Legionella spp. Causes Pneumonia and Respiratory Failure in a Patient

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A 62-year-old female presents to the hospital with severe pneumonia and respiratory failure, along with renal and bone marrow failure. One year prior to admission, the patient underwent a bone marrow transplant for multiple myeloma. Patient has since been under treatment for multiple myeloma. Several clinical specimens such as sputa and endotracheal aspirate were sent to the clinical microbiology laboratory for culture.

Lab Testing

Based on the patients’ clinical diagnosis, a respiratory culture was set up on both the sputum and endotracheal aspirate. In addition to routine bacteriology, culture media for fastidious respiratory pathogens was also inoculated. The incubation growth of the routine bacteriology culture was negative, however growth on the fastidious media (Buffered Charcoal Yeast Extract (BCYE)) was positive for gram-negative rods. The organism was subsequently identified as Legionella spp. Growth of opalescent, blue-green colonies was detected on BCYE agar.

Cause of Symptoms

Legionella spp. is the causative agent of Legionnaires Disease. The most common species isolated is Legionella pneumophila serogroup 1. Legionella spp. can cause a spectrum of disease, Legionnaires Disease (pneumonia) or Pontiac Fever (respiratory disease with the absence of pneumonia). Symptoms can include pneumonia, memory loss, confusion, cough, fever and chest pain. No human-to-human transmission has been documented. Legionnaires Disease acquired its name in 1976 when an outbreak of pneumonia occurred among people attending an American Legion convention in Philadelphia.

Legionella spp. is found naturally in fresh water and can contaminate water tanks and cooling towers of large air conditioners, which can often be the source of exposure to humans. Legionnaires Disease is a serious infection with a case fatality rate of 5-40%.


Patient was treated with levofloxacin (fluoroquinolone) and recovered. Alternative regimens can include azithromycin and doxycycline.

Contact Information

Nicole Jackson, clinmicro@asmusa.org