Methicillin-resistant Staphylococcus aureus in horses and horse personnel: An investigation of several outbreaks

Department of Infectious Diseases and Immunology, Faculty of Veterinary Medicine, PO Box 80165, 3508 TD Utrecht, Utrecht University, The Netherlands.
Veterinary Microbiology (Impact Factor: 2.51). 09/2009; 141(1-2):96-102. DOI: 10.1016/j.vetmic.2009.08.009
Source: PubMed


At the Veterinary Microbiological Diagnostic Center, the Netherlands, the percentage of methicillin-resistant Staphylococcus aureus (MRSA) isolates found in equine clinical samples increased from 0% in 2002 to 37% in 2008. MRSA of spa-type t064, belonging to MLST ST8 and spa-types t011 and t2123, both belonging to the livestock-associated MLST ST398, predominated. During an outbreak of post-surgical MRSA infections in horses at a veterinary teaching hospital in 2006/2007, MRSA isolates of spa-type t2123 were cultured from 7 horses and 4/61 personnel which indicated zoonotic transmission. After intervention the outbreak stopped. However, another outbreak occurred in 2008, where 17 equine MRSA isolates of spa-type t011 (n=12), t2123 (n=4), and t064 (n=1) were found. This time, 16/170 personnel were positive for MRSA with spa-type t011 (n=11) and t2123 (n=5). Personnel in close contact with horses were more often MRSA-positive (15/106) than those without (1/64). Screening of horses upon admission showed that 9.3% were MRSA-positive predominantly with spa-type t011. Weekly cross-sectional sampling of all hospitalized horses for 5 weeks showed that 42% of the horses were MRSA-positive at least once, again predominantly with spa-type t011, which suggests that nosocomial transmission took place. Fifty-three percent of the environmental samples were MRSA-positive, including samples from students' and staff members' rooms, and all were spa-type t011. This indicates that humans contribute to spreading the organism. Culturing of samples employing high-salt pre-enrichment performed better than a comparable method without pre-enrichment. Our results show that nosocomial transmission occurs in equine clinics and suggests that personnel play a role in the transmission.

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    • "Furthermore , nasal colonization of veterinary personnel attending horses was reported [22,31–33]. The majority of MRSA CC398 isolates from horse clinics exhibited a typical pattern of characteristics when subjected to typing: spa type t011, more rarely t6867, SCCmecIVa, and phenotypic resistance to gentamicin based on the aacA-aphD gene [22] [31] [32]. A more detailed analysis of the population-structure through mutation discovery at 97 loci revealed that MRSA CC398 from horse clinics exhibiting the above mentioned characteristics represent a particular subpopulation (clade) of LA-MRSA CC398 [34]. "
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    ABSTRACT: A total of 272 methicillin-resistant Staphylococcus aureus (MRSA) from equine infections originating from 17 equine hospitals and 39 veterinary practices in Germany as well as 67 isolates from personnel working at equine clinics were subjected to molecular typing. The majority of isolates from horses was attributed to clonal complex (CC) 398 (82.7%). Within CC398, 66% of isolates belonged to a subpopulation (clade) of CC398, which is associated with equine clinics. MRSA attributed to CC8 (ST254, t009, t036, SCC. mecIV; ST8, t064, SCC. mecIV) were less frequent (16.5%). Single isolates were attributed to ST1, CC22, ST130, and ST1660. The emergence of MRSA CC22 and ST130 in horses was not reported so far. Nasal MRSA colonization was found in 19.5% of veterinary personnel with occupational exposure to horses. The typing characteristics of these isolates corresponded to isolates from equine infections. Comparing typing characteristics of equine isolates with those of a substantial number of isolates from human infections typed at the German Reference Center for Staphylococci and Enterococci (2006-2014; n=10864) yielded that the proportion of isolates exhibiting characteristics of MRSA from equine medicine is very low (<. 0.5%). As this low proportion was also found among MRSA originating from nasal screenings of human carriers not suffering from a staphylococcal infection (n=5546) transmission of MRSA from equine clinics to the community seems to be rare so far.
    Full-text · Article · Jan 2016
    • "These persons are the presumably source for LA-MRSA transmission to other parts of the human population. Furthermore, transmissions to non-food-producing animals, in particular to horses, but also to other companion animals occur and these animals could act as contaminated vectors (Loeffler et al., 2011; van Duijkeren et al., 2010; Vincze et al., 2014). "
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    ABSTRACT: In the past decade, livestock-associated methicillin-resistant Staphylococcus aureus (LA-MRSA) strains in particular of the clonal complex (CC) 398 have emerged in many parts of the world especially in areas with a high density of pig farming. In those regions, farmworkers and other individuals with professional contact to livestock are very frequently colonized with LA-MRSA. These persons are the presumably source for LA-MRSA transmission to household members and other parts of the human population. Altogether, colonization and/or infection of these individuals lead to the introduction of LA-MRSA into hospitals and other healthcare facilities. Since LA-MRSA CC398 have been found to be specifically adapted to their animal hosts in terms of the equipment with virulence factors, their pathogenicity to human patients is a matter of debate with first reports about clinical cases. Meanwhile, case reports, case series and few studies have demonstrated the capability of LA-MRSA to cause all types of infections attributed to S. aureus in general including fatal courses. Human infections observed comprise e.g. bacteremia, pneumonia, osteomyelitis, endocarditis and many manifestations of skin and soft tissue infections. However, inpatients affected by MRSA CC398 generally show different demographic (e.g. younger, shorter length of hospital stay) and clinical characteristics (e.g. less severe complications) which may explain or at least contribute to a lower disease burden of LA-MRSA compared to other MRSA clonal lineages.
    No preview · Article · Nov 2015 · Veterinary Microbiology
    • "Methicillin-resistant S. aureus infections have also been reported in horses [7] [8] and have been associated with metritis, dermatitis, wound-penetrating infections, and surgical-site infections [9] [10] [11] [12] [13]. Although MRSA infections have been considered more severe than methicillinsensitive S. aureus (MSSA) infections in horses, there is insufficient information to support this assumption [9] [13]. "
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    ABSTRACT: The aims of this study were (1) to evaluate the antibacterial effects of equine platelet concentrates (PCs) and other blood-derived preparations on methicillin-resistant Staphylococcus aureus (MRSA); (2) to determine the effect of MRSA on the concentration of transforming growth factor beta 1 and platelet-derived growth factor BB over time; and (3) to determine the correlations between MRSA growth and blood cell counts (platelets and leukocytes), as well as growth factor (GF) concentrations, in PCs and other blood-derived preparations. Blood from 14 clinically healthy horses was used to prepare the different blood-derived preparations. Bacterial growth was significantly inhibited by the different PCs and the cell-free plasma products, mainly during the first 8 hours. Growth factor concentrations were not significantly affected by the presence of bacteria. No correlation between MRSA growth inhibition and blood cells and/or GFs was found. The in vitro bacteriostatic effect of PCs on MRSA could be predominantly attributed to the plasma complement.
    No preview · Article · Mar 2015 · Journal of Equine Veterinary Science
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