Lung abscess due to nontyphoid Salmonella in an immunocompromised host. Case report with review of the literature.

Lung abscess due to nontyphoid Salmonella (NTS) with or without other intestinal or extra-intestinal involvement is very rare. A literature review (Medline search) revealed only 20 cases including ours with this extra-intestinal manifestation of Salmonella infection. The case of a 49-year-old, HIV-positive man from Zaire is reported. Diagnosis was established by direct transthoracal CT-guided puncture of the abscess, a hitherto not reported procedure in this setting. Treatment with oral ciprofloxacin resulted in clinical and radiographic improvement. Underlying immunodeficiency seems to play an important role, but the real pathophysiological mechanisms remain unsolved. It is particularly seen in HIV-positive patients with impaired cellular immunity since Salmonella is an intracellular pathogen whose eradication involves natural killer cells and antibody-induced cellular cytotoxicity. A possible explanation is that NT-Salmonella bacteraemia is much more frequent in AIDS-patients as compared to the general population. Salmonella bacteraemia can then spread to other tissues and organs such as the lungs, but why only the lungs are involved in some cases remains unclear. The characteristics of Salmonella lung abscess is discussed and the literature reviewed.