Pseudomonas aeruginosa is a type of bacteria commonly found throughout the environment, in places like soil and water. While it can cause mild illnesses in healthy individuals, it poses a more significant threat to those with pre-existing health conditions or in healthcare settings. The term “multidrug-resistant” (MDR) means a strain of this bacterium can withstand multiple antibiotics. This resistance makes infections difficult to treat and is a major concern in hospitals and long-term care facilities. In 2017, MDR P. aeruginosa was responsible for an estimated 32,600 infections among hospitalized patients in the United States alone.
How Infections Occur and Who is at Risk
Pseudomonas aeruginosa is an opportunistic pathogen, meaning it primarily causes illness in individuals whose natural defenses are already lowered. The bacterium is widespread in nature, thriving in moist environments and even on the surfaces of fresh produce. In healthcare facilities, it can contaminate medical equipment, sinks, and other surfaces, becoming a source of transmission. The bacteria can spread through contact with these contaminated surfaces or from the hands of healthcare workers.
Patients in hospitals, particularly those in intensive care units (ICUs), face a heightened risk. The use of medical devices that bypass the body’s natural barriers, such as breathing machines (ventilators) and urinary or intravenous catheters, creates entry points for the bacteria. Individuals with extensive surgical wounds or severe burns are also highly susceptible, as their primary defense, the skin, is compromised.
The state of a person’s immune system is another factor. Patients undergoing chemotherapy for cancer or those with conditions that weaken the immune system, like HIV, are at increased risk. Similarly, individuals with chronic lung diseases, most notably cystic fibrosis, are particularly vulnerable to persistent lung infections with P. aeruginosa. In these patients, long-term infection can lead to the bacteria developing resistance to numerous antibiotics.
Signs and Symptoms of Infection
The specific signs of a Pseudomonas aeruginosa infection are directly related to the part of the body affected. An infection in the lungs, known as pneumonia, can cause symptoms such as fever, chills, and difficulty breathing. A cough that produces greenish or bloody mucus may also be present.
When the bacteria enter the bloodstream, a condition called bacteremia, it can lead to a systemic and life-threatening response. Patients may experience high fever, chills, and profound fatigue. This can progress to sepsis, which involves a rapid heart rate, a dangerous drop in blood pressure, and can lead to shock and organ failure.
Infections can also localize in other areas. A urinary tract infection (UTI) from P. aeruginosa causes a frequent or painful need to urinate, sometimes with fever and abdominal pain. If the bacteria colonize a burn or surgical wound, the site will show signs of inflammation and may produce a distinctive greenish pus or drainage with a grape-like odor. Milder cases include skin rashes or ear infections (“swimmer’s ear”), which cause pain, itching, and discharge.
Diagnosis and Treatment Approaches
Diagnosing a Pseudomonas aeruginosa infection begins with collecting a sample from the suspected site of infection, such as blood, urine, wound drainage, or sputum. The sample is sent to a laboratory to be cultured, a process that grows the bacteria for identification.
Once P. aeruginosa is confirmed as the cause, the next step is antibiotic susceptibility testing. This laboratory test exposes the specific bacterial strain to a panel of different antibiotics to see which ones are effective at stopping its growth. This testing determines if the strain is multidrug-resistant and reveals the limited options for treatment.
Treating MDR P. aeruginosa is challenging because standard antibiotics are often ineffective. Physicians often use combination therapy, with two or more different antibiotics simultaneously. The strategy is that the bacteria may be susceptible to at least one of the drugs. For highly resistant strains, doctors may use newer antibiotics reserved for these infections.
As resistance continues to grow, researchers are exploring alternative strategies. One emerging field is bacteriophage therapy, which uses viruses that naturally infect and kill bacteria. While still largely experimental, phage therapy is a potential future treatment for infections that are unresponsive to all available antibiotics.
Prevention in Healthcare and Community Settings
Preventing the spread of MDR Pseudomonas is a part of patient safety, especially in healthcare environments. Hospitals and clinics follow strict infection control protocols, including rigorous hand hygiene for all staff to prevent moving germs between patients or surfaces. Thorough cleaning and disinfection of patient rooms and medical equipment are also standard.
Further measures in healthcare settings involve sterilizing all surgical instruments. For patients who are known to be carrying an MDR organism, isolation precautions may be implemented. This may involve placing the patient in a single room and requiring staff to wear gowns and gloves. Healthcare facilities are also encouraged to maintain a water management plan to reduce bacterial growth in the building’s water systems.
Outside the hospital, at-risk individuals can take steps to reduce their infection risk. This includes avoiding poorly maintained public hot tubs or swimming pools, as these warm, moist environments are ideal for Pseudomonas growth. Practicing good personal hygiene and proper wound care is also important. Keeping any breaks in the skin clean and covered helps prevent bacteria from entering the body.