Methicillin-resistant Staphylococcus aureus is an emerging problem in veterinary medicine. Community-acquired MRSA has been identified as a major factor in the rise of infection in companion animals, and a growing body of evidence points toward its zoonotic transmission. As a result, the AVMA identified MRSA as an occupational risk for veterinary professionals, in a backgrounder published in October 2008 in cooperation with the American College of Veterinary Internal Medicine.
"MRSA is a significant issue in veterinary medicine, even though it is primarily a human health problem. The potential for zoonotic transmission places both people and animals at risk," said Dr. Carolynn T. MacAllister, director of continuing education and veterinary extension with the Oklahoma State University Center for Veterinary Health Sciences. "That is why veterinarians should take steps to help prevent transmission by adhering to established infection control practices and educating pet owners on the appropriate precautions to take at home."
Dr. MacAllister, a trustee of the AVMA Group Health and Life Insurance Trust, and Kristy Bradley, DVM, MPH, Oklahoma's state epidemiologist and state public health veterinarian, co-authored a paper for veterinarians to use in educating pet owners on MRSA—including information on screening, treatment, and prevention. The paper is available at http://osufacts.okstate.edu by searching for "MRSA."
Screening for infection
When a person suffers with recurring MRSA infections and lives with one or more pets, screening of all animals and humans in the household is advised.
"Animals can serve as reservoirs for transmission to people, but it is more likely that asymptomatic persons are a source of MRSA," Dr. MacAllister noted. "Thus, it is important for the veterinarian to coordinate screening with the family's physician."
All animals in the household should be screened for MRSA infection, and these results should be shared with the physician performing similar screening on the humans in the household—to ensure an appropriate course of treatment is undertaken.
Treatment of humans and animals depends on the strain of MRSA. While all strains are resistant to beta-lactam antimicrobials, some strains are resistant to other antimicrobials. Testing is required to determine the best antimicrobial for treating the specific strain. Topical treatment for skin and soft tissue infections also may be effective, but in people with a localized skin infection, incision and drainage with routine wound care is preferable to administering antimicrobials.
An antimicrobial solution developed by researchers at the University of Georgia College of Veterinary Medicine may be the latest weapon in fighting MRSA infections. The topical solution increases the potency of currently available antimicrobials, making the bacteria more vulnerable to the drugs while reducing pain in the area of the wound and healing time.
Currently there isn't an established antimicrobial regimen that is reliably effective for treating a MRSA-infected animal. Most animals will clear the MRSA spontaneously within a few weeks if they are protected from reinfection. As such, temporarily isolating the animal from contact with the infected person should be satisfactory. This may require temporary boarding or placement in another location such as a kennel or veterinary clinic.
Treatment for infected people is typically nasal ointment and/or antimicrobials for oral administration. However, it is neither needed nor recommended for most people, unless an individual is at a high risk for infection or is in contact with high-risk individuals.
To prevent MRSA transmission in the practice setting, veterinarians should instruct their staffs to follow established infection control guidelines, beginning with proper hand hygiene and disinfection of hard surfaces and equipment between patients.
Something as basic as hand sanitizer is highly effective. A recent study from the University College London Medical School found that each extra milliliter of alcohol hand sanitizer used in British hospitals per patient per day lowered MRSA infection rates by 1 percent.
Veterinarians and staff also should take the following precautions:
- Wear gloves, disposable aprons, and masks when changing dressings on infected wounds and to prevent potential contact with body fluids or contaminated tissues.
- Wear eye protection if splashing or aerosols are expected.
- Admit MRSA-infected animals directly to an isolation room or designated examination room, and prevent them from coming into contact with other animals.
- Cover infected sites and wounds, and treat used bandage materials as a high-risk item when disposing.
The Model Infection Control Plan for Veterinary Practices, published by the National Association of State Public Health Veterinarians, provides comprehensive guidelines for the prevention and control of MRSA infections in animals and humans. The document is available on the AVMA Web site at www.avma.org/services/model_infection_control_plan.rtf.
Pet owners who are treating a MRSA-infected wound on their pets at home, under the supervision of a veterinarian, should be advised to take the following precautions:
- Wear disposable gloves when treating open wounds and changing bandages.
- Use a household disinfectant or chlorine bleach solution to clean and wipe any hard surfaces contaminated by wound drainage.
- Avoid touching the nose, eyes, face, and mouth when caring for an animal or cleaning surrounding areas.
- Wash hands frequently with soap and warm water, or use an alcohol-based hand sanitizer.
- Wash animal bedding in hot water and laundry detergent, and dry in a hot dryer.
"While advances are being made in the detection and treatment of MRSA, preventing transmission is still the best course of action we can take to reduce infection rates," Dr. MacAllister said.
More information concerning MRSA is available at www.cdc.gov/ncidod/dhqp/ar.html.