What Infections Do Bacteria Cause?
Bacteria are single‑celled organisms found worldwide. Some live in soil or water, but others live normally on the skin or in the airways, mouth, digestive tract, or urinary tract. Some usually cause disease, some cause disease only under certain conditions, and many are harmless.
Wounds in your pet's skin can allow bacteria to enter the body. These bacteria might be normal skin bacteria or come from dirt or other environmental sources. Puncture wounds often trap bacteria in the skin and form abscesses (pockets of pus). Some abscesses respond to treatment with antibiotics alone, but others must be opened surgically and drained, in addition to being treated with an antibiotic.
Bacterial infections also occur inside the body. Examples include:
food poisoning from bacteria in spoiled food
tooth root abscesses from mouth bacteria, usually if there is gum disease or a broken tooth
infections in organs like intestines or kidneys when these organs are damaged
infections after surgery, which is why antibiotics are sometimes given around the time of an operation
Bacteremia and Sepsis
Bacteria often enter the bloodstream, but usually in small numbers that are quickly removed by white blood cells. When many bacteria enter the bloodstream (a condition called bacteremia) or the body can't remove them effectively, a serious bloodstream infection called sepsis can develop.
Sepsis is less common and more serious than bacteremia, and it can develop when bacteremia spreads bacteria through the bloodstream to different parts of the body, causing an overwhelming reaction by the immune system. IV lines, surgical drainage tubes, and other foreign objects in the body (like metal plates, screws, or wires implanted to help broken bones heal) increase sepsis risk, especially if left in place for a long time. Animals with weakened immune systems are at higher risk for developing sepsis. Most, but not all, cases of sepsis are caused by bacteria.
Without prompt treatment, sepsis can be fatal to animals. Bacteremia can spread to many organs, causing inflammation and infection:
meningitis (inflammation and infection of the brain)
pericarditis (inflammation and infection of the sac around the heart)
osteomyelitis (bone inflammation and infection)
infectious arthritis (joint inflammation and infection)
abscesses in various organs, especially from staph bacteria
Sepsis is an emergency that can lead to collapse and shock. Antibiotics must be started immediately. Waiting decreases survival chances. At first, one or more antibiotics effective against a wide variety of bacteria are chosen, based on the likely source of infection. Often 2–3 antibiotics are used together. Once culture results demonstrate which bacteria are present and what drugs are best used to kill them, antibiotics might be changed to those that are most effective. Surgery is sometimes needed to remove the source of infection.
Septic Shock
Septic shock is a life‑threatening condition in which sepsis causes blood pressure to drop dangerously and the body's organs to fail. Animals with low white blood cell counts or other chronic diseases are especially at risk for developing sepsis.
As septic shock progresses, multiple organs in the body fail:
Kidneys produce little or no urine, causing toxic waste products to build up in the bloodstream.
Lungs fail to function properly so that the body suffers from a lack of oxygen.
The heart can fail, causing fluid buildup and swelling in the body's organs.
Blood clots can form inside blood vessels.
Any animal with sepsis or septic shock must be treated aggressively in the hospital with many drugs, and often multiple antibiotics. Even with proper treatment, some animals do not survive.
