A review published in the July edition of The Lancet Infectious Diseases discusses septic syndromes and bite-related infections caused by cats and dogs. It is written by Dr Richard Oehler, of the University of South Florida College of Medicine, Tampa, FL, USA, and his team. The review informs on how MRSA (methicillin-resistant Staphylococcus aureus) infections are increasing. They are transmitted between dogs or cats and their human handlers, and vice-versa, and cause infections of the skin and soft-tissue. Surgical infections are the most common.
In the USA and Europe, dog and cat bites consist of about one percent of emergency room visits annually. Women and the elderly are most at risk of cat-bite. Individuals aged under 20 are most likely to be injured. Most bite exposures occur in young children and involve unrestrained dogs on the owner’s property. About 20 percent involve a non-neutered dog. Young boys aged 5 to 9 years are at higher risk because of their small size and because they are unable to understand provocative behavior. Children often receive bites to the face, neck, or head due to their small height. Adults are most often bitten on the hand, followed by face, scalp, neck, thigh or leg.
Immediate treatment of canine and feline bites is necessary whether the injury is superficial or deep. Then management of the risk of acute infection is essential, including washing with high pressure saline if possible, and antibiotics in some cases. In about 20 percent of all cases severe infections can occur. They are caused by Pasteurella, Streptococcus, Fusobacterium, and Capnocytophaga bacteria from the animal’s mouth, added possibly other pathogens from the human’s skin. Rabies prophylaxis should be considered in countries with endemic rabies.
There can be severe complications of bite wounds, such as sepsis, particularly those infected with C canimorsus, P multocida, Staphylococcus spp (including MRSA), and Streptococcus spp. Individuals with leukaemia and lupus, and those receiving chronic steroids might develop bite-wound sepsis infected with Bacteroides, Fusobacterium, Neisseria, and Prevotella.
Since the incidence of community-acquired strains of MRSA increases, a growing body of clinical evidence has documented MRSA colonisation in domestic animals. It often suggests direct acquisition of S aureus infection from their human owners. There is acknowledgement of MRSA colonisation in pet animals, such as horse, dogs and cats. These animals are considered as potential reservoirs of infection. MRSA-related skin infections of pets seem to occur in various manifestations, including simple dermatitis, and even perineal cellulitis. It can easily spread to the owners. Pet-associated MRSA infections are treated with specific therapy similar to regimens used in most community-acquired MRSA syndromes. The authors explain: “Much more remains to be learned about MRSA and pet-associated human infections.”
They say in conclusion: “Pet owners are often unaware of the potential for transmission of life-threatening pathogens from their canine and feline companions. Bite injuries are a major cause of injury in the USA and Europe each year, particularly in children. Bites to the hands, forearms, neck, and head have the potential for the highest morbidity… Health-care providers are at the forefront of protecting the vital relationships between people and their pets. Clinicians must continue to promote loving pet ownership, take an adequate pet history, and be aware that associated diseases are preventable via recognition, education, and simple precautions.”
“Bite-related and septic syndromes caused by cats and dogs”
Richard L Oehler, Ana P Velez, Michelle Mizrachi, Jorge Lamarche, Sandra Gompf
Lancet Infect Dis 2009; 9: 439-47
Written by Stephanie Brunner (B.A.)