The Case


Fever and cough


59yF HIV on ART last CD4 716, undetectable VL, HTN, CKD p/w non-productive cough and fever x10d. 5d PTA she presented to the ED for dry cough, had CXR WNL, lab values WNL except Cr 3.2 and was discharged with f/u. Symptoms have continued since and she returns now because she has dyspnea at rest x 1d. Also c/o fatigue, chills and loose stools. She denies chest pain, headache, change in vision, rash, sick contacts or recent travel.


PSH: none
Meds: HAART, losartan, spirinolactone, chlorthalidone, crestor, clonidine, amlodipine

Physical Exam

BP 120/70 HR 104 Resp 20s Sat 92% on 2LNC Temp 102.9F
General: tachypneic but in NAD
CV: tachy, no m/r/g
Pulm: CTA throughout, but tachypneic on 2L O2
Abdomen: protuberant, soft, nondistended, no ttp, rebound or guarding
Neuro: Awake, alert, oriented, normal strength, sensation, coordination
Ext: normal active ROM, no deformities or edema
Skin: no diaphoresis, rashes, or lesions. Warm and dry.


  1. What is your differential for this patient? What’s at the top of your list?

    PNA, aspiration, opportunistic infection, PCP, gastroenteritis, dehydration, etc. Also consider GI infections, HIV related opportunistic infections. Tachypnea with not much on lung exam might also be explained by acidosis.

  2. What are the next steps in management of this patient and your anticipated disposition?

    Management of sepsis including IVF 30cc/kg with good access. Early ABX. Critical care

  3. What one lab test would you send, if you had to clinch the diagnosis?

    Urine Legionella Ag vs sputum culture

More Info


  • The incidence of Legionnares’ disease depends upon the degree of water reservoir contamination, intensity of exposure, and susceptibility of the host
    • Legionella species are aerobic, gram negative bacilli that do not grow on routine bacteriologic media
      • Need to use specialized media, buffered charcoal yeast extract media
      • Growth = 3-5d


  • Source
    • The natural habitats for Legionella are aquatic bodies, including lakes and streams.
    • Man-made reservoirs such as water distribution systems act as amplifiers for the growth and proliferation of the disease
  • Responsible for 1-9% of cases of CAP
  • Incidence has increased in the US and the UK recently, tripling from 2000 to 2009 per the CDC
    • Possible from increased flooding/rainfall vs better testing
  • Hospital acquired
    • Legionella colonizes 12-70% of hospitals (hot water distribution) in specific areas
  • Host risk factors
    • Most common = smoking and chronic lung disease
    • Rate of infection increases with age
    • Transplant recipients = highest risk
    • Steroids and chronic immunosuppression are also RFs
    • Importantly, neutropenia/HIV does not demonstrate higher incidence
      • Although mortality is higher
    • Mode of transmission
      • Inhalation of aerosols
      • Drinking contaminated water
      • Aspiration of contaminated water
      • *Person to person transmission has never been demonstrated (no need for contact)


  • The organism attaches to respiratory epithelial cells and alveolar macrophages
  • Phagocytosis occurs and then the organism evades intracellular destruction
  • Host defense
    • Cell mediated immunity, which is why depression with steroids/autoimmune meds are RFs

Clinical Manifestations

  • PNA is the predominant clinical manifestation
  • However, respiratory symptoms are not prominent initially
    • The cough is at first mild and only slight productive
  • GI symptoms are often prominent with d, n, v, and abd pain
  • Fever is almost always present and is usually >39C
  • Labs can show
    • Renal and hepatic dysfunction
    • Thrombocytopenia
    • Leukocytosis
    • Hypophosphatemia
    • Hyponatremia is also common
  • CXR abnormalities usually in everyone by day 3
    • Patchy unilobular infiltrate progressing to consolidation
  • Pontiac fever
    • Mild disease with fever, chills, fatigue, HA, and no resp Sx
  • Extrapulmonary disease
    • Can mimic many other things, affecting the skin, joints, pancreas, abdomen, and kidneys
    • Most common site is the heart = ex. Myocarditis/pericarditis and rarely endocarditis


  • The most important test = legionella culture of a resp specimen
    • Buffered charcoal yest extract
  • Legionella urinary antigen assay is more readily available, cheap, fast, easy
    • But only tests for L penumophila serogroup 1 (90% of CAP)
    • Useful bc urine will remain positive for days after starting empiric therapy
    • When pretest likelihood is high consider asking lab to run additional assays
    • When pretest probability is high
      • you can test for types 2-6 with a serum test
    • Treatment
      • Macrolides and some quinolones (levofloxacin) are main options
        • Quinolones = rapid defervescence, fewer complications, and shorter hospital stay
        • Levofloxacin = 750mg daily
        • Azithro = 1g day 1, 500mg daily
        • Consider IV treatment when GI symptoms are severe
      • Treat for 7-10d, up to 21d if severe
      • Isolation is not needed, since transmission from person to person does not occur