It’s quite common to find Legionella species other than Legionella pneumophila in cooling towers and water distribution systems. To date, more than 58 Legionella species have been described in published articles. Of these approximately 25 are linked to disease, namely Legionella pneumophila species serogroup 1, 3, 4, and 6.

Legionella pneumophila serogroup 1 is the most virulent strain causing the majority of infections. The remaining non-pneumophila species (found in water and soil) are considered nonpathogenic until shown to cause disease. Of the CDC reported cases less than 5% is attributed to non-pathognenic species. Since risk for infection is rare, adjusting your response to an adequate threat level is appropriate.

To learn more, click the table rows below for each Legionella species.

Legionella Species
Serogroup
Human Infection
Reference
L. adelaidensis
No
Legionella adelaidensis, a new species isolated from cooling tower water. Benson RF, et al.) J Clin Microbiol. 1991 May;29(5):1004-6
L. anisa
Yes
Pleural infection caused by Legionella anisa. Bornstein N, et al. J Clin Microbiol. 1989 Sep;27(9):2100-1.
L. beliardensis
No
Legionella gresilensis sp. nov. and Legionella beliardensis sp. nov., isolated from water in France. Lo Presti F, et al. Int J Syst Evol Microbiol. 2001 Nov;51(Pt 6):1949-57.
L. birminghamensis
Yes
Legionella birminghamensis sp. nov. isolated from a cardiac transplant recipient. Wilkinson H, et al. J Clin Microbiol. 1987 Nov;25(11):2120-2
L. bozemanii
1
Yes
Pneumonia due to Legionella bozemanii: first report of a case in Europe. Mitchell RG. et al. J Infect. 1984 May;8(3):251-5
L. bozemanii
2
Yes
Legionella bozemanii serogroup 2: a new etiological agent. Tang PW. et al. J Clin Microbiol. 1984 Jan;19(1):30-3.
L. brunensis
No
Legionella moravica sp. nov. and Legionella brunensis sp. nov. isolated from cooling-tower water. Wilkinson HW. et al. Ann Inst Pasteur Microbiol. 1988 Jul-Aug;139(4):393-402.
L. busanensis
No
Legionella busanensis sp. nov., isolated from cooling tower water in Korea. Park MY. et al. Int J Syst Evol Microbiol. 2003 Jan;53(Pt 1):77-80.
L. cardiaca
Yes
Legionella cardiaca sp. nov., isolated from a case of native valve endocarditis in a human heart. Pearce MM et al. Int J Syst Evol Microbiol. 2012 Dec;62(Pt 12):2946-54. doi: 10.1099/ijs.0.039248-0. Epub 2012 Jan 27.
L. cherrii
Yes
Disease due to the Legionellaceae (other than Legionella pneumophila). Historical, microbiological, clinical, and epidemiological review. Fang GD et al. Medicine (Baltimore). 1989 Mar;68(2):116-32.
L. cincinnatiensis
Yes
Legionella cincinnatiensis sp. nov. isolated from a patient with pneumonia. Thacker WL. J Clin Microbiol. 1988 Mar;26(3):418-20.
L. clemsonensis
Yes
Legionella clemsonensis sp. nov., - a green fluorescing Legionella strain from a patient with pneumonia. Palmer A, Painter J., et al., Microbiol Immunol. 2016 Sep 13. doi: 10.1111/1348-0421.12439. [Epub ahead of print]
L. donaldsonii
No
Legionella prevalence in wastewater treatment plants of Taiwan. Huang SW et al. Water Sci Technol. 2009;60(5):1303-10. doi: 10.2166/wst.2009.410
L. drancourtii
No
Legionella drancourtii sp. nov., a strictly intracellular amoebal pathogen. La Scola B et al. Int J Syst Evol Microbiol. 2004 May;54(Pt 3):699-703.
L. dresdenensis
No
Legionella dresdenensis sp. nov., isolated from river water. Lück PC. et al. Int J Syst Evol Microbiol. 2010 Nov;60(Pt 11):2557-62. doi: 10.1099/ijs.0.017863-0. Epub 2009 Dec 11.
L. drozanskii
No
Legionella drozanskii sp. nov., Legionella rowbothamii sp. nov. and Legionella fallonii sp. nov.: three unusual new Legionella species. Adeleke AA et al.Int J Syst Evol Microbiol. 2001 May;51(Pt 3):1151-60.
L. dumoffii
Yes
Legionnaires' disease caused by Legionella dumoffii in distilled water. Joly JR. et al. CMAJ. 1986 Dec 1;135(11):1274-7.
L. erythra
No
Lipopolysaccharides of Legionella erythra and Legionella oakridgensis. Sonesson A. et al. Can J Microbiol. 1994 Aug;40(8):666-71.
L. fairfieldensis
No
Legionella fairfieldensis sp. nov. isolated from cooling tower waters in Australia. Thacker WL et al. J Clin Microbiol. 1991 Mar;29(3):475-8.
L. fallonii
No
Legionella drozanskii sp. nov., Legionella rowbothamii sp. nov. and Legionella fallonii sp. nov.: three unusual new Legionella species. Adeleke AA et al. Int J Syst Evol Microbiol. 2001 May;51(Pt 3):1151-60.
L. feeleii
1
Yes
Legionella feeleii-associated pneumonia in humans. Palutke WA et al. Am J Clin Pathol. 1986 Sep;86(3):348-51.
L. feeleii
2
Yes
Second serogroup of Legionella feeleii strains isolated from humans. Thacker WL et al. J Clin Microbiol. 1985 Jul;22(1):1-4.
L. geestiana
No
Five new Legionella species isolated from water. Dennis PJ et al. Int J Syst Bacteriol. 1993 Apr;43(2):329-37.
L. genomospecies 1
No
Legionella waltersii sp. nov. and an unnamed Legionella genomospecies isolated from water in Australia. Benson RF et al. Int J Syst Bacteriol. 1996 Jul;46(3):631-4.
L. gormanii
Yes
First isolation of Legionella gormanii from human disease. Griffith ME et al. J Clin Microbiol. 1988 Feb;26(2):380-1.
L. gratiana
No
Legionella gratiana sp. nov. isolated from French spa water. Bornstein N et al. Res Microbiol. 1989 Oct;140(8):541-52.
L. gresilensis
No
Legionella gresilensis sp. nov. and Legionella beliardensis sp. nov., isolated from water in France. Lo Presti F. et al. Int J Syst Evol Microbiol. 2001 Nov;51(Pt 6):1949-57.
L. hackeliae
1
Yes
Ten new species of Legionella. Brenner DJ, et al. Int. J. Syst. Bacteriol. 35: 50-59, 1985.
L. hackeliae
2
Yes
Second serogroup of Legionella hackeliae isolated from a patient with pneumonia. Wilkinson HW, et al. J Clin Microbiol. 1985 Oct;22(4):488-9.
L. impletisoli
No
Legionella impletisoli sp. nov. and Legionella yabuuchiae sp. nov., isolated from soils contaminated with industrial wastes in Japan. Kuroki H, et al. Syst Appl Microbiol. 2007 Jun;30(4):273-9. Epub 2007 Jan 2.
L. israelensis
No
Seasonal distribution of legionellae isolated from various types of water in Israel. Bercovier H, et al. Isr J Med Sci. 1986 Sep;22(9):644-6.
L. jamestowniensis
No
Infection of macrophage-like cells by Legionella species that have not been associated with disease. O'Connell WA, et al. Infect Immun. 1996 Oct;64(10):4381-4.
Candidatus L. jeonii
No
Phylogenetic characterization of Legionella-like endosymbiotic X-bacteria in Amoeba proteus: a proposal for 'Candidatus Legionella jeonii' sp. nov. Park M, et al. Environ Microbiol. 2004 Dec;6(12):1252-63.
L. jordanis
Yes
Aortic valve endocarditis associated with Legionella infection after Mycoplasma pneumonia. Littrup P, et al. Br Heart J. 1987 Sep;58(3):293-5.
L. lansingensis
Yes
Legionella lansingensis sp. nov. isolated from a patient with pneumonia and underlying chronic lymphocytic leukemia. Thacker WL, et al. J Clin Microbiol. 1992 Sep;30(9):2398-401.
L. londiniensis
No
Five new Legionella species isolated from water. Dennis PJ, et al. Int J Syst Bacteriol. 1993 Apr;43(2):329-37.
L. longbeachae
1
Yes
Legionella longbeachae species nova, another etiologic agent of human pneumonia. McKinney RM, et al. Ann Intern Med. 1981 Jun;94(6):739-43.
L. longbeachae
2
Yes
Recognition of a second serogroup of Legionella longbeachae. Bibb WF, et al. J Clin Microbiol. 1981 Dec;14(6):674-7.
L. lytica
No
Legionella-like and other amoebal pathogens as agents of community-acquired pneumonia. Marrie TJ, et al. Emerg Infect Dis. 2001 Nov-Dec;7(6):1026-9.
L. maceachernii
Yes
Fatal Legionella maceachernii pneumonia. Wilkinson HW, et al. J Clin Microbiol. 1985 Dec;22(6):1055.
L. massiliensis
No
Legionella tunisiensis sp. nov. and Legionella massiliensis sp. nov., isolated from environmental water samples. Campocasso A, et al. Int J Syst Evol Microbiol. 2012 Dec;62(Pt 12):3003-6. doi: 10.1099/ijs.0.037853-0. Epub 2012 Feb 3.
L. micdadei
Yes
Opportunistic lung infection due to "Pittsburgh Pneumonia Agent". Myerowitz RL, et al. N Engl J Med. 1979 Nov 1;301(18):953-8.
L. moravica
No
Legionella moravica sp. nov. and Legionella brunensis sp. nov. isolated from cooling-tower water. Wilkinson HW, et al. Ann Inst Pasteur Microbiol. 1988 Jul-Aug;139(4):393-402.
L. nagasakii/nagasakiensis
No
Legionella nagasakiensis sp. nov., isolated from water samples and from a patient with pneumonia. Yang G, et al. nt J Syst Evol Microbiol. 2012 Feb;62(Pt 2):284-8. doi: 10.1099/ijs.0.027193-0. Epub 2011 Mar 11.
L. nautarum
No
Five new Legionella species isolated from water. Dennis PJ, et al. Int J Syst Bacteriol. 1993 Apr;43(2):329-37.
L. norrlandica
No
Legionella norrlandica sp. nov., isolated from the biopurification systems of wood processing plants. Rizzardi K, Winiecka-Krusnell J. et al.,Int J Syst Evol Microbiol. 2015 Feb;65(Pt 2):598-603. doi: 10.1099/ijs.0.068940-0. Epub 2014 Nov 18.
L. oakridgensis
Yes
Legionella oakridgensis: laboratory diagnosis of a human infection. Tang PW, et al. J Clin Microbiol. 1985 Mar;21(3):462-3.
L. parisiensis
Yes
The first clinical isolate of Legionella parisiensis from a liver transplant patient with pneumonia. Lo Presti F, et al. J Clin Microbiol. 1997 Jul;35(7):1706-9.
L. pneumophila (Philadelphia 1)
1
Yes
Classification of the Legionnaires' disease bacterium: Legionella pneumophila, genus novum, species nova, of the family Legionellaceae, familia nova. Brenner DJ, et a. Ann Intern Med. 1979 Apr;90(4):656-8.
L. pneumophila (Knoxville 1)
1
Yes
Legionellae isolated from clinical and environmental samples in Spain (1983-90): monoclonal typing of Legionella pneumophila serogroup 1 isolates. Pelaz C, et al. Epidemiol Infect. 1992 Jun;108(3):397-402.
L. pneumophila (Benidorm 030 E)
1
Yes
Outbreak of Legionnaires' disease at University Hospital, Nottingham. Epidemiology, microbiology and control. Colville A, et al. Epidemiol Infect. 1993 Feb;110(1):105-16.
L. pneumophila (France 5811)
1
Yes
Evaluation of different primers for DNA fingerprinting of Legionella pneumophila serogroup 1 strains by polymerase chain reaction. Wiese J, et al. Int J Med Microbiol. 2004 Oct;294(6):401-6.
L. pneumophila (Allentown 1)
1
Yes
Legionellae isolated from clinical and environmental samples in Spain (1983-90): monoclonal typing of Legionella pneumophila serogroup 1 isolates. Pelaz C, et al. Epidemiol Infect. 1992 Jun;108(3):397-402.
L. pneumophila (OLDA)
1
Yes
Legionella pneumophila serogroup 1 population in Italy by monoclonal subtyping. Castellani Pastoris M., et al. Epidemiol Infect. 1990 Aug;105(1):169-74.
Legionella pneumophila (Oxford 4032 E)
1
Yes
Epidemiological studies using monoclonal antibodies to Legionella pneumophila serogroup 1. Tobin JO, et al. Isr J Med Sci. 1986 Oct;22(10):711-4.
Legionella pneumophila (Bellingham)
1
Yes
Legionella pneumophila serogroup 1 population in Italy by monoclonal subtyping. Castellani Pastoris M, et al. Epidemiol Infect. 1990 Aug;105(1):169-74.
Legionella pneumophila (Heysham 1)
1
Yes
Development of a standardized subgrouping scheme for Legionella pneumophila serogroup 1 using monoclonal antibodies. Joly JR, et al. J Clin Microbiol. 1986 Apr;23(4):768-71.
Legionella pneumophila (Camperdown 1)
1
Yes
Legionella pneumophila serogroup 1 population in Italy by monoclonal subtyping. Castellani Pastoris M, et al. Epidemiol Infect. 1990 Aug;105(1):169-74.
Legionella pneumophila (Togus 1)
2
Yes
Recognition of a new serogroup of Legionnaires disease bacterium. McKinney RM, et al. J Clin Microbiol. 1979 Jan;9(1):103-7.
Legionella pneumophila (Bloomington 2)
3
Yes
Fatal pneumonia caused by Legionella pneumophila, serogroup 3: demonstration of the bacilli in extrathoracic organs. Watts JC, et al. Ann Intern Med. 1980 Feb;92(2 Pt 1):186-8.
Legionella pneumophila (Los Angeles)
4
Yes
Pyelonephritis associated with Legionella pneumophila, serogroup 4. Dorman SA, et al. Ann Intern Med. 1980 Dec;93(6):835-7.
L. pneumophila (Portland1)
4
Yes
Legionella pneumophila serogroup Lansing 3 isolated from a patient with fatal pneumonia, and descriptions of L. pneumophila subsp. pneumophila subsp. nov., L. pneumophila subsp. fraseri subsp. nov., and L. pneumophila subsp. pascullei subsp. nov. Brenner DJ, et al. J Clin Microbiol. 1988 Sep;26(9):1695-703.
L. pneumophila (Dallas 1E)
5
Yes
Serological and genotypic diversity among serogroup 5- reacting environmental Legionella isolates. Garrity GM, et al. J Clin Microbiol. 1982 Apr;15(4):646-53.
L. pneumophila (Cambridge 1)
5
Yes
Legionella pneumophila: monoclonal antibody typing of clinical and environmental isolates. Brindle RJ, et al. J Clin Microbiol. 1982 Apr;15(4):646-53.
L. pneumophila (Chicago 1)
6
Yes
Legionella pneumophila serogroup six: isolation from cases of legionellosis, identification by immunofluorescence staining, and immunological response to infection. McKinney RM, et al. J Clin Microbiol. 1980 Sep;12(3):395-401.
L. pneumophila (Chicago 8)
7
Yes
Isolation and characterization of a seventh serogroup of Legionella pneumophila. Bibb WF, et al. J Clin Microbiol. 1983 Feb;17(2):346-8.
L. pneumophila (Concord 3)
8
Yes
New serogroup of Legionella pneumophila, serogroup 8. Bissett ML, et al. J Clin Microbiol. 1983 May;17(5):887-91.
Legionella pneumophila (IN-23-G1-C2)
9
Yes
Legionella pneumophila serogroup 9: a cause of human pneumonia. Edelstein PH, et al. Ann Intern Med. 1984 Aug;101(2):196-8.
Legionella pneumophila (Leiden 1)
10
Yes
Water-related nosocomial pneumonia caused by Legionella pneumophila serogroups 1 and 10. Meenhorst PL, et al. Infect Dis. 1985 Aug;152(2):356-64.
L. pneumophila (797-PA-H)
11
Yes
11th serogroup of Legionella pneumophila isolated from a patient with fatal pneumonia. Thacker WL, et al. J Clin Microbiol. 1986 Jun;23(6):1146-7.
Legionella pneumophila (570-CO-H)
12
Yes
Legionella pneumophila serogroup 12 isolated from human and environmental sources. Thacker WL, et al. J Clin Microbiol. 1987 Mar;25(3):569-70.
Legionella pneumophila (82A3105)
13
Yes
Thirteenth serogroup of Legionella pneumophila isolated from patients with pneumonia. Lindquist DS, et al. J Clin Microbiol. 1988 Mar;26(3):586-7.
Legionella pneumophila (1169-MN-H)
14
Yes
Legionella pneumophila serogroup 14 isolated from patients with fatal pneumonia. Benson RF, et al. J Clin Microbiol. 1988 Feb;26(2):382.
Legionella pneumophila (Lansing 3)
15
Yes
Legionella pneumophila serogroup Lansing 3 isolated from a patient with fatal pneumonia, and descriptions of L. pneumophila subsp. pneumophila subsp. nov., L. pneumophila subsp. fraseri subsp. nov., and L. pneumophila subsp. pascullei subsp. nov. Brenner DJ, et al. J Clin Microbiol. 1988 Sep;26(9):1695-703.
L. quateirensis
No
Five new Legionella species isolated from water. Dennis PJ, et al. Int J Syst Bacteriol. 1993 Apr;43(2):329-37.
L. quinlivanii
1
No
Legionella quinlivanii sp. nov. isolated from water. Benson RF, et al. Curr. Microbiol. 18: 195-197, 1989
L. quinlivanii
2
No
Second serogroup of Legionella quinlivanii isolated from two unrelated sources in the United Kingdom. Birtles RJ, et al. J Appl Bacteriol. 1991 Nov;71(5):402-6.
L. rowbothamii
No
Legionella drozanskii sp. nov., Legionella rowbothamii sp. nov. and Legionella fallonii sp. nov.: three unusual new Legionella species. Adeleke AA, et al. Int J Syst Evol Microbiol. 2001 May;51(Pt 3):1151-60.
L. rubrilucens
Yes
Isolation of Legionella rubrilucens from a pneumonia patient co-infected with Legionella pneumophila. Matsui M, et al. J Med Microbiol. 2010 Oct;59(Pt 10):1242-6. doi: 10.1099/jmm.0.016089-0. Epub 2010 Jun 17
L. sainthelensi
1
Yes
Infections due to Legionella sainthelensi in New Zealand. Chereshsky AY, et al. N Z Med J. 1986 May 14;99(801):335.
L. sainthelensi
2
Yes
Legionella sainthelensi serogroup 2 isolated from patients with pneumonia. Benson RF, et al. Res Microbiol. 1990 May;141(4):453-63.
L. santicrucis
No
Growth of 28 Legionella species on selective culture media: a comparative study. Lee TC, et al. J Clin Microbiol. 1993 Oct;31(10):2764-8.
L. saoudiensis
No
Legionella saoudiensis sp. nov., isolated from sewage water sample. Leena Hussein Bajrai1, Esam Ibraheem Azhar2, et. al. International Journal of Systematic and Evolutionary (Published Ahead of Print: 02 August, 2016)
L. shakespearei
No
Legionella shakespearei sp. nov., isolated from cooling tower water. Verma UK, et al. Int J Syst Bacteriol. 1992 Jul;42(3):404-7.
L. spiritensis
1
No
Serological diversity within the species Legionella spiritensis. Harrison TG, et al. J Appl Bacteriol. 1988 Nov;65(5):425-31.
L. steelei
No
Legionella steelei sp. nov., isolated from human respiratory specimens in California, USA, and South Australia. Edelstein PH, et al. Int J Syst Evol Microbiol. 2012 Aug;62(Pt 8):1766-71. doi: 10.1099/ijs.0.035709-0. Epub 2011 Sep 23.
L. steigerwaltii
No
Ten New Species of Legionella. Brenner DJ, et al. Int. J. Syst. Bacteriol. 35: 50-59, 1985
L. taurinenesis
No
Legionella taurinensis sp. nov., a new species antigenically similar to Legionella spiritensis., Lo Presti F, et al. Int J Syst Bacteriol. 1999 Apr;49 Pt 2:397-403.
L. tucsonensis
Yes
Legionella tucsonensis sp. nov. isolated from a renal transplant recipient.Thacker WL, et al. J Clin Microbiol. 1989 Aug;27(8):1831-4.
L. tunisiensis
No
Legionella tunisiensis sp. nov. and Legionella massiliensis sp. nov., isolated from environmental water samples. Campocasso A., Int J Syst Evol Microbiol. 2012 Dec;62(Pt 12):3003-6. doi: 10.1099/ijs.0.037853-0. Epub 2012 Feb 3.
L. wadsworthii
Yes
Legionella wadsworthii species nova: a cause of human pneumonia. Edelstein PH, et al. Ann Intern Med. 1982 Dec;97(6):809-13.
L. waltersii
No
Legionella waltersii--a novel cause of pneumonia? König C, et al. Acta Paediatr. 2005 Oct;94(10):1505-7.
L. worsleiensis
No
Five new Legionella species isolated from water. Dennis PJ, et al. Int J Syst Bacteriol. 1993 Apr;43(2):329-37.
L. yabuuchiae
No
Legionella impletisoli sp. nov. and Legionella yabuuchiae sp. nov., isolated from soils contaminated with industrial wastes in Japan. Kuroki H, et al. Syst Appl Microbiol. 2007 Jun;30(4):273-9. Epub 2007 Jan 2.