Pulmonary coinfection by Salmonella enteritidis and Pneumocystis carinii in a patient with the acquired immunodeficiency syndrome

A Molecular Window into the Biology and Epidemiology of Pneumocystis spp

Pneumocystis, a unique atypical fungus with an elusive lifestyle, has had an important medical history. It came to prominence as an opportunistic pathogen that not only can cause life-threatening pneumonia in patients with HIV infection and other immunodeficiencies but also can colonize the lungs of healthy individuals from a very early age. The genus Pneumocystis includes a group of closely related but heterogeneous organisms that have a worldwide distribution, have been detected in multiple mammalian species, are highly host species specific, inhabit the lungs almost exclusively, and have never convincingly been cultured in vitro, making Pneumocystis a fascinating but difficult-to-study organism. Improved molecular biologic methodologies have opened a new window into the biology and epidemiology of Pneumocystis. Advances include an improved taxonomic classification, identification of an extremely reduced genome and concomitant inability to metabolize and grow independent of the host lungs, insights into its transmission mode, recognition of its widespread colonization in both immunocompetent and immunodeficient hosts, and utilization of strain variation to study drug resistance, epidemiology, and outbreaks of infection among transplant patients. This review summarizes these advances and also identifies some major questions and challenges that need to be addressed to better understand Pneumocystis biology and its relevance to clinical care.

An unusual case of Salmonella Enteritidis causing pneumonia, septic shock and multiple organ failure in an immunocompetent patient

Salmonella species are facultative intracellular pathogens that most frequently cause self-limiting gastrointestinal disease, often acquired through the ingestion of contaminated food. We report the case of a 33-year-old otherwise healthy, not overtly immunosuppressed, man who was transferred to our facility with the chief complaint of respiratory failure and septic shock. Computed tomography of the chest revealed multifocal pneumonia in both lungs. A bronchial alveolar lavage was performed in the right middle lobe and cultures predominantly grew Salmonella enterica serovar Enteritidis. The patient received a prolonged course of antimicrobials, ultimately changing to oral levofloxacin. The etiology of the salmonella infection likely occurred through an aspiration event. Salmonella species are not a typical respiratory pathogen in immunocompetent hosts; however, clinicians should be aware of the possibility that salmonella species may be a pathogenic source of infection in the lungs; a prolonged course of antimicrobials may be warranted.