Pseudomonas Infections
Pseudomonas infections are caused by any of several types of the gram-negative bacteria Pseudomonas, especially Pseudomonas aeruginosa.
Pseudomonas is present throughout the world in soil, water, and on the skin of animals and people. Pseudomonas favors moist areas, such as sinks, toilets, pools, and hot tubs, and usually can withstand standard levels of pool chlorination. The bacteria have even been known to live in antiseptic solutions.
Pseudomonas can cause minor skin infection or serious, life-threatening illness. The most serious infections from Pseudomonas develop in debilitated and hospitalized people, particularly those with a weakened immune system. People with diabetes are particularly prone to Pseudomonas infections. Pseudomonas can infect the blood, skin, bones, ears, eyes, urinary tract, heart valves, and lungs.
Symptoms and Diagnosis
Two minor Pseudomonas infections that can affect otherwise healthy people are swimmer's ear and hot-tub folliculitis. Swimmer's ear (otitis externa) is infection of the external ear canal that produces pain and drainage (see Section 19, Chapter 219). Hot-tub folliculitis is an itchy skin rash consisting of tiny pimples, some of which may contain a drop of pus in their center (see Section 18, Chapter 211).
Malignant external otitis, a deeply penetrating Pseudomonas ear infection, can cause severe ear pain and nerve damage and is most common in people with diabetes.
Pseudomonas can cause ulcers in the eye after gaining entry through an eye injury, a contaminated contact lens, or contaminated contact lens fluid. The ulcers are painful and may lead to a loss of vision. Pseudomonas can cause infection in deep puncture wounds, especially those occurring in the feet of children. When Pseudomonas infects a wound, growth in the soiled dressings often gives off a characteristic fruity odor.
Pseudomonas can cause severe pneumonia in hospitalized people, especially those in intensive care. Pseudomonas can also cause urinary tract infections, usually in people who have had urologic procedures or those who have an obstruction of the urinary tract.
These bacteria often invade the blood of people with burns and those who have cancer. Without treatment, an overwhelming infection can lead to dangerously low blood pressure (shock) and death. The infection usually causes purple-black spots to appear on the skin. These spots are about 3/8 inch in diameter with a sore at the center surrounded by redness and swelling. The spots often occur in the underarm and groin.
Rarely, Pseudomonas infects heart valves. People who have received an artificial heart valve are more vulnerable; however, natural heart valves can be infected, especially in injecting drug users.
Doctors diagnose Pseudomonas infections by growing the bacteria in cultures of blood or other body fluids.
Prevention and Treatment
Swimmer's ear can usually be prevented by irrigating the ears with a mixture of alcohol and acetic acid before and after swimming. If infection is treated with acetic acid drops and locally applied antibiotics, it usually improves quickly. Hot-tub folliculitis usually goes away without treatment.
Pseudomonas eye infections are treated with highly concentrated antibiotic drops. Sometimes, antibiotics must be injected directly into the eye.
Serious Pseudomonas infections are difficult to treat. Malignant external otitis, internal infections, and blood infections require weeks of intravenous antibiotic therapy, usually with a combination of antibiotics. Sometimes an infected heart valve can be cured with antibiotics, but often open-heart surgery to replace the valve is needed (see Section 3, Chapter 28).
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