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Updated: Dec 9, 2025
Biosensor for Detection of Antibiotic Resistant Staphylococcus Bacteria
Published on: May 8, 2013
Early Detection and Control of Methicillin resistant Staphylococcus aureus Outbreak in an Intensive Care Unit
Banu Bayraktar1, Alper Gündüz1, Erman Oryaşın2
1Department of Clinical Microbiology, University of Health Sciences Şişli Hamidiye Etfal Training and Research Hospital, İstanbul, Turkey.
Background:
Although Methicillin resistant Staphylococcus aureus (MRSA) is one of the major pathogens of healthcare associated infections, we had only sporadic cases in our intensive care unit (ICU) for years.
Aims:
To investigate the sudden increase in the number of MRSA cases in ICU.
Study Design:
Descriptive study.
Methods:
From the 5th December 2016 to 26th January 2017, we detected 11 new MRSA cases in ICU. Screening of 73 ICU healthcare workers (HCWs) and screening of 13 patients was performed for outbreak investigation. Nine clinical isolates available in stocks and eight screening MRSA isolates were included in molecular studies. PFGE, spa-mecA-mecC-PVL in-house multiplex PCR assay and spa typing, SCCmec typing were performed for all isolates. Sequence type of the representative strain was determined by Multi-Locus Sequence typing (MLST).
Results:
All strains were mecA positive, PVL negative, and have the same antimicrobial susceptibility pattern except for two strains. All clinical, two patient screening and three nasal isolates of HCWs showed the same pulsotype, named clone A. The spa type of outbreak isolates is t030 and the SCCmec type is SCCmecIII; the MLST type of representative strain is ST239 (PFGE pulsotype A, ST239-SCCmecIII-t030). Unrelated three isolates had PFGE pulsotype B-SCCmecI-t030, PFGE pulsotype C-SCCmecIII-t459, PFGE pulsotype D-SCCmecIII.
Conclusion:
Molecular typing techniques are the cornerstones for the investigation of outbreaks. Infection control measures, such as enhancing cleaning procedures, promoting hand hygiene, should be enforced in the ICU unit. All patients, including those who have already been discharged to other departments, must be put on contact isolation. HCWs carrying the MRSA strains could be offered decolonization.
Insights
A sudden increase in Methicillin-resistant Staphylococcus aureus (MRSA) cases in the ICU was investigated. Molecular typing identified a dominant clone (ST239-SCCmecIII-t030) linked to the outbreak, emphasizing enhanced infection control measures.
Area of Science:
- Medical Microbiology
- Infectious Diseases
- Epidemiology
Background:
- Methicillin-resistant Staphylococcus aureus (MRSA) is a significant cause of healthcare-associated infections.
- Sporadic cases of MRSA were previously observed in the intensive care unit (ICU).
- A sudden increase in MRSA cases within the ICU necessitated an investigation.
Purpose of the Study:
- To investigate the cause of a sudden rise in MRSA cases within the ICU.
- To identify the molecular characteristics of the MRSA strains involved in the outbreak.
Main Methods:
- A descriptive study was conducted from December 5, 2016, to January 26, 2017.
- MRSA outbreak investigation involved screening 73 healthcare workers (HCWs) and 13 patients.
- Molecular analyses included PFGE, spa typing, SCCmec typing, and MLST on clinical and screening isolates.
Main Results:
- Eleven new MRSA cases were detected in the ICU during the study period.
- All investigated strains were mecA positive and PVL negative, with similar antimicrobial susceptibility.
- A predominant clone (PFGE pulsotype A, ST239-SCCmecIII-t030) was identified in clinical isolates, patient screening, and HCW nasal isolates.
Conclusions:
- Molecular typing is crucial for investigating MRSA outbreaks.
- Enhanced infection control measures, including stringent hygiene and isolation protocols, are recommended for the ICU.
- Decolonization strategies for HCWs carrying MRSA strains should be considered.
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