Legion of Doom

A healthy 45yM presents to your ED at Canadian Janus General Hospital with complaints progressive weakness, lethargy, fever, diarrhea and shortness of breath over the past five days. This morning his wife found him to be drowsy, off-balance and slurring his speech at times.

At triage, his vitals are: HR 122 BP 140/90 RR 24 Temp 38.5C O2 Sat 87% on room air

The patient complains of myalgias and vague disorientation. He denies travel, but reports that his wife was sick with a flu-like illness last week and improved on a “Z-pack”. He hasn’t urinated yet today.

On exam, you repeat his BP, and now it’s 160/105. On a NRB mask, his O2 sat is 93%. He seems anxious. His speech is slightly dysarthric but he is alert, oriented and follows commands. There is no lymphadenopathy, and his throat is clear. CVS exam is unremarkable. Auscultation of his chest reveals decreased air entry to the right base with crackles. There is no peripheral edema.

You order some labs and a CXR as well as 2L of crystalloid bolus and antibiotics, suspecting pneumonia (azithromycin and ceftriaxone).

CXR is first to come back:


A large right-sided infiltrate with possible effusion.

The labs start to trickle in: WBC is 17, Hb 118. Na is 129, K is 5.8 and Creatinine is 560. Lactate is 4.6

The patient continues to be tachycardic at 105 despite 2L of saline and BP is now 195/115. He hasn’t produced any urine yet.

Assessment: Community acquired pneumonia (CAP) with severe sepsis and acute kidney injury (AKI).

So is this run-of-the-mill CAP with sepsis and “pre-renal” AKI? You recount the history and physical and scrutinize the labs more carefully. With neurologic findings, GI involvement and AKI, you become suspicious of Legionella pneumophila and order a Legionella Urinary Antigen test and call your ICU staff on call and at the same time call your nephrologist to give a “heads up.”

A bit about L. pneumophila or Legionnaires Disease:

  • Gram Negative Aerobic Bacillus (1)
  • Incubation is 2-14 days (1)
  • Signs and symptoms can include any of the following (2): Fever; SOB/tachypnea, chest pain, focal crackles; interestingly, cough may be absent or minimal; extrapulmonary symptoms such as diarrhea, altered mental status/dysarthria/ataxis, acute renal failure
  • Mortality has been reported as 5-30%! (3)
  • Reservoirs include: naturally found fresh water sources such as rivers/lakes/ponds; also plumbing/water heaters/spas (1)
  • According to the CDC, specific testing for Legionella (usually urinary antigen – 70-100% sensitive and 100% specific) should be considered in the following conditions: When outpatient antibiotic therapy has failed; severe pneumonia requiring intensive care; immunocompromised; in the setting of a legionellosis outbreak; travel history or suspected of healthcare-associated pneumonia

The mainstay of treatment, of course, is antibiotics. According to the Public Health Agency of Canada website, antibiotic susceptibility is as follows:

  • L. pneumophila is susceptible to macrolides, tetracycline, respiratory quinolones (moxifloxacin and levofloxacin), and aminoglycosides
  • Beta-lactam antibiotics such as penicillins and cephalosporins are not effective

In Canada, the USA and many other countries, Legionnaires Disease is a reportable illness to the local public health authorities.

Case resolution

The patient’s blood pressure remained high, and after over 5 L of crystalloid and persistent severe oliguria, he was admitted to the ICU and started on emergent hemodialysis. The minimal urine sample provided tested positive for Legionella antigen. He was maintained on azithromycin and his respiratory symptoms improved. Renal function returns slowly and dialysis discontinued on the tenth day of hospital stay. A collection of water from a roof leak was identified by family three days after hospital admission, presumed to be the source.

Take-home Points

  • In a patient with pneumonia plus extra-pulmonary symptoms, especially AKI/GI/neurologic,  think Legionella.
  • In a patient with severe pneumonia requiring ICU, think Legionella.
  • Legionella = bad. High mortality!
  • Antibiotic choice: macrolides or respiratory quinolones.


  1. Public Health Agency of Canada website http://www.phac-aspc.gc.ca/lab-bio/res/psds-ftss/legionella-eng.php
  2. e-Medicine “Legionnaire’s Disease” http://emedicine.medscape.com/article/220163-overview
  3. Center for Disease Control (CDC) website http://www.cdc.gov/legionella/clinicians.html

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