VII48-6 MANUAL OF METHODS FOR PURE CULTURE STUDY 



The required amount of material is drawn into a sterile syringe; 

 with the needle held up, air and any excess material is expelled onto 

 cotton moistened with a suitable disinfectant, which should be kept 

 away from the tip of the needle. Any undesirable disinfectant may 

 be removed with cotton moistened with alcohol. The following types 

 of injection are used: — 



Cutaneous. This is a rather loose term and includes rubbing into, 

 or scratching the skin or placing the inoculum under an adhesive 

 patch. The precise method is determined by the object to be at- 

 tained. If it is desired to determine whether an organism can pene- 

 trate the normal skin, the material should be spread over the skin. 

 Irritation from shaving or depilation should be avoided. The skin 

 should be cleansed and sterilized with an antiseptic that has brief 

 action. The inoculated area may be covered with sterile gauze pro- 

 vided the adhesive does not aflfect the skin. Coating the skin with 

 collodion excludes air and may make the conditions abnormal and 

 affect the skin-penetrating power of the organism. It is common 

 practice in cutaneous inoculation to abrade the epidermis by scratch- 

 ing or scraping with a sharp instrument. This aids penetration by 

 removing the outer defensive layer and is similar to intracutaneous 

 injection. 



Intracutaneous. By intracutaneous injection is meant the intro- 

 duction of material between the intradermal layers. The formation 

 of a bleb indicates successful injection. It is advisable to use animals 

 with unpigmented skin and rabbits should not be in moult. A 27- 

 gage needle is best. Shaving and the application of antiseptics, 

 particularly those that penetrate the skin, may interfere with the 

 test and should be used judiciously. 



Subcutaneous. The skin may be shaved or the hair clipped with- 

 out interfering with the test. The point of puncture before injection 

 and the puncture after inoculation should be disinfected with a non- 

 irritating disinfectant such as tincture of zephiran chloride, alcohol, 

 merthiolate or, best of all, green soap and water. The area may be 

 marked with an indelible pencil. Material should be injected into 

 the subcutaneous tissue, with care not to puncture the peritoneal 

 wall when done in the abdomen. 



If the material will not pass through the needle, the skin may be 

 sterilized, after removing hair, and a V-shaped opening cut in the skin 

 with sterile scissors. The flap is then lifted up and loosened until a 

 pocket is formed and the material to be tested is inserted. The flap 

 is replaced, sterilized and covered with collodion, or sutured asepti- 

 cally. 



Intramuscular. The skin is treated as for subcutaneous injection 

 and the culture injected deep into the muscles. 



Intravenous. The choice of a vein is mainly a matter of con- 

 venience and varies with the experimental animal. Rabbits usually 

 are injected in the marginal ear vein, mice and rats in the tail veins, 

 guinea pigs in the ear vein or jugular vein, horses and cows in the 

 jugular vein, swine in the ear, dogs and cats in the jugular or the vein 

 crossing the inner surface of the thigh and fowl in the radial vein that 



