550 BACILLUS BOTULINUS 



Fischer and Landmann have also recorded an outbreak of food poisoning at 

 Darmstadt attributable to the same organism. In this epidemic the illness was 

 traced to some preserved peas mixed with which were some fragments of meat. 

 Twenty- one persons were affected of whom eleven died. 



Van Ermengem recovered the bacillus from the spleen of a patient who had died 

 of botulism. Kempner isolated the Bacillus botulinus from the excreta of pigs. 



The Bacillus botulinus is now generally accepted to be the specific cause of 

 botulism. It appears to be normally a saprophyte which does not multiply to any 

 extent in the living body. Botulism is regarded therefore as a toxaemia due to 

 the consumption of meat which has been accidentally contaminated with the B. 

 botulinus and in which the toxin is present at the time it is eaten. 



The toxin is quite easily destroyed by boiling and by other methods of cooking 

 so that the danger of botulism is limited to the consumption of uncooked or very 

 insufficiently cooked food ; and Sacquepee points out that the symptoms of botulism 

 only follow the consumption of " preserved " foods, that is to say, of such articles 

 of diet as sausages which are made some months before they are eaten, ham, meats 

 preserved in tins and bottles, game pies, etc. 



Experimental inoculation. The inoculation of a large quantity (10-20 c.c.) 

 of an emulsion of a culture of the bacillus or of an infected food proves fatal 

 to rabbits in 48 hours. Small doses lead to a chronic illness which however 

 ultimately terminates in the death of the inoculated animal. 



Guinea-pigs and mice are also susceptible. 



The most characteristic results are obtained with cats. * The inoculation 

 of cultures of the Bacillus botulinus into cats is followed by a typical attack 

 of botulism with its characteristic symptoms of bulbar paralysis. 



Morphology. The Bacillus botulinus is a straight, rod-shaped, slightly 

 motile organism with rounded ends. It measures from 4^-9/x x 0'9-1'2/A. The 

 bacilli are often seen in pairs and in short chains and resemble closely the 

 bacilli of malignant oedema and quarter ill. 



Under favourable conditions, e.g. on an alkaline gelatin medium incubated 

 at 20-25 C. the bacillus forms oval spores ; these are generally terminally 

 situated and are rather wider than the bacillus. Spores are not formed at 

 37 C. 



The Bacillus botulinus stains with the ordinary aniline dyes and is gram- 

 positive though relatively somewhat easily decolourized. 



Cultural characteristics. The bacillus is a strictly anaerobic organism. 

 The optimum temperature of growth is below that of the majority of patho- 

 genic micro-organisms, viz. 20-30 C. 



The bacillus will not grow except on media made with meat, and pig's flesh is 

 better than that of either cattle or sheep. 



In agar media it produces a considerable amount of gas with a strong 

 odour of butyric acid. 



In gelatin the growth is characteristic. Circular, transparent, yellowish- 

 brown colonies appear in 4-6 days and around each colony the medium is 

 liquefied. The gas which is formed either splits the medium or, if the latter 

 be largely liquefied, rises to the surface and forms a layer of bubbles. In 

 stab culture the growth assumes an arborescent form (Distaso). 



In milk the bacillus grows slowly but does not coagulate the medium 

 (Distaso). Von Hibler however finds that the B. botulinus first coagulates 

 the milk and then peptonizes the clot. 



Vitality. The spores of the Bacillus botulinus retain their vitality for about 

 a year. They can be destroyed in 15 minutes at 85 C. and in 30 minutes 

 at 80 C. 



Toxin. Van Ermengem was the first to show that the Bacillus botulinus 

 produces an extra-cellular toxin which has all the generic properties of the 



