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Updated: Jul 7, 2025
Subcutaneous Infection of Methicillin Resistant Staphylococcus Aureus MRSA
Published on: February 9, 2011
Emergence and control of an outbreak of PVL-positive MRSA in a UK-based maternity setting
H Barnsley1, S McFall1, R White2
1Faculty of Public Health, London, UK.
Abstract:
This paper aims to describe the investigation and control of an outbreak of USA300 ST8 Panton-Valentine leucocidin (PVL)-positive meticillin-resistant Staphylococcus aureus (MRSA), confirmed by whole genome sequencing (WGS), within a maternity and neonatal setting in the UK. The identification of two linked PVL-MRSA cases led to an outbreak investigation. A lookback exercise conducted using the infection control surveillance database, typing of saved MRSA isolates, enhanced patient screening, and staff screening were used to identify further cases. Environmental screening was also performed. Genetic relatedness between isolates was assessed by WGS. During the outbreak, 18 cases were identified between 11th July 2021 and 22nd December 2022: 10 cases were infections and eight cases were colonizations. A healthcare worker (HCW) tested positive for colonization with the same strain, and environmental swabbing identified contaminated information technology equipment in the hospital. The outbreak was brought to an end by exclusion of the colonized HCW from work, and infection prevention and control measures. Since the end of the outbreak, cases of PVL-MRSA with similar molecular profiles have been found in the community. It is likely that the HCW played a role in the transmission of PVL-MRSA. Their exclusion from work and decolonization were key to preventing further cases. WGS was valuable in identifying and linking cases. The identification of community cases of PVL-MRSA with similar molecular profiles confirms transmission of the organism outside of healthcare settings.
Insights
An outbreak of Panton-Valentine leucocidin (PVL)-positive meticillin-resistant Staphylococcus aureus (MRSA) in a UK hospital was investigated using whole genome sequencing (WGS). A colonized healthcare worker was identified as the likely source, and their removal stopped the spread.
Area of Science:
- Clinical microbiology
- Infectious disease epidemiology
- Genomic epidemiology
Background:
- Panton-Valentine leucocidin (PVL)-positive meticillin-resistant Staphylococcus aureus (MRSA) poses a significant healthcare challenge.
- Outbreaks of PVL-MRSA require rapid and effective investigation and control strategies.
- Maternity and neonatal settings are vulnerable to healthcare-associated infections.
Purpose of the Study:
- To describe the investigation and control of a PVL-MRSA outbreak in a UK maternity and neonatal unit.
- To identify the source and transmission dynamics of the outbreak using whole genome sequencing (WGS).
- To evaluate the effectiveness of infection prevention and control measures.
Main Methods:
- Case identification through surveillance database review, isolate typing, and enhanced patient/staff screening.
- Environmental screening to detect potential reservoirs of MRSA.
- Whole genome sequencing (WGS) for molecular typing and genetic relatedness assessment of MRSA isolates.
- Implementation of infection control measures, including healthcare worker exclusion and decolonization.
Main Results:
- Eighteen cases of PVL-MRSA (10 infections, 8 colonizations) were identified between July 2021 and December 2022.
- A healthcare worker was found to be colonized with the outbreak strain, and contaminated IT equipment was identified.
- WGS confirmed the genetic relatedness of isolates and supported the link to the healthcare worker.
- The outbreak was successfully controlled following the colonized healthcare worker's exclusion and implementation of control measures.
Conclusions:
- Whole genome sequencing (WGS) is a valuable tool for investigating and linking MRSA cases during outbreaks.
- A colonized healthcare worker was the likely source of transmission in this PVL-MRSA outbreak.
- Exclusion of the colonized healthcare worker and decolonization were critical for outbreak control.
- The emergence of similar PVL-MRSA strains in the community suggests transmission beyond healthcare settings.
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