Livestock-Associated methicillin resistant Staphylococcus aureus in animals and humans
Institute for Risk Assessment Sciences, Division Environmental Epidemiology, Utrecht University, P.O. Box 80.176, 3508 TD Utrecht, The Netherlands. International journal of medical microbiology: IJMM
(Impact Factor: 3.61).
12/2011; 301(8):630-4. DOI: 10.1016/j.ijmm.2011.09.004
Since 2004 MRSA emerged in animals, particularly in pigs and veal calves. This new MRSA variant was since its first appearance referred to as Livestock Associated-MRSA (LA-MRSA). In Europe and Northern America, LA-MRSA belongs predominantly to clonal complex (CC) 398 whereas in Asia ST9 seems to be dominant in pigs. Persons in direct contact with LA-MRSA-positive animals have an increased risk of becoming MRSA positive. The risk of carriage is mainly related with the intensity of animal contact and with MRSA prevalence among animals on the farm. In contrast with its success in animals, it seemed that MRSA CC398 is a poor persistent colonizer in humans. MRSA ST398 can, however, cause serious (invasive) infections and outbreaks, although, only incidentally reported so far. Farm hygiene and antimicrobial use contributed to MRSA occurrence in animals. Therefore these two determinants should in principle be incorporated into MRSA-control programmes in animal production. Like any other microorganism, LA-MRSA is expected to be able to adapt to new hosts and may change over time in the potential to colonize and to produce toxins. Also, the current circulating clone CC398 may be replaced by another clone in Western countries or emerge in countries where this clone is currently low-prevalent. Ongoing MRSA surveillance in humans and animals is needed to detect changes in epidemiology and to implement effective control measures.
Available from: Mohamed Abdelbary
- "The first MRSA in animals was reported from cases of mastitis in dairy cattle in 1972, followed by sporadic observations of infections in various animals including postsurgical wound infections in horses . Since 2006 MRSA attributed to clonal complex CC398 received specific attention since these so-called livestock-associated MRSA (LA-MRSA) is widely disseminated among various livestock animals mainly as an asymptomatic nasal colonizer  . Because of its capacity to cause a variety of infections in humans such as skin and soft-tissue infections, surgical wound and joint infections, invasive device infections (catheter, endoprostheses), ventilator-associated pneumonia, and septicemia    MRSA CC398 became a public health issue. "
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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.
Available from: Yhu-Chering Huang
- "Community-associated MRSA (CA-MRSA) strains are genetically distinct from healthcare-associated MRSA (HA- MRSA) strains, but various clones spread between the community and hospitals and the distinction between CA-MRSA and HA-MRSA has become blurred . Recently, another MRSA clone emerged in livestock and humans exposed to livestock    . MRSA sequence type 398 (ST398), also referred to as livestock-associated MRSA (LA-MRSA), isolated from pigs and pig farmers has been reported in European countries and North America     . "
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ABSTRACT: In addition to being a human pathogen, Staphylococcus aureus causes an array of infections in economically important livestock animals, particularly pigs. In Asia, there have been few reports on livestock-associated meticillin-resistant S. aureus (LA-MRSA), mostly from developed countries, with very few data available from resource-limited countries, not because of low prevalence but probably due to a shortage of diagnostic facilities. Unlike the wide spread of sequence type 398 (ST398) LA-MRSA in European countries and North America, ST9 predominates in most Asian countries. The prevalence of LA-MRSA among pigs in Asian countries varied widely (0.9–42.5%). The prevalence may vary by geographic location, age of pigs and sampling methodologies. Among pig farmers, the prevalence of nasal MRSA colonisation varied from 5.5% in Malaysia to 15% in China and 19.2% in Taiwan. Although most LA-MRSA isolates in Asia are of the same ST, molecular characteristics are not all the same. Dominant isolates in China were characterised as spa type t899-SCCmec III and t899-SCCmec IVb or V for isolates in Hong Kong, and t899-untypeable SCCmec for Taiwan. Dominant isolates in Malaysia were spa type t4358-SCCmec V and t337-SCCmec IX for isolates in Thailand. In addition, MRSA ST221 was reported in Japan and MRSA ST398 was isolated from commercial pigs in South Korea. Attention should be paid because pigs could become an important reservoir for MRSA and spread them to humans, as observed in many countries. There is a potential risk from the livestock reservoir to community and hospitals.
Available from: Dirk Werling
- "Although most S. aureus strains are considered to be host specific (Fitzgerald, 2012), interest in livestock-associated S. aureus was renewed with the discovery of MRSA sequence type (ST) 398, initially in pigs and more recently in calves, chickens, horses, and pets (Armand-Lefevre et al., 2005; Graveland et al., 2011). ST398, as determined by multilocus sequence typing (MLST), is considered a newly emerging, pathogenic and zoonotic strain and the major cause of LA-MRSA in Europe and North America (Smith et al., 2009; Graveland et al., 2010), displaying significant diversity and high content of antimicrobial resistance genes, but so far, no significant virulence genes compared to other ST-lineages have been identified (Jamrozy et al., 2012). "
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ABSTRACT: TwoTIR-like domain containing proteins in a newly emerging zoonotic Staphylococcus aureus strain sequence type 398 are potential virulence factors by impacting on the host innate immune response Staphylococcus aureus, sequence type (ST) 398, is an emerging pathogen and the leading cause of livestock-associated methicillin-resistant S. aureus infections in Europe and North America. This strain is characterized by high promiscuity in terms of host-species and also lacks several traditional S. aureus virulence factors. This does not, however, explain the apparent ease with which it crosses species-barriers. Recently, TIR-domain containing proteins (Tcps) which inhibit the innate immune response were identified in some Gram-negative bacteria. Here we report the presence of two proteins, S. aureus TIR-like Protein 1 (SaTlp1) and S. aureus TIR-like Protein 2 (SaTlp2), expressed by ST398 which contain domain of unknown function 1863 (DUF1863), similar to the Toll/IL-1 receptor (TIR) domain. In contrast to the Tcps in Gram-negative bacteria, our data suggest that SaTlp1 and SaTlp2 increase activation of the transcription factor NF-κB as well as downstream pro-inflammatory cytokines and immune effectors. To assess the role of both proteins as potential virulence factors knock-out mutants were created. These showed a slightly enhanced survival rate in a murine infectious model compared to the wild-type strain at one dose. Our data suggest that both proteins may act as factors contributing to the enhanced ability of ST398 to cross species-barriers.
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