238 DISEASE CONTROL 



tonitis caused by pneumococci and streptococci (Table 44). This sub- 

 stance was found to be effective against five different types of pneumo- 

 cocci, eleven types of group A streptococci, and three strains of group C 

 streptococci. It was, however, almost completely ineffective when ad- 

 ministered into animal tissues by the intravenous, intramuscular, or 

 subcutaneous route, because of its lack of activity under these conditions. 



TABLE 44. BACTERICIDAL EFFECT OF TYROTHRICIN UPON 

 DIFFERENT BACTERIA 



From Dubos and Cattaneo (203). 



*— no growth on blood agar, + reduced growth, MM abundant growth. 



t NR no reduction of methylene blue, PR partial reduction, CR complete reduction. 



§ N no lysis, P partial lysis, C complete lysis. 



Tyrothricin exerted a lethal action m vitro on 1 8-hour broth cultures 

 of S. hemolyticus^ S. aureus, and C. difhtheriae, in a final dilution of 

 1 : 1,000,000; freshly isolated strains of meningococcus were affected in 

 a dilution of i: 100,000 (807). Two monkeys which carried in the 

 nasopharynx and throat gram-positive hemolytic streptococci and gram- 

 negative hemolytic bacilli showed disappearance of these bacteria within 

 1 hours following the administration of tyrothricin. Five days after a 

 single treatment no hemolytic organisms were found in one monkey, 

 and, in the other, only throat cultures were positive. A second applica- 

 tion of the material gave completely negative cultures within 3 hours. 



