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Can the Human Race stay Healthy

PORKER

Well-known member
From insects to man: identification of virulence factors involved in the adaptation of the emerging pathogen Photorhabdus asymbiotica to human hosts

Abstract number: 1733_565

Forquin M., Esque J., Pimenta A.

http://images.google.com/images?hl=en&q=Photorhabdus&um=1&ie=UTF-8&ei=8f9wSt3gDMSHtgfX7qSKDA&sa=X&oi=image_result_group&ct=title&resnum=4

Photorhabdus are entomopathogenic bacteria currently used for the biological control of crop pests. Recently, an increasing number of Photorhabdus strains have been isolated from human clinical specimens, associated with locally invasive soft tissue infections and disseminated bacteraemia.

Objectives: In view of their growing use in biological control, which increases the human potential rate of exposure to these pathogens, we undertook a comparative study between insect and human pathogenic strains of Photorhabdus, in an attempt to understand the genetic mechanisms involved in their recently acquired capacity to infect humans.

Methods: Three Photorhabdus strains, two human (P. asymbiotica SN and ATCC43949) and one insect pathogen (Photorhabdus sp Q617), were tested for their ability to bind to two major components of the human extracellular matrix (ECM), fibronectin (Fn) and vitronectin (Vn), to infect or invade human epithelial cells in culture, and to interact with the cellular cytoskeleton.

Adherence, infection and invasion experiments were performed in 96-well microtiter plates coated either with Fn, Vn or with monolayers of human epithelial HaCaT cells. Bacterial invasion was quantified by the gentamicin survival assay. In inhibition assays, anti-Fn, anti-Vn antibodies, or genistein were added to epithelial cell monolayers. For immunofluorescence, HaCaT monolayers on glass coverslips were infected and labelled with phalloidine-TRITC and DAPI.

Results: Only P. asymbiotica human pathogenic isolates ATCC43949 and SN were able to adhere to human fibronectin and/or vitronectin, and to infect/invade HaCaT cells. This was inhibited in the presence of antibodies against human Fn or Vn. Only strain ATCC43949 induced cytotoxic effects after 6h co-culture with human cells. Cytoskeleton involvement in the P. asymbiotica infective process was indicated by blockage of infection and invasion by genistein, and by immunofluorescence analysis of infected cells.

Conclusion: The acquisition of virulence factors enabling P. asymbiotica to interact with human ECM and to human cells is a key factor in its evolution towards the colonisation of human hosts. ECM proteins are involved in the primary events during P. asymbiotica colonisation of human epithelial tissues, and the host cytoskeleton is solicited during the P. asymbiotica-epithelial cells interaction. Possible mechanisms used by P. asymbiotica to colonise human tissues are discussed.


Time: 00:00-00:00
Session name: European Society of Clinical Microbiology and Infectious Diseases
Subject:
Location: ICC, Munich, Germany
 

PORKER

Well-known member
Silbergeld, now a professor of environmental health sciences at the Bloomberg School of Public Health, is one of several researchers at Johns Hopkins and around the world assembling evidence that the industrial farming of chickens, pigs, and cattle is cultivating more than poultry and livestock — it's cultivating bacteria that medicine is losing the ability to fight. Antimicrobial drugs, including antibiotics like penicillin, ciprofloxacin, and methicillin, kill pathogenic bacteria.


http://baltimorechronicle.com/2009/080309Keiger.shtml



and MRSA is in food animals, tests find drug-resistant bacteria in store-bought pork | KVAL CBS 13 - News, Weather and Sports - Eugene, OR - Eugene, Oregon | Local & Regional News.
The scientists followed standard testing protocols and found MRSA in three different samples; all were ground pork. The positive samples were from purchases made in Oregon, California and Idaho -- three of the four states where we tested. "The interesting situation here," said Samadpour, "is that now we have something that you would worry about in terms of wound infections in foods." Like most other bacteria, MRSA will die if it's thoroughly cooked. But unlike E. coli or salmonella, MRSA causes skin infections, so just touching raw pork that has the bacteria could be a problem, according to both Samadpour and Goldburg. "So that raises the possibility," says Goldburg, "that simply handling meat could potentially give you a very nasty infection." Canada and several European countries already test pork in grocery stores for MRSA. We contacted the USDA and were told they have no plans for any testing. "It really disturbs me," said Boutte. "We have enough things out there that we can catch, we don't need any help from other sources, and if the government is not going to be able to step up and help us out - what's the point?" The National Pork Board just began testing pork in retail markets. Their study won't be finished for another six months, but their preliminary results are similar to ours: about a three percent positive rate for MRSA. The Pork Board said MRSA is a priority, but they don't know if it's a risk to you.
 

PORKER

Well-known member
The first MRSA isolate was found in 2003, and since then it has been found with increasing frequency. The geographic origin of NT-MRSA correlates with the density of pig populations. This association was confirmed by the results from this case-control study, which show that NT-MRSA is significantly related to contact with pigs. In addition, a significant association was found with cattle. After multivariate analysis, contact with pigs and cattle were the only 2 significant independent variables.

What are the implications of these findings? Persons working or living in close contact with pigs or cows are at increased risk of becoming colonized and infected with MRSA. Infections can be severe, as is indicated by the hospital admission rate. Also, a case of endocarditis has been reported recently (24). At present, whether this strain is spreading further in the community is not clear. Before final recommendations for control can be made, the current size of the reservoir in farm animals and in humans has to be determined at an international level.A traceback system using RFID boluses or tags will need to be for animals from birth to slaughter and then to the consumer for full traceableility to stop the spread of MRSA


American Dairymen Dairy Farms
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More Livestock Infected with MRSA
Submitted by shelley on Fri, 02/20/2009 - 11:29am
Written By:
TheCattleSite News Desk

US - A strain of methicillin-resistant Staphylococcus aureus (MRSA) is reported to be becoming increasingly prevalent in pigs, dairy cows and chickens, according to a recent survey. Although this strain rarely causes illness in humans, Food Animal Concerns Trusts is calling for greater restrictions on the use of antibiotics for livestock. Livestock herds could become a vast breeding ground for methicillin-resistant Staphylococcus aureus (MRSA), a formerly rare bacteria found mostly in hospitals but now spreading beyond health care settings, reports Oregon Live.

More than 90,000 people become ill and 18,000 die from MRSA infections each year in the US, by one recent estimate. To date, the vast majority of human infections are caused by strains that emerged in hospitals because of heavy antibiotic use. Resistant mutants survive treatment and multiply.

But researchers are finding that MRSA bacteria are becoming widespread among pigs, dairy cattle and possibly chickens. The MRSA strain found in livestock has been implicated in only a few cases of illness in people. But health officials are concerned that livestock herds could act as a reservoir from which the bacteria increasingly could spread to vulnerable people.

"We know it's a potential reservoir right now; the question is, what is the best way to manage the risk," said Steve Roach, public health program director for Food Animal Concerns Trusts, a Chicago-based non-profit organisation involved in promoting food safety, animal welfare and family farming.

Dutch authorities in 2003 were the first to detect MRSA in farm animals. They identified a new strain, called ST398, in pigs. Studies since have found the ST398 strain in pigs, cattle and broiler chickens in various European countries. Pigs have also tested positive in Canada and, most recently, the US.

Researchers in Iowa found MRSA in nearly half of 299 pigs tested at two large-scale pork producers in Iowa and Illinois. The bacteria also showed up in nine of 14 workers tested at one of the sites, researchers reported last month in the journal PLoS One.

None of the farm workers became ill, but the strain has caused human infections in Europe – justifying concerns that livestock could serve as a reservoir for spreading illness among people.

Cooking easily kills the bacteria, so it is not dangerous to eat fully cooked meat from animals harbouring MRSA, said Emilio DeBess, public health veterinarian with Oregon Department of Human Services. But workers who come in contact with live and slaughtered animals could pick up the bacteria and become sick or spread the bacteria to others who are vulnerable.

Mr Roach told Oregon Live that the government should be doing more to confront the problem. He said health authorities should alert hospitals about the risk posed by patients who may be carrying the bacteria from farms and meatpacking plants. And he said regulators should curb the large-scale use of antibiotics in farm animals.

Livestock growers routinely feed a variety of antibiotics to hogs, cattle and poultry to boost growth. Studies have found that the practice can promote the rise of drug-resistant bacterial strains.

"There is enough evidence, including the rise of MRSA in livestock, to suggest we should reduce the amount of antimicrobials we are using," said Mr Roach, whose group is part of a campaign called Keep Antibiotics Safe. Other groups include the Center for Science in the Public Interest, the Humane Society of the United States and the Union of Concerned Scientists.

The European Union banned the use of antibiotics as growth promoters three years ago. The US Food and Drug Administration proposed a rule that would have limited the use of one class of antibiotics. But the agency withdrew the proposal in December.

The advocacy groups want the government to create a roster of antibiotics that are essential for fighting human infections, then ban the use of these agents in non-sick animals and restrict their use in sick animals, concludes the report in Oregon Live.
 

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