Stenotrophomonas Maltophilia Differential Diagnoses

Updated: Sep 16, 2021
  • Author: Sara Ahmed, MBBS, FCPS, MRCP(UK); Chief Editor: Michael Stuart Bronze, MD  more...
  • Print

Diagnostic Considerations

The main clinical problem presented by S maltophilia is failing to recognize its significance in the clinical context. The recovery of S maltophilia from respiratory secretions or from the urine of catheterized patients should be regarded as colonization until proven otherwise. S maltophilia is a common cause of catheter-associated bacteruria in hospitalized patients.

S maltophilia commonly colonizes the urine and is potentially pathogenic only in those with impaired host defenses, ie, patients with organ transplants, diabetes, systemic lupus erythematosus (SLE), alcoholic cirrhosismultiple myeloma, and those on steroids or immunosuppressed due to some other reasons.

S maltophilia recovered from blood cultures may have come from contaminated intravenous fluids or from a distant infected source, eg, secondary bacteremia from the urinary tract in a patient who recently underwent instrumentation during a genitourinary (GU) procedure.

S maltophilia recovered from a wound with a clear or a serosanguineous discharge is of no clinical significance. If recovered from a purulent wound, S maltophilia may be the cause of the patient's wound infection.

The most common cause of confusion regarding S maltophilia is assuming that its recovery from body sites implies a pathogenic role, eg, sacral decubitus ulcer/osteomyelitis. It has been reported as a cause of osteomyelitis. [18]  S maltophilia is a rare cause of nosocomial pneumonia in patients who are ventilated and presumed to have nosocomial pneumonia because of fever, pulmonary infiltrates, and leukocytosis. [19] The recovery of S maltophilia from respiratory secretions almost always represents colonization rather than infection, and, unless proven otherwise, its presence should not be addressed therapeutically.

S maltophilia may cause community-acquired pneumonia (CAP) in individuals with alcoholic cirrhosis.

Other common sites of infection include skin and soft tissues, keratitis (especially in contact lens wearers),endopthalmitis and device related infections. [20, 21, 22]

Stenotrophomonashas been reported as a rare cause of nosocomial meningitis and endocarditis. [23, 24]

Table. Hospital-Acquired S maltophilia Infections (Open Table in a new window)


Predisposing Factor

Catheter-associated bacteriuria

Indwelling urinary catheters

Intravenous line infections

Central intravenous catheters


Urinary tract instrumentation

Primary bacteremia

Arterial monitoring devices


Contamination of blood during collection/processing of blood cultures