DIPHTHERIA BACILLUS 87 



amined. It is desirable to establish the bacteriological diagnosis in suspected 

 cases of diphtheria early as possible, and for this reason both culture and slides 

 should be obtained from the patient. 



Occasionally diphtheria bacilli will be found in the nose and not in the mouth 

 or throat, hence slides and cultures should be made from both the nose and 

 throat. 



TECHNIQUE 



Take two tubes of sterile Loeffler's blood-serum medium, two sticks or pieces 

 of wire about 6 inches long having cotton wrapped around one end (when made 

 such swabs are placed in test-tubes stoppered with cotton, and the tubes con- 

 taining swabs are sterilized at i4oC. for i hour in hot-air sterilizer) and several 

 clean glass slides. 



Inspect the patient's mouth and throat; if grayish- white spots or areas of 

 inflammation are observed rub the swab over these and immediately draw across 

 the surface of the Loeffler's medium; then rub the swab on one or more glass 

 slides and replace it in its original container. If no grayish spots or areas of 

 inflammation are observed draw the swab over each tonsil and the pharynx. 



Take the second swab and pass it into each nostril, then draw it across the 

 surface of a sterile tube of Loeffler's medium and make slides from it; finally, 

 replace this swab in its original container. 



Place the blood-serum culture tubes in incubator at 37C.; stain the slides 

 for 5 minutes with Loeffler's methylene blue, wash them in water, dry and 

 examine under the microscope. If diphtheria bacilli are observed the diag- 

 nosis is apparent. 



After 1 6 to 24 hours remove cultures from incubator, note the macroscopic 

 appearance of colonies that have developed; remove some of the growth with 

 a sterile platinum loop and smear on slides, fix by gently heating slides until 

 dry, stain with Loeffler's methylene blue and examine microscopically. 



When slides and cultures from a true case of diphtheria are examined many 

 diphtheria bacilli are usually found, occasionally they are few. They may be 

 found in pure culture no other organism appearing; as a rule, however, staphy- 

 lococci, streptococci or pneumococci are found together with the diphtheria 

 bacilli. 



' Usually virulent diphtheria bacilli, as observed in smears made directly 

 from the nose and throat or from 16 to 20-hour-old blood-serum cultures, are 

 slim, straight and curved rods showing granular or barred staining. 



When such smears show, almost entirely, solid staining, short, stout rods, 

 the organisms usually are not virulent, toxin-producing bacteria. 



There are so many exceptions to these rules, however, that occasional error 

 is inevitable when diagnosis is based on the appearance of bacteria, and under 

 such conditions the welfare of patients and public is best served by making a 

 diagnosis of diphtheria whenever smears or cultures obtained from a patient 

 having sore throat, fever and signs of toxemia, show organisms having the mor- 

 phology of either the diphtheria or pseudodiphtheria bacilli. 



