Legionella infection

Legionella infection - Acute
Rahul Soman, M. Pharm

 

Definition  

Infection caused by a member of the genus Legionella

 

Medical History  

* Environmental Exposure

* Smoking

* Chronic obstructive pulmonary disease

* Patient immunocompromised

* Transplantation

* Mechanical ventilation [Mechanical ventilation]

* Pulmonary aspiration

 

Findings  

* Fever

* Cough

* Dyspnea - Acute

* Chest pain - Acute

* Diarrhea - Acute

* Headache

* Altered mental status

 

Tests  

 

Suspected legionellosis in hospitalized patients with community acquired pneumonia  

* Legionella urine antigen: The Legionella urinary antigen test is positive on day 1 of illness and for weeks thereafter .

 

Suspected Legionnaire's disease  

* Legionella species culture: A positive culture for Legionella species is diagnostic of acute Legionella infection; culture may be falsely negative .

 

Suspected Legionella pneumonia  

* Plain chest X-ray: Chest radiographic findings are nonspecific and cannot be used to reliably differentiate pneumonia due to Legionella from other bacterial pneumonia .

 

Suspected Legionella pneumonia  

* Sodium measurement, serum: Hyponatremia is seen more often in Legionella pneumonia than pneumonia due to other organisms, but the finding alone cannot reliably distinguish two .

* Serum creatine kinase measurement: An elevated creatine kinase is seen in Legionella pneumonia, but the finding alone cannot reliably diagnose the disease .

* Hepatic function panel: Hepatic dysfunction occurs more often in Legionella pneumonia than in other types of pneumonia .

 

Hospitalized patients with community acquired pneumonia  

* Gram stain, sputum: Sputum Gram stain is indicated in some hospitalized patients, broadens initial empiric antibiotic coverage for less common etiologies, and validates sputum culture results .

 

Suspected or known community-acquired pneumonia  

* White blood cell count: A WBC count less than 4,000 cells/mm3 is an indicator of severe pneumonia and the need for more extensive initial diagnostic testing .

 

Differential Diagnosis  

* Legionella pneumonia

* Pontiac fever

* Extrapulmonary legionella infection

* Pneumococcal pneumonia

* Mycoplasma pneumonia

* Chlamydia pneumoniae pneumonia

* Staphylococcal pneumonia

* Viral pneumonia

* Influenza

* Pulmonary embolism - Acute

 

Treatment  

 

Drug Therapy  

 

Suspected and known Legionella infection  

 

AZITHROMYCIN  

Adults: 500 mg IV or orally once daily; may switch to oral therapy once patient is clinically stabilized; total course, 7 to 10 days

 

LEVOFLOXACIN  

Adults: 750 mg IV or orally once daily; may switch to oral therapy once patient is clinically stabilized; total course, 10 to 21 days

 

MOXIFLOXACIN HYDROCHLORIDE  

Adults: 400 mg IV or orally once daily; may switch to oral therapy once patient is clinically stabilized; total course, 10 to 21 days

 

GEMIFLOXACIN MESYLATE  

Adults: 320 mg orally daily for 10 to 21 days

 

 

Fever  

 

ACETAMINOPHEN

Adults: 650 to 1,000 mg orally every 4 to 6 hours as needed (maximum 4 g/day)

Pediatrics: 10 to 15 mg/kg orally or rectally every 4 to 6 hours as needed (maximum 5 doses or 4 g/day)

 

IBUPROFEN

Adults: 200 to 800 mg orally every 6 to 8 hours as needed (maximum 3.2 g/day)

Pediatrics: 5 to 10 mg/kg orally every 6 to 8 hours as needed (maximum, lesser of 40 mg/kg/day or 2.4 g/day)

 

To prevent patients with pneumonia from developing future complications of pneumococcal infection  

 

PNEUMOCOCCAL VACCINE POLYVALENT  

 

Patients with community-acquired pneumonia at risk for influenza  

 

INFLUENZA VIRUS VACCINE (SUBVIRION)  

Adults: 0.5 mL IM once annually

Pediatrics (6-35 months): 0.25 mL IM for 1 or 2 doses (second dose is recommended for vaccine-naive children and should be given at least 4 weeks after first dose)

Pediatrics (3-8 years): 0.5 mL IM for 1 or 2 doses (second dose is recommended for vaccine-naive children and should be given at least 4 weeks after first dose)

Pediatrics (?9 years): 0.5 mL IM once annually

 

Procedural Therapy  

 

Hypoxic, hospitalized patients with community acquired pneumonia  

* Oxygen therapy: The goal of supplemental oxygen is to maintain a PaO2 of 8 kPa or higher and an SaO2 of 92% or higher .

 

Selected patients with acute respiratory failure caused by severe community-acquired pneumonia  

* Noninvasive positive pressure ventilation: In certain patients, noninvasive positive pressure ventilation decreases the need for intubation and decreases length of ICU stay .

 

Respiratory distress  

* Airway management: Airway management must assume the first priority in the management of any seriously ill or injured patient .

 

Dehydration  

* Intravenous fluid replacement: Intravenous fluid replacement is indicated for patients with dehydration when oral replacement cannot be accomplished .

 

Non-Procedural Therapy  

 

Cigarette smoker  

* Smoking Cessation