Related Experiment Videos
Food-initiated outbreak of methicillin-resistant Staphylococcus aureus analyzed by pheno- and genotyping
J Kluytmans1, W van Leeuwen, W Goessens
1Department of Bacteriology, University Hospital Dijkzigt, Rotterdam, The Netherlands.
Abstract:
An outbreak of methicillin-resistant Staphylococcus aureus (MRSA) involving 27 patients and 14 health-care workers (HCW) was studied. The outbreak started in the hematology unit of the University Hospital Rotterdam, Dijkzigt, The Netherlands, and spread to the surgical unit. Twenty-one patients (77.8%) developed clinical disease, and five died. Subsequently, MRSA was detected in food and in the throat of one of the HCW who prepared food for hematology patients. Food contaminated by an HCW most likely caused the first case of MRSA septicemia. This route of transmission has not been described before. The outbreak strain was probably transmitted to the surgical unit by a colonized nurse, where it caused an explosive outbreak. Airborne probably transmitted to the surgical unit by a colonized nurse, where it caused an explosive outbreak. Airborne MRSA transmission played an important role in disseminating the organism. The outbreak was controlled within 6 months by intensifying surveillance, temporarily closing the affected wards, treating carriers, and instituting an MRSA ward outside the hospital. Phage typing, insertion sequence probing, protein A gene typing, and DNA fingerprinting by PCR revealed that all outbreak-related isolates were identical. By pulsed-field gel electrophoresis, all but one of the outbreak-related isolates were determined to be identical. Protein A gene typing identified numerous (11) repeat units in all outbreak-related isolates, which supports the suggestion that the outbreak strain may have been more virulent and more transmissible than other MRSA strains. Pheno- and genotyping studies underlined the value of DNA fingerprinting methods for investigation of MRSA epidemiology. Optimal discriminatory power was achieved by combining the results of four genotyping methods.
Insights
A methicillin-resistant Staphylococcus aureus (MRSA) outbreak spread through food contamination and airborne transmission, causing severe illness and deaths. Control required intensive surveillance, ward closure, and carrier treatment.
Area of Science:
- Infectious Diseases
- Epidemiology
- Microbiology
Background:
- An extensive outbreak of methicillin-resistant Staphylococcus aureus (MRSA) occurred at the University Hospital Rotterdam, affecting both patients and healthcare workers (HCW).
- The outbreak originated in the hematology unit and subsequently spread to the surgical unit, leading to significant clinical disease and mortality.
Purpose of the Study:
- To investigate the epidemiology and transmission routes of an MRSA outbreak.
- To evaluate the effectiveness of control measures and the role of genotyping in outbreak investigation.
Main Methods:
- Epidemiological investigation including patient and HCW surveillance.
- Microbiological analysis, including detection of MRSA in food and HCW throat cultures.
- Molecular typing of MRSA isolates using phage typing, insertion sequence probing, protein A gene typing, and DNA fingerprinting by PCR and pulsed-field gel electrophoresis.
Main Results:
- MRSA was detected in food and an HCW's throat, suggesting food contamination as a likely source of initial septicemia.
- Airborne transmission and spread by a colonized nurse were implicated in the dissemination to the surgical unit.
- Genotyping confirmed a single, highly virulent and transmissible MRSA strain responsible for the outbreak.
- Control measures, including surveillance, ward closure, and carrier treatment, successfully contained the outbreak within six months.
Conclusions:
- Food contamination by an HCW represents a novel transmission route for MRSA.
- Airborne transmission played a significant role in the outbreak's spread.
- Combining multiple genotyping methods provides optimal discriminatory power for MRSA outbreak investigations.
- Intensified surveillance and targeted interventions are crucial for controlling MRSA outbreaks.