20 THE NATURE AND IDENTIFICATION OF BACTERIA 



Destjlphovibrio desulphuricans can be isolated from mud and 

 sulphur-containing waters. It is a comma-shaped organism which, 

 in some media, grows to give spiral-shaped organisms of con- 

 siderable length and marked motility. It reduces sulphate to 

 hydrogen sulphide. 



Family V 



Micrococcus pyogenes var. aureus (Staphylococcus aureus) is 

 the common organism producing pus in Wounds, boils, etc. It is a 

 spherical organism producing orange colonies on solid media. It is 

 one of the organisms which cause septicaemia and ostiomyelitis. 



Family VI 



Neisseria intracelluxaris (Meningococcus) is the causal organism 



of meningitis. 

 Neisseria gonorrhoeae (Gonococcus) is the causal agent in 



gonorrhoea. 



Family VII 



Streptococcus haemolyticus, the causal organism of scarlet fever, 



streptococcal septicaemia, puerperal fever, and streptococcal throat. 



The organism causes lysis of red blood-cells by secretion of a 



haemolysin and the species has been divided into serological groups 



and types; the human pathogens belong mainly to group A. 

 Streptococcus eaecalis, one of the common intestinal inhabitants. 



It is non-pathogenic although some variants are haemolytic and 



belong to the haemolytic group D. 

 Streptococcus lactis, the common non-pathogenic streptococcus 



of milk. This organism can be clearly differentiated from S. 



faecalis by biochemical and serological tests. Both S. faecalis and 



S. lactis are used for nutritional assay procedures (see p. 110). 

 Lactobacillus caset, one of several species used for nutritional 



studies and normally found in milk. 



Family VIII 



CoRYNEBACTERiUM DiPHTHERiAE, the causal Organism of diphtheria. 



Family X 



Escherichia coli, numerically the most common intestinal bacterium. 

 This organism is easily grown in large quantities, is non-pathogenic, 

 has very wide chemical activities, and has consequently been 

 subjected to more intense biochemical investigation than any 

 other bacterium. 



Aerobacter aerogenes, an organism' whose chemical activities are 

 similar to those of EscJi. coli but which is more commonly found in 

 association with soil and plant materials than in intestinal contents. 



Proteus vulgaris, a highly motile soil organism usually found in 

 association with putrefying material. It often proves a nuisance 

 when it becomes established in wounds since, although it is non- 

 pathogenic, it is insensitive to almost all the present antibacterial 

 agents used in chemotherapy. 



