MRSA infections have become a major concern in hospitals, but few people are aware that animals and humans can infect each other.
In the United States, one in three people carries a staph bacterium, an opportunistic pathogen causing hospital and community infections worldwide. Healthy people infected by this agent usually can be treated by an antibiotic.
One specific staph bacterium, however, called methicillin-resistant Staphylococcus aureus (MRSA), carries a gene that proves resistant to the most common antimicrobial drugs. This makes it difficult to treat, and it can even be life threatening among immunocompromised people: the very old or very young, diabetics and people who had recent surgery or have open wounds.
MRSA has been on the rise and well known for many years, especially in hospitals, nursing homes, dialysis centers and other health care settings. It also can be transmitted in the community via skin-to-skin contact among groups such as child care workers.
What is less well known about MRSA is that pet owners can transmit it to their dogs, cats, birds and other animals — and vice versa. Since 2005, Professor Armando Hoet, director of the Veterinary Public Health Program at The Ohio State University, has studied MRSA in veterinary settings, including among dogs brought to the university’s Veterinary Medical Center.
“If a dog has MRSA, a person is the most likely source,” Hoet explained. “If someone in the house has MRSA, it can be transmitted to a pet through kissing, licking, bathing, or other direct contact with infected sites such as wounds.”
The bacterium also can be spread in veterinary offices, kennels and other areas where pets may come into direct contact with other animals. Research showed that pure breeds and short-haired animals are more likely to be colonized, that is, to carry the MRSA bacterium, sometimes without symptoms of infection. Other high-risk factors include living with health care workers or visiting human hospitals or nursing homes, as therapy dogs often do.
Awareness makes a difference
Hoet previously conducted research in Venezuela on treating staph mastitis, an infection in cow udders. When he came to Ohio State in 2005, he learned that more dogs, cats and horses were being brought to the clinic with MRSA. He began a study of how they acquired the infection, what forms it took and their resistance to treatment.
At that time, about 5 percent of the dogs arriving at the university’s specialized clinic had or carried MRSA, and they were likely to have been referred by other veterinarians. Today, that figure has dropped to less than 0.9 percent, due to increased awareness of the bacterium among veterinarians.
Unlike humans, most pets colonized with MRSA will not become infected unless they are immunocompromised — young, old, unhealthy or having cuts. The bacterium simply goes away after a few weeks or months. Some animals may be carriers without any MRSA symptoms. Visible symptoms might include crusts, scaling, papules, pustules, erythema, hair loss, inflammation in the ear or skin infections.
Linda Nowakowski, of Carlisle, Ohio, was referred to Ohio State’s Veterinary Medical Center by her regular vet. Her 9-month-old gray tabby cat, Cloudy, had been scratching the top of his head, his ears and chin. The antibiotic prescribed had worked briefly, but the symptoms returned. She was sent to Dayton to see a veterinary dermatologist, who thought the problem was ear mites and prescribed the drug Revolution.
“He only got worse,” Nowakowski said. “He scratched constantly and had open wounds on his head.”
She brought Cloudy to Ohio State, and they saw Dr. Stephanie Abrams, a veterinary dermatologist resident working with Dr. Gwendolen Lorch. Abrams conducted a skin biopsy and prescribed clindamycin. Within a month, Cloudy was significantly better: He had some of his fur back, and the open wounds closed and scabbed over.
The source of the cat’s MRSA infection remains a mystery. None of the kittens in the litter was infected. Nowakowski had her own physician check to see that she was free of MRSA after returning from a surgery on her leg when the cat was only 6 weeks old. “He stayed with me the entire time when I was recovering,” she said. “He stayed in my bed and followed me whenever I got up.”
Nowakowski can’t say enough to praise the staff at Ohio State’s Veterinary Medical Center. “They put us in an isolation room and wore protective uniforms — and they helped ‘my baby.’ Now, when we go for follow-up visits, the whole staff are eager to see Cloudy. They’ve been truly incredible!”
With a new lease on life for owner and cat, Nowakowski may have to change Cloudy’s name to “Sunny.”
Whenever animal-to-human disease transmission is mentioned, misconceptions can occur. Some people even choose to remove pets from their homes. Potential transmission of MRSA is rare and not cause for drastic action. Here are the things to know about MRSA:
Companion animals can get MRSA from humans.
It’s important to take precautions to protect your pet from MRSA, especially if you work in a health care environment, or if someone in your home has MRSA. Transmission to animals can occur from kissing, licking, bathing or any direct contact with an infected person.
Also be careful when you take your pet to visit a high-risk environment, such as a nursing home or human hospital. When it’s time to see a veterinarian for any reason, ask what methods the office uses to prevent transmission of germs such as MRSA.
You can get MRSA from your pet.
Transmission of MRSA infections from animals to humans is rare, but people can become infected outside hospital settings if they come in direct contact with a person, animal or object contaminated with MRSA.
If your pet has been diagnosed with MRSA, the veterinarian will provide precautionary instructions, including social distancing — no “kissing” for a while! Precautions should be taken especially if someone in the home is immunocompromised, such as diabetic, very young or old, has had recent surgery or has an open wound.
If an animal has an active MRSA infection, it can be transmitted to humans by direct contact with the infected area or with contaminated items, such as bedding, food or water bowls or a toy with saliva on it.
Colonized animals (those who carry the organism but show no signs of infection) often carry the bacterium around the nose and anus. People should be especially careful to wash and sanitize their hands after touching the affected animals or picking up feces. Once the pet has been cured, you can resume normal contact.
Dogs are colonized for only a few weeks to a couple of months.
If the behavior of the owner who caused the dog to be colonized — poor hygiene or direct contact by an infected person — is changed, a healthy dog’s condition will usually clear up without treatment. If the dog is immunocompromised from surgery, poor health or age, treatment for MRSA may be necessary — but not in every case.
Even animals that have been colonized with MRSA may not require treatment. Many factors enter into the decision to treat or not to treat. For a healthy colonized dog living with a low-risk family, for example, treatment would usually not be advised. For an infected dog with another medical condition living with a high-risk family, treatment would generally be recommended. Your veterinarian is the best source of advice concerning MRSA issues.
MRSA infections are not common in dogs and cats.
While MRSA is a major issue in human health, dogs are more likely to be affected by a different bacterial strain called methicillin-resistant Staphylococcus pseudintermedius or MRSP. These infections usually infect dogs through skin wounds, surgical sites and ears. Like MRSA, they are difficult to treat.
Healthy animals should not be routinely tested for MRSA.
A veterinarian can screen an animal for MRSA by swabbing nasal or perianal areas and any skin lesion for culture. However, this type of test should not be a routine procedure because many animals that test positive for MRSA are not actually infected.
As with other human conditions, pets should be tested for MRSA only if everyone else in the house and other close contacts are tested. If testing for MRSA is indicated and there is more than one animal in the home, all the animals should be tested, since MRSA can infect some animals and not others. It also can be transmitted from one animal to another.