[Legionella and Legionellosis]

Area of Science:

• Medical Microbiology
• Infectious Diseases
• Pulmonology

Background:

• Diagnosed Legionella pneumonias show a slight increase in recent years.
• Increased diagnostic testing may contribute to the observed rise in reported cases.
• Legionella is a significant cause of community-acquired and hospital-acquired pneumonia.

Purpose of the Study:

• To review current diagnostic and treatment strategies for Legionella pneumonia.
• To evaluate the role of nucleic acid amplification methods and antibiotic efficacy.
• To provide updated treatment guidelines for confirmed legionellosis.

Main Methods:

• Review of recent in vitro data on antibiotic efficacy.
• Analysis of clinical cohort data for treatment outcomes.
• Evaluation of diagnostic test performance, including urinary antigen tests and nucleic acid amplification methods.

Main Results:

• Nucleic acid amplification tests offer improved spectrum and sensitivity over urinary antigen tests for severe pneumonia.
• Levofloxacin demonstrates enhanced efficacy compared to macrolides in vitro and in clinical cohorts.
• A 7-day treatment duration is generally sufficient for most legionellosis cases.

Conclusions:

• Levofloxacin (750-1000 mg/d) is the recommended treatment of choice for confirmed Legionnaires' disease.
• Azithromycin or moxifloxacin serve as second-line treatment options.
• Routine resistance testing for Legionella is not necessary due to rare development of resistance.