Legionella pneumophila sp. nov.: The Legionnaires' Disease Bacterium 



the LDB. Since the LDB was mitially isolated by methods designed for rickettsiae (77), com- 

 parisons with R quintana were especially indicated. Flavobacterium meningosepticum and Flavo- 

 bacterium IIB were tested because these organisms have similarities to the LDB. The only known 

 group of gram-negative organisms that have predominantly branched-chain fatty acids are in the 

 genus Flavobacterium (15). They are pigmented, their antibiotic resistance profile is similar to 

 that of the LDB US), and the GC content in the DNA of some flavobacteria is similar to that of 

 the LDB. FrancisL'Ua tularensis, yersiniae, and Pasteurella multocida were tested because some 

 patients from whom F. tularensis and Yersinia pestis had been isolated had elevated serum titers 

 to the LDB. Additional species in the genus Pasteurella and several species found in the environ- 

 ment were also tested. 



Table 1 . 



DNA relatedness of LDB strains to several species 



selected at random 



Reaction^ % DNA relatedness at 60°C'' 



E. coli K-\2*IE. coll K.-12 100 (85) 



£. CO/; K-I2*/Philadelphia 1 ' 3 



£■. c-o//K-i:*/Flint 1 (D8711) 1 



P. mirabilis 1 *IP. mirabilis 1 100 (74) 



P. mirabilis 1 */Philadelphia 1 2 



P. mirabilis 1*/Flint 1 (087 11) 3 



}'. enterocolitica 498-70*/}', enterocoUtica 498-70 100 (74) 



Y. e/!rero<:o//r;t'a498-70*/Philadelphia 1 



Y. enterocolitica 498-70*/Flint 1 (D87 11) 



E. tarda 3889-64*/£', tarda 3889-64 100 (64) 



E. tarda 3889-64*/Philadelphia 1 - 

 a: ?fl/-(7ff3889-64*/Flint 1 (08711) . 



V. cholerae 1845-73*/F, cholerae 1845-73 100 (81) 



V. cholerae 1845-73*/F. cholerae 1320-72 100 



V. cholerae 1845-73*/K cholerae 5540-70 95 



V. cholerae 1845-73*/F, parahaemolyticus A8633 32 



V. cholerae 1845-73*/K, alginolyticus C68 14 22 



F, c/zo/erae 1845-73*/Philadelphia 1 

 V. cholerae 1845-73*/Flint 1 (0871 1) 



A. hydrophila*IA. hydrophila 100 (67) 



A. /7vt/ro/;/H7a*/Philadelphia 1 ' 



A. hydrophila* l¥\m\ 1 (0871 1) 



S. epidermidis */S. epidermidis 1 00 ( 6 1 ) 



S. ep/<ie/TO/d/s*/Philadelphia 1 1 



B. pernissis*IB. pertussis 100 (65) 

 B. pem/is/s*/Philadelphia 1 



B. pertussis* If \\M \ {D87 \ V) 



a Labeled DNA is indicated by an asterisk. 



bThc figures in parentheses are the actual values obtained in homologous reactions. These are arbitrarily designated 100%, and 

 heterologous values are nomialized to them. The B pertussis reactions were done at 65°C due to the high GC of B. pertussis 

 DNA. 



61 



