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[Typing, resistance behavior and occurrence of methicillin-resistant Staphylococcus aureus strains in a surgical
F J Schmitz1, R Geisel, S Wagner
1Institut für Medizinische Mikrobiologie und Virologie, Heinrich-Heine-Universität, Düsseldorf.
Abstract:
Over a period of three years, the frequency of the appearance of methicillin-resistant S. aureus strains (MRSA) was observed on a surgical intensive care unit. During this above-mentioned period of investigation it came to a heaped occurrence of nosocomial infections on this ICU with altogether 332 S. aureus-stems being isolated from different patient specimen. 204 (61.5%) of these were resistant against methicillin and could be divided into 48 first- and 156 follow-up-isolates. The thereupon accomplished differentiation of the 48 MRSA-first isolates by means of lysotyping and the pioneered GenePath Strain Typing System for a standardized pulsed-field-gel-electrophoresis (PFGE) gave the proof of 7 different MRSA-types. Around 7 different, in part parallel chains of infection on this ICU were observed, which could be led back to different strains. In reference to all analyzed S. aureus, an especially high rate (90%) of MRSA on this ICU could be isolated in taken wound-swabs, followed by 83.3% MRSA at catheter tips and 71,9% in tracheal and bronchial secretion. A consideration of the antibiotic susceptibility yielded, that also gentamicin and the quinolones showed an in-vitro resistance against MRSA, while fosfomycin, fusidic acid, chloramphenicol and trimethoprim/sulfamethoxazole reached positive responding rates between 80 and 100%. On the other hand, presently still 100% of the explored MRSA-strains are susceptible for glycopeptides such as vancomycin and teicoplanin. Because of intensive hospital hygienic measures the number of newly isolated MRSA could be reduced clearly on this ward.
Insights
Methicillin-resistant Staphylococcus aureus (MRSA) infections were frequent in a surgical ICU, with 7 distinct MRSA strains identified. Intensive hygiene measures successfully reduced new MRSA cases on the ward.
Area of Science:
- Medical Microbiology
- Infectious Diseases
- Hospital Epidemiology
Background:
- Nosocomial infections pose a significant threat in intensive care units.
- Methicillin-resistant Staphylococcus aureus (MRSA) is a major cause of healthcare-associated infections.
- Surveillance of MRSA strains is crucial for effective infection control.
Purpose of the Study:
- To investigate the frequency and characteristics of MRSA strains in a surgical intensive care unit (ICU) over three years.
- To identify different MRSA strain types and their transmission patterns within the ICU.
- To assess the antibiotic susceptibility of isolated MRSA strains.
Main Methods:
- Isolation and identification of 332 Staphylococcus aureus strains from patient specimens.
- Determination of methicillin resistance in S. aureus isolates.
- MRSA strain typing using lysotyping and GenePath Strain Typing System (pulsed-field-gel-electrophoresis - PFGE).
- Antibiotic susceptibility testing of MRSA isolates.
Main Results:
- 204 out of 332 (61.5%) S. aureus isolates were identified as MRSA.
- Seven distinct MRSA strain types were identified, indicating multiple infection chains.
- High MRSA rates were observed in wound swabs (90%), catheter tips (83.3%), and respiratory secretions (71.9%).
- MRSA showed in-vitro resistance to gentamicin and quinolones, but remained susceptible to vancomycin and teicoplanin.
- Intensive hospital hygiene measures led to a significant reduction in new MRSA isolates.
Conclusions:
- MRSA is a prevalent pathogen in surgical ICUs, with diverse strains contributing to nosocomial infections.
- Effective infection control strategies, including stringent hygiene protocols, are essential for reducing MRSA transmission.
- Monitoring antibiotic susceptibility patterns is vital for guiding treatment decisions and preventing further resistance.