Changing characteristics of livestock-associated meticillin-resistant Staphylococcus aureus isolated from humans - emergence of a subclade transmitted without livestock exposure, the Netherlands, 2003 to 2014

• Published in: Euro surveillance : bulletin européen sur les maladies transmissibles Vol. 21; no. 21; p. 1
• Main Authors: Bosch, Thijs, van Luit, Martijn, Pluister, Gerlinde N, Frentz, Dineke, Haenen, Anja, Landman, Fabian, Witteveen, Sandra, van Marm-Wattimena, Naomi, van der Heide, Han G, Schouls, Leo M
• Format: Journal Article
• Language: English
• Published: Sweden Centre Europeen pour la Surveillance Epidemiologique du SIDA (European Centre for the Epidemiological Monitoring of AIDS) 26.05.2016
• Subjects: Adolescent; Adult; Aged; Aged, 80 and over; Animals; Biological Evolution; Child; Child, Preschool; Communicable Diseases, Emerging - epidemiology; Communicable Diseases, Emerging - microbiology; Communicable Diseases, Emerging - transmission; Drug resistance; Environmental Exposure - statistics & numerical data; Female; Genotype; Gram-positive bacteria; Humans; Infant; Infant, Newborn; Livestock; Livestock - microbiology; Male; Methicillin-Resistant Staphylococcus aureus - classification; Methicillin-Resistant Staphylococcus aureus - genetics; Methicillin-Resistant Staphylococcus aureus - isolation & purification; Middle Aged; Netherlands - epidemiology; Pathogenesis; Prevalence; Risk Factors; Species Specificity; Staphylococcal Infections - epidemiology; Staphylococcal Infections - microbiology; Staphylococcal Infections - veterinary; Staphylococcus infections; Surveillance; Young Adult; Netherlands; single nucleotide polymorphism; next generation sequencing; MRSA; Whole genome multilocus sequence typing; LA-MRSA; surveillance; Staphylococcus aureus
• ISSN: 1560-7917; 1025-496X; 1560-7917
• DOI: 10.2807/1560-7917.ES.2016.21.21.30236

Since 2007, livestock-associated meticillin-resistant Staphylococcus aureus (LA-MRSA) has become the predominant MRSA clade isolated from humans in the Netherlands. To assess possible temporal changes, we molecularly characterised over 9,000 LA-MRSA isolates submitted from 2003 to 2014 to the Dutch MRSA surveillance. After an initial rapid increase with a peak in 2009 (n = 1,368), the total number of submitted LA-MRSA isolates has been slowly decreasing to 968 in 2014 and over 80% of LA-MRSA belonged to one of three predominant MLVA/spa-types. Next generation sequencing (n=118) showed that MT569/t034 isolates were genetically more diverse than MT398/t011 and MT572/t108. Concurrent with the decrease in LA-MRSA, fewer people reported having contact with livestock and this was most prominent for people carrying MT569/t034 LA-MRSA. The proportion of LA-MRSA isolated from infection-related materials increased from 6% in 2009, to 13% in 2014 and most of these isolates originated from patients older than 50 years of age. Remarkably, 83% of these patients reported not having contact with livestock. The results reveal an ongoing change in the genotypic and epidemiological characteristics of Dutch LA-MRSA isolated from humans with the emergence of a LA-MRSA subclade independent of livestock exposure, suggesting LA-MRSA starts to resemble non-LA-MRSA in terms of transmissibility and pathogenicity.