Antibiotic Use in European Pig Production: Less Is More.

The goal of this study is to describe the current use of antibiotics in the European pig industry based on an extensive literature review. To achieve this, an overview of results from national (n = 15) and multi-country (n = 2) cross-sectional and longitudinal (n = 2) surveys, which describe antimicrobial use in pigs, is presented. Results are further linked to the outcome of the European Surveillance of Veterinary Antimicrobial Consumption (ESVAC) project. Overall, it was found that weaned piglets received the most antibiotics, followed by suckling piglets resulting in over 80% of the treatments being administered to animals before 10 weeks of age. Furthermore, it was observed that antibiotic use (ABU) was significantly associated across age categories, indicating that farms with a high use in piglets also used more antibiotics in their finishers. This may, among other things, be explained by farmers' habits and behavior. However, above all, the studies showed surprisingly large differences in ABU between the countries. These differences may be related to the differences in disease prevalence and/or differences in the level of biosecurity. However, they may also reflect variations in rules and regulations between countries and/or a difference in attitude towards ABU of farmers and veterinarians that are not necessarily linked to the true animal health situation. Furthermore, it was observed that already a substantial proportion of the European pig production is able to successfully raise pigs without any group treatments, indicating that it is possible to rear pigs without systematic use of antibiotics. Based on the ESVAC data, a decline of 43.2% was observed in sales of antibiotics for animals in Europe between 2011 and 2020. To enable efficient antimicrobial quantification and stewardship, 15 European countries have already established systems for herd level monitoring ABU in pigs.

Monitoring of Farm-Level Antimicrobial Use to Guide Stewardship: Overview of Existing Systems and Analysis of Key Components and Processes.

The acknowledgment of antimicrobial resistance (AMR) as a major health challenge in humans, animals and plants, has led to increased efforts to reduce antimicrobial use (AMU). To better understand factors influencing AMR and implement and evaluate stewardship measures for reducing AMU, it is important to have sufficiently detailed information on the quantity of AMU, preferably at the level of the user (farmer, veterinarian) and/or prescriber or provider (veterinarian, feed mill). Recently, several countries have established or are developing systems for monitoring AMU in animals. The aim of this publication is to provide an overview of known systems for monitoring AMU at farm-level, with a descriptive analysis of their key components and processes. As of March 2020, 38 active farm-level AMU monitoring systems from 16 countries were identified. These systems differ in many ways, including which data are collected, the type of analyses conducted and their respective output. At the same time, they share key components (data collection, analysis, benchmarking, and reporting), resulting in similar challenges to be faced with similar decisions to be made. Suggestions are provided with respect to the different components and important aspects of various data types and methods are discussed. This overview should provide support for establishing or working with such a system and could lead to a better implementation of stewardship actions and a more uniform communication about and understanding of AMU data at farm-level. Harmonization of methods and processes could lead to an improved comparability of outcomes and less confusion when interpreting results across systems. However, it is important to note that the development of systems also depends on specific local needs, resources and aims.

Biofilm formation of ica operon-positive Staphylococcus epidermidis from different sources.

Information on the prevalence of biofilm-related factors (PIA, Bhp, Aap, Embp) in Staphylococcus epidermidis of animal origin is scarce. In this study, 263 S. epidermidis isolates of diverse origin (animal, farmers, patients, and laboratory staff) were investigated for the presence of the ica operon (icaRADBC). The icaRADBC-positive isolates were further characterized by means of biofilm formation, presence of other biofilm-related genes, antimicrobial resistance, and population structure. Of all isolates, 28.5% (n = 75) were icaRADBC-positive, including 16.5% of animal origin, 29.1% farmer isolates, and 44.6% hospital-associated isolates (including patients and laboratory staff isolates). Most icaRADBC-positive isolates carried embp (n = 73), aap (n = 57), bhp (n = 22), and IS256 (n = 29). Statistical differences were found between animal and patient isolates for the presence of icaRADBC, bhp, and aap. No statistically significant relation was found between the presence of one or more genes and the level of biofilm formation. Most icaRADBC-positive isolates belonged to the clonal complex 5 (formerly 2) and most sequence types corresponded to types previously observed in community and nosocomial S. epidermidis populations. Although the prevalence of S. epidermidis in the nasal cavity of bovines and poultry is low, some isolates belong to STs related to ica-positive clinical strains.

Antimicrobial resistance and population structure of Staphylococcus epidermidis recovered from animals and humans.

While Staphylococcus epidermidis, as part of the commensal flora, is a well-known human opportunistic pathogen, only little is known about the genetic relatedness of S. epidermidis carriage isolates from animal and human origin. This study aimed to compare S. epidermidis recovered from livestock, livestock-farmers and humans associated with the hospital environment. A total of 193 S. epidermidis isolates from three populations [animals (n=33), farmers (n=86) and hospital-associated (n=74)] were characterized by broth microdilution antimicrobial susceptibility testing, staphylococcal cassette chromosome mec (SCCmec) typing, pulsed field gel electrophoresis (PFGE) and multilocus sequence typing (MLST). The overall S. epidermidis nasal colonization rate was low in animals (1-9%) but high among farmers (75%). High levels of multi-resistance were found in all populations. Tetracycline resistance was high in animal and farmer isolates; resistance to erythromycin, clindamycin and trimethoprim was high in animal and hospital-associated isolates. Methicillin-resistant S. epidermidis - MRSE isolates were found in all collections, with 22 (67%) MRSE in animals, 44 (51%) MRSE in farmers and 42 (57%) MRSE associated with the hospital-setting. Known SCCmec types and variants were detected in 79% of MRSE; the rest were non-typeable cassettes. In total 79 PFGE-types were found, of which 22 were shared between livestock, farmers and the hospital settings. Clonal complex 2 was predominant in all three populations and most STs corresponded to types previously observed in community and nosocomial S. epidermidis populations. S. epidermidis isolates from livestock, farmers and hospital-setting showed a high level of diversity, but some clones can be found in humans as well as in animals.

Diversity of antimicrobial resistance and virulence genes in methicillin-resistant non-Staphylococcus aureus staphylococci from veal calves.

In this study we determined whether methicillin-resistant non-Staphylococcus aureus (MRNAS) from veal calves may be a potential reservoir of antimicrobial-resistance and virulence genes. Fifty-eight MRNAS were studied by means of DNA-microarray and PCR for detection of antimicrobial resistance and virulence genes. The isolates carried a variety of antimicrobial-resistance genes [aacA-aphD, aadD, aph3, aadE, sat, spc, ampA, erm(A), erm(B), erm(C), erm(F), erm(T), lnu(A), msr(A)-msr(B), vga(A), mph(C), tet(K), tet(M), tet(L), cat, fexA, dfrA, dfrD, dfrG, dfrK, cfr, fusB, fosB, qacA, qacC, merA-merB]. Some isolates carried resistance genes without showing the corresponding resistance phenotype. Most MRNAS carried typical S. aureus virulence factors like proteases (sspP) and enterotoxins (seg) genes. Most Staphylococcus epidermidis isolates carried the arginine catabolic element, and nearly 40% of the Staphylococcus sciuri isolates carried leukocidins, and/or fibronectin-binding protein genes. MRNAS were highly multi-resistant and represent an important reservoir of antimicrobial resistance and virulence genes.

Antimicrobial resistance and population structure of Staphylococcus epidermidis recovered from pig farms in Belgium.

Pigs are known to harbour a variety of staphylococcal bacteria, including Staphylococcus epidermidis, in the upper respiratory tract. The aim of the present study was to determine the prevalence, genetic diversity, virulence and antimicrobial resistance of S. epidermidis in healthy pigs, as well as to identify the potential role of pigs as a reservoir of zoonotic infection. The overall prevalence of S. epidermidis carriage was 28%, with approximately half of the pigs tested (13.5%) carrying methicillin-resistant S. epidermidis (MRSE). Some isolates belonged to multilocus sequence types, associated with healthy human carriers or healthcare personnel (ST88, ST210) whereas others were related to animal or environmental strains (ST100, ST273). Most MRSE isolates carried SCCmec type IV, with SCCmec type V or a non-typeable SCCmec detected in the remaining isolates. Both MRSE and methicillin-susceptible S. epidermidis isolates showed a degree of antimicrobial resistance, with most resistant to tetracycline and/or trimethoprim antimicrobial drugs. Isolates subjected to micro-array analysis carried the antimicrobial resistance genes tet(K), tet(M) and dfrS1, while half carried the arginine catabolic element (ACME) associated with colonisation. Some MRSE ST273 strains also carried the ica operon involved in biofilm formation. These research findings provide insight into the population structure and characteristics of S. epidermidis carried by healthy pigs, suggesting a role for these strains as a potential reservoir for antimicrobial and virulence genes and indicating that exchange of strains might occur between pigs and humans.

Identification, typing, ecology and epidemiology of coagulase negative staphylococci associated with ruminants.

Since phenotypic methods to identify coagulase negative staphylococci (CNS) from the milk of ruminants often yield unreliable results, methods for molecular identification based on gene sequencing or fingerprinting techniques have been developed. In addition to culture-based detection of isolates, culture-independent methods may be of interest. On the basis of molecular studies, the five CNS species commonly causing intramammary infections (IMI) are Staphylococcus chromogenes, Staphylococcus epidermidis, Staphylococcus haemolyticus, Staphylococcus simulans and Staphylococcus xylosus. Current knowledge suggests that S. chromogenes is a bovine-adapted species, with most cases of IMI due to this bacterium being opportunistic. S. haemolyticus also appears to be an opportunistic pathogen, but this bacterium occupies a variety of habitats, the importance of which as a source of IMI remains to be elucidated. S. xylosus appears to be a versatile species, but little is known of its epidemiology. S. epidermidis is considered to be a human-adapted species and most cases of IMI appear to arise from human sources, but the organism is capable of residing in other habitats. S. simulans typically causes contagious IMI, but opportunistic cases also occur and the ecology of this bacterium requires further study. Further studies of the ecology and epidemiology of CNS as a cause of IMI in cattle are required, along with careful attention to classification of these bacteria and the diseases they cause.

Characterization of methicillin-resistant Staphylococcus sciuri isolates from industrially raised pigs, cattle and broiler chickens.

OBJECTIVES: This study aimed at assessing the epidemiology and genetic diversity of methicillin-resistant Staphylococcus sciuri (MRSS) from different farm animal species. METHODS: Nasal swabs were collected from 200 pigs, 100 dairy cows, 100 beef cows, 150 veal calves and 200 broilers. Colonies were isolated on selective media containing cefoxitin and the mecA gene was detected by PCR. Antimicrobial resistance was determined by broth microdilution. The genetic diversity was assessed by PFGE and resistance and virulence genes were detected by microarray analysis. RESULTS: The total MRSS prevalence at the animal level was estimated at 9.5%, varying from ∼10% in veal (13.3%), broilers (12.5%) and dairy cows (10.0%) to 6.5% in pigs and 3.0% in beef cows. mecA was detected in all isolates. SCCmec elements of type III and non-typeable ones were seen most frequently. More than 90% of isolates were non-wild-type (NWT) for gentamicin, penicillin, tiamulin, clindamycin and quinupristin/dalfopristin. The frequency of NWT isolates for fusidic acid and trimethoprim ranged between 78% and 87%. PFGE analysis allowed distinction between two major clusters. Most isolates tested by microarray carried erm and tet genes. Virulence genes were also detected, including an isa gene encoding an immune-evasion factor and the hsdS2 gene encoding a site-specific deoxyribonuclease. CONCLUSIONS: This study shows that multiresistant MRSS is carried by different farm animal species. Although some animals shared the same strain, PFGE showed different patterns, indicating high diversity among the MRSS isolates recovered. The absence of clusters associated with a certain animal species suggests low host specificity.

High genetic diversity of methicillin-susceptible Staphylococcus aureus (MSSA) from humans and animals on livestock farms and presence of SCCmec remnant DNA in MSSA CC398.

OBJECTIVES: To investigate the genetic diversity of methicillin-susceptible Staphylococcus aureus (MSSA) carriage isolates from animals and humans on pig, veal, dairy, beef and broiler farms. METHODS: S. aureus isolates were genotyped using spa typing and multilocus sequence typing (MLST). Antimicrobial susceptibility phenotypes and genotypes were determined. The presence of staphylococcal cassette chromosome mec (SCCmec)-associated DNA was characterized by PCR and sequencing among isolates of clonal complex (CC) 398. RESULTS: Overall, 41 MSSA isolates in humans and 141 in animals were found, originating from all farm types. These MSSA were mainly assigned to CC398, CC1, CC5, CC9, CC30, CC97, CC133 and CC705/151. MSSA CC398 showed resistance to tetracycline, trimethoprim, macrolides and/or lincosamides, aminoglycosides, ciprofloxacin, spectinomycin and quinupristin/dalfopristin, whereas non-CC398 MSSA showed considerably less resistance. Three porcine MSSA CC398-t011 isolates harboured remnant DNA of a composite SCCmec V(5C2&5)c element that lacked the mec gene complex. This resulted from an MRSA-to-MSSA conversion due to recombination between the ccrC genes flanking the mec gene complex. The SCC remnant still contained an intact J1 region harbouring czrC and tet(K), encoding zinc and tetracycline resistance, respectively, thereby illustrating the capacity of S. aureus CC398 to adapt to different antibiotic selection pressures in the farming environment. Processes such as mec gene complex deletion probably contribute to the enormous diversity of SCC(mec) elements observed in staphylococci. CONCLUSIONS: MSSA CC398 precursors from which MRSA CC398 might (re)emerge were present on pig, veal and broiler farms, all of which are livestock sectors commonly known to be affected by MRSA CC398. The multiresistance phenotype of S. aureus CC398 appears to be independent of methicillin resistance.

Transmission Dynamics of Methicillin-Resistant Staphylococcus aureus in Pigs.

From the mid-2000s on, numerous studies have shown that methicillin-resistant Staphylococcus aureus (MRSA), renowned as human pathogen, has a reservoir in pigs and other livestock. In Europe and North America, clonal complex (CC) 398 appears to be the predominant lineage involved. Especially worrisome is its capacity to contaminate humans in close contact with affected animals. Indeed, the typical multi-resistant phenotype of MRSA CC398 and its observed ability of easily acquiring genetic material suggests that MRSA CC398 strains with an increased virulence potential may emerge, for which few therapeutic options would remain. This questions the need to implement interventions to control the presence and spread of MRSA CC398 among pigs. MRSA CC398 shows a high but not fully understood transmission potential in the pig population and is able to persist within that population. Although direct contact is probably the main route for MRSA transmission between pigs, also environmental contamination, the presence of other livestock, the herd size, and farm management are factors that may be involved in the dissemination of MRSA CC398. The current review aims at summarizing the research that has so far been done on the transmission dynamics and risk factors for introduction and persistence of MRSA CC398 in farms.

High-resolution typing by MLVF unveils extensive heterogeneity of European livestock-associated methicillin-resistant Staphylococcus aureus isolates with the sequence type 398.

Methicillin-resistant Staphylococcus aureus sequence type 398 (MRSA ST398) has emerged in livestock worldwide. In particular, areas in Europe with high densities of livestock farming are affected. Consequently, the incidence of human colonization and infection with ST398 is rapidly increasing. Distinguishing different ST398 isolates with standard typing tools is problematic. The objective of this study was to examine the discriminatory power of Multiple-Locus Variable number tandem repeat Fingerprinting (MLVF) on a highly diverse ST398 collection. Our data show that MLVF combined with spa-typing is an attractive approach for high-resolution typing of ST398 isolates and unveiling their relatedness.

Prevalence, risk factors and genetic diversity of methicillin-resistant Staphylococcus aureus carried by humans and animals across livestock production sectors.

OBJECTIVES: This study aimed to assess the prevalence of methicillin-resistant Staphylococcus aureus (MRSA) in animals and humans on veal, dairy, beef and broiler farms and to compare the risk for human MRSA carriage with that of strictly horticulture farmers. The genetic background, resistance phenotypes and genotypes and toxin gene content of the isolated MRSA strains were compared with MRSA collected on MRSA clonal complex (CC)398-positive pig farms. METHODS: MRSA carriage isolates were genotyped (spa, SCCmec and multilocus sequence typing), resistance to 16 antimicrobials was determined and resistance and toxin genes were detected. RESULTS: MRSA carriage rates were higher (P<0.01) on veal farms (calves, 64%; farmers, 72%) compared with on dairy (cows, 1%), beef (cows, 5%; farmers, 11%), broiler (pooled broths, 5%; farmers, 3%) and horticulture (farmers, 3%) farms. The intensity of animal contact was identified as a risk factor for human MRSA carriage. The vast majority of MRSA (n=344), including those from pigs, were CC398 (98%). SCCmec V(5C2), V(5C2&5)c, IV(2B) and IV(2B&5) predominated. MRSA CC130 and CC599 carrying mecC were detected in beef and dairy cattle. MRSA from veal calves were significantly more resistant than MRSA from pigs (P<0.01). A few isolates, including mecC-carrying MRSA, harboured pyrogenic superantigen toxins. Human- and animal-derived MRSA from individual farms showed similar characteristics. CONCLUSIONS: This systematic cross-sector survey revealed a high prevalence of multiresistant livestock-associated MRSA on Belgian veal calf farms as compared with other farm types. MRSA harbouring mecC was detected at a low frequency in beef and dairy cows, but not in humans.

Serological profiles in nursery piglets colonized with Staphylococcus aureus.

At present, the immune response of pigs in relation to Staphylococcus aureus carriage is poorly understood. This study was aimed at investigating the dynamics of the anti-staphylococcal humoral immune response in methicillin-susceptible S. aureus (MSSA)-positive piglets and at assessing the effect of the experimental introduction of a methicillin-resistant S. aureus (MRSA) Sequence Type (ST) 398 strain. Therefore, serum samples were collected at different times from 31 weaned piglets originating from four different sows. Twenty-four out of the 31 piglets were challenged with MRSA ST398. The serum samples were analyzed for IgG antibodies to 39 S. aureus antigens, using a multiplex bead-based assay (xMAP technology, Luminex Corporation). Though antibody responses showed broad inter-individual variability, serological results appeared to be clustered by litter of origin. For most antigens, an age-related response was observed with an apparent increase in antibody titers directed against staphylococcal microbial surface components recognizing adhesive matrix molecules (MSCRAMM), which have been shown to play a role in S. aureus colonization. In most animals, antibody titers directed against staphylococcal toxins or immune-modulating proteins decreased with age, possibly reflecting the absence of bacterial invasion. The introduction of MRSA ST398 did not elicit a significant humoral immune reaction.This study describes, for the first time, the humoral immune response in weaned pigs colonized with S. aureus.

Characterization of methicillin-resistant non-Staphylococcus aureus staphylococci carriage isolates from different bovine populations.

OBJECTIVES: This study aimed at investigating bovine non-Staphylococcus aureus staphylococci for their role as a potential reservoir for methicillin resistance. METHODS: Nasal swab samples were collected from 150 veal calves on 15 veal farms, 100 dairy cows on 10 dairy farms and 100 beef cows on 10 beef farms. Suspected staphylococcal isolates were investigated by PCR for the presence of the classic mecA and mecA(LGA251). Methicillin-resistant non-S. aureus staphylococci (MRNAS) were genotypically identified and were characterized by broth microdilution antimicrobial susceptibility testing and staphylococcal cassette chromosome mec (SCCmec) typing. RESULTS: The MRNAS (n = 101) carriage rate was estimated as 30.29% (95% CI 6.14%-74.28%) in veal calves, 13.1% (95% CI 1.28%-63.72%) in dairy cows and 24.8% (95% CI 11.97%-44.42%) in beef cows. Carriage rates were not significantly different between the three populations (P > 0.05). mecA(LGA251) was not detected. Most (n = 80) MRNAS were identified as Staphylococcus sciuri, Staphylococcus lentus or Staphylococcus fleurettii. Resistance to aminoglycosides, macrolide-lincosamide-streptogramin antimicrobials, tetracycline and ciprofloxacin was frequently detected. Two linezolid-resistant MRNAS from veal calves carried the multidrug-resistance gene cfr. SCCmec cassettes of type III predominated (n = 46); another 40 SCCmec cassettes harboured a class A mec complex without identifiable ccr complex; type IVa, type V and several other non-typeable cassettes were detected in low frequencies, especially in methicillin-resistant Staphylococcus epidermidis. CONCLUSIONS: The SCCmec types predominating in bovine MRNAS differ from those mostly detected in livestock-associated methicillin-resistant S. aureus strains. Yet, the detection of cfr and the high level of other antimicrobial resistances suggest a potentially important role of bovine MRNAS as a reservoir for resistance determinants other than SCCmec.

Emerging Chlamydia psittaci infections in the chicken industry and pathology of Chlamydia psittaci genotype B and D strains in specific pathogen free chickens.

Sera of 30 Belgian and 10 Northern French chicken farms were tested by a Chlamydia (C.) psittaci major outer membrane protein (MOMP) based ELISA. Ninety-six percent, 93% and 90% of the Belgian broilers, broiler breeders and layers were seropositive. Ninety-one percent of the French broilers were seropositive. In addition, tissues of 5 Belgian and 5 French broiler farms were examined at slaughter. All French farms were culture positive while C. psittaci was cultured from the lungs of 80% of examined Belgian farms. C. psittaci infections are apparently emerging in chickens raised in Belgium and Northern France. We could proof Hill-Evans postulates for chicken-derived C. psittaci genotype B and D strains. Chicken-processing plant employees should be considered a risk group for human psittacosis. There is a need for higher awareness and for efficient risk assessment and management of C. psittaci infections in chickens as chlamydiosis in broilers seems to be underdiagnosed and infections with highly virulent strains do occur.

Low MRSA prevalence in horses at farm level.

BACKGROUND: In Europe, methicillin-resistant Staphylococcus aureus (MRSA) belonging to the clonal complex (CC) 398 has become an important pathogen in horses, circulating in equine clinics and causing both colonization and infection. Whether equine MRSA is bound to hospitals or can also circulate in the general horse population is currently unknown. This study, therefore, reports the nasal and perianal MRSA screening of 189 horses on 10 farms in a suspected high prevalence region (East- and West-Flanders, Belgium). RESULTS: Only one horse (0.53%) from one farm (10%) tested positive in the nose. It carried a spa type t011-SCCmecV isolate, resistant to ß-lactams and tetracycline, which is typical for livestock-associated MRSA CC398. CONCLUSION: In the region tested here, horses on horse farms seem unlikely to substantially contribute to the large animal associated ST398 MRSA reservoir present at intensive animal production units.

Species and staphylococcal cassette chromosome mec (SCCmec) diversity among methicillin-resistant non-Staphylococcus aureus staphylococci isolated from pigs.

While methicillin-resistant Staphylococcus aureus (MRSA) ST398 is known to be widespread in pig farms, few studies have investigated the species diversity and SCCmec types of methicillin-resistant non-S. aureus staphylococci (MRNAS) residing in the nose of pigs. We examined nasal swab samples of 200 pigs originating from 10 Belgian pig farms previously found positive for MRSA ST398. Suspected staphylococcal isolates were subjected to a 16S rRNA-mecA-nuc PCR. Confirmed MRNAS were genotypically identified to the species level and investigated with a SCCmec typing PCR. MRNAS (n=72) were detected on all 10 farms and were carried by 29.5% of the pigs. Seven MRNAS species were found: Staphylococcus epidermidis (38.9%), Staphylococcus sciuri (18.1%), Staphylococcus pasteuri (18.1%), Staphylococcus rostri (12.5%), Staphylococcus warneri (8.3%), Staphylococcus haemolyticus (2.7%) and Staphylococcus hominis (1.4%). SCCmec cassettes were of type IVa (29.2%), type IVc (25%), type III (22.2%), type V (5.6%) or could not be assigned to any of the known types (NT types) (18.1%). Five distinct NT types were found. The predominance of methicillin-resistant S. epidermidis (MRSE) in our samples is remarkable, as MRSE is mainly associated with humans. The finding of three different SCCmec elements (IVa, V, NT type 1) in MRNAS that also prevail or predominate in MRSA ST398 shows that MRNAS might be an important SCCmec reservoir for MRSA in pigs. Yet, the occurrence of multiple other SCCmec types illustrates that further studies are required to understand the presence and spread of SCCmec in methicillin-resistant staphylococci from animals.

Screening for methicillin-resistant staphylococci in dogs admitted to a veterinary teaching hospital.

This study investigated the nasal carriage of methicillin-resistant staphylococci (MRS) in dogs (n=177) prior to medical examination or surgery in a veterinary teaching hospital. Nasal swab samples were collected after induction of anaesthesia and incubated overnight in salt enriched trypticase-soy broth. Cultures were analysed on two different agar media containing cefoxitin. Suspected MRS isolates were genotypically identified and characterised by antimicrobial susceptibility testing and staphylococcal cassette chromosome mec (SCCmec)-typing. Methicillin-resistant Staphylococcus aureus (MRSA) isolates were additionally characterised by spa-typing and multilocus sequence typing. The presence of Panton-Valentine leukocidin (pvl) genes was determined by PCR. MRS carriage was compared between animals with or without an infectious process. Two MRSA were isolated, both belonging to typical Belgian human hospital clones and lacking pvl. Additionally a methicillin-resistant Staphylococcus haemolyticus carrying a type V SCCmec was detected. No relationship was observed between MRS carriage and presence of infections. The results suggest that MRS are present in dogs originating from the community, albeit at a low prevalence. This could pose risks for cross contamination of dogs and their owners.

Colonization and transmission of methicillin-resistant Staphylococcus aureus ST398 in nursery piglets.

A transmission experiment was performed to evaluate the spread of methicillin-resistant Staphylococcus aureus (MRSA) ST398 in nursery piglets. Reproduction ratios (R(0)) in three experimental groups were found to vary between 3.92 and 52.54, indicating that after introduction, MRSA ST398 will spread easily among weaned piglets, with a tendency to become established.