Bacterial Diseases in Psittacines

We have all read sensational headlines about the dangers of the new flesh-eating bacteria and the bacteria with the weird, unpronounceable name of MRSA (pronounced mer-suh). You might even know someone diagnosed with a dangerous bacterial infection.

What do you need to know about protecting your birds from dangerous bacterial infections? Let's start with the basics. It is now time for our microbiology lesson so we can become educated about bacteria in general and pathogenic bacteria, in particular.

Bacteria are just about everywhere. Bacteria are one-celled organisms that aren't visible to the naked eye. They live and reproduce by dividing, as a general rule. Some are motile and can use flagella to propel themselves around, and others can't. There are many ways to classify bacteria. Most of us are familiar with Gram's staining, which is one way to classify bacteria by the way they pick up a particular color when stained. Another way to classify them is by their shape.

There are bacteria that perform beneficial functions in living organisms, bacteria that help break down refuse, bacteria that are actually good for you and some that are found in birds and people that are just passing through.

Bacteria that are capable of causing disease or infections are called pathogens. Others are called opportunists, meaning that if the situation is right they may cause infection.

There have been studies performed that show that birds that drink out of water bowls tend to have higher levels of bacteria in their oral cavities and gastro-intestinal tracts than birds that drink out of water bottles. Some of these bacteria could have the potential for causing an infection, given the right set of circumstances, so one way to keep your birds safer, is to offer them water from a water bottle that is cleaned and filled daily.

I recently spoke with the head microbiologist at Antech Diagnostic Labs, in New York, about MRSA and other potentially dangerous bacteria isolated from bird cultures submitted to the laboratory. He agreed that the lab has seen MRSA isolated from birds. For most pet birds, MRSA will only be contracted by a bird if exposed to it by a human carrying it or from another bird (such as in a situation of a bird sanctuary or boarding facility where it will be exposed to many other birds that have had contact with many humans). The microbiologist has not seen any of the organisms responsible for flesh-eating disease in birds to date.

What is MRSA? MRSA stands for methicillin-resistant Staphylococcus aureus. Staphylococcus, or staph for short, is a group of Gram positive bacteria that live on the skin and in the nose, usually without causing harm. Staph classically looks like a bunch of grapes (called cocci) under the microscope. MRSA is a type of staph that is resistant to several different antibiotic types. There are over 40 different types of staph identified at this time.

In addition to MRSA, there are also methicillin-resistant Staphylococcus non-aureus, usually Staph pseudointermedius. I suppose those could be classified as MRS, since they are not aureus. There are many different groups of staph that are identified by how they act on certain growth media. There are coagulase positive and coagulase negative staph, depending on whether or not they produce coagulase, an enzyme that causes blood clot formation. MRSA are considered so dangerous because they are resistant to many of the commonly prescribed antibiotics.

The next scary organism is Streptococcus pyogenes. Like staph, it is a Gram positive round (coccus) organism, but this one grows in chains. Dubbed "the flesh-eating bacterium," causing necrotizing fasciitis, this is a rare infection of the deeper layers of the skin and subcutaneous tissues which spreads along the tissue planes, making it a very dangerous disease, indeed. Streptococcus or strep for short, are classified into six groups, A-F. Most cases of necrotizing fasciitis are caused by strep in the group A. Other group A strep are responsible for human cases of strep throat and rheumatic fever. Sometimes, other organisms can cause necrotizing fasciitis, including Staphylococcus aureus, Clostridium perfringens and Vibrio vulnificus.

So, how would a pet bird acquire a dangerous bacterial infection anyway? MRSA is carried on the skin and in the nose of healthy people (and some pets). A person or animal that has been found to carry the bacteria but does not show signs of disease is called "colonized." A person or animal that is sick from the bacteria is called "infected." There are two types of MRSA: CA-MRSA, called community associated MRSA, usually from skin infections. This form of MRSA is thought to be the major factor in the rise of MRSA infections in animals. Not all humans or animals who encounter MRSA will become sick from it. It appears those only a small percentage of those infected become ill, as most eliminate the organism or may become colonized without developing any symptoms. Healthy individuals may carry MRSA for months or years without becoming ill.

The other form of MRSA is a hospital-acquired one, abbreviated HA-MRSA. These types of infections usually occur in people with weakened immune systems in hospitals or health care centers.

MRSA is usually spread by direct physical contact with another person (or animal) that is carrying the organism. The organism can also be spread by objects that are contaminated (including towels, bedding, bandages, medical equipment or sports equipment). MRSA can be transmitted from human to animal (reverse zoonoses) or from animal to human (zoonoses). Once exposed to MRSA, animals, including birds, can become colonized and may then transmit the organism to other animals, as well as back to humans (reinfection). Unless a colonized animal or bird is also treated after a human has been diagnosed with a MRSA infection and then effectively treated, the pet can re-transmit the bacterium to a human. Then also human to human infections can occur.

The risk factors for animals and humans contracting MRSA include crowding, skin punctures, scratches or scrapes, contaminated items or surfaces and poor hygiene. While healthy people with healthy skin are at low risk for acquiring a MRSA infection, this has occurred.

Certain birds are at higher risk for acquiring a MRSA skin infection. Risk factors may include living with immunocompromised people, living with human health care workers, living with veterinary clinic personnel or birds that provide therapeutic visits to hospitals, nursing homes or long-term care facilities.

It is agreed that MOST birds that test positive for MRSA or that develop a MRSA infection acquire that infection from their human steward or from a human who has handled the bird or has touched items in the home that birds come in contact with.

A bacterial culture and sensitivity is a relatively simple test that can identify the type of bacteria found in an infection, and will also provide a list of antibiotics that a specific organism is susceptible or resistant to. This test can also be used to identify any humans or birds colonized with MRSA. It is a simple matter to swab the inside of the nostrils of humans to test for MRSA. Cultures can also be taken to test birds for MRSA.

Hand-washing frequently with soap and hot water is the best way to prevent the introduction of dangerous bacteria into your body and your home. Avoid touching your face during the day, especially your nose, as that is one possible way to introduce MRSA bacteria. Consult your avian veterinarian for advice about preventing the introduction of potentially dangerous organisms into your home and pet birds.

Cadeusus
Copyright 2013 Margaret A. Wissman, D.V.M., D.A.B.V.P.
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