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Highlights & Basics
- Legionella infection is acquired by inhalation of aerosolized bacteria or, rarely, microaspiration of contaminated drinking water.
- Presentation includes respiratory symptoms such as cough (may not be productive) and shortness of breath, fever, chills, and chest pain. Other symptoms include headache, nausea, vomiting, abdominal pain, or diarrhea.
- Definitive diagnosis is made with a positive laboratory test.
- First-line treatment is with a fluoroquinolone or a newer-generation macrolide.
- Complications are the same as those for pneumonia and include respiratory failure, parapneumonic effusion, empyema, lung abscess, and death.
Quick Reference
History & Exam
Key Factors
Other Factors
Diagnostics Tests
Treatment Options
Definition
Epidemiology
Etiology
Pathophysiology
Images
Chest x-ray showing infection: right lower lobe infiltrate consistent with pneumonia (arrow). confirmed positive with urinary antigen test
Chest x-ray (lateral) showing infection: posterior segment of lower lobe consistent with pneumonia; the area in the triangle is normally clear (black). confirmed with positive urinary antigen test
A portable anterior/posterior chest radiograph showing a right lower lobe infiltrate consistent with Legionnaire's disease
The superior aspect of a CT abdomen with contrast showing a right lower lobe, dense, lobar infiltrate consistent with Legionnaires' disease causing pneumonia with a small left pleural effusion
Citations
Phin N, Parry-Ford F, Harrison T, et al. Epidemiology and clinical management of Legionnaires' disease. Lancet Infect Dis. 2014 Oct;14(10):1011-21.[Abstract][Full Text]
Centers for Disease Control and Prevention. CDC Yellow Book 2024: health information for international travel. Section 5: travel-associated infections & diseases (bacterial) - legionnaires' disease & pontiac fever. May 2023 [internet publication].[Full Text]
US Centers for Disease Control and Prevention. Legionella (Legionnaires' disease and pontiac fever): diagnosis, treatment, & prevention. March 2021 [internet publication].[Full Text]
Metlay JP, Waterer GW, Long AC, et al. Diagnosis and treatment of adults with community-acquired pneumonia. An official clinical practice guideline of the American Thoracic Society and Infectious Diseases Society of America. Am J Respir Crit Care Med. 2019 Oct 1;200(7):e45-67.[Abstract][Full Text]
1. Cianciotto NP. Pathogenicity of Legionella pneumophila. Int J Med Microbiol. 2001 Nov;291(5):331-43. [Abstract]
2. Gupta SK, Imperiale TF, Sarosi GA. Evaluation of the Winthrop-University Hospital criteria to identify Legionella pneumonia. Chest. 2001 Oct;120(4):1064-71.[Abstract]
3. Lowry PW, Tompkins LS. Nosocomial legionellosis: a review of pulmonary and extrapulmonary syndromes. Am J Infect Control. 1993 Feb;21(1):21-7.[Abstract]
4. Phin N, Parry-Ford F, Harrison T, et al. Epidemiology and clinical management of Legionnaires' disease. Lancet Infect Dis. 2014 Oct;14(10):1011-21.[Abstract][Full Text]
5. Hlavsa MC, Aluko SK, Miller AD, et al. Outbreaks associated with treated recreational water - United States, 2015-2019. MMWR Morb Mortal Wkly Rep. 2021 May 21;70(20):733-38.[Abstract][Full Text]
6. US Centers for Disease Control and Prevention. Legionnaires' disease surveillance summary report, United States 2018-2019. Mar 2021 [internet publication].[Full Text][Full Text]
7. European Centre for Disease Prevention and Control (ECDC). Legionnaires' disease: annual epidemiological report for 2021. Jul 2023 [internet publication].[Full Text]
8. Allgaier J, Lagu T, Haessler S, et al. Risk factors, management, and outcomes of Legionella pneumonia in a large, Nationally Representative Sample. Chest. 2021 May;159(5):1782-92.[Abstract]
9. Beauté J, The European Legionnaires' Disease Surveillance Network. Legionnaires' disease in Europe, 2011 to 2015. Euro Surveill. 2017 Jul 6;22(27).[Abstract][Full Text]
10. Centers for Disease Control and Prevention. CDC Yellow Book 2024: health information for international travel. Section 5: travel-associated infections & diseases (bacterial) - legionnaires' disease & pontiac fever. May 2023 [internet publication].[Full Text]
11. Neil K, Berkelman R. Increasing incidence of legionellosis in the United States, 1990-2005: changing epidemiologic trends. Clin Infect Dis. 2008 Sep 1;47(5):591-9.[Abstract]
12. Soda EA, Barskey AE, Shah PP, et al. Vital signs: health care-associated Legionnaires' disease surveillance data from 20 states and a large metropolitan area - United States, 2015. MMWR Morb Mortal Wkly Rep. 2017 Jun 9;66(22):584-9.[Abstract]
13. Fields BS, Benson RF, Besser RE. Legionella and Legionnaires' disease: 25 years of investigation. Clin Microbiol Rev. 2002 Jul;15(3):506-26.[Abstract]
14. Gomez-Valero L, Rusniok C, Buchrieser C. Legionella pneumophila: population genetics, phylogeny and genomics. Infect Genet Evol. 2009 Sep;9(5):727-39. [Abstract]
15. Sabria M, Yu VL. Hospital-acquired legionellosis: solutions for a preventable infection. Lancet Infect Dis. 2002 Jun;2(6):368-73.[Abstract]
16. Payne NR, Horwitz MA. Phagocytosis of Legionella pneumophila is mediated by human monocyte complement receptors. J Exp Med. 1987 Nov 1;166(5):1377-89.[Abstract][Full Text]
17. Winn WC Jr, Myerowitz RL. The pathology of the Legionella pneumonias: A review of 74 cases and the literature. Hum Pathol. 1981 May;12(5):401-22.[Abstract]
18. Straus WL, Plouffe JF, File TM, et al. Risk factors for domestic acquisition of Legionnaires disease. Ohio Legionnaires Disease Group. Arch Intern Med. 1996 Aug 12-26;156(15):1685-92.[Abstract]
19. Den Boer JW, Nijhof J, Friesema I. Risk factors for sporadic community-acquired Legionnaires' disease. A 3-year national case-control study. Public Health. 2006 Jun;120(6):566-71.[Abstract]
20. el-Ebiary M, Sarmiento X, Torres A, et al. Prognostic factors of severe Legionella pneumonia requiring admission to ICU. Am J Respir Crit Care Med. 1997 Nov;156(5):1467-72.[Abstract][Full Text]
21. Lanternier F, Tubach F, Ravaud P, et al. Incidence and risk factors of Legionella pneumophila pneumonia during anti-tumor necrosis factor therapy: a prospective French study. Chest. 2013 Sep;144(3):990-8.[Abstract]
22. Centers for Disease Control and Prevention. Morbidity and mortality weekly report: suspected Legionella transmission from a single donor to two lung transplant recipients - Pennsylvania, May 2022. Sep 2023 [internet publication].[Full Text]
23. Stout JE, Yu V. Legionellosis. N Engl J Med. 1997 Sep 4;337(10):682-7.[Abstract]
24. Jernigan DB, Hofmann J, Cetron MS, et al. Outbreak of Legionnaires' disease among cruise ship passengers exposed to a contaminated whirlpool spa. Lancet. 1996 Feb 24;347(9000):494-9.[Abstract]
25. Miyamoto H, Jitsurong S, Shiota R, et al. Molecular determination of infection source of a sporadic Legionella pneumonia case associated with a hot spring bath. Microbiol Immunol. 1997;41(3):197-202.[Abstract]
26. Bhopal RS, Fallon RJ, Buist EC, et al. Proximity of the home to a cooling tower and risk of non-outbreak Legionnaires' disease. BMJ. 1991 Feb 16;302(6773):378-83.[Abstract]
27. Marrie TJ, Haldane D, MacDonald S, et al. Control of endemic nosocomial Legionnaires' disease by using sterile potable water for high risk patients. Epidemiol Infect. 1991 Dec;107(3):591-605.[Abstract]
28. Hlady WG, Mullen RC, Mintz CS, et al. Outbreak of Legionnaire's disease linked to a decorative fountain by molecular epidemiology. Am J Epidemiol. 1993 Oct 15;138(8):555-62.[Abstract]
29. Bangsborg JM, Uldum S, Jensen JS, et al. Nosocomial legionellosis in three heart-lung transplant patients: case reports and environmental observations. Eur J Clin Microbiol Infect Dis. 1995 Feb;14(2):99-104.[Abstract]
30. Franzin L, Scolfaro C, Cabodi D, et al. Legionella pneumophila pneumonia in a newborn after water birth: a new mode of transmissions. Clin Infect Dis. 2001 Nov 1;33(9):e103-4.[Abstract]
31. Nolt D, O'Leary ST, Aucott SW. Risks of infectious diseases in newborns exposed to alternative perinatal practices. Pediatrics. 2022 Feb 1;149(2):e2021055554.[Abstract][Full Text]
32. Currie SL, Beattie TK, Knapp CW, et al. Legionella spp. in UK composts-a potential public health issue? Clin Microbiol Infect. 2014 Apr;20(4):O224-9.[Abstract]
33. Garcia-Vidal C, Labori M, Viasus D, et al. Rainfall is a risk factor for sporadic cases of Legionella pneumophila pneumonia. PLoS One. 2013 Apr 16;8(4):e61036.[Abstract][Full Text]
34. Centers for Disease Control and Prevention. Environmental infection control guidelines. 2019 [internet publication].[Full Text]
35. Cachafeiro SP, Naveira IM, García IG. Is copper-silver ionisation safe and effective in controlling legionella? J Hosp Infect. 2007 Nov;67(3):209-16. [Abstract]
36. Mulazimoglu L, Yu VL. Can Legionnaires disease be diagnosed by clinical criteria? A critical review. Chest. 2001 Oct;120(4):1049-53.[Abstract]
37. Carratala J, Garcia-Vidal C. An update on Legionella. Cur Opin Infect Dis. 2010 Apr;23(2):152-7.[Abstract]
38. Shimada T, Noguchi Y, Jackson JL, et al. Systematic review and metaanalysis: urinary antigen tests for Legionellosis. Chest. 2009 Dec;136(6):1576-85.[Abstract]
39. Public Health England. Guidance on investigating cases, clusters and outbreaks of Legionnaires' disease. January 2021 [internet publication].[Full Text]
40. US Centers for Disease Control and Prevention. Legionella (Legionnaires' disease and pontiac fever): diagnosis, treatment, & prevention. March 2021 [internet publication].[Full Text]
41. Maze MJ, Slow S, Cumins AM, et al. Enhanced detection of Legionnaires' disease by PCR testing of induced sputum and throat swabs. Eur Respir J. 2014 Feb;43(2):644-6.[Abstract][Full Text]
42. Edelstein PH, Cianciotto NP. In: Mandell GL, Bennett JE, Dolin R, eds. Principles and Practice of Infectious Diseases. 6th ed. Philadelphia, PA: Elsevier; 2005:2711-24.
43. Dominguez J, Gali N, Blanco S, et al. Assessment of a new test to detect Legionella urinary antigen for the diagnosis of Legionnaires' disease. Diagn Microbiol Infect Dis. 2001 Dec;41(4):199-203.[Abstract]
44. Dominguez J, Gali N, Matas L, et al. Evaluation of a rapid immunochromatographic assay for the detection of Legionella antigen in urine samples. Eur J Clin Microbiol Infect Dis. 1999 Dec;18(12):896-8.[Abstract]
45. Ramirez JA, Ahkee S, Tolentino A, et al. Diagnosis of Legionella pneumophila, Mycoplasma pneumoniae, or Chlamydia pneumoniae lower respiratory infection using the polymerase chain reaction on a single throat swab specimen. Diagn Microbiol Infect Dis. 1996 Jan;24(1):7-14.[Abstract]
46. Stout, JE, Rihs, JD, Yu, VL. Legionella. In: Murray PR, Baron EJ, Jorgensen JH, et al, eds. Manual of clinical microbiology. Washington, D.C.: ASM Press; 2003.
47. Plouffe JF, File TM, Breiman RF; et al. Reevaluation of the definition of Legionnaires' disease: use of the urinary antigen assay. Community Based Pneumonia Incidence Study Group. Clin Infect Dis. 1995 May;20(5):1286-91.[Abstract]
48. González-Moraleja J, Sesma P, González C, et al. [What is the cost of inappropriate admission of pneumonia patients?]. [in spa]. Arch Bronconeumol. 1999 Jul-Aug;35(7):312-6.[Abstract]
49. Fine MJ, Auble TE, Yealy DM, et al. A prediction rule to identify low-risk patients with community-acquired pneumonia. N Engl J Med. 1997 Jan 23;336(4):243-50.[Abstract]
50. Lim WS, van der Eerden MM, Laing R, et al. Defining community acquired pneumonia severity on presentation to hospital: an international derivation and validation study. Thorax. 2003 May;58(5):377-82.[Abstract][Full Text]
51. España PP, Capelastegui A, Gorordo I, et al. Development and validation of a clinical prediction rule for severe community-acquired pneumonia. Am J Respir Crit Care Med. 2006 Dec 1;174(11):1249-56.[Abstract][Full Text]
52. Charles PG, Wolfe R, Whitby M, et al. SMART-COP: a tool for predicting the need for intensive respiratory or vasopressor support in community-acquired pneumonia. Clin Infect Dis. 2008 Aug 1;47(3):375-84.[Abstract][Full Text]
53. Restrepo MI, Mortensen EM, Rello J, et al. Late admission to the ICU in patients with community-acquired pneumonia is associated with higher mortality. Chest. 2010 Mar;137(3):552-7.[Abstract][Full Text]
54. Metlay JP, Waterer GW, Long AC, et al. Diagnosis and treatment of adults with community-acquired pneumonia. An official clinical practice guideline of the American Thoracic Society and Infectious Diseases Society of America. Am J Respir Crit Care Med. 2019 Oct 1;200(7):e45-67.[Abstract][Full Text]
55. Brown SM, Jones JP, Aronsky D, et al. Relationships among initial hospital triage, disease progression and mortality in community-acquired pneumonia. Respirology. 2012 Nov;17(8):1207-13.[Abstract][Full Text]
56. Phua J, Ngerng WJ, Lim TK. The impact of a delay in intensive care unit admission for community-acquired pneumonia. Eur Respir J. 2010 Oct;36(4):826-33.[Abstract][Full Text]
57. Aliberti S, Ramirez J, Cosentini R, et al. Low CURB-65 is of limited value in deciding discharge of patients with community-acquired pneumonia. Respir Med. 2011 Nov;105(11):1732-8.[Abstract][Full Text]
58. Sharp AL, Jones JP, Wu I, et al. CURB-65 performance among admitted and discharged emergency department patients with community-acquired pneumonia. Acad Emerg Med. 2016 Apr;23(4):400-5.[Abstract][Full Text]
59. Chahin A, Opal SM. Severe pneumonia caused by Legionella pneumophila: differential diagnosis and therapeutic considerations. Infect Dis Clin North Am. 2017 Mar;31(1):111-21.[Abstract][Full Text]
60. Benin AL, Benson RF, Besser RE. Trends in Legionnaires disease, 1980-1998: declining mortality and new patterns of diagnosis. Clin Infect Dis. 2002 Nov 1;35(9):1039-46.[Abstract]
61. Heath CH, Grove DI, Looke DFM. Delay in appropriate therapy of Legionella pneumonia associated with increased mortality. Eur J Clin Microbiol Infect Dis. 1996 Apr;15(4):286-90.[Abstract]
62. Arnold F, Summersgill JT, Lajoie AS, et al. A worldwide perspective of atypical pathogens in community-acquired pneumonia. Am J Respir Crit Care Med. 2007 May 15;175(10):1086-93.[Abstract]
63. Mills GD, Oehley MR, Arrol B. Effectiveness of beta lactam antibiotics compared with antibiotics active against atypical pathogens in non-severe community acquired pneumonia: meta-analysis. BMJ. 2005 Feb 26;330(7489):456.[Abstract][Full Text]
64. Shefet D, Robenshtok E, Paul M, et al. Empirical atypical coverage for inpatients with community-acquired pneumonia: systematic review of randomized controlled trials. Arch Intern Med. 2005 Sep 26;165(17):1992-2000.[Abstract][Full Text]
65. British Thoracic Society. 2015 - annotated BTS guideline for the mangement of CAP in adults (2009) summary of recommendations. Jan 2015 [internet publication].[Full Text]
66. National Institute for Health and Care Excellence. Pneumonia (community-acquired): antimicrobial prescribing. Sep 2019 [internet publication].[Full Text]
67. Mykietiuk A, Carratala J, Fernandez-Sabe N, et al. Clinical outcomes for hospitalized patients with Legionella pneumonia in the antigenuria era: the influence of levofloxacin therapy. Clin Infect Dis. 2005 Mar 15;40(6):794-9.[Abstract]
68. Edelstein PH, Shinzato T, Doyle E, et al. In vitro activity of gemifloxacin (SB-265805, LB20304a) against Legionella pneumophila and its pharmacokinetics in guinea pigs with L. pneumophila pneumonia. Antimicrob Agents Chemother. 2001 Aug;45(8):2204-9.[Abstract][Full Text]
69. Blazquez-Garrido RM, Espinosa-Parra FJ, Alemany-Frances L, et al. Antimicrobial chemotherapy for Legionnaires disease: levofloxacin versus macrolides. Clin Infect Dis. 2005 Mar 15;40(6):800-6.[Abstract]
70. Sabria M, Pedro-Botet ML, Gomez J, et al. Fluoroquinolones vs macrolides in the treatment of Legionnaires disease. Chest. 2005 Sep;128(3):1401-5.[Abstract]
71. Griffin AT, Peyrani P, Wiemken T, et al. Macrolides versus quinolones in Legionella pneumonia: results from the Community-Acquired Pneumonia Organization international study. Int J Tuberc Lung Dis. 2010 Apr;14(4):495-9.[Abstract]
72. Rusu A, Munteanu AC, Arbănași EM, et al. Overview of side-effects of antibacterial fluoroquinolones: new drugs versus old drugs, a step forward in the safety profile? Pharmaceutics. 2023 Mar 1;15(3):804.[Abstract][Full Text]
73. Dournon E, Mayaud CH, Wolff M, et al. Comparison of the activity of three antibiotic regimens in severe LD. J. Antimicrob Chemother. 1990 Oct;(suppl B):129-39.[Abstract]
74. Roig J, Rello J. Legionnaires' disease: a rational approach to therapy. J Antimicrob Chemother. 2003 May;51(5):1119-29.[Abstract][Full Text]
75. Grau S, Antonio JM, Ribes E, et al. Impact of rifampicin addition to clarithromycin in Legionella pneumophila pneumonia. Int J Antimicrob Agents. 2006 Sep;28(3):249-52. [Abstract]
76. Mallegol J, Fernandes P, Melano RG, et al. Antimicrobial activity of solithromycin against clinical isolates of Legionella pneumophila serogroup 1. Antimicrob Agents Chemother. 2014;58:909-15.[Abstract]
77. Dillon C, Guarascio AJ, Covvey JR. Lefamulin: a promising new pleuromutilin antibiotic in the pipeline. Expert Rev Anti Infect Ther. 2019 Jan;17(1):5-15.[Abstract]
78. Alexander E, Goldberg L, Das AF, et al. Oral lefamulin vs moxifloxacin for early clinical response among adults with community-acquired bacterial pneumonia: The LEAP 2 randomized clinical trial. JAMA. 2019 Nov 5;322(17):1661-71.[Abstract][Full Text]
79. National Institute for Health and Care Excellence. Pneumonia in adults: diagnosis and management. Oct 2023 [internet publication]. [Full Text]
80. El Moussaoui R, Opmeer BC, de Borgie CA, et al. Long-term symptom recovery and health-related quality of life in patients with mild-to-moderate-severe community-acquired pneumonia. Chest. 2006 Oct;130(4):1165-72.[Abstract]
81. Lettinga KD, Verbon A, Nieuwkerk PT, et al. Health-related quality of life and posttraumatic. stress disorder among survivors of an outbreak of Legionnaires disease. Clin Infect Dis. 2002 Jul 1;35(1):11-7.[Abstract][Full Text]
82. Dominguez A, Alvarez J, Sabria M, et al. Factors influencing the case-fatality rate of Legionnaires' disease. Int J Tuberc Lung Dis. 2009 Mar;13(3):407-12.[Abstract]
83. Garcia-Vidal C, Carratala J. Current clinical management of Legionnaires' disease. Expert Rev Anti Infect Ther. 2006 Dec;4(6):995-1004.[Abstract]
84. Centers for Disease Control and Prevention. Guidelines for prevention of nosocomial pneumonia. MMWR Recomm Rep. 1997 Jan 3;46(RR-1):1-79.[Abstract][Full Text]
85. European Centre for Disease Prevention and Control. European Legionnaires' Disease Surveillance Network (ELDSNet): operating procedures. January 2012 [internet publication].[Full Text]
