MRSA In Pigs Research Articles

Safety Evaluation of an Intranasally Applied Cocktail of Lactococcus lactis Strains in Pigs.

Three Lactococcus lactis strains from the nasal microbiota of healthy pigs were identified as candidates for reducing MRSA in pigs. The safety of nasal administration of a cocktail of these strains was examined in new-born piglets. Six days pre-farrowing, twelve sows were assigned to the placebo or cocktail group (n = 6/group). After farrowing, piglets were administered with either 0.5 mL of the placebo or the cocktail to each nostril. Health status and body weight were monitored at regular time points. Two piglets from three sows/treatment group were euthanised at 24 h, 96 h and 14 d after birth, and conchae, lung and tonsil samples were collected for histopathological and gene expression analysis. Health scores were improved in the cocktail group between d1-5. Body weight and daily gains did not differ between groups. Both groups displayed histological indications of euthanasia and inflammation in the lungs, signifying the findings were not treatment related. The expression of pBD2, TLR9 and IL-1β in the nasal conchae differed between groups, indicating the cocktail has the potential to modulate immune responses. In summary, the L. lactis cocktail was well tolerated by piglets and there was no negative impact on health scores, growth or lung histopathology indicating that it is safe for administration to new-born piglets.

Isolation of ST398 methicillin-resistant Staphylococcus aureus from pigs at abattoirs in Tohoku region, Japan.

Here, we investigated the presence of ST398 livestock-associated methicillin-resistant Staphylococcus aureus (LA-MRSA) in nasal swabs of 420 slaughtered pigs from 84 farms at three abattoirs in Tohoku, Japan. MRSA were isolated from 13 (3.1%) samples from 9 (10.7%) farms at two abattoirs. All isolates were classified as ST398 and were resistant to ampicillin and tetracycline. Ten and three isolates were classified as Staphylococcal Cassette Chromosome mec (SCCmec) types V and IVa, respectively. All type V isolates possessed czrC. The minimum inhibitory concentrations (MICs) of zinc chloride against types IVa and V were 1 and 4 mM, respectively. This study shows the presence of ST398 MRSA in pigs in this region. Antimicrobials and zinc compounds in feed and drugs might select SCCmec type V ST398 MRSA.

MRSA in Pigs and the Environment as a Risk for Employees in Pig-Dense Areas of Sri Lanka

Livestock-associated methicillin-resistant Staphylococcus aureus (LA-MRSA) is widely spread in intensive farming systems and considered an occupational risk for humans. MRSA is a common nosocomial pathogen in Sri Lanka, but information about prevalence of MRSA in pig farming in Sri Lanka is scarce. Farming is largely a small-scale confined system, and antimicrobial use in these systems is poorly regulated with no veterinary oversight for use. This study identified on 100 pig farms a MRSA prevalence of 10%, with MRSA-positive samples in pigs, farm workers, and dust of 1.2% (6/493), 2.2% (5/228), and 0.8% (1/119), respectively. The genotypes of these strains were compared with 22 human MRSA strains from a hospital; identified in pig farms were CC1/ST1/t127, CC5/ST5/t002, CC6/ST6/t304, or t4403, singleton ST3841/t10744, of which CC1/ST1/t127 and CC/ST5/t002 were present both in isolates from pigs and humans, suggesting a human origin. LA-MRSA types associated with intensive farming (ST398, ST9) were not detected. The low MRSA prevalence at farm level (10% vs. up to 70% in intensive farming systems) might be due to the management of these farms—open air and low dust. We conclude that in Sri Lanka the occupational risk for MRSA acquisition of people working with pigs in the described management systems is negligible.

512 The challenge of Antimicrobial resistance on the animal-human-environment interface.

Antibiotic resistant microorganisms represent a challenge for livestock farming worldwide. In addition to the sometimes dramatic reduction of therapeutic options for treatment of diseased animals, the possible transmission of these pathogens to humans via animal food products is also a very important issue. While in the past there were usually specific, resistant pathogens, today there is increasing focus on commensal, resistant microorganisms, since these primarily harmless bacteria can transfer their resistance genes to pathogenic pathogens under antibiotic therapy. Currently, MRSA in pigs, ESBL-producing E. coli and MCR1-positive E. coli in pigs and poultry, as well as increasingly also carbapenem-resistant E. coli, are of special interest. The causes and ways for the emergence and spread of these resistant pathogens are different. Common to all these resistant pathogens is that they are often transmitted across different stages of production. In addition, only a few pathogens are usually required for a colonization of susceptible animals and a selection pressure by antibiotic treatment is not mandatory. In addition, factors for higher environmental tenacity and colonization ability also appear to be encoded on the resistance plasmids of the resistant bacteria, e.g. at ESBL-E. coli. The entry of these pathogens into the farms takes place via newly staked animals or through contaminated feed, infected rodents and flies or colonized employees. Once in the stable, these pathogens can persist for very long time and even intensive disinfection measures are often unsuccessful, since even very low numbers of pathogens can lead to a new infection. In addition, some disinfectants can also cause resistance themselves, including co-resistance to antibiotics. Finally, resistant microorganisms are emitted from the stables into the environment with the exhaust air and with litter and manure. There they pose a risk to wildlife, to local residents or for re-entrance into neighboring farms.

Experimental nasal colonization of piglets with methicillin-susceptible and methicillin-resistant Staphylococcus aureus

Methicillin-resistant Staphylococcus aureus sequence type (ST)398 is widely spread among livestock. People in contact with livestock have a higher risk of testing positive for MRSA. Several experimental settings have been described to study in vivo colonization of MRSA in pigs, each having its own limitations. The aim of this study was to develop a nose-colonization model in pigs to quantitatively study the colonization of MRSA and the co-colonization of MSSA and MRSA.Two experiments were performed: in the first experiment piglets received an intranasal inoculation with MRSA ST398, spa-type t011, and in the second experiment piglets received an intranasal inoculation with two MSSA strains (ST398, spa-type t011 and t034) and two MRSA strains (also ST398, spa-type t011 and t034) to investigate co-colonization. Colonization was quantitatively monitored for 2 weeks in both experiments.Nasal colonization was successfully established in all piglets with stable numbers of S. aureus between 104 and 106CFU. MSSA and MRSA were able to co-colonize.

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?The studies on MRSA in pigs that were identified by literature research were heterogeneous with respect to the risk factors investigated and the type of herds focused on. Therefore we decided to carry out a pooling analysis on herd level rather than a typical meta-analysis. Eligible herd data were identified based on the published literature and communication with the authors. The final data set covered 400 fattening pig herds from 10 different studies and 12 risk factors. The prevalence of MRSA in the 400 fattening pig herds was 53.5%.Data were analyzed using generalized estimating equations (GEE). The resulting multivariate model confirmed previously identified risk factors for MRSA in pig herds (herd size and herd type). It also identified further risk factors: group treatment of fattening pigs with antimicrobial drugs (OR=1.79) and housing fattening pig herds on at least partially slatted floors (OR=2.39) compared to plain floor. In contrast, according to the model, fattening pig herds on farms keeping other livestock along with pigs were less likely to harbor MRSA (OR=0.54).The results underline the benefits from a pooling analysis and cooperative re-evaluation of published data.

Interspecific Epidemiology of MRSA in Pig Farming

The populations of MRSA are classified in relation to their origin, distinguishing S. aureus Healthcare-Acquired aureus (HA), Community-Acquired (CA) and Livestock-Acquired (LA). For LA-MRSA livestock animals have an important epidemiological role. This has raised the suspicion that the intensive husbandry may be, for the frequency and intensity of use of antibacterial treatments, an elective field of clonal selection of antibiotic resistance. The presence of LA- MRSA in pig production is sure in many countries and the pig is considered a reservoir for transmission to humans and other animals. In fact, farmers and production workers have a higher rate of colonization than the rest of the population. This work reports the presence of MRSA in slaughter pigs (2.3% positivity of the tonsils), sows (10% positivity of nasal swabs) and veterinarians employed in pig production (25% of nasal carriers). Many of the isolates from pigs and man belong to the same genomic patterns.

Antibiotic resistance and genetic diversity in Staphylococcus aureus from slaughter pigs in Switzerland

Nasal carriage of Staphylococcus aureus was evaluated in pigs at slaughterhouse. The nasal cavities of 304 pigs from 54 herds were screened. Eighty-nine percent of the farms harbored pigs that were colonized with S. aureus. Among them, no MRSA were found, indicating a low prevalence. However, pigs were found to harbor S. aureus, which displayed resistance to penicillin (blaZ) (62.5%), tetracycline [tet(M)] (33.3%), streptomycin (strpS194) (27%), clindamycin [erm(B)] (4.1%), erythromycin [erm(B)] (4.1%), kanamycin (4.1%), chloramphenicol (catpC194) (2%) and gentamicin [aac(6')-Ie-aph(2')-Ia] (2%). The S. aureus isolates mainly belong to Ridom spa type t034 (31.3%), t208 (14.6%) and t899 (12.5%). These pig-associated spa types have not yet been detected in hospitalized human patients in Switzerland. Surveillance programs are now necessary at both inland and import levels to rapidly detect and suppress the emergence of MRSA in pigs in Switzerland.