NEWS SCAN: MRSA in meat, frog Salmonella update, bedbugs and resistant bugs, zoonotic research launch, C diff virulence

May 11, 2011

Human-type MRSA found in Detroit raw meat
Researchers testing retail meat samples in Detroit found that almost a fourth contained Staphylococcus aureus and 2% contained methicillin-resistant S aureus (MRSA). In a letter to Emerging Infectious Diseases today, the scientists report that they collected 289 raw meat samples (156 beef, 76 chicken, and 57 turkey) from 30 grocery stores from August 2009 through January 2010. Of those samples, 65 (22.5%) yielded S aureus via coagulase test and polymerase chain reaction (PCR): 32 beef (20.5%), 19 chicken (25.0%), and 14 turkey (24.6%) samples. Six samples (2 beef [1.3%], 3 chicken [3.9%], and 1 turkey [1.7%]), were positive for MRSA, while only one sample, a beef one, contained multidrug-resistant MRSA. Furthermore, the MRSA was the human type, USA300, which the authors said could indicate a human rather than animal source of meat contamination. They said similar studies in European meat typically show ST398, an animal MRSA clone. They noted that the percentage of positive MRSA samples is lower than in an earlier study in Louisiana meat, perhaps because the Michigan researchers didn't test pork, noting that swine production has been identified as a reservoir of MRSA. They wrote that although USA300 might be better adapted to meat processing in the United States, ST398 might someday appear as a contaminant in US meat, given its recent identification in US swine.
May 11 Emerg Infect Dis letter

Case total grows in frog-linked Salmonella outbreak
Four more Salmonella infections have been linked to a nationwide outbreak tied to contact with African dwarf water frogs, raising the total to 222 cases from 41 states, the US Centers for Disease Control and Prevention (CDC) said yesterday. Surveillance suggests that the outbreak may have been ongoing since April 2008. Findings of several investigations have linked the illnesses to a single frog breeder in California, and isolates from the facility that were tested at the CDC were positive for the Salmonella enterica serotype Typhimurium outbreak strain. In two instances, the strain was confirmed in aquarium samples from sick patients' homes.
May 10 CDC update

Bedbugs found to carry drug-resistant bacteria
Canadian researchers report that bedbugs found on three patients hospitalized in Vancouver carried two kinds of antibiotic-resistant bacteria: MRSA and vancomycin-resistant Enterococcus faecium (VRE). The patients were residents of Vancouver's Downtown Eastside, an impoverished neighborhood, the researchers wrote in a letter today in Emerging Infectious Diseases. Hypothesizing that the bedbugs might carry resistant pathogens, the authors collected five of the bugs and tested them. They found that two bedbugs from two patients carried VRE, while three bedbugs, all from the same patient, carried MRSA. There is no clear evidence that bedbugs spread disease, the letter says. But bedbug infestations are common in Downtown Eastside, and MRSA is also a substantial problem there. "These insects may act as a hidden environmental reservoir for MRSA and may promote the spread of MRSA in impoverished and overcrowded communities," the authors write. "Further studies are needed to characterize the association between S aureus and bedbugs."
May 11 Emerg Infect Dis letter

DEFRA launches zoonotic disease research network
The United Kingdom's Department for Environment, Food, and Rural Affairs (DEFRA) today launched a global research network focusing on zoonotic diseases such as avian influenza and foot-and-mouth disease. In a statement yesterday, DEFRA said the network will be supported by $1.4 million from the European Union. The group so far includes 17 countries, covering three regions: the Americas, Asia and Australia, and Europe. It said it hopes countries in the African region will join the group. Jim Paice, DEFRA's agriculture and food minister, said in the statement that global trade and traffic increases the risk of zoonotic disease spread. "Countries acting on their own just don't have the resources to research every disease, all of the time, so sharing resources like this will get us maximum protection and value for money," he said. DEFRA said the global research network will speed the sharing of new zoonotic disease developments and help improve the control of existing diseases, which helps improve livestock production.
May 10 DEFRA statement

C diff study finds virulence profile
Scandinavian researchers, using a large Danish patient databases, today reported that those infected with Clostridium difficile strains that have binary toxin genes and genes encoding toxin A and B have a higher case-fatality rate than C difficile strains that have only toxins A and B. The group said the binary toxin could be a marker for more virulent C difficile strains and could be useful for clinical management. They conducted the 17-month study in 2008 through part of 2009. Patients were grouped by their binary toxin and toxin A and B status. Researchers also categorized them by PCR ribotype 027, which has been linked to more severe disease and increased C difficile death rates. The investigation included data on 2,299 patients, of which 477 isolates were sent for genotyping. In addition to finding a more virulent genetic profile, the team found that case-fatality rates were similar in patients who had either PCR ribotype 027 or non-027. They concluded that methods to control infections should target all virulent strains, not just the ribotype 027 ones.
May 11 Emerg Infect Dis study

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