene transfer and its impact on multidrug resistance.
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