112 AIDS TO BACTERIOLOGY 



glucose neutral red sheep-blood serum containing 1 

 per cent, potassium sulphocyanate (Myer Coplans). 

 B. Hofmanni grows yellow! 



Bacteriological Diagnosis. The diphtheria bacillus 

 can occasionally be identified by direct examination of a 

 teased-up fragment of membrane, or in expert hands it 

 may be recognised in a smear made from a swabbing. 

 But generally a cultivation is necessary. The throat may 

 be touched with a platinum wire, and successive streaks 

 made along the surface of a sloped tube of Loftier' s serum. 

 Or an ' outfit,' consisting of a sterile cotton-wool swab 

 in a sterile tube, may be used. The swab is rubbed 

 over the suspected portion of the throat, replaced in the 

 tube, and sent to the laboratory. The use of antiseptic 

 gargles or tablets shortly before swabbing must not be 

 allowed, nor should swabbing be performed soon after a 

 meal, since particles of food containing bacteria may 

 render the examination more difficult. The early morn- 

 ing is a most suitable time for routine swabbings. In 

 contacts and convalescents, where no obviously diseased 

 patches are to be seen, the swab should be rubbed on 

 both tonsils. The swab is rubbed over the surfaces of 

 two serum-tubes in turn thoroughly, so that all parts 

 of the swab come in contact with the serum, but lightly, 

 so as to avoid ploughing up the surface, and the tubes 

 are incubated at blood-heat for twelve to twenty-four 

 hours. Cover-glass preparations are then made from the 

 most likely colonies. If no growth is visible, a scraping 

 of the whole surface should be taken, and should a micro- 

 scopical examination of this preparation be negative, 

 the tubes should be incubated for a further twenty-four 

 hours. 



Millard, while regarding the ' long granular ' organism 

 as the B. diphtherice par excellence, expects solid stained 

 bacilli to show granules if further incubated. For 

 diagnostic purposes the barred forms are less satisfactory, 

 as B. coryzce segmentosus, commonly found in the nose in 

 a common cold, B. xerosis (vide infra), and B. auris and 

 B. ceruminis, found in the ear, are very similar. 



Diphtheroids. In many healthy throats or throats 

 diseased but not with diphtheria, are to be found bacilli 

 that closely resemble the Klebs-Loffler bacillus in every 

 particular except that of virulence, and it can hardly be 



