Pneumonia caused by Shigella sonnei with an atypical clinical presentation

BACKGROUND: Pneumonia caused by shigellosis with or without typical dysentery in immunocompetent patients is an uncommon entity. CASE REPORT: We describe a case of pneumonia in an immunocompetent, previously healthy middle-aged man from Switzerland without relevant travel history which was presumably caused by Shigella sonnei. He was originally admitted for suspected lung cancer. The clinical picture was remarkable as the patient presented with cough and purulent sputum production, but otherwise no classical signs of pneumonia. Furthermore, there was no diarrhoeal episode in the recent history. It is an uncommon presentation of shigellosis in an immunocompetent person without underlying severe predisposing conditions. CONCLUSION: We report an unusual identification of S. sonnei as the only identified pathogen from respiratory specimens, which we therefore consider the most likely etiology of this subacute atypical pneumonia. This case illustrates the importance of a complete work-up in a patient whose suspected malignancy could not be proven.