title: 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.
abstract: 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.
authors.affiliation: National Institute for Public Health and the Environment (RIVM), Centre for Infectious Disease Control, Bilthoven, the Netherlands.
authors.forename: Thijs
authors.initials: T
authors.lastname: Bosch
authors.forename: Martijn
authors.initials: M
authors.lastname: van Luit
authors.forename: Gerlinde N
authors.initials: GN
authors.lastname: Pluister
authors.forename: Dineke
authors.initials: D
authors.lastname: Frentz
authors.forename: Anja
authors.initials: A
authors.lastname: Haenen
authors.forename: Fabian
authors.initials: F
authors.lastname: Landman
authors.forename: Sandra
authors.initials: S
authors.lastname: Witteveen
authors.forename: Naomi
authors.initials: N
authors.lastname: van Marm-Wattimena
authors.forename: Han G
authors.initials: HG
authors.lastname: van der Heide
authors.forename: Leo M
authors.initials: LM
authors.lastname: Schouls
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000818:Animals; D005075:Biological Evolution; D002648:Child; D002675:Child, Preschool; D021821:Communicable Diseases, Emerging / Q000453:epidemiology / Q000382:microbiology* / Q000635:transmission; D004781:Environmental Exposure / Q000706:statistics & numerical data; D005260:Female; D005838:Genotype; D006801:Humans; D007223:Infant; D007231:Infant, Newborn; D058751:Livestock / Q000382:microbiology*; D008297:Male; D055624:Methicillin-Resistant Staphylococcus aureus / Q000145:classification / Q000235:genetics* / Q000302:isolation & purification*; D008875:Middle Aged; D009426:Netherlands / Q000453:epidemiology; D015995:Prevalence; D012307:Risk Factors; D013045:Species Specificity; D013203:Staphylococcal Infections / Q000453:epidemiology / Q000382:microbiology* / Q000662:veterinary*; D055815:Young Adult
keywords: LA-MRSA; MRSA; Staphylococcus aureus; Whole genome multilocus sequence typing; next generation sequencing; single nucleotide polymorphism; surveillance