You, your pets and staph

Posted on 24 Apr 2008 at 5:58pm
By Bob Roehr – Contributing Writer

Drug-resistant MRSA bug can be transmitted from humans to pets, and from pets to humans in a vicious circle of infection

Although hand-to-fur contact is probably the most common mode of transmission of MRSA between pets and their humans, "playing "kissy-face" with your furry baby can be a more direct route.



Gays and lesbians love their pets. They can be a wonderful source of comfort and unconditional love, particularly when relationships with friends and family go sour.

But that closeness can also bring disease, and infection can be a two-way street.

The risks can run from the nuisance of fleas to a hypothetical pandemic catastrophe of avian flu.

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. Screening found the bug in the nose of other family members, even though they had no signs of active infections.

They were treated and recovered, but the mother’s abscesses came back returned despite treatment.

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, because she was no longer being re-infected by the family pets.

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, says 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 no re-infection," said J. Scott Weese, a professor at the Ontario Veterinary Collage 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."

Fortunately, the immune system of most animals can handle the bug, experts said, but that makes it difficult to study the MRSA link between humans and household pets.

It is possible that the infection came from the animal to infect the owner, but the pet has cleared it by the time the human develops symptoms or the animal is tested. It also makes it difficult to identify transfer between animals within a household.

Bender has studied MRSA sample taken from household pets and found that the majority of them are healthcare-associated strains of the bacteria.

"When we interviewed the owners we found that a fair number of them worked in healthcare, had recently been hospitalized, or were caring for someone who had been hospitalized," Bender said. "So we found that a lot of our pets were picking it up from their caretakers."

Hands likely are the most common mode of transmission, from human nose to animal fur and vice versa, though playing "kissey-face" with your "baby" may be a more direct route of exposure.

The animal’s licking and grooming can spread the bacteria to other parts of the body.

MRSA is most commonly found in the nose, mouth and anus of dogs and cats.

Pet owners really do have to think of the four-legged members of the household when dealing with disease control, to protect the health of animals and humans alike, experts warn.

The most important thing is for pet owners to wash their hands thoroughly: People are diagnosed with MRSA should recognize they may be putting their pets at risk and wash their hands before touching the animal. They should also recognize that their pets can put human health at risk, and wash their hands after touching their animals.

Because most household pets quickly fight off MRSA, it generally is not necessary to treat them, the experts said.

That can change if the animal has a wound that won’t heal or if the owner has a recurring MRSA infection.

Weese said, "The main thing to remember is that MRSA is still staph aureus; it’s just drug resistant. So the general principles of antibiotic therapy apply."

Those principles include testing to determine resistance and selecting a drug that will be effective and safe.

Pet owners should also remember not to medicate their pets by slipping "Boots" a bit of human antibiotic, Weese warned.

"A cat is not a small person," he said, adding that every animal species is different in terms of the absorption, metabolism and safety of each drug.

Misuse of an antibiotic will not only waste time and money, it may also lead to resistance that makes the infection harder to treat, or it may directly harm the animal, Weese said.

This article appeared in the Dallas Voice print edition April 25, 2008.

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