Legionella Infection Follow-up

Updated: Nov 13, 2018
  • Author: Mobeen H Rathore, MD, CPE, FAAP, FIDSA; Chief Editor: Russell W Steele, MD  more...
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Further Outpatient Care

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  • Outpatient treatment with oral antibiotics may be considered for selected patients with mild disease if they can be closely monitored for signs of deterioration.

  • Continue outpatient treatment after the patient is discharged from the hospital until antibiotic therapy is completed and symptoms resolve.


Further Inpatient Care

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  • Most patients with Legionnaires disease (LD) require initial hospitalization for intravenous antibiotics.

    • Closely monitor patients for signs of shock and/or respiratory or multiorgan failure and the need for ICU care.

    • Patients who begin to steadily improve can be switched to oral antibiotics.

    • Continue to monitor patients in the hospital for at least 1 day after switching to oral antimicrobial therapy because relapse is possible.

  • Patients with Pontiac fever do not require hospitalization.


Inpatient & Outpatient Medications

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  • See Medication.



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  • Patients with Legionnaires disease do not require contact or respiratory isolation (person-to-person transmission has never been demonstrated). Standard precautions are recommended. [1]

  • For water births, the colonization of tap water with Legionella can be reduced by installation of a filter system into the supply hose of the birthing tub.

  • Strategies the Centers for Disease Control and Prevention (CDC) recommend to prevent healthcare-associated (HCA) Legionnaires disease include the following:

    • Maintain a high index of suspicion for the diagnosis of HCA Legionnaires disease, and perform appropriate laboratory tests for Legionnaires disease.

    • Facilities with transplantation programs should consider routine Legionella cultures of water samples from the potable water systems as part of the facilities comprehensive program to prevent and control HCA Legionnaires disease.

    • Maintain potable water at the outlet at temperatures not suitable for the growth of Legionella species.

    • Cooling towers should receive routine maintenance, and only sterile water should be used to fill and rinse respiratory therapy devices.

    • Initiate an investigation for the source of Legionella organisms when one case of Legionnaires disease is identified in an inpatient transplant recipient or when 2 cases occurring within 6 months of each other are identified in transplant recipients who visited an outpatient unit during the 2-10 months before the onset of illness.

    • If the water system is implicated, decontaminate the system by superheating water to 71-77°C, and maintain until distal sites are flushed. If thermal shock is not possible, use shock chlorination as an alternative. [37]

  • Some experts have recommended to culture the tap water of pediatric hospitals, especially to sample the higher risk areas (eg, NICU, PICU, transplant units) for Legionella. Children with hospital-acquired pneumonia in hospitals with positive surveillance cultures should undergo Legionella testing. [38]

  • Additionally, it has been recommended that transplant recipients boil their water, cool it, and store it for drinking. [39]



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  • The following complications may persist for weeks to months after disease onset:

    • Empyema

    • Pulmonary cavitation

    • Bullous emphysema

    • Renal failure

    • Memory loss

    • Fatigue

    • Neurologic disorders

    • Multiorgan failure

  • Legionnaires disease can be fatal.



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  • With early initiation of appropriate therapy, most patients experience defervescence and symptomatic improvement within 3-5 days.

  • Factors that predict a poor outcome include advanced age, underlying disease (including prematurity), delayed therapy, and respiratory failure.

  • Subsequent episodes are rare.