A study we just published in the journal Veterinary Record Floras et al, 2010 described an MRSA outbreak in a dog breeding kennel. That's a little unusual in itself, but considering how MRSA is spreading amongst the dog population, it's not really astounding. What was unique about this outbreak was the strain that was involved, sequence type 398 ST398.ST398 MRSA is commonly referred to as livestock-associated MRSA, since this strain seems to have originated in pigs, and is commonly found in pigs and calves in some regions. It can also infect people, and high rates of carriage of this MRSA strain can be found in pig farmers, pig vets and other people with close contact with livestock. In some areas of Europe, this strain is a big problem, accounting for a large percentage of human infections. Interestingly, it seems to be a rare cause of illness in people in North America at least at the moment.
via Livestock-associated MRSA in dogs : Worms and Germs Blog.
A third of the farmers carried MRSA, and in all but four cases the strain was identified as ST398, say the researchers. Statistical analysis revealed “strong associations” between MRSA carriage and the time workers spent in contact with the animals as well as specific farming tasks, such as feeding the calves and giving them veterinary care.
Overall, almost 16% of the study participants, who lived and worked on veal calf farms, carried MRSA. By comparison, the prevalence of MRSA in the Dutch community is estimated to be 1%.
The prevalence of MRSA among the calves was almost double that of the people studied, with 28% of the 2150 calves tested found to be carrying the bug. Almost all these bacteria were of the ST398 strain, and MRSA was more often found in calves that had been treated with antibiotics.
“This is the strongest evidence of a direct relationship between antibiotic use in animals and transfer of antimicrobial resistant organisms to humans at present,” write Graveland and colleagues.
via News.
To determine the prevalence of LA-MRSA in the general population in Canada, Golding and colleagues analysed 3687 MRSA isolates collected in Saskatchewan and Manitoba between 2007 and 2008. The sample represented about 66% of all MRSA samples collected in Saskatchewan and 17% of those collected in Manitoba during this period, both provinces with a low density of pig farming. The researchers found five isolates with genes characteristic of LA-MRSA, four of which were associated with cases of skin and soft-tissue infection. One of the isolates came from a post-operative infection in a patient who was unlikely to have had any contact with livestock, according to the authors.
via News.
Livestock has recently been identified as a new reservoir of methicillin-resistant Staphylococcus aureus MRSA. Most isolates belong to ST398 and are non-typeable with PFGE using SmaI, making it difficult to study transmission and outbreaks.Therefore, a new PFGE using Cfr9I, an neoschizomer of SmaI was optimized and evaluated to investigate ST398 isolates.Results: After optimizing and evaluating the Cfr9I PFGE, clear and reproducible banding patterns were obtained from all previously non-typeable MRSA NTSmaI -MRSA isolates. The PFGE patterns of ST398 isolates showed more diversity than with spa-typing and/or MLST.The PFGE results showed diversity within and between the two most prevalent spa-types of NTSmaI -MRSA t011 and t108. No match was found, when comparing banding patterns of the NTSmaI -MRSA with 700 different PFGE types, obtained with SmaI digestion, in our database of more than 4000 strains.Furthermore, possible transmission among veterinarians and their family members was investigated and an outbreak of ST398 MRSA in a residential care facility was confirmed with the Cfr9I PFGE.
via PFGE diversity within the methicillin-resistant Staphylococcus aureus clonal lineage ST398 – 7thSpace Interactive.
In the Netherlands, MRSA ST398 has emerged in hospitals and human carriers have been associated with exposure to pigs and cattle, explain van Giessen and co-authors. They add that high prevalence 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 to 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 three brown rats (Rattus norvegicus) were collected from 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, conclude van de Giessen and co-authors.
via Holland – Rats are a plague to pig farmers.
There is a concern that the numbers of MRSA or other antimicrobial-resistant bacteria might increase further when human isolates become established in animals, as this can amplify the numbers of such bacteria by dissemination within animal groups with subsequent spread back to humans. Certain antimicrobials have been implicated in the selection of MRSA, ESBL-producing bacteria and predisposition to infection by C. difficile. Guidelines for treatment and prevention of infections by MRSA, ESBL-producing bacteria and C. difficile were discussed and evidence-based policies were recommended for both humans and animals.
via Antimicrobial-resistant pathogens in animals and man: prescribing, practices and policies « InfectoNews – Jorge Omar Calabrese.
Writing in Clinical Microbiology and Infection, Dr. Jan Kluytmans of Amphia Hospital in Breda, the Netherlands, recounts the identification of MRSA multilocus sequence type 398 (or ST398). On Dutch farms, from 23% to 81% of pigs have been found colonized with the strain, carrying it without being made sick by it. When farmers on those farms were surveyed, they were colonized with an identical strain.
ST398 appears to be less virulent and less transmissible than the community-associated strains of MRSA common in the United States, which have very low prevalence in the Netherlands. “The impact of ST398 on [human] public health may be limited,” Kluytmans writes, “but close monitoring of its evolution over time will be required.”
The strain’s presence in meat after slaughter—it has been found in beef, lamb, and chicken and other birds in addition to pork—raises uncertainties over the degree of its movement into the food chain. While staph species are known to cause staphylococcal food poisoning, MRSA ST398 to date lacks the toxin-producing genes that would produce similar illness.
The chief concern, Kluytmans writes, is the possibility that people preparing MRSA-contaminated meat for cooking will become colonized with the organism on their skin or mucous membranes, moving it into a broad new ecological niche and positioning it as a possible cause of further human infections.
via CIDRAP >> MRSA clone in food animals worrisome, expert says.
MRSA has been found in pigs in 17 of 24 EU member states – but not the UK, according to the first Europe-wide survey of the bacteria.
The highest level of MRSA positives was in Spain, in 51 per cent of breeding pig herds, followed by Germany, Belgium and Italy, research published by the European Food Safety Authority EFSA showed.
Despite the failure to find the ‘superbug’ in Britain, the Soil Association is calling for improved testing claiming it could ‘easily have been missed due to a poor testing method which had not been checked before the survey began’.
via Fears over rising MRSA levels in EU pigs | News | Farmers Guardian.
The survey was carried out in 24 Member States, 17 of which found some type of MRSA in their holdings with breeding pigs and 7 none at all. On average, different types of MRSA were found in 1 out of 4 holdings with breeding pigs across the EU, but the survey also says that figures vary greatly between Member States. MRSA ST398 was the most reported type of MRSA among the holdings with breeding pigs in the EU; some Member States also reported other types, but their prevalence was much lower.
MRSA is a major concern for public health and its various types are recognised as an important cause of hospital-acquired (or nosocomial) infections in humans. The specific type MRSA ST398 has been identified in some domestic animals and is considered an occupational health risk for farmers, veterinarians and their families, who may become exposed to it through direct or indirect contact with these animals.
In an opinion published earlier this year, EFSA’s Biological Hazards (BIOHAZ) Panel assessed the public health significance of MRSA in animals and food and concluded that the MRSA ST398 strain is less likely to contribute to the spread of MRSA in hospitals than other types carried by humans. The Panel also said that there is currently no evidence that MRSA ST398 can be transmitted to humans by eating or handling contaminated food.
More Here
