Stenotrophomonas maltophilia, a Pathogen of Increasing Relevance to Dermatologists: A Case Report and Review of the Literature

Abstract

Stenotrophomonas maltophilia is a Gram-negative bacillus that causes skin and soft tissue infections (SSTI), as well as bacteremia, pneumonia, and urinary tract infections. S. maltophilia infections are typically nosocomial and are often transmitted through water sources. Although historically described in immunocompromised hosts, S. maltophilia prevalence is increasing in both immunocompromised and immunocompetent populations. In light of high morbidity and mortality, it is critical that dermatologists are aware of this organism because of the limited options for therapy. Here, we describe a case of a S. maltophilia abscess with bacteremia in a patient with chronic lymphocytic leukemia and aplastic anemia that was successfully treated with trimethoprim-sulfamethoxazole. We also review the current standard of care and propose an algorithm for the treatment of S. maltophilia infection.

Keywords: Gram-negative bacteria; Stenotrophomonas maltophilia; multidrug-resistant; nosocomial infection; skin and soft tissue infection.

Figure 1

Dermatologic examination demonstrated a purple-red indurated nodule with central ulceration and yellow crust in the right groin.

Figure 2

Histopathology (hematoxylin and eosin) demonstrated numerous organisms with a rod to focally filamentous morphology, as well as edema, dilated blood vessels, extravasated erythrocytes, and mixed inflammatory infiltrate at 40× (a), 200× (b), and 400× (c). Gram stain confirmed the presence of Gram-negative organisms, consistent with S. maltophilia (d, 400×). Individual organisms were visualized at the edge of the tissue specimen (arrows).

Figure 3

At follow up, the nodule had decreased in size and induration with interval improvement of the erythema, ulceration, and crust.

Figure 4

Diagnostic and treatment algorithm for the patient with suspected S. maltophilia SSTI. ^† In the case of sulfonamide allergy, desensitization may be pursued. If this is not possible, treatment with levofloxacin or minocycline should be initiated if the culture demonstrates sensitivity. * Consider combination therapy such as trimethoprim–sulfamethoxazole plus a third-generation cephalosporin or extended-spectrum penicillin [15].