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MRSA ST398 PRESENT IN MIDWESTERN US SWINE AND SWINE WORKERS

flounder

Well-known member
Methicillin-Resistant Staphylococcus aureus (MRSA) Strain ST398 Is Present in Midwestern U.S. Swine and Swine Workers

Tara C. Smith1,2*, Michael J. Male1,2, Abby L. Harper1,2, Jennifer S. Kroeger3, Gregory P. Tinkler2, Erin D. Moritz1,2, Ana W. Capuano1,2, Loreen A. Herwaldt1,3,4, Daniel J. Diekema3,4,5

1 Department of Epidemiology, University of Iowa College of Public Health, Iowa City, Iowa, United States of America, 2 Center for Emerging Infectious Diseases, University of Iowa College of Public Health, Iowa City, Iowa, United States of America, 3 Department of Medicine, University of Iowa Carver College of Medicine, Iowa City, Iowa, United States of America, 4 Program of Hospital Epidemiology, University of Iowa Hospitals and Clinics, Iowa City, Iowa, United States of America, 5 Department of Pathology, University of Iowa Carver College of Medicine, Iowa City, Iowa, United States of America

Abstract Background Recent research has demonstrated that many swine and swine farmers in the Netherlands and Canada are colonized with MRSA. However, no studies to date have investigated carriage of MRSA among swine and swine farmers in the United States (U.S.).

Methods We sampled the nares of 299 swine and 20 workers from two different production systems in Iowa and Illinois, comprising approximately 87,000 live animals. MRSA isolates were typed by pulsed field gel electrophoresis (PFGE) using SmaI and EagI restriction enzymes, and by multi locus sequence typing (MLST). PCR was used to determine SCCmec type and presence of the pvl gene.

Results In this pilot study, overall MRSA prevalence in swine was 49% (147/299) and 45% (9/20) in workers. The prevalence of MRSA carriage among production system A's swine varied by age, ranging from 36% (11/30) in adult swine to 100% (60/60) of animals aged 9 and 12 weeks. The prevalence among production system A's workers was 64% (9/14). MRSA was not isolated from production system B's swine or workers. Isolates examined were not typeable by PFGE when SmaI was used, but digestion with EagI revealed that the isolates were clonal and were not related to common human types in Iowa (USA100, USA300, and USA400). MLST documented that the isolates were ST398.

Conclusions These results show that colonization of swine by MRSA was very common on one swine production system in the midwestern U.S., suggesting that agricultural animals could become an important reservoir for this bacterium. MRSA strain ST398 was the only strain documented on this farm. Further studies are examining carriage rates on additional farms.

Citation: Smith TC, Male MJ, Harper AL, Kroeger JS, Tinkler GP, et al. (2008) Methicillin-Resistant Staphylococcus aureus (MRSA) Strain ST398 Is Present in Midwestern U.S. Swine and Swine Workers. PLoS ONE 4(1): e4258. doi:10.1371/journal.pone.0004258

Editor: Ulrich Dobrindt, University of Würzburg, Germany

Received: October 9, 2008; Accepted: December 19, 2008; Published: January 23, 2008

Copyright: © 2009 Smith et al. This is an open-access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.

Funding: This study was funded with departmental startup funds (TCS). The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.

Competing interests: The authors have declared that no competing interests exist.

* E-mail: [email protected]

Introduction ...snip...end

see full text ;


http://www.plosone.org/article/info%3Adoi%2F10.1371%2Fjournal.pone.0004258


http://staphmrsa.blogspot.com/2009/01/methicillin-resistant-staphylococcus.html


MRSA

http://staphmrsa.blogspot.com/


TSS
 

PORKER

Well-known member
Our findings pose a warning to public health surveillance: if the ST398 MSSA virulence toward humans would be maintained within the ST398 MRSA lineage from pigs, care should be taken not to introduce this strain into humans. We consider it to be likely that ST398 MRSA from pigs is capable of causing serious infection in humans even though its primary host seems to be pigs.

Dr van Belkum is with the Department of Medical Microbiology and Infectious Diseases, University Medical Center Rotterdam, Rotterdam, the Netherlands. His research interests include MRSA.


Hope we can keep it out of cattle.
 

Tex

Well-known member
PORKER said:
Our findings pose a warning to public health surveillance: if the ST398 MSSA virulence toward humans would be maintained within the ST398 MRSA lineage from pigs, care should be taken not to introduce this strain into humans. We consider it to be likely that ST398 MRSA from pigs is capable of causing serious infection in humans even though its primary host seems to be pigs.

Dr van Belkum is with the Department of Medical Microbiology and Infectious Diseases, University Medical Center Rotterdam, Rotterdam, the Netherlands. His research interests include MRSA.


Hope we can keep it out of cattle.

As I understand it, pigs are closer related to humans as far as disease transfer goes. These "super bugs" are showing up in part because we are allowing antibiotics to be used in livestock without assessing the risks and long term costs. We are just looking at the marginal money that is saved by using drugs and antibiotics when we put animals in such high confinement that causes the stress that doesn't allow them to overcome infections naturally.

Short term profits over long term thinking yet again. I wonder how much damage money in politics is doing to keep this system going.
 

PORKER

Well-known member
Tex, If this ST398 MRSA gets a big foot hold , Traceability then becomes the food safety issue of the 21st century.
 

mrj

Well-known member
While MRSA is a definite problem needing skillful handling and caution, along with research, it isn't all that rare and not necessarily a death threat.

I know a person who worked in a nursing home, and had been diagnosed with cancer tho was still working, who contracted MRSA which has been found in at least some who work in hospitals/nursing homes. She did recover tho cancer and other health problems still plague her.

mrj
 

Tex

Well-known member
mrj said:
While MRSA is a definite problem needing skillful handling and caution, along with research, it isn't all that rare and not necessarily a death threat.

I know a person who worked in a nursing home, and had been diagnosed with cancer tho was still working, who contracted MRSA which has been found in at least some who work in hospitals/nursing homes. She did recover tho cancer and other health problems still plague her.

mrj

MRJ, there are a lot of MRSA types, some worse than others. It is as if we have lost the first row of defense in the biological battle where the lines behind are not as fortified just to allow the meat producers to compete with each other. I am not sure it was worth the cost.

There was an article in a feed magazine that claimed the EU's experience with outlawing antibiotics was not negative as was touted by the industry.

I had a friend who had one of the MRSAs and had a visiting doctor not noticed what was happening, would have died. Almost did.
 

burnt

Well-known member
Tex said:
. . . . I am not sure it was worth the cost . . . .

History has a way of making some of the "smartest" look like complete fools. Today's wisdom has often proven to be tomorrow's folly. I cannot remember what the subject of the discussion was, but not too long ago our kids asked why we (meaning the previous generation) used to do some particular thing a certain way, or, for what reason. They saw it as redundant or very primitive, even harmful. I could only tell them that it was the best we knew at the time!

I think that as some of our "solutions" to negative life issues become more complex, so will the outcomes. We may end up saying "I am not sure it was worth the cost" many, many more times as the broader consequences of some of our wonderful follies unfold.
 

flounder

Well-known member
Press Release 24 November 2009


EFSA publishes results of the first survey on MRSA in pigs in the EU

The European Food Safety Authority (EFSA) has published the first EU-wide survey on MRSA (Methicillin-resistant Staphylococcus aureus) in breeding pigs. The results indicate that MRSA, a bacterium resistant to many antibiotics, is commonly detected in holdings with breeding pigs in some EU Member States. The survey provides estimates of its occurrence and makes recommendations for further monitoring and investigation of the causes and implications of MRSA findings in pig holdings in the EU. The survey was carried out in 24 Member States[1], 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[2].

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[3] and concluded that the MRSA ST398[4] 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.

In the survey published today, EFSA recommends monitoring of pigs and other food producing animals for MRSA. It also says further research should be carried out, so that the reasons for differences in the prevalence of MRSA in the various Member States can be identified and used to propose options on possible control measures.

_________________________________________ Note to editors:

The Staphylococcus aureus is a bacterium that can be persistently or intermittently carried by healthy humans and is a very common cause of minor skin infections that usually do not require treatment. In patients in hospitals, Staphylococcus aureus is a common cause of hospital-acquired infections. Its variant Methicillin-Resistant Staphylococcus aureus (MRSA) emerged in the 1970s and is now often found in hospitals in many European Member States. MRSA is resistant to many commonly used antibiotics. In recent years, clones of MRSA have evolved outside the hospitals, causing infections among people who have no connection with hospitals. Most recently MRSA has also been detected in several farm animal species.

EFSA’s Zoonoses Unit monitors and analyses the situation on zoonoses, zoonotic agents, antimicrobial resistance, microbiological contaminants and food-borne outbreaks across Europe. The Unit is supported by a Task Force on Zoonoses Data Collection consisting of a pan-European network of national representatives of Member States, other reporting countries, as well as World Health Organisation (WHO) and World organisation for animal health (OIE). They gather each year data in their respective countries.

EFSA’s BIOHAZ Panel provides scientific advice on biological hazards in relation to food safety and food-borne diseases. This covers food-borne zoonoses (animal diseases transmissible to humans), Transmissible spongiform Encephalopathies (BSE/TSEs), food microbiology, food hygiene and associated waste management issues. The Panel’s risk assessment work helps to provide a sound foundation for European policies and legislation and supports risk managers in taking effective and timely decisions.

Analysis of the baseline survey on the prevalence of methicillin-resistant Staphylococcus aureus (MRSA) in holdings with breeding pigs, in the EU, 2008 [1] - Part A: MRSA prevalence estimates

EFSA’s previous work on MRSA:

EFSA’s BIOHAZ Panel “Assessment of the Public Health significance of Methicillin-resistant Staphylococcus aureus (MRSA) in animals and foods” Joint scientific report of ECDC, EFSA and EMEA on Methicillin-resistant Staphylococcus aureus (MRSA) in livestock, companion animals and food

Joint Opinion of ECDC, EFSA, EMEA and SCENIHR on antimicrobial resistance (AMR) focused on zoonotic infections

--------------------------------------------------------------------------------

[1] The sampling took place during 2008. Dust samples were taken in the environment of pigs in a total of 5,073 holdings from 24 EU Member States and two non-Member States. The pooled sample of each holding was tested for the presence of the various MRSA strains. [2] Only six Member States and one non-Member State reported MRSA non-ST398 in the holdings with breeding pigs. The prevalence of MRSA non-ST398 in holdings with breeding pigs across the participating Member States was substantially lower than the prevalence of MRSA and MRSA ST398. [3] EFSA’s BIOHAZ Panel opinion on the “Assessment of the Public Health significance of Methicillin-resistant Staphylococcus aureus (MRSA) in animals and foods” of March 2009 [4] In its opinion the BIOHAZ Panel refers to CC398 which corresponds to MRSA ST398.


http://www.efsa.europa.eu/EFSA/efsa_locale-1178620753812_1211903070258.htm


http://staphmrsa.blogspot.com/


TSS


Tuesday, December 1, 2009


EFSA publishes results of the first survey on MRSA in pigs in the EU


http://staphmrsa.blogspot.com/2009/12/efsa-publishes-results-of-first-survey.html
 

MoGal

Well-known member
I find this all interesting........... first there was a anasplasmosis thread on cattle today, then Texan's microplasma thread, then Milkmaid's thread on the neuropathic calf on CT, then a brucellosis thread on Ct...... now MRSA here. The hubby is rarely sick but he's had MRSA twice this year and the 2nd time he was hospitalized.....

Microplasma was patented by the US during WWII as a biological warfare weapon and there are now over 200 types. Microplasmas can be aerobic or anaerobic (I personally wonder if this is the same as gram positive or gram negative and you would have to know which type it is to get the right antibiotic.) Brucella is a similar bacteria as microplasma. Its hard telling about MM's neuro calf unless they did a necropsy.... maybe it was a reaction to vaccines, do they use chicken poultry litter/mushroom compost as fertilizer (as many use arsenic and in a chicken it passes through and is spread on the soil by the farmer), perhaps it was a virus/bacteria which caused the neuropathy........

A couple of years ago, I started reading up about chemtrails and HAARP. If you have never searched weather modification, chemtrails and bacteria, Haarp........... etc..... then there's a boatload of info on the net. Our government has controlled the weather for quite some time..... I saw the article on yahoo news a few weeks ago (I still have the link, but the article has been removed and you have to search for it) but China made it snow in Beijing.......... not to be outdone by China we just recently a few weeks ago had snow in places that haven't had snow. Bacteria and virus are added to chemtrails to test areas for contamination.

Since the microplasma thread for the last month or so I've been searching for state or federal laws which ban or prohibit the Dept. of Defense, NASA, NSA or Homeland Security from using biological warfare weapons on the American people, the environment, plants or animals............. and guess what? I can't find any laws which prohibit them from using us as guinea pigs.

If someone has any info out there to the contrary, please let me know.

Start putting it together.......... the USDA wants NAIS so they can comply with OIE standards........

Laugh if you want, but I think we'll have a disease break out within the next 18 months on our cattle ( could also be pigs, goats, sheep, etc) so they can implement NAIS......... and no one will be looking at our own government as the culprit through chemtrails. No one will think to test their snow, or rainwater for virus and bacteria.........
Don't you find it odd that these sick calves followed behind some serious rainfall???

Get your mineral program up to snuff. Get your soil tested for your pastures and get the trace minerals up to snuff. Virus and bacteria cannot live in an alkaline environment and you need a balanced ph in your soil as well as in your cow.
 

PORKER

Well-known member
mrj , check this out!

OSLO, Norway -- Aker University Hospital is a dingy place to heal. The
floors are streaked and scratched. A light layer of dust coats the blood
pressure monitors. A faint stench of urine and bleach wafts from a pile
of soiled bedsheets dropped in a corner.

Look closer, however, at a microscopic level, and this place is
pristine. There is no sign of a dangerous and contagious staph infection
that killed tens of thousands of patients in the most sophisticated
hospitals of Europe, North America and Asia last year, soaring virtually
unchecked.

The reason: Norwegians stopped taking so many drugs.

Twenty-five years ago, Norwegians were also losing their lives to this
bacteria. But Norway's public health system fought back with an
aggressive program that made it the most infection-free country in the
world. A key part of that program was cutting back severely on the use
of antibiotics.

Now a spate of new studies from around the world prove that Norway's
model can be replicated with extraordinary success, and public health
experts are saying these deaths -- 19,000 in the U.S. each year alone,
more than from AIDS -- are unnecessary.

``It's a very sad situation that in some places so many are dying from
this, because we have shown here in Norway that Methicillin-resistant
Staphylococcus aureus [MRSA] can be controlled, and with not too much
effort,'' said Jan Hendrik-Binder, Oslo's MRSA medical advisor. ``But
you have to take it seriously, you have to give it attention and you
must not give up.''

The World Health Organization says antibiotic resistance is one of the
leading public health threats on the planet. A six-month investigation
by The Associated Press found overuse and misuse of medicines has led to
mutations in once curable diseases like tuberculosis and malaria, making
them harder and in some cases impossible to treat.

Now, in Norway's simple solution, there's a glimmer of hope.

ANTIBIOTICS MISSING

Dr. John Birger Haug shuffles down Aker's scuffed corridors, patting the
pocket of his baggy white scrubs. ``My bible,'' the infectious disease
specialist says, pulling out a little red Antibiotic Guide that details
this country's impressive MRSA solution.

It's what's missing from this book -- an array of antibiotics -- that
makes it so remarkable.

``There are times I must show these golden rules to our doctors and tell
them they cannot prescribe something, but our patients do not suffer
more and our nation, as a result, is mostly infection free,'' he says.

Norway's model is surprisingly straightforward.

• Norwegian doctors prescribe fewer antibiotics than any other country,
so people do not have a chance to develop resistance to them.

• Patients with MRSA are isolated and medical staff who test positive
stay home.

• Doctors track each case of MRSA by its individual strain, interviewing
patients about where they've been and who they've been with, testing
anyone who has been in contact with them.

``We don't throw antibiotics at every person with a fever,'' says Haug.
``We tell them to hang on, wait and see, and we give them a Tylenol to
feel better.''

U.S. REACTION

Dr. John Jernigan at the U.S. Centers for Disease Control and Prevention
said they incorporate some of Norway's solutions in varying degrees, and
his agency ``requires hospitals to move the needle, to show improvement,
and if they don't show improvement they need to do more.''

And if they don't?

``Nobody is accountable to our recommendations,'' he said, ``but I
assume hospitals and institutions are interested in doing the right
thing.''

Around the world, various medical providers have successfully adapted
Norway's program with encouraging results. A medical center in Billings,
Mont., cut MRSA infections by 89 percent by increasing screening,
isolating patients and making all staff -- not just doctors --
responsible for increasing hygiene.

In 2001, the CDC approached a Veterans Affairs hospital in Pittsburgh
about conducting a small test program. It started in one unit, and
within four years, the entire hospital was screening everyone who came
through the door for MRSA. The result: an 80 percent decrease in MRSA
infections.

The program has now been expanded to all 153 VA hospitals, resulting in
a 50 percent drop in MRSA bloodstream infections, said Dr. Robert Muder,
chief of infectious diseases at the VA Pittsburgh Healthcare System.

``It's kind of a no-brainer,'' he said. ``You save people pain, you save
people the work of taking care of them, you save money, you save lives
and you can export what you learn to other hospital-acquired
infections.''

``So, how do you pay for it?'' Muder asked. ``Well, we just don't pay
for MRSA infections, that's all.''
 

mrj

Well-known member
Yes, PORKER, it is interesting.

I also just heard a report from CDC on radio this morning stating that of over 10,000 cases of MRSA infections investigated there has not been evidence of contracting it from livestock.

Some reports have, however, indicated it appears that animals, pigs, I believe, likely contracted it from humans.

Obviously, we have long had a problem with patients demanding, and some doctors too eagerly prescribing, antibiotics for illness and problems which will not be helped by antibiotics.

THAT is where I believe the problem with over use of antibiotics really is.

How many patients actually pay for those antibiotics they demand? Whether Medicaid, insurance, or 'other', there are few people truly paying their own medical costs, or even their own insurance premiums.

On the other hand, it is unlikely there are ANY farmer/rancher types who do NOT pay for the antibiotics they use for animals, making it far less likely they will use animal antibiotics indiscriminately, IMO.

mrj
 

PORKER

Well-known member
Flounder dug this up!

Staphylococcus aureus is one of the most common and devastating human pathogens [1]. Though approximately a third of the population is colonized with S. aureus [2,3], colonization by strains of S. aureus that are resistant to methicillin (methicillin-resistant S. aureus, MRSA) is less common. A recent publication estimated that 1.5% of the United States (U.S.) population (,4.1 million persons) is colonized with MRSA [4]. Klevens et al. recently showed that deaths from MRSA infections in the U.S. have eclipsed those from many other infectious diseases, including HIV/AIDS. On the basis of data from several major metropolitan areas in the U.S., these investigators estimated that MRSA caused 94,000 infections and over 18,000 deaths in the U.S. in 2005 [5].

Moreover, MRSA has been found in a variety of animals, including horses [6,7], cattle [8], dogs, cats [9], and swine [10,11,12]. Voss et al. reported that the prevalence of MRSA among pig farmers was >760 times higher than that among patients admitted to Dutch hospitals [13]. Multi locus sequence typing (MLST) suggested that these MRSA isolates belonged to sequence type 398 (ST398), and had been transmitted from pigs to pig farmers, among pig farmers and their family members, and from the colonized son of a swine veterinarian to a hospital nurse. A subsequent study found that 4.6% of veterinarians and veterinary students were colonized with MRSA compared with a population-based estimate of 1% [14].
Additional studies in swine have shown that isolates obtained from swine and their human caretakers are frequently indistinguishable, suggesting transmission between the two animal species [11,12]. Indeed, investigations in the Netherlands demonstrated that ST398 now accounts for 20% of all MRSA detected in that country, documenting the importance of considering livestock and PLoS ONE | www.plosone.org 1 January 2009 | Volume 4 | Issue 1 | e4258 other animals when examining the epidemiology of MRSA [15]. However, despite research examining swine-associated MRSA in the Netherlands and Canada [10,12], currently the prevalence of MRSA in swine or their caretakers is unknown in the U.S. In a rural state such as Iowa, which produces 25% of the swine raised in the U.S., transmission of MRSA on swine farms or in veterinary facilities could complicate efforts to reduce MRSA transmission statewide and beyond. Therefore, we conducted a pilot culture survey to examine the prevalence of MRSA in swine and swine workers in two swine farming production systems in Iowa and Illinois.
 

flounder

Well-known member
DOI: 10.3201/eid1604.091435

Suggested citation for this article: Golding GR, Bryden L, Levett PN, McDonald RR, Wong A, Wylie J, et al.

Livestock-associated methicillin-resistant Staphylococcus aureus sequence type 398 in humans, Canada.

Emerg Infect Dis; [Epub ahead of print]


Livestock-associated Methicillin-Resistant Staphylococcus aureus Sequence Type 398 in Humans, Canada

George R. Golding, Louis Bryden, Paul N. Levett, Ryan R. McDonald, Alice Wong, John Wylie, Morag R. Graham, Shaun Tyler, Gary Van Domselaar, Andrew E. Simor, Denise Gravel, and Michael R. Mulvey
Author affiliations: National Microbiology Laboratory, Winnipeg, Manitoba, Canada (G.R. Golding, L. Bryden, M.R. Graham, S. Tyler, G. Van Domselaar, M.R. Mulvey); Saskatchewan Disease Control Laboratory, Regina, Saskatchewan, Canada (P.N. Levett, R.R. McDonald); Royal University Hospital, Saskatoon, Saskatchewan, Canada (A. Wong); Cadham Provincial Laboratories, Winnipeg (J. Wylie); Sunnybrook Health Sciences Centre, Toronto, Ontario, Canada (A.E. Simor); and Public Health Agency of Canada, Ottawa, Ontario, Canada (D. Gravel)

Rates of colonization with livestock-associated methicillin-resistant Staphylococcus aureus (MRSA) sequence type 398 have been high for pigs and pig farmers in Canada, but prevalence rates for the general human population are unknown. In this study, 5 LA-MRSA isolates, 4 of which were obtained from skin and soft tissue infections, were identified from 3,687 tested MRSA isolates from persons in Manitoba and Saskatchewan, Canada. Further molecular characterization determined that these isolates all contained staphylococcal cassette chromosome (SCC) mecV, were negative for Panton-Valentine leukocidin, and were closely related by macrorestriction analysis with the restriction enzyme Cfr91. The complete DNA sequence of the SCCmec region from the isolate showed a novel subtype of SCCmecV harboring clustered regularly interspaced short palindromic repeats and associated genes. Although prevalence of livestock-associated MRSA seems to be low for the general population in Canada, recent emergence of infections resulting from this strain is of public health concern.

High prevalence of colonization with livestock-associated (LA) methicillin-resistant Staphylococcus aureus (MRSA) sequence type (ST) 398 among pigs and pig farmers was first

Page 1 of 16

reported in the Netherlands (1) and has since been identified in Canada (2) and the United States (3). In Canada, this LA-MRSA strain was identified in pigs and pig farmers in southwestern Ontario, where prevalence of MRSA colonization was 24.9% (71/285) and 20% (5/25), respectively (2). In the United States, nasal samples from 20 production system workers and 299 swine from 2 farms in Illinois and Iowa showed that 45% (9/20) and 49% (147/299), respectively, were colonized with LA-MRSA (3). Despite such high prevalence of MRSA colonization on these tested farms, to our knowledge, no human or animal infections resulting from LA-MRSA strains have been reported in North America.
To determine whether LA-MRSA has recently emerged in the general population of Canada, we identified human infections and colonizations associated with the LA-MRSA strain in Canada and molecularly characterized the isolates. We also identified a novel staphylococcal cassette chromosome (SCC) mecV subtype harboring clustered regularly interspaced short palindromic repeats (CRISPR) and CRISPR-associated genes (cas).

SNIP...


Discussion

The high prevalence of LA-MRSA colonization of pigs and pig farmers in Canada (2) and the United States (3) and this report of human infections suggest that this LA-MRSA strain from Canada poses potential public and occupational health concern in North America. This strain has been associated with various types of infections in pigs (17,18) and humans (19,20) and is transmissible from animal patients to veterinary workers (21), healthcare workers (22), and family members (1). Evidence also suggests that this strain might be spreading from animals to the environment, which may facilitate the colonization or infection of persons who are not involved in animal husbandry (23). Whereas in 2006 in the Netherlands LA-MRSA accounted for >20% of all MRSA isolated (24), carriage of this strain in the general population of 2 provinces in Canada (Manitoba and Saskatchewan) appears rare (0.14%). This difference could be attributed to the substantially higher density of pigs in the Netherlands (1,244 pigs/km2) than in Manitoba (55 pigs/km2), Saskatchewan (6 pigs/km2), and Ontario (91 pigs/km2) (www.agriculture.gov.sk.ca/Pig_Densities). It is also plausible that the much lower proportions of LA-MRSA in Canada, relative to a country with low MRSA endemicity such as the Netherlands, is attributable to competition with other highly successful human epidemic MRSA clones circulating in Canada, including CMRSA2 (USA200/800), CMRSA7 (USA400), and CMRSA10 (USA300) (25,26).
The tested LA-MRSA isolates were highly susceptible to most classes of antimicrobial drugs, except β-lactams and tetracyclines, the latter of which has been attributed to its high usage in animal husbandry (27). The complete sequence of the SCCmec region showed a novel SCCmecV subtype sharing sequence identity in its J1 and J3 regions with chromosomal genes in the S. epidermidis RP62A chromosome (GenBank accession no. CP000029), including a

Page 6 of 16

CRISPR system. CRISPRs and associated cas genes are present in many other bacterial (≈40%) and archaeal (≈90%) genomes (28,29) and have been shown to be involved in sequence-directed immunity against phages (30,31) and plasmids (32). The resistance to plasmids and phages encoded by this system could explain why many of these ST398-MRSA-V strains contain fewer antimicrobial drug resistance genes and phage-encoded virulence factors than do other epidemic MRSA strains (33,34). The origin of this CRISPR system is unknown, but the propagation of CRISPR loci throughout prokaryote genomes has been proposed to occur through horizontal gene transfer by conjugation of megaplasmids >40 kb (35). Because the CRISPR system identified in this study is encoded within a putative mobile genetic element, we propose that an additional mechanism of mobilization to other methicillin-susceptible Staphylococcus spp. is plausible.

This novel subtype of SCCmecV was found in only 4 of the 6 LA-MRSA isolates identified in this study. One isolate not containing this novel SCCmec subtype (08 BA 08100) could also be distinguished by a different but closely related spa type (t1250) (Table 1) and variant PFGE fingerprint (Figure 2) when compared with the other LA-MRSA isolates, which suggests that at least 2 epidemiologically different strains of LA-MRSA circulate in Saskatchewan. The other LA-MRSA isolate that did not contain this novel SCCmec element was obtained in Ontario. However, this isolate was the same spa type (t034) and was closely related, according to PFGE, to the LA-MRSA isolates identified in Saskatchewan. Therefore, in addition to PFGE and spa typing, SCCmec subtyping could provide a useful epidemiologic tool for surveillance, outbreak investigations, or traceability studies of this emerging strain. For detection of this SCCmecV subtype (tentatively designated V.2.1.2; Vb), we propose using primer set 1 (spanning orfX into Sk02 in the J3 region) and primer set 7 (spanning Sk20 into cas1 in the J1 region) (Table 4).

Visual comparison of PFGE fingerprints from this study with those reported from patients from the Dominican Republic and the United States (northern Manhattan, New York, NY) (36), showed substantial variations in fingerprint patterns, as well as related but different spa types. These variations suggest further molecular and geographic diversity of these LA-MRSA strains on a global scale.

Page 7 of 16

Because cases of LA-MRSA infections have only recently been identified in Canada, additional surveillance efforts are required to monitor the emergence and clinical relevance of this MRSA strain in Canada, including communities, the environment, livestock, farmers, and production facility workers. Whether these strains pose a major threat to human health in light of the low livestock density and continued spread of epidemic hospital and community strains of MRSA in Canada remains unknown.

http://www.cdc.gov/eid/content/16/4/pdfs/09-1435.pdf


TSS
 

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