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



DNA relatedness was used to classify strains of tlie LDB. Tliese DNA comparisons showed 

 that all strains of LDB were members of the same species. Included were strains isolated from the 

 environment and strains with three different O antigens. DNA from LDB was not significantly 

 related to DNA from any other group of bacteria tested. Biochemical data, growth character- 

 istics, and GC ratios were used to rule out the possibility that LDB was significantly related to 

 members of genera whose DNA was not tested. 



On the basis of these data, we propose that LDB be named Legionella pneuiiiophila sp. nov., 

 the type species of the genus Legionella. 



ACKNOWLEDGEMENTS 



We are greatly indebted to Drs. W. B. Cherry, J. C. Feeley, C. W. Moss, C. C. Shepard, and 

 R. E. Weaver for providing strains, allowing access to their unpublished data, and for their critical 

 comments and encouragement. 



We are grateful to Dr. M. Mandel for purified DNA from Microcycliis major. Dr. E. Shotts 

 for the Aeromonas hydwphila DNA, and Dr. W. Kloos for the Bonletella pertussis DNA and the 

 Staphylococcus epiderniidis DNA. 



Cytophaga johnsonae UASM E-1-25 (ATCC 29586), C. johnsonae UASM 4539 (ATCC 

 29588), and Flexibacter canadensis UASM 9D were sent to CDC by P. Christensen of the 

 University of Alberta Soil Microbiology Laboratory. They were cultivated and given to us by J. 

 C. Feeley. Pasteurella lutemolytica KC228 and P. ureae KC518 were cultivated and given to us by 

 R. E. Weaver. 



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