BACTERIUM DIPHTHERIA 101 



grow readily on most laboratory culture media. Solidified 

 blood serum is the preferred artificial foodstuff. Upon it 

 they grow in such a manner as to render diagnosis easy, both 

 by the naked-eye appearance and by their shapes under the 

 microscope. These bacilli grow best at the body temperature, 

 37 C. or 98 F., but also at a lower point. 



They are killed at 58 C. or 140 F. for ten minutes. Boil- 

 ing kills in one minute. In the dry state, protected from 

 daylight, these organisms may live several months. With 

 such protection, when moist or in exudate, as from the throat, 

 life may persist for at least four months. Direct sunlight 

 kills within half an hour. On cloth or other absorbing 

 material their life is long, but indeterminate. On coins they 

 die in twelve to thirty-six hours. On toys, lead- and slate- 

 pencils and tumblers they may live several weeks. They 

 do not live long in cultures unless frequently transferred to 

 fresh food. They resist cold. These data concerning the 

 viability of the Klebs-LofBer bacillus in the outer world help 

 to explain the sudden and otherwise inexplicable outbreaks 

 of diphtheria, and the difficulties of their eradication. To 

 disinfectants they present a slightly greater resistance than 

 most non-spore-bearing bacilli. Carbolic acid, 1 to 100, 

 kills in ten minutes; corrosive sublimate, 1 to 1000, in twenty 

 minutes. Hydrogen peroxide kills them rather easily. 

 These figures are for bacteria suspended in water. 



Diphtheria bacilli will kill most experimental animals, 

 but the guinea-pig is the most susceptible. Here they 

 characteristically produce a sloughing at the site of inocula- 

 tion, a peritonitis, and a congestion of the adrenal gland. 

 Sometimes organisms suggestive of diphtheria bacilli are 

 found in the throat without a membrane. In order to prove 

 if these be true diphtheria forms, some of a culture is injected 

 under the skin of a guinea-pig. If the changes described are 

 produced, and the animal dies in three days, it shows that 

 the organism in question was a true virulent diphtheria 

 bacillus. 



