MRSA (Mersa) Questions

Antimicrobial resistance--animals and the environment

Link: The 2008 Garrod Lecture: Antimicrobial resistance--animals and the environment -- Lord Soulsby of Swaffham Prior, 10.1093/jac/dkn183 -- Journal of Antimicrobial Chemotherapy.

The evolution of resistance to microbes is one of the most significant problems in modern medicine, posing serious threats to human and animal health. The early work on the use of antibiotics to bacterial infections gave much hope that infectious diseases were no longer a problem, especially in the human field. However, as their use, indeed over-use, progressed, resistance (both monoresistance and multiresistance), which was often transferable between different strains and species of bacteria, emerged. In addition, the situation is increasingly complex, as various mechanisms of resistance, including a wide range of β-lactamases, are now complicating the issue. The use of antibiotics in animals, especially those used for growth promotion, has come in for serious criticism, especially those where their use should be reserved for difficult human infections. To lend control, certain antibiotic growth promoters have been banned from use in the EU and the UK. Antimicrobial resistance is not confined to bacteria but occurs in viruses, protozoa and helminths. In many of these, the mechanism of resistance is unknown, and hence their control is still in question. It is likely, however, that the mechanisms are no less complicated than those pertaining to bacteria.

10% 0f dogs MRSA carriers?

Link: Beware of Fido: chief vet warns of the risk of disease transmission - Times Online.

Some 10 per cent of dogs are thought to carry the superbug MRSA. Research by a team at Liverpool University Veterinary School showed that many dog owners appeared unaware of, or unconcerned about any health risks from their pet. According to a survey of 260 households in a semi-rural town in the South Wirral, where most pets were labradors or Jack Russells, almost 20 per cent of the animals slept in the bedroom and 14 per cent on a person’s bed. Dr Landeg’s warning also coincides with a review of pet travel rules on the Continent by the European Commission.

Cat reinfects owner with MRSA

Link: The Bay Area Reporter Online | Keeping you and your pets healthy.

Include on that list the overly-hyped infection MRSA, methicillin-resistant Staphylococcus aureus. The family cat was the source of a recurring MRSA infection in an otherwise healthy German woman, according to a report published in the New England Journal of Medicine in March. The woman developed multiple deep skin abscesses caused by MRSA. She was treated but the infection came back. Screening found the bug in the nose of other family members, even though they had no signs of active infections. They were treated, but the mother s abscesses came back. In desperation the doctor swabbed the throats of the three family cats, and one of them came back positive for MRSA. The bacteria sample from the cat had the same patterns of drug resistance seen in the mother. The animal was treated and so was the woman. This time her sores cleared up for good. She was no longer being reinfected by others in the household. Veterinarians first noticed MRSA in the milk of a cow in 1972, but reports of the infection in all types of animals really have exploded in the last five years, said Jeff Bender, a professor of veterinary public health at the University of Minnesota. "Typically pets clear this rather rapidly, in a couple of weeks, as long as there is not reinfection," said J. Scott Weese, a professor at the Ontario Veterinary College at the University of Guelph, in Canada. "If you see long-term colonization, usually it is because it is passing between different individuals in the household, humans or animals."

Beware of the dog: you may catch MRSA

Link: Beware of the dog: you may catch MRSA - Times Online.

They might be man’s best friend, but dogs should be sold with a health warning, a study suggests. Letting a dog lick your face, picking up its mess or allowing it to sleep on your bed could put you at risk of catching salmonella, campylobacter or MRSA. Research commissioned by the Department for Environment, Food and Rural Affairs (Defra) from the University of Liverpool Veterinary School, has identified health risks in the interaction between man and dog. The findings, published in The Veterinary Record, may enrage the country’s 6.5 million dog owners. Men, in particular, may have to learn cleaner habits because it seems they have a problem picking up dog mess. Risks of infection from dog to Man at present are low.

Doctors urge caution over hospital animal visits

Link: The Canadian Press: Hedgehogs bad, Labradors good: group issues new advice for hospital pet visits.

Hedgehogs, prairie dogs, non-human primates and alpacas shouldn't be making rounds in hospitals and long-term care facilities, according to new infection control advice for popular animal visitation programs. Therapy animals shouldn't be permitted access to patients' bathrooms, where they could pick up bugs like Clostridium difficile by licking surfaces or drinking from toilet bowls. And animals at high risk of carrying salmonella - turtles and dogs fed a raw food diet - should be barred from participating in animal therapy programs, the guidelines say. The lengthy list of recommendations, recently published in the American Journal of Infection Control, was the product of a consensus conference held in Toronto in January 2007. The conference, which drew in animal and human health experts, therapy animal program operators and infection control specialists, was sponsored by the Public Health Agency of Canada and the University of Guelph's Centre for Public Health and Zoonoses. (Zoonoses are the diseases that move back and forth between two-and four-legged animals.) The idea behind the guidelines is to minimize the risk that visiting animals will spread more than love as they make their way from patient to patient.

11% Dutch pork is contaminated with MRSA bacteria

Link: Pig Progress | Pig News | 11% pork is contaminated with MRSA bacteria.

A recent study carried out by the risk department of the Dutch Food and Consumer Product Safety Authority (VWA) revealed that 11% of meat products in the retail sector is contaminated with the hospital bacteria ‘MRSA’. In 84% of the cases, the nt-MRSA (non-typable MRSA), which affects pigs, calves and livestock farmers is present. MRSA is the name given to a group of bacteria that belong to the Staphylococcus aureus (SA) family of bacteria. The people who are most at risk of becoming either colonised or infected with MRSA are those in close contact with people who may be carrying the bacteria, for example in hospital wards that care for ill people. Nt-MRSA is a clone of MRSA. According to the Authority, meat does not contribute to the spread of the bacteria, which is resistant to most antibiotics. However, nt-MRSA can be spread where livestock is kept.

Pig MRSA spreading into humans in Holland

Link: First outbreak of methicillin-resistant Staphylococcus aureus ST398 in a Dutch hospital, June 2007.

In June 2007, MRSA was cultured from a diabetic foot ulcer of a patient on a surgical ward. Subsequent screening of contacts among patients and healthcare workers revealed four additional patients with MRSA infection and/or colonisation and five healthcare workers who carried MRSA. Two of the five affected patients (one with prostate carcinoma and one with a diabetic foot) were successfully decolonised with mupirocin nasal ointment, chlorhexidine wash, and treatment with trimetoprim/rifampicin. A further colonised patient with a gastro-intestinal malignancy and two patients with infected diabetic foot ulcers remained colonised, despite several decolonisation regimens. Of 238 healthcare workers who were screened, five were colonised in the nose and/or throat and had no skin conditions. All five have been treated with mupirocin nasal ointment and chlorhexidine wash and successfully decolonised. All strains were resistant to tetracycline and non-typable by PFGE. Spa-typing showed that all strains were spa-type t567. This spa-type corresponds to MLST type 398, a type previously found in pigs. None of the patients had had contact with pigs or veal calves. One healthcare worker lived on the grounds of a pig farm but neither she nor her partner came into contact with pigs themselves. While we presume that this health care worker was the source of the infection, this could not be proven. Permission to sample the pigs on this farm was not granted. Conclusions The NT-MRSA strain responsible for this outbreak was spa-type t567, which corresponds to MLST type ST398, the clonal complex to which most of NT-MRSA strains belong. This outbreak shows that transmission on a larger scale than a one-on-one transmission between caretaker and patient can occur with NT-MRSA in a hospital setting.

MRSA spreading from Animals to Humans

Link: HighWire Press -- Medline Abstract.

In 2003 in the Netherlands, a new methicillin-resistant Staphylococcus aureus (MRSA) strain emerged that could not be typed with Sma1 pulsed-field gel electrophoresis (NT-MRSA). The association of NT-MRSA in humans with a reservoir in animals was investigated. The frequency of NT-MRSA increased from 0% in 2002 to >21% after intensified surveillance was implemented in July 2006. Geographically, NT-MRSA clustered with pig farming. A case-control study showed that carriers of NT-MRSA were more often pig or cattle farmers (pig farmers odds ratio [OR] 12.2, 95% confidence interval [CI] 3.1-48.6; cattle farmers OR 19.7, 95% CI 2.3-169.5). Molecular typing showed that the NT-MRSA strains belonged to a new clonal complex, ST 398. This study shows that MRSA from an animal reservoir has recently entered the human population and is now responsible for >20% of all MRSA in the Netherlands.

Human and animal MRSA Differences

Link: Bacteriological Characteristics of Staphylococcus aureus Isolates from Humans and Bulk Milk -- Hata et al. 91 (2): 564 -- Journal of Dairy Science.

The aim of this study was to clarify the epidemiological association and bacteriological characteristics of human and animal Staphylococcus aureus isolates. Pulsed-field gel electrophoresis showed that pulsotypes (PT) of isolates from bulk milk differed from PT from human isolates, suggesting that there is no epidemiological association between isolates from these 2 sources. The absence of a common PT could result from the lack of contact between the sources. Methicillin-resistant S. aureus from human secretions and S. aureus from bulk milk in Japan consisted of 1 and 2 dominant clusters, respectively, whereas methicillin-susceptible S. aureus from humans consisted of assorted clusters. Isolates belonging to the dominant clusters showed the coagulase serotype, the capsule serotype, detection of exotoxin genes, and antimicrobial susceptibility. Isolates from bulk milk did not show the penicillin-binding protein 2a gene, and 252 of 275 isolates belonging to the 2 dominant clusters of bulk milk were susceptible to ampicillin, cefazolin, erythromycin, chloramphenicol, oxacillin, and vancomycin. Moreover, the LukM/LukF'-PV leukotoxin gene was detected in 233 of 275 isolates belonging to the dominant clusters in bulk milk isolates. These results support the hypothesis that a number of factors play a role in the adaptation of S. aureus isolates to specific hosts.

Antibiotic resistance found in wild birds

Link: Medical News Today News Article.

In the latest issue of the journal Emerging Infectious Diseases, Swedish researchers report that birds captured in the hyperboreal tundra, in connection with the tundra expedition "Beringia 2005," were carriers of antibiotics-resistant bacteria. These findings indicate that resistance to antibiotics has spread into nature, which is an alarming prospect for future health care. The scientists took samples from 97 birds in northeastern Siberia, northern Alaska, and northern Greenland. These samples were cultivated directly in special laboratories that the researchers had installed onboard the icebreaker Oden and were further analyzed at the microbiological laboratory at the Central Hospital in V�xj�, Sweden. "We were extremely surprised," says Bj�rn Olsen, professor of infectious diseases at Uppsala University and at the Laboratory for Zoonosis Research at the University of Kalmar. "We took samples from birds living far out on the tundra and had no contact with people. This further confirms that resistance to antibiotics has become a global phenomenon and that virtually no region of the earth, with the possible exception of the Antarctic, is unaffected." The researchers' hypothesis is that immigrating birds have passed through regions in Southeast Asia, for example, where there is a great deal of antibiotics pressure and carried with them the resistant bacteria to the tundra.