Stenotrophomonas maltophilia (S. maltophilia) infection is a type of bacterial infection. S. maltophilia is found mostly in wet environments. In the hospital setting, S. maltophilia can be found in fluids, such as irrigation solutions (fluids used to clean a wound or wash out a body cavity like the ear canal or bladder) and intravenous (IV) fluids, as well as patient secretions, such as mucus from the respiratory tract and urine. The bacteria causes problems mainly in people who have a weakened immune system. To cause infections in healthy people, S maltophilia must bypass the normal human defenses, as can happen with the use of certain medical devices, such as catheters or IV lines. People who are hospitalized and receiving treatment for other serious medical conditions may be more susceptible to an infection, especially if their immune system is weakened. Symptoms vary depending on the area of the body infected.

Diagnosis of S. maltophilia infection, along with other bacterial infections, may be suspected by symptoms and risk factors. A culture of body fluids, such a blood, urine, sputum, or abdominal fluid, is used to confirm the specific type of bacteria. A consultation with an infectious disease specialist is important to differentiate bacterial colonization (where the bacteria are found in the body but do not cause symptoms) from an infection and to determine the best treatment options.

Stenotrophomonas maltophilia (S. maltophilia) infection depend on which area of the body or organ system is infected. The most common sites of infection are the lungs and blood. When the lungs are infected, symptoms of S. maltophilia are similar to other bacterial pneumonia and may include fever, cough, mucus, shortness of breath, and chest pain. Symptoms of a blood infection (bacteremia) may include a fever, rapid heart rate, low blood pressure, abdominal pain, nausea, vomiting, diarrhea, and confusion.

Less commonly, people infected by S. maltophilia experience infections of the heart (endocarditis), the bone behind the ear (mastoiditis), lining of the abdomen and internal organs (peritonitis), cerebral spinal fluid (meningitis), soft tissue, wounds, urinary tract, and/or eye. The symptoms are similar to other bacterial infections of the same sites. An infection can also cause skin symptoms or complications such as cellulitis, infected ulcers, and ecthyma gangrenosum.

Stenotrophomonas maltophilia (S. maltophilia) infections are caused by the S. maltophilia bacteria. These bacteria live in wet environments. In a hospital setting, they are able to survive and multiply in fluids such as mucus of the respiratory system, urine, intravenous (IV) fluids, and irrigation fluids used to clean wounds or body cavities such as the ear canal or bladder. S. maltophilia can also grow in medical devices exposed to these fluids including urinary catheters, IV lines, and breathing machines (ventilators).

Most healthy people do not get S. maltophilia infections even when exposed to the bacteria. However, people who are hospitalized and receiving treatment for other serious medical conditions may be more susceptible to an infection, especially if their immune system is weakened. Factors that increase the risk for S. maltophilia infection include admission to an intensive care unit (ICU), prolonged hospitalization, HIV infection, cancer, cystic fibrosis, neutropenia, recent surgery, serious trauma or injury, being on a breathing machine (ventilator), and previous treatment with broad-spectrum antibiotics (medications that target a wide range of bacteria).

Stenotrophomonas maltophilia (S. maltophilia) infection is usually suspected when there are symptoms of a bacterial infection along with certain risk factors. A small sample of body fluid such as blood, mucus, urine, or abdominal fluid will be cultured to confirm which bacteria is causing the infection. When an infection is suspected, other possible sites of infection including wounds, intravenous (IV) catheters, urinary catheters, and breathing machines should also be tested for the presence of thebacteria.

Because S. maltophilia may sometimes grow in parts of the respiratory system or other parts of the body without causing infection (colonization), an infectious disease specialist should be consulted to determine if there is a true infection.

Stenotrophomonas maltophilia (S. maltophilia) infection will depend on many factors including the site of the infection, severity of the infection, response to antibiotics, and presence and severity of other health problems. S. maltophilia infections may be life-threatening, especially for people with severely weakened immune systems.