DIPHTHERIA 161 



attack the bacillus frequently persists in the throat for weeks, 

 and as infection may be transmitted in this way, strict isola- 

 tion of convalescents should, where possible, be insisted on, 

 until the bacillus has disappeared. The bacillus is usually 

 found in such cases in involution forms, such as long and 

 short rods together. These are rarely found before the 

 disease has run its course. 



A person frequently entering diphtheria wards, as a 

 nurse or medical man, may very often have the bacillus in 

 the throat without contracting the disease. 



Method of Staining. — The diphtheria bacillus is readily 

 stained with the usual aqueous basic aniline dyes. Loffler's 

 methylene blue is the best general staining reagent for 

 cover-glass preparations. It is also stained by Gram's 

 method. 



Bacteriological Diagnosis of Diphtheria.— A suitable ' out- 

 fit ' for this purpose consists of a small box containing two 

 stout glass test-tubes, both cotton-wool-plugged and sterilised ; 

 the one holds a cotton-covered iron wire, the other contains 

 Loffler's medium, duly sloped. 



With one end of the cotton swab, the suspected portion of 

 the throat is rubbed and the infection transferred to the 

 surface of the medium, taking care to rub lightly, so as not 

 to abrade the surface. 



, The tube is now plugged, and either posted to a laboratory 

 or placed in the incubator, or it may be incubated on the 

 person by placing in the waistcoat pocket and buttoning 

 the coat over it. Better results are obtained by using an 

 ■ordinary platinum wire to inoculate the tube with, instead 

 ■of the cotton-covered swab, and when a platinum wire is 

 used, three streaks should be made on the medium, after 

 touching the throat once only. By this means a part of 

 one of these three streaks will probably be a pure culture of 

 the Klebs-Loffler, if it be present. 



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