MRSA CC398 in the pig production chain

In 2005, a distinct clone of methicillin resistant Staphylococcus aureus (MRSA CC398) was found in pigs and people in contact with pigs. The structure of the pig production chain in high technology pig husbandry enables pathogens to spread during animal trading, with an increasing prevalence in herds further down the chain. The objective of this study was to quantify the effect of the MRSA status of the supplying herd on the MRSA status of the receiving herd in order to gain more insight into the role of animal trading as a transmission route for MRSA CC398. Nasal samples (60-80 pigs per herd) were collected from 38 herds; in 20 herds, environmental samples were collected as well. Ten MRSA-positive herds (based on the results of nasal swabs of 10 individual pigs per herd) from a prior study were included in the data analysis. Herds were classified as MRSA positive if at least one sample tested positive. The 48 herds were part of 14 complete (40 herds) and 4 incomplete (8 herds) pig production chains. Fifty-six percent of the herds were classified as MRSA positive. MRSA-positive herds were observed at the start (breeding herds), middle (farrowing herds) and the end (finishing herds) of the pig production chain. All of the herds in 8 chains tested MRSA positive;, all of the herds in 5 chains tested MRSA negative and in the remaining 5 chains, MRSA-positive and MRSA-negative herds were detected. Seven spa types were found, which were all previously confirmed to belong to CC398. All of the isolates were susceptible to mupirocin, linezolid, rifampicin, fusidic acid and cotrimoxazole. Resistance against tetracycline, erythromycin and clindamycin was found in 100, 74 and 76% of the isolates, respectively. Seventy-nine percent of herds with a MRSA-positive supplier of pigs were MRSA positive, whereas 23% of herds with a MRSA-negative supplier were MRSA positive (OR=10.8; 95% CI: 1.5-110.1; P=0.011). The presence of entirely MRSA-positive and MRSA-negative chains and the strong association between the MRSA status of herds and their suppliers illustrates a large risk associated with purchasing pigs from MRSA-positive herds; a top-down strategy for future control programs is, therefore, a basic requirement. However, 23% of herds with a MRSA-negative supplier were MRSA positive and furthermore, 46% of the herds at the top of the pig production chain without a supplier tested MRSA positive. This underlined the need for the identification of additional risk factors for MRSA.     

Distance to pig farms as risk factor for community‐onset livestock‐associated MRSA CC398 infection in persons without known contact to pig farms—A nationwide study

MRSA CC398 is an emerging MRSA strain found in livestock, mainly in pigs. Direct occupational livestock contact is the principal risk factor for human MRSA CC398 infection. Nonetheless, in recent years, an increasing number of MRSA CC398 cases has been observed in persons without known pig contact. Such cases, referred to as MRSA CC398 of unknown origin (MUO CC398), have, like livestock‐onset (LO) MRSA CC398 cases, been found concentrated in rural, livestock‐producing areas. The presence of MUO CC398 cases indicates alternative and unknown MRSA CC398 transmission pathways into the community. We performed a nationwide study in Denmark of the geographic distributions of MRSA cases in general and persons with MUO CC398 or LO MRSA CC398 infections (1 January 2006–11 February 2015), with the Danish population as background population. Place of living of study persons was mapped using the ArcGIS software, and information on pig farms was retrieved from the Central Husbandry Register. The incidence of MUO CC398 infections was clearly higher in rural than in urban areas, and such cases lived on average closer to pig farms than the general population. However, within three pig‐farming‐dense municipalities, patients with MUO CC398 infections did not live closer to pig farms than population controls. This shows that direct environmental spread from neighbouring pig farms of MRSA CC398 is unlikely. Instead, community spread through other means of transmission than direct spread from farms may more likely explain the clustering of MUO CC398 in livestock‐dense areas.     

Occurrence of methicillin-resistant Staphylococcus aureus in rats living on pig farms

In The Netherlands, MRSA ST398 has emerged in hospitals and human carriers have been associated with exposure to pigs and cattle. High prevalences of MRSA ST398 in pigs and pig farmers have been determined and the transmission routes of MRSA on pig farms need to be elucidated. In the south of the Netherlands, in recent years, the black rat (Rattus rattus) has emerged as a prominent rodent on livestock farms. From March till May 2008, a survey on MRSA in rats living on livestock farms in the south of The Netherlands and the north of Belgium was conducted. In total, 40 black rats (R. rattus) and 3 brown rats (Rattus norvegicus) were collected on 12 farms including five pig farms, five poultry farms, one mixed pig and veal farm and one goat farm. MRSA ST398 was detected in black rats captured at two of the five pig farms as well as in a black rat living on the mixed pig and veal farm. From one black rat captured at another pig farm MRSA ST 97 was isolated. Considering the behaviour of rats on livestock farms, it is concluded that rats might play a role in the spread and persistence of MRSA on pig farms.     

Low prevalence of zoonotic multidrug‐resistant bacteria in veterinarians in a country with prudent use of antimicrobials in animals

The occurrence of multidrug‐resistant zoonotic bacteria in animals has been increasing worldwide. Working in close contact with livestock increases the risk of carriage of these bacteria. We investigated the occurrence of extended‐spectrum beta‐lactamase (ESBL) and plasmidic AmpC beta‐lactamase producing Enterobacteriaceae (ESBL/pAmpC‐PE) and livestock‐associated methicillin‐resistant Staphylococcus aureus (LA‐MRSA) in Finnish veterinarians (n = 320). In addition to microbiological samples, background information was collected. Bacterial whole genome sequencing was performed to deduce sequence types (STs), spa types and resistance genes of the isolates. In total, 3.0% (9/297) of the veterinarians carried ESBL producing Escherichia coli, with one ESBL producing E. coli isolate producing also AmpC. Seven different STs, sequences of several different plasmid groups as well as several different bla_ESBL/pAmpC genes existed in different combinations. No carbapenemase or colistin resistance genes were detected. MRSA was detected in 0.3% (1/320) of the samples. The strain belonged to LA‐MRSA clonal complex (CC) 398 (ST398, spa type 011, lacking Panton‐Valentine leukocidin genes). In conclusion, this study shows low carriage of multidrug‐resistant zoonotic bacteria in Finnish veterinarians. However, finding LA‐MRSA for the first time in a sample from a veterinarian in a country with prudent use of animal antimicrobials and regarding the recent rise of LA‐MRSA on Finnish pig farms, a strong recommendation to protect people working in close contact with animals carrying LA‐MRSA CC398 is given. Further studies are needed to explain why the prevalence of LA‐MRSA in veterinarians is lower in Finland than in other European countries.     

Prevalence and risk factor analysis of livestock associated MRSA-positive pig herds in The Netherlands

In 2005, methicillin-resistant Staphylococcus aureus was found in pig herds and in humans in contact with pigs. To determine the prevalence of, this now-called livestock-associated (LA) MRSA among pig herds in The Netherlands and to identify and quantify risk factors, an observational study of 202 pig herds was performed between 2007 and 2008. Five environmental wipes and 60 nasal swabs from each herd were collected, and microbiological analysis was performed on single environmental samples and pooled nasal samples. A herd was considered MRSA-positive if ≥1 sample tested positive. The prevalence of MRSA-positive herds was 67% in breeding herds and 71% in finishing herds. Multivariable logistic regression analysis was then performed on data from 171 breeding herds. The number of MRSA-positive herds increased from ～30% at the start to ～75% at the end of the study, most likely due to transmission between herds. The prevalence of MRSA increased with herd size, as ～40% of smaller herds (<250 sows) were MRSA-positive compared to >80% of larger herds (>500 sows). Other risk factors (e.g. antimicrobial use, purchase of gilts and hygiene measures) were not significantly associated with MRSA, though associated with herd size. Herd size appeared to be a compilation of several factors, which made larger herds more often MRSA positive.     

Zinc resistance of Staphylococcus aureus of animal origin is strongly associated with methicillin resistance

This study was conducted to determine the occurrence of zinc and copper resistances in methicillin-resistant Staphylococcus aureus (MRSA) from swine and veal calves in a global strain collection. The test population consisted of 476 porcine MRSA isolates from ten European countries, 18 porcine MRSA isolates from Canada and seven MRSA from China, 92 MRSA and 60 methicillin-susceptible S. aureus (MSSA) isolates from veal calves in the Netherlands and 88 porcine MSSA isolates from four European countries. Most porcine MRSA (n=454) and all bovine MRSA belonged to clonal complex (CC) 398 whereas 37 of the pig MRSA from Europe and the seven Chinese isolates belonged to other CCs and 3 isolates were not classified into a CC. All isolates were tested for susceptibility to zinc chloride and copper sulphate using agar dilution and tested by PCR for the czrC gene encoding zinc resistance. Phenotypic zinc resistance (MIC>2mM) was observed in 74% (n=324) and 42% (n=39) of European MRSA CC398 from pigs and veal calves, respectively, and in 44% of the Canadian isolates (n=8), but not among the Chinese isolates. Almost all (99%) zinc-resistant MRSA carried czrC. Of the 37 European non-CC398 MRSA, 62% were resistant to zinc, but only 46% of them carried czrC. The MICs of the MSSA isolates to zinc chloride ranged from 1 to 4mM and none carried czrC. The MICs of copper sulphate were associated neither with methicillin resistance nor with the detection of czrC. This study showed that zinc resistance and the czrC gene are widespread among CC398 MRSA isolates. This suggests that the use of zinc in feed might have contributed to the emergence of MRSA.     

Transmission of MRSA CC398 strains between pig farms related by trade of animals

Meticillin-resistant Staphylococcus aureus (MRSA) clonal complex (CC) 398 is a genetic lineage associated with livestock, especially pigs. The authors investigated the role of pig trade in the transmission of MRSA CC398 between farms using pulsed-field gel electrophoresis (PFGE), a highly discriminatory method for strain typing. PFGE analysis of 58 MRSA isolates from a retrospective study in the Netherlands and a prospective study in Denmark provided molecular evidence that the strains present in five of the eight recipient farms were indistinguishable from those occurring in the corresponding supplying farm. The molecular typing data confirm the findings of a previous risk-analysis study indicating that trading of colonised pigs is a vehicle for transmission of MRSA CC398.     

Methicillin‐Resistant Staphylococcus aureus (MRSA) ST398 in Pig Farms and Multispecies Farms

During the last few years, methicillin‐resistant Staphylococcus aureus (MRSA) ST398 has been isolated frequently from livestock, especially from pigs and to a lesser extent from cattle and poultry. To gain insight into the distribution of this bacterium in pig farms versus multispecies farms, 30 Belgian farms (10 pig, 10 pig/poultry and 10 pig/cattle farms) were screened for the presence of MRSA. On each farm, 10 nasal swabs were taken from pigs. When present, cattle (n = 10) were sampled in the nares and poultry (n = 10) in the nares, earlobes and cloaca. A selection of the obtained isolates were further characterized using multilocus sequence typing (MLST), spa typing, SCCmec typing, pulsed field gel electrophoresis (PFGE), multiple‐locus variable‐number tandem repeat analysis (MLVA) and antimicrobial susceptibility testing. On 26 of 30 farms, MRSA was isolated from pigs. Furthermore, MRSA was also isolated from poultry and cattle on one pig/poultry and five pig/cattle farms, respectively. All tested MRSA isolates belonged to ST398. Eight spa types (t011, t034, t567, t571, t1451, t2974, t3423 and t5943) were detected, among which t011 predominated. SCCmec cassettes type IVa and V were present in 20% and 72% of the isolates, respectively. When combining the results of the two remaining typing methods, PFGE and MLVA, eighteen genotypes were obtained of which one genotype predominated (56% of the positive farms). All MRSA isolates were resistant to tetracycline. Resistance to trimethoprim, aminoglycosides, macrolides, lincosamides, fluoroquinolones and chloramphenicol was also observed. In conclusion, there was no effect of the farm type on the MRSA status of the pigs. A statistically significant difference was observed when comparing the pig/poultry or the pig/cattle MRSA status on the multispecies farms. Additionally, a wide variety of MRSA ST398 strains was found within certain farms when combining different typing methods.     

Prevalence and antimicrobial resistance of MRSA across different pig age groups in an intensive pig production system in Australia

This observational study aimed to determine MRSA prevalence using strain‐specific real‐time PCR at the pig level, stratified by age groupings, within a pig enterprise. A total of 658 samples were collected from individual pigs (n = 618) and the piggery environment (n = 40), distributed amongst five different pig age groups. Presumptive MRSA isolates were confirmed by the presence of mecA, and MALDI‐TOF was performed for species verification. All isolates were tested against 18 different antimicrobials. MRSA was isolated from 75.2% (95% CI 71.8–78.6) of samples collected from pigs, and 71% of the MRSA isolates from this source were identified as community‐associated (CA)‐MRSA ST93, while the remainder were livestock‐associated (LA)‐MRSA ST398. Amongst environmental isolates, 80% (CI 64.3–95.7) were ST93 and the remainder ST398. All MRSA isolates from pigs and the environment were susceptible to ciprofloxacin, gentamicin, linezolid, mupirocin, rifampicin, sulfamethoxazole–trimethoprim, teicoplanin and vancomycin. Phenotypic rates of resistance were penicillin (100%), clindamycin (97.6%), erythromycin (96.3%), ceftiofur (93.7%), chloramphenicol (81.2%), tetracycline (63.1%) and amoxicillin–clavulanate (63.9%). A low prevalence of resistance (9.2%) was observed against neomycin and quinupristin–dalfopristin. The probability of MRSA carriage in dry sows (42.2%) was found to be significantly lower (p < .001) when compared to other age groups: farrowing sows (76.8%, RR1.82), weaners (97.8%, RR 2.32), growers (94.2%, RR 2.23) and finishers (98.3%, RR 2.33). Amongst different production age groups, a significant difference was also found in antimicrobial resistance for amoxicillin–clavulanate, neomycin, chloramphenicol and tetracycline. Using the RT‐PCR assay adopted in this study, filtering of highly prevalent ST93 and non‐ST93 isolates was performed at high throughput and low cost. In conclusion, this study found that weaner pigs presented a higher risk for CA‐MRSA and antimicrobial resistance compared to other age groups. These findings have major implications for how investigations of MRSA outbreaks should be approached under the One‐Health context.     

Methicillin‐Resistant Staphylococcus aureus (MRSA) in Three Dairy Herds in Southwest Germany

The objective of this study was to analyse the occurrence of methicillin‐resistant Staphylococcus aureus (MRSA) in three dairy herds in the southwest of Germany that had experienced individual cases of clinical and subclinical mastitis associated with MRSA. The herds were identified by the detection of MRSA during routine resistance testing of mastitis pathogens. All quarters of all cows in the herds that were positive on California Mastitis Test were sampled for bacteriological analysis on two occasions. Bulk tank milk samples were also tested. Furthermore, nasal swabs were collected from people working on the farms and from cattle. Environmental samples were collected from associated pig holdings. Isolates were characterized using spa‐typing and testing for antimicrobial resistance. Our results revealed a substantial spread of MRSA in the three dairy herds. In the first of the two investigations carried out on all cows in the three herds, milk samples of 5.1–16.7% of dairy cows were found positive for MRSA. The respective proportions in the second herd level investigation were 1.4–10.0%. Quarters harbouring MRSA had higher somatic cell counts than quarters that were negative on culture. Methicillin‐resistant Staphylococcus aureus were also detected in nasal swabs of staff (7/9), cows (7/15) and calves (4/7), bulk tank milk samples (3/3) and environmental samples from pig premises (4/5) on the farm. Herds B and C had no contact to herd A. However, in all three herds MRSA of spa‐type t011 were detected in milk samples. Results show that MRSA of spa‐type t011 is a problem in dairy farms that needs urgent attention.     

Colonization of Butchers with Livestock‐Associated Methicillin‐Resistant Staphylococcus aureus

Reports have documented colonization of swine in Europe, North America and more recently in China with livestock‐associated methicillin‐resistant Staphylococcus aureus (LA‐MRSA). Contamination of pig farmers, veterinarians and abattoir workers with these strains has been observed. However, although contamination levels of 10% of retail pork were reported from the Netherlands and Canada, there are limited data of contamination rates of workers handling raw meat. We investigated the rates of MRSA contamination of local butchers working in wet markets, where recently slaughtered pigs are cut up. Nasal swabs collected from 300 pork butchers at markets throughout Hong Kong were enriched in brain heart infusion broth with 5% salt and cultured on MRSASelect^®. Isolates were confirmed as Staphylococcus aureus and susceptibility testing performed. The presence of mecA was confirmed, SCCmec and spa type determined and relatedness investigated by PFGE. Subjects completed a questionnaire on MRSA carriage risk factors. Seventeen samples (5.6%) yielded MRSA, 15 harbouring SCCmec IVb. Ten strains were t899 (CC9), previously reported from local pig carcasses. Five strains were healthcare associated: SCCmec type II, t701(CC6), colonizing two subjects at the same establishment, and single isolates of t008 (CC8), t002 (CC5) and t123 (CC45). The remaining isolates were t359 (CC97), previously reported from buffaloes, and t375 (CC5), reported from bovine milk. None of these butchers reported recent hospitalization or a healthcare worker in the family. Two had recently received antibiotics, one for a skin infection. Four reported wound infections within the last year. All were exposed to meat for >9 h per day. Carriage of MRSA was higher in butchers than in the general community. Although five strains were probably of healthcare origin, the high incidence of t899 (CC9) suggests that cross‐contamination from pork occurs frequently. Washing of hands after touching raw pork is advised.     

Characterization of methicillin-resistant Staphylococcus aureus CC398 obtained from humans and animals on dairy farms

In this study MRSA isolates from dairy farms were investigated for their genetic relationships and antimicrobial susceptibility. In total, 125 MRSA isolates from 26 dairy farms were studied, including isolates from milk samples (n=46), dairy cattle (n=24), calves (n=6), dust samples from pig (n=16) and veal calf sheds (n=1), dogs (n=2), a horse, a sheep and humans (n=28). CC398-specific PCRs, spa typing, SCCmec typing and ApaI macrorestriction analysis were conducted. Susceptibility testing was performed by broth microdilution. All 125 isolates belonged to CC398. Eight spa types (t011, t108, t034, t567, t1184, t1451, t2287 and t3934) were detected. SCCmec elements of types IV (n=48) and V (n=67) were identified with 10 isolates being non-typeable. Six main macrorestriction patterns - with up to 23 sub-patterns - and twelve resistance patterns were identified. Sixty-eight isolates showed a multiresistance phenotype. Farm-by-farm analysis revealed different scenarios: in some farms, the MRSA CC398 isolates from dairy cattle, humans, pig sheds and/or sheep were indistinguishable suggesting an interspecies exchange of the same MRSA CC398 subtype. In other farms, several MRSA CC398 subtypes were detected in different host species/sources with occasionally even more than one MRSA CC398 subtype from the same host species/source. These latter results may suggest that either different MRSA subtypes associated with humans or animals have been imported into the respective farm or that one MRSA CC398 strain has undergone diversification, reflected by more or less expanded changes in PFGE patterns, spa type or resistance pattern, during colonization of different hosts on the same farm.     

Staphylococcus aureus (MSSA) and MRSA (CC398) isolated from post-mortem samples from pigs

There are many reports on the occurrence of Livestock Associated Methicilline resistant Staphylococcus aureus (LA-MRSA, CC398) in healthy pigs. There are however, very few reports of LA-MRSA being associated with pathological lesions in pigs. With this study we try to find the answers to the questions: (1) how often is S. aureus found in post-mortem material from pigs, (2) how many of these isolates are methicillin resistant, (3) are these equally distributed over the years? Here we report the isolation of MRSA and of methicillin sensitive S. aureus (MSSA) from samples derived from post-mortem examinations at the Animal Health Service in The Netherlands in the period from 2003 through October 2008. The MSSA and MRSA described here were isolated from 159 pathological lesions and from 7 submissions of aborted foetuses derived from a total of 116 animals, representing 103 submissions coming from 92 different herds. This is approximately 0.5% of all pigs submitted for post mortem examination in those years. The proportion of pigs from which S. aureus (both MSSA and MRSA) was isolated from, did not increase over the years. MSSA (N=97) and LA-MRSA CC398 (N=18) were present mainly in (peri)arthritis in over 30% of all cases, but were also isolated from internal organs such as lung, brain, spleen, kidneys, heart, indicating septicaemia. Remarkably, one non-CC398 MRSA (ST1) was isolated in a joint and a kidney of one pig. This isolate was resistant to 5 out of 6 antimicrobials tested. There was no significant difference in the type of lesions in which LA-MRSA was found compared to MSSA. The number of antimicrobials these isolates were resistant to, increased rapidly after 2004. LA-MRSA was isolated for the first time in 2005 and then again in 2007 and 2008, suggesting that this is an emerging pathogen. However, due to changes in the panel of antimicrobials used to test S. aureus for antimicrobial susceptibility in 2005 and 2007, the possibility exists that we may have missed some MRSA isolates. LA-MRSA isolates are resistant to at least three but sometimes five out of six antimicrobials tested. All isolates were susceptible to the combination of Trimethoprim/Sulfamethaxol.     

Bovine-associated MRSA ST398 in The Netherlands

During routinely screening (50.000 milk samples on an annual basis) 14 MRSA ST398 strains were identified in the period of January 2008 to September 2008 in 14 different dairy herds located in the provinces Overijssel and Gelderland, The Netherlands. Molecular analysis was performed by Cfr9I PFGE, ST398-specific diagnostic PCR, spa typing, SCCmec typing and Panton-Valentine Leukocidin (PVL) gene PCR. The molecular analyses of 14 MRSA (one MRSA strain per herd) strains revealed that all strains belong to ST398 with 3 closely related spa types (t011, t108 and t889, all commonly found in pigs) and carry 2 different SCCmec types, IVa and V. All MRSA strains were resistant to two or more classes of antibiotics and also PVL negative. The majority of farms (n = 9, 64%) harboured combined livestock with both cows and pigs present. Our study contributes to the growing evidence that MRSA ST398 is transmitted among various animal species and can be considered as an etiological agent of mastitis in dairy cows.     

High prevalence of methicillin resistant Staphylococcus aureus in pigs

Recently methicillin resistant Staphylococcus aureus (MRSA) was isolated from pigs and pig farmers in The Netherlands. In order to assess the dissemination of MRSA in the Dutch pig population, we screened 540 pigs in 9 slaughterhouses, where a representative portion of Dutch pigs (63%) was slaughtered in 2005. We found 209 (39%) of the pigs to carry MRSA in their nares. Forty-four of 54 groups of 10 consecutive pigs (81%), each group from a different farm, and all slaughterhouses were affected. All MRSA isolates belonged to 1 clonal group, showing Multi-Locus Sequence Type 398 and closely related spa types (mainly t011, t108 and t1254). Three types of the Staphylococcal Chromosome Cassette (SCCmec) were found: III (3%), IVa (39%) and V (57%). All 44 tested isolates (1 isolate per group) were resistant to tetracycline, reflecting the high and predominant use of tetracyclines in pig husbandry. Twenty-three percent of the isolates were resistant to both erythromycin and clindamycin and 36% to kanamycin, gentamicin and tobramycin but only a single isolate was resistant to co-trimoxazole and none to ciprofloxacin and several other antibiotics. The percentage of MRSA positive pigs was significantly different among slaughterhouses and among groups within slaughterhouses, indicating a high prevalence of MRSA in pigs delivered from the farms as well as cross contamination in the slaughterhouses.     

Study of methicillin resistant Staphylococcus aureus (MRSA) in Danish pigs at slaughter and in imported retail meat reveals a novel MRSA type in slaughter pigs

Methicillin-resistant Staphylococcus aureus (MRSA), especially CC398, have emerged in livestock worldwide. We investigated the occurrence of MRSA in pigs at slaughter and in retail meat. During 2009, nasal swabs (n=789) were taken from pigs at slaughter. Moreover, 866 meat samples [Danish: pork (153), broiler meat (121), beef (142) and; imported: pork (173), broiler meat (193), and beef (84)] were randomly collected in retail stores and outlets. MRSA was isolated from nasal swabs or from meat samples after preenrichment (Mueller Hinton broth with 6.5% NaCl), selective enrichment (tryptone soya broth with 4 mg/L cefoxitine and 75 mg/L aztreonam) and selective plating on Brilliance Chromogenic MRSA agar. The presence of mecA was confirmed by PCR and the MRSA isolates were spa typed. Novel MRSA spa types were characterized by MLST, PFGE and SCCmec typing. Thirteen percent (101/789) of the pigs had MRSA. Based on spa types 93% corresponded to CC398 (spa t011, t034, t1451, t2876, t2974), 4% to CC30 (t1333) and one isolate to CC1 (t0127). The spa type t1333 (CC30), which is common among methicillin susceptible S. aureus (MSSA) from pigs in Denmark, contained a SCCmec cassette type V and czrC zinc resistance gene. Imported broiler meat had the highest occurrence (18%) of MRSA, followed by imported pork (7.5%) and Danish pork (4.6%). MRSA ST398 was found for the first time in Danish beef (1.4%). The finding of MRSA CC30 (spa t1333) suggest possible spread of the SCCmec cassette normally associated with ST398 into another S. aureus lineage common in pigs.     

Reproductive performance in pigs reared under organic conditions compared with conventionally reared pigs

Background

To achieve a competitive reproductive performance in organic pig farming is a major challenge for this farming practise. Practices and research data regarding conventional pig production are not always applicable to organic production, why field studies are needed to identify differences in performance between organic and conventional pig farms in order to identify areas for improvement.

Results

Performance data for one year was collected from 5 organic herds that had more than 30 sows in production and used a computerized recording system, and data from five nearby conventional farms with more than 30 sows and the same recording system were used as a comparison. In total data from 4697 farrowings were analyzed. In the organic pig herds, there were a higher total number of piglets born per litter (p=0.001), a higher number of piglets stillborn per litter (p<0.001), but a tendency (p<0.06) to lower number of weaned pigs per litter and longer nursing period (p<0.001) and farrowing interval (p<0.001).

Conclusions

The reproductive performance was lower in the organic herds and the variation in reproductive performance among the organic herds was larger than among the conventional ones, suggesting options for improvement in the organic herds.     

Occurrence of MRSA in air and housing environment of pig barns

A high prevalence of MRSA among farm animals, especially pigs, has been observed for some time. However, knowledge on transmission routes of MRSA in livestock production is still scarce. Therefore, the aim of this study was to determine the occurrence of MRSA in pig house air as well as in samples from pigs and their housing environment in 27 MRSA positive pig barns of different sizes and production types. In 85.2% of all barns MRSA was detected in the animal house air. Impingement turned out to be a more sensitive sampling technique than filtration. Other environmental samples such as boot swabs or faeces showed prevalences of MRSA from 55.6% to 85.2% at sample level. The level of MRSA was 88.3% for pooled and 82.1% for single nasal swabs, in skin swabs the one was 87.7%, the others was 78.7%. Spa typing of isolates from air and nasal swabs showed predominantly spa types t011 and t034. MRSA prevalences in pigs as well as in various environmental samples were significantly higher in fattening farms than in breeding farms. This study provides good reference that there could be an airborne transmission of MRSA within pig herds indicating a potential contamination of the environment of barns.     

Risk factors for MRSA in fattening pig herds – A meta-analysis using pooled data

The importance of livestock-associated methicillin-resistant Staphylococcus aureus (LA-MRSA) as an infectious agent for humans has increased in recent years in Germany. Although it is well known that the prevalence of MRSA in pig farms is high, risk factors for the presence of MRSA in herds of fattening pigs are still poorly understood. The aim of this study was to evaluate available data from previous studies on MRSA in fattening pigs in a meta-analysis to answer the question: What are the factors associated with the occurrence of MRSA in fattening pig herds?     

Occurrence of MRSA in pigs and in humans involved in pig production--preliminary results of a study in the northwest of Germany

In 2007, 678 pigs of all age groups out of 347 different farms from Lower Saxony and Northrhine-Westphalia and 86 persons occupationally exposed to pigs were investigated for their nasal colonisation with methicillin-resistant Staphylococcus areus (MRSA) by the Field Station for Epidemiology of the University of Veterinary Medicine Hannover and the Robert Koch-Institute. At the individual animal level, a frequency of positive results of 13% (n = 85 positive animals) and at the herd level, a frequency of positive results of 18% (n = 62 positive herds) were found. All isolates were assigned to the Multilocus Sequence Typing Type ST398. Within MRSA-positive herds, there were more MRSA-negative than MRSA-positive animals. Among the occupationally exposed persons (veterinarians, laboratory personnel and meat inspection personnel), 20 persons (23%) showed a nasal colonisation with MRSA ST398. A quite strong association between the intensity of the contact to pigs with the frequency of nasal colonisation in the occupationally exposed persons was detected. None of the animals or the humans nasally colonised by MRSA ST398 showed any clinical symptoms of a staphylococcal infection. Conclusions are drawn on the herd and intra-herd prevalence of the nasal colonisation of pigs with MRSA ST398 in pigs, but especially on which questions need to be addressed by further research.