Stenotrophomonas (Xianthomonas) maltophilia as an emerging opportunistic pathogen in association with HIV infection:: A 10-year surveillance study

Background: Stenotrophomonas (Xanthomonas) maltophilia has been increasingly reported as a nosocomial opportunistic pathogen, responsible for serious infectious complications in immunocompromised patients. At present very Limited information is available concerning its clinical significance in the setting of HIV infection. Patients and Methods: A retrospective survey of clinical and microbiological records of 1,374 HIV-infected patients referring to our tertiary care center during a 10-year period (1991-2000) was performed to identify all episodes of S. maltophilia infection and analyze epidemiological, clinical and Laboratory variables. The episodes of S. maltophilia bacteremia were compared with those caused by non-typhoid Salmonella spp. occurring in HIV-infected patients referring to our center during the same period, in order to evaluate eventual predisposing risk factors. Results: 61 episodes of S. maltophilia infection were observed in 59 HIV-infected patients: sepsis/bacteremia in 48 cases (78.7%), Lower airways infection in five, urinary tract infection in four, pharyngitis in two, Lymphadenitis and Liver abscess in one case each. 47 of 61 episodes (77%) of S. maltophilia infection occurred as nosocomial disease (i.e. were diagnosed after the 3rd day of hospitalization) and bacterial isolates showed an elevated resistance profile against many beta-lactam compounds, aztreonam, imipenem and aminoglycosides. At the same time, 38 episodes of bacteremia due to non-typhoid Salmonella spp. were diagnosed in our patients, 13 of which were nosocomial infections. Conclusion: When compared with non-typhoid Salmonella spp. bacteremia, a significantly higher risk of developing S. maltophilia disseminated infection was seen in association with advanced immunodeficiency, Leukopenia-neutropenia, central venous catheterization, prior broad-spectrum antimicrobial therapy and/or corticosteroid treatment.