86 LOCALIZED INFECTIONS OF PUS NATURE 



which are commonly the result of infection with bacteria 

 of high virulence. This germ, unlike the staphylococcus, 

 cannot infect through the undamaged skin, demanding a 

 wound for its entrance. Streptococci vary in virulence, and 

 when the particular family of germs happens to be very 

 virulent a single coccus may transmit an infection. The 

 streptococcus is of considerable importance in the production 

 of sore-throat; it is transmitted from person to person directly 

 or in some manner that brings it to the pharynx, milk for 

 example. Septic sore-throat usually appears in epidemic 

 form distributed by milk which has been contaminated by a 

 milkman having the disease or from a cow infected with 

 human streptococci. Streptococci in the pharynx seem to 

 be a source of danger in such conditions as scarlatina and 

 measles because they not uncommonly are responsible for 

 complications. Careful mouth hygiene is indicated. 



In diagnosticating streptococcic infections it is necessary 

 to make smears on glass slides and cultures in appropriate 

 media. The germs are found to be very small single cocci 

 varying from ^foir to 2Tirro of an incn > dividing only in 

 one plane and therefore growing in chains. They are unable 

 to move of themselves, stain well by most methods, multiply 

 best at 37 C. (98 R), but also at lower temperatures, and 

 grow as very delicate gray colonies. They have no effect 

 upon milk or gelatin. On media containing blood they have 

 the property of dissolving the red coloring matter. 



They are killed in ten minutes when exposed to 52 C. 

 (126 R). When dried in blood or pus they may live for a 

 considerable time at room temperature, but die quickly at 

 body heat unless their food is repeatedly renewed. They 

 are killed by corrosive sublimate, 1 to 1000; carbolic acid, 

 1 to 100; and hydrogen peroxide, 1 to 100, in ten minutes if 

 exposed in water. Pus supplies a protective envelope, and 

 the germicide must be allowed to act longer. Streptococci 

 are very virulent for most lower animals and the same lesions 

 may be produced by artificial injection as arise spontaneously 



