242 DISEASE CONTROL 



by daily bacteriological examination of the milk over periods ranging 

 from 1 5 to 8 1 days. 



Sterile mineral oil was later found (536, 537) to be a suitable, non- 

 irritating medium for the administration of the gramicidin, though 

 some of the cows thus treated gave severe reactions. An alcoholic solu- 

 tion (2 to 3 ml.) of 80 to 120 mg. gramicidin was emulsified in 15 ml. 

 sterile distilled water, and the emulsion mixed with 25 ml. of heavy 

 mineral oil. The mixture was injected into the cistern shortly after the 

 morning milking and allowed to remain until the evening milking. The 

 treatment was repeated for several days in succession. Of 3 1 quarters 

 naturally infected with Streptococcus agalactiae and treated by the 

 gramicidin-oil mixture, 26 seemed to have responded by a complete dis- 

 appearance of the streptococci. The infection in some of the cases was of 

 severe chronic nature. 



Less satisfactory results were obtained in the treatment of bovine 

 mastitis caused by Streftococcus uberis; of 4 cases treated, only one re- 

 sponded satisfactorily. The final recommendations consisted in using 

 20 to 40 mg. gramicidin in oil, daily, for four consecutive days. These 

 results were confirmed by various investigators (16, 888), who re- 

 ported 60 to 90 per cent cure for two to three treatments (585). 



A comparison of tyrothricin, trypaflavin, and novoxil for eradicating 

 S. agalactiae from infected udders showed best results for the first. In- 

 fections with S. uberis and Streptococcus dysgalactiae also responded 

 well, but not staphylococcic infections (793). The efficacy of the treat- 

 ment is influenced by several factors, namely, (a) site of chronic infec- 

 tion, (b) selection of suitable cases, and (c) stage of lactation. Too ex- 

 tensive administration may damage the secretory tissues (622). In 

 some experiments, as many as 90 per cent of the cases were cleared up 

 with tyrothricin (95). 



Gramicidin-like preparations were also used successfully in the treat- 

 ment of local infections in man, such as osteomyelitis (553), and for 

 various local administrations, such as conjunctivitis, as well as for in- 

 fected diabetic and ulcerating lesions of cancer ( 1007). The active ma- 

 terial must be used locally on infected cavities which do not communi- 

 cate with the blood stream (3 1 8a, 401 ). Tyrothricin has also been used 

 (78, 154) successfully in the treatment of acute otitis media, acute and 



