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Methicillin resistant Staphylococcus aureus strains in the greater Düsseldorf area
F J Schmitz1, C R MacKenzie, R Geisel
1Institute für Medizinische Mikrobiologie und Virologie, Heinrich-Heine-Universität, Düsseldorf, Germany.
Abstract:
Over a period of three years the incidence of methicillin resistant Staphylococcus aureus (MRSA) isolates in 11 hospitals in the greater Düsseldorf area was observed. From a total of 7,814 S. aureus isolates, 489 (6.3%) were methicillin resistant. From 198 different patients, MRSA first isolates and 291 second isolates could be cultured. Methicillin resistance among all S. aureus isolates from 11 hospitals in the greater Düsseldorf area, ranged from 0.5 to 7.8% dependant on the size of the hospital. The highest incidence (7.8%) was found in a 1,500 bed hospital and the lowest incidence in a smaller 200 bed hospital (0.5%). With respect to the distribution among clinical departments the highest incidence of MRSA isolates was found on intensive care units and surgical wards, 25.5% and 13.0% respectively. The commonest specimen from which the MRSA isolates were cultured were respiratory secretions (17.6%) followed by central venous catheter tips (12.8%). In terms of the drug resistance pattern: all isolates were resistant to the aminoglycosides and gyrase inhibitors, whereas between 80% and 90% were sensitive to fusidic acid, chloramphenicol and pyrimethamine-sulfamethoxazole. All the strains were sensitive to the glycopeptide antibiotics, vancomycin and teicoplanin. Strain typing of 181 available first isolates (from a total of 198 first isolates) by PFGE and phage lysotyping produced identical results in more than 90% of all cases. Twenty-eight different MRSA strain types were identified by PFGE and in total 23 lysotypes could be determined. During the period of investigation an increased incidence of MRSA on an intensive care unit was observed, in which a total of 204 MRSA (42% of the total number) were isolated. The strain typing using both methods showed that on that ICU eight different MRSA types were involved in this outbreak. A hygiene plan was implemented on the unit with considerable success in reducing the incidence and spread of MRSA.
Insights
Methicillin-resistant Staphylococcus aureus (MRSA) incidence in Düsseldorf hospitals was 6.3% over three years. A hygiene plan on an ICU significantly reduced MRSA spread during an outbreak.
Area of Science:
- Medical Microbiology
- Infectious Diseases
- Hospital Epidemiology
Background:
- Methicillin-resistant Staphylococcus aureus (MRSA) poses a significant threat in healthcare settings.
- Surveillance of MRSA incidence is crucial for effective infection control strategies.
Purpose of the Study:
- To determine the incidence and characteristics of MRSA isolates in hospitals in the greater Düsseldorf area.
- To analyze MRSA prevalence across different hospital sizes, clinical departments, and specimen types.
- To investigate the drug resistance patterns and strain diversity of MRSA isolates.
Main Methods:
- Prospective observational study over three years across 11 hospitals.
- Culture and identification of Staphylococcus aureus and MRSA isolates.
- Analysis of isolate data including patient origin, specimen type, and clinical department.
- Antimicrobial susceptibility testing for various drug classes.
- Strain typing using Pulse Field Gel Electrophoresis (PFGE) and phage lysotyping.
Main Results:
- Overall MRSA incidence was 6.3% (489/7,814 S. aureus isolates).
- Incidence varied by hospital size (0.5%–7.8%) and was highest in intensive care units (25.5%) and surgical wards (13.0%).
- Respiratory secretions and central venous catheter tips were common sources; isolates showed resistance to aminoglycosides and gyrase inhibitors but sensitivity to vancomycin and teicoplanin.
- Strain typing identified 28 PFGE types and 23 lysotypes; an ICU outbreak involved eight MRSA types, which was controlled by a hygiene plan.
Conclusions:
- MRSA prevalence in the Düsseldorf area is significant, with higher rates in ICUs and surgical wards.
- Effective strain typing methods confirmed the diversity of MRSA strains and aided in outbreak investigation.
- Implementation of a targeted hygiene plan successfully reduced MRSA incidence and spread during an ICU outbreak.