Biomaterial Database

Virulent to avirulent conversion of Legionnaires' disease bacterium (Legionella pneumophila)--its effect on isolation techniques. 1979

J E McDade, and C C Shepard

Suspensions of the Legionnaries' disease bacterium (Legionella pneumophila; LDB) were prepared from the yolk sacs of infected egg embryos, the spleens of infected guinea pigs, and cultures of the organism propagated on enriched Mueller-Hinton agar. Each suspension was titrated to determine the number of bacterial colonies (cfu), yolk sac 50% lethal doses (YSLD50), guinea pig 50% infectious doses (GPID50), and guinea pig 50% lethal doses (GPLD50) produced by 1 ml of inoculum. The numbers of cfu/YSLD50, GPID50, and GPLD50 were then calculated for each suspension. The suspension from yolk sacs had 1 cfu/YSLD50 and 10 cfu/GPID50. The suspension from spleens of guinea pigs also had 1 cfu/YSLD50. Organisms propagated on Mueller-Hinton agar, however, had greater than 10(7) cfu/YSLD50 and 10(5) cfu/GPID50. Thus, the LDB lost virulence when it was cultivated on agar. Guinea pigs vaccinated either subcutaneously or intraperitoneally with LDB grown on Mueller-Hinton agar resisted challenge with virulent LDB.

UI	MeSH Term	Description	Entries
D007877	Legionnaires' Disease	An acute, sometimes fatal, pneumonia-like bacterial infection characterized by high fever, malaise, muscle aches, respiratory disorders and headache. It is named for an outbreak at the 1976 Philadelphia convention of the American Legion.	Legionella pneumophila Infections,Infections, Legionella pneumophila,Legionnaire Disease,Pontiac Fever,Disease, Legionnaire,Disease, Legionnaires',Fever, Pontiac,Infection, Legionella pneumophila,Legionella pneumophila Infection,Legionnaire's Disease,Legionnaires Disease
D007928	Lethal Dose 50	The dose amount of poisonous or toxic substance or dose of ionizing radiation required to kill 50% of the tested population.	LD50,Dose 50, Lethal
D006168	Guinea Pigs	A common name used for the genus Cavia. The most common species is Cavia porcellus which is the domesticated guinea pig used for pets and biomedical research.	Cavia,Cavia porcellus,Guinea Pig,Pig, Guinea,Pigs, Guinea
D006801	Humans	Members of the species Homo sapiens.	Homo sapiens,Man (Taxonomy),Human,Man, Modern,Modern Man
D000818	Animals	Unicellular or multicellular, heterotrophic organisms, that have sensation and the power of voluntary movement. Under the older five kingdom paradigm, Animalia was one of the kingdoms. Under the modern three domain model, Animalia represents one of the many groups in the domain EUKARYOTA.	Animal,Metazoa,Animalia
D001419	Bacteria	One of the three domains of life (the others being Eukarya and ARCHAEA), also called Eubacteria. They are unicellular prokaryotic microorganisms which generally possess rigid cell walls, multiply by cell division, and exhibit three principal forms: round or coccal, rodlike or bacillary, and spiral or spirochetal. Bacteria can be classified by their response to OXYGEN: aerobic, anaerobic, or facultatively anaerobic; by the mode by which they obtain their energy: chemotrophy (via chemical reaction) or PHOTOTROPHY (via light reaction); for chemotrophs by their source of chemical energy: CHEMOLITHOTROPHY (from inorganic compounds) or chemoorganotrophy (from organic compounds); and by their source for CARBON; NITROGEN; etc.; HETEROTROPHY (from organic sources) or AUTOTROPHY (from CARBON DIOXIDE). They can also be classified by whether or not they stain (based on the structure of their CELL WALLS) with CRYSTAL VIOLET dye: gram-negative or gram-positive.	Eubacteria
D014774	Virulence	The degree of pathogenicity within a group or species of microorganisms or viruses as indicated by case fatality rates and/or the ability of the organism to invade the tissues of the host. The pathogenic capacity of an organism is determined by its VIRULENCE FACTORS.	Pathogenicity