See also: Other Bacteria
Staphylococcus bacteria is bacteria in the Staphylococcus genus, a very common bacterial genus which is very widely distributed throughout the world, making it a familiar sight in doctor’s offices, veterinary clinics, and labs. Knowledge of Staph bacteria is needed in order to prevent or reduce infections caused by these bacteria in pet's as well as humans. You and your pets are hosting a few Staphylococcus species right this very minute, because these bacteria are part of the body's natural bacterial flora.
In humans, the most famous Staphylococcus species is probably S. aureus, the bacterium responsible for the well-known "Staph" infections which plague people of all ages. In dogs and cats, Staph aureus can be found. However, it is less common than other Staph species such as Staph pseudintermedius, Staph schleiferi, and Staph hyicus. Multi-drug resistant Staph (MDR Staph) is a real problem for both humans and animals. Many multi-drug resistant Staph bacteria can become resistant to the antibiotic methicillin.
Once Staph bacteria become "methicillin resistant", the number of useful antibiotics shrinks drastically. Methicillin resistant Staph aureus (MRSA) is the most notorious of the Staph bacteria because of the difficulty in eradicating infection. This bacterium is difficult not only because of its resistance to many antibiotics but also because it possesses many virulence factors that increase its ability to damage body tissue and evade the body's host defenses. Fortunately, MRSA is not found as often in dogs and cats as it is in humans. Humans may be a source for transmitting MRSA to cats.
In dogs and cats, Staph most commonly causes skin infections like folliculitis, furunculosis, boils, and cellulitis. In dogs and cats, Staph infections are usually secondary infections. What this means is that something must be compromising the pet's skin's ability to fight off infection to allow a Staph infection to occur.
The most common reason for recurring or chronic Staph infections in dogs is allergic skin disease. How allergic skin disease weakens the canine skin to Staph infection is not conclusively known. However, theories incude: pruritus (itchiness) resulting in self-trauma and damage to the skin surface and direct effect of allergies on the skin makes it more suitable for the growth of bacteria.
Staph skin infections in dogs will continue until the allergy is controlled. No amount of antibiotic can sterilize the skin. Allergic skin is unhealthy skin just waiting for the next Staph bacteria to come along. Since Staph is found everywhere, even on the skin of healthy pets and humans, the next skin infection for an allergic dog is just around the corner. With each subsequent infection, the chance for bacteria to learn resistance against antibiotics increases, until a situation occurs where there are no antibiotics available that will work for methicillin resistant Staph. There are no hard and fast guidelines for number of skin infections which might be "acceptable" (indeed if any number is acceptable), but if your dog has more than two Staph bacterial infections per year, that is too many.
In dogs, Staph infections can look like red bumps/pimples (papules) or pus-filled (pustules), or round areas with a red or dark center and red crusty border. Hair loss occurs and sometimes the hair comes out in clusters resembling a paint brush. In dogs with long hair coats, it may appear as large patches of hair with smooth skin in the center and a crusty border. Deep Staph infections often progress from folliculitis to furunculosis, in which the hair breaks apart under the skin surface causing swelling, seeping of fluid and sometimes bleeding from the skin. Furunculosis is more common around the feet or limbs.
Fortunately, most dogs do not feel ill from their Staph infection unless it becomes deep in the skin and is widespread.
Treating Staph Infection
At the same time that antibiotics are dispensed and topical antiseptic or antimicrobial therapies are dispensed, dermatologists will discuss a plan to control any underlying allergies or any other health problems that are affecting the ability of your pet's skin to fight infections. The duration of antibiotic therapy for dogs with bacterial folliculitis is a minimum of 20 days. This length is necessary because of the inefficiency of the allergic dog's skin in fighting the infection. Deep infections require longer duration of antibiotic therapy, such as 4-6 weeks.
Again unless the underlying cause, usually an allergy, is determined, the Staph infections will continue to recur. This is why veterinary dermatologists, the veterinary specialists of allergy, are commonly consulted regarding chronic skin infections. Until the health of the skin is improved, typically by controlling allergic skin disease, the resistance of the Staph bacteria will increase until the only antibiotics that may be effective will be those with greater chance of adverse effects for the pet.
See also: Other Bacteria