Personal protective equipment, handwashing are recommended
Large-animal veterinarians’ adherence to infection control policies and procedures may be a bit spotty, but a report published in October on Methicillin-resistant Staphylococcus aureus, or MRSA, by the American Veterinary Medical Association might change that. If so, Vet-Advantage readers might notice a greater demand among their customers for personal protective equipment and sharps safety devices. Absent that, sales reps might take it upon themselves to point out the need for such equipment.

The backgrounder was published by the American Veterinary Medical Association in cooperation with the American College of Veterinary Internal Medicine. “MRSA is gaining recognition in the veterinary community, so we wanted to educate our members on it,” says Kimberly Anne May, DVM, MS, DACVS, assistant director, department of professional and public affairs for the AVMA. “In addition, AVMA wanted to draw attention to the role that animals can play in the transmission or reverse transmission of MRSA. This has been largely unrecognized by physicians and nurses.”

Not just a human pathogen
For many years, MRSA was considered a human pathogen only, according to the AVMA. In fact, it was considered to be solely a hospital problem until the last decade, when an increasing percentage of cases were reported occurring in the community among people with no known healthcare-associated risk factors for acquisition, according to the Centers for Disease Control and Prevention. Drug-resistant pathogens such as MRSA present a threat because persons infected with them are more likely to have longer hospital stays and require treatment with second- or third-choice drugs that may be less effective, more toxic and/or more expensive, according to the CDC.

Reports of an MRSA infection in a dairy cow in 1972 pointed to a connection between animals and humans. “It has now become an increasingly urgent problem in veterinary medicine, with MRSA infections reported in horses, dogs, cats, pet birds, cattle and pigs,” according to the AVMA report.

The predominant strain in food animals (e.g., pigs and cattle) seems to be animal in origin and its emergence is probably unrelated to the epidemiology of MRSA in the community, the report says. It was first thought that the transmission of MRSA occurred solely from human to animal, with MRSA colonization and infection typically occurring with contact between the hands of the human and nostrils of the animal. There is now increasing evidence that MRSA can be transmitted in both directions, from human to animal and from animal to human, according to the AVMA.

“As much as vets handle animals, there’s the concern of the vet getting infected, then infecting other animals and people,” says May.

Hard to detect

Although some studies have shown a higher incidence of MRSA among large-animal vets than small-animal ones, other evidence shows that MRSA “is a broad professional risk,” affecting all vets equally, says May. Evidence does seem to indicate that small animals are more likely to be colonized by the USA100/CMRSA-2 strain, while large animals tend to be colonized by the USA500/CMRSA-5 strain. “We don’t know the significance of that,” says May. That said, the USA100/CMRSA-2 strain appears to have a hospital origin, while would make sense, given the close contact that convalescing people have with their pets.

Among animals, the most commonly reported clinical signs of MRSA are postoperative and wound infections, with less-reported incidences of intravenous catheter site infections, urinary tract infections, pneumonia, and skin and ear infections, according to AVMA.

That said, only a small percentage of animals infected with MRSA develop clinical signs. According to AVMA, there’s little data on colonization rates in non-clinically-affected animals. Furthermore, routine screening of all animals is not practical at this point in time, and rapid diagnosis of MRSA in animals is still in its early stages of development. The bottom line is, the large-animal vet probably won’t know which of his or her patients are infected with MRSA and which are not.

Precautions

On the human side, providers have been urged to develop thorough risk assessments followed by surveillance or screening programs. The Association for Professionals in Infection Control and Epidemiology has urged caregivers to follow basic infection control practices to guard against contracting MRSA. Those include practicing hand hygiene (including the use of gloves and frequent handwashing); thorough cleaning and decontamination of equipment, hospital rooms, etc; and appropriate contact precautions (i.e., isolating MRSA patients, and using gloves, gowns and other precautions to avoid transmission to other patients or environments).

Vets should consider adopting some of these practices as well, according to AVMA. Because MRSA colonization and transmission usually occurs through contact from the hands of the human and the nostrils of the animal, masks and gloves should be worn. Good hand hygiene – washing hands with soap and water or alcohol gel – can also cut down the incidence of transmission, studies show. In addition, efforts should be made to decontaminate the shared surroundings of animals and humans.

In veterinary hospitals, the use of a chlorhexidine surgical scrub has proven effective in eradicating the transmission of Staphylococcus aureus, according to the backgrounder. Surgical scrubs containing both chlorhexidine and alcohol have been more effective against multiple strains of MRSA.

A move in the right direction

If concerns about MRSA nudge veterinarians toward better infection-control practices, that would be a step in the right direction. According to a study published in the June 15, 2008, issue of the Journal of the American Veterinary Medical Association, many small-animal, large-animal and equine veterinarians fail to engage in protective behaviors or use personal protective equipment considered appropriate to protect against zoonotic disease transmission. In fact, most U.S. vets are unaware of appropriate personal protective equipment use, according to the study.

Even when they are, circumstances can intervene, says May. “The high-quality clinics will implement something as simple as handwashing between patients,” she says. “But throw in an emergency –a dog in the waiting room who has been hit by a car – and it’s hard to wash your hands. It’s not that people are lazy or don’t care. But they do get busy.”