Methicillin-resistant Staphylococcus aureus in the environment of public transport: data from the metropolitan network in Lyon, France

• Screening of MRSA contamination on the metropolitan network of Lyon, the second largest city in France.
• No MRSA was found on Lyon's Métro.
• Public transport in Lyon is at low risk for MRSA transmission and dissemination.
• Absence of MRSA contamination was unexpected compared with other European cities.
• MRSA spreading is a key to understanding variation in MRSA infection between countries.

Methicillin-resistant Staphylococcus aureus (MRSA) is involved in community-acquired and nosocomial diseases. The means of MRSA transmission and dissemination in the community remain uncertain. Studies have shown that public transport systems could be a source of MRSA and may serve as a potential source for community-acquired MRSA infections. This study aimed to investigate MRSA contamination on Lyon's metropolitan network (Métro) in France. Hand-touched surfaces were sampled with sterile swabs (Transystem®) during a 1-day transversal study by collecting 50 samples in seven hub stations and two trains for each of the four Métro lines. Then, during a longitudinal study, one sample was collected twice daily for 30 consecutive days in the busiest and most congested hub station. All swabs were incubated in enrichment medium for 24 h and then each suspension was plated onto a chromogenic selective medium for MRSA. After 24 h at 36 °C, all presumptive MRSA colonies were tested using VITEK® MS to confirm identification as S. aureus as well as by Alere™ PBP2a Culture Colony Test and mecA/mecC PCR to check methicillin resistance. Of the 110 swabs tested, 24 presumptive MRSA colonies were isolated, of which 2 were confirmed as S. aureus by VITEK® MS. These two isolates were tested negative using the PBP2a Culture Colony Test and PCR. Unlike other foreign cities such as Lisbon, the current data suggest a low level of MRSA contamination of hand-touched surfaces on Lyon's Métro. This should be put in perspective with the low level of MRSA colonisation in the French community.