330 Microbes and You 



patients with antiserum that was specific for their particular type 

 of pneumococcus infection. If a patient had type I pneumonia, he 

 had to be administered type I antiserum if beneficial results were to 

 be expected. Cross benefits between these antisera do not exist. 

 Antisera are prepared by the injection of rabbits or horses with 

 killed suspension of the specific pneumococci. These animals 

 build up antibodies against particular pneumococcus types, and 

 the blood serum of the rabbits or horses contains antibodies that 

 will act specifically on the organisms against which they are 

 prepared. 



When type specific antiserum is placed in contact with the 

 HOMOLOGOUS ( samc ) organisms, a marked swelling of the bacterial 

 capsule can be demonstrated under the microscope. This is called 

 the Neufeld capsular swelling reaction or the Quellung reaction, 

 and this result is the basis for classifying pneumococci into types. 

 Attempting to determine the exact type of pneumococcus involved 

 in a given infection is time consuming. If a bacteriologist en- 

 countered difficulty in typing the organisms found in the patient's 

 sputum, precious time was lost, and this often spelled the difference 

 between life and death for the patient. Modern treatment with 

 antibiotics can be initiated without regard to the type of pneu- 

 mococcus involved, and the time saved by this immediate therapy 

 is reflected both in a lower mortality rate and in a shorter con- 

 valescence for the patient. 



STREPTOCOCCI 



Non-motile cells, spherical or ovoid, occurring in pairs, short 

 or long chains. Gram positive, usually facultative aerobes. Cap- 

 sules not regularly formed. Optimum temperature varies with 

 the species. Found in the mouth and intestines of man and other 

 animals, in dairy products, and in fermenting plant juices. Some 

 species are highly pathogenic. 



While not all streptococci are pathogenic, the virulent members 

 of the group are of great importance in pyogenic (pus-producing) 

 infections. They are generally hemolytic, and they have a growth 

 temperature range of from 10° C. to 45° C. When streptococci 



