3 14 BACTERIA 



ceiving, at one time, some support. But whilst opinion is 

 divided on the role of various extraneous and concomitant 

 bacteria in lung disease, importance is attached to Fraenkel's 

 and Friedlander's organisms. 



The diplococcus of Fraenkel is a small, oval diplococcus 

 found in the " rusty " sputum of croupous pneumonia. It 

 is non-motile, non-liquefying, and aerobic. When examined 

 from cultures the diplococci are frequently seen in chains, 

 not unlike a streptococcus, and there is some reason to sup- 

 pose that this form gave rise to the belief that it was another 

 species ; when examined from the tissues it possesses a cap- 

 sule, but in culture this is lost. It is difficult to cultivate, 

 but grows on glycerine agar and blood serum at blood-heat. 

 On ordinary gelatine at room temperature it does not grow, 

 or, if so, very slightly. The ideal fluid is a slightly alkaline 

 liquid medium, and in twenty-four hours a powdery growth 

 will occur in such broth. On potato there is apparently no 

 growth. It rapidly loses its virulence on solid media, and 

 is said to be non-virulent after three or four sub-culturings. 

 A temperature of 54-58 C. for a few minutes kills the bac- 

 teria, but not the toxin. This, however, is removed by 

 filtration, and is therefore probably intracellular. It is 

 attenuated by heating to 70 C. 



Fraenkel's diplococcus occurs, then, in the acute stage of 

 pneumonia, in company with streptococci and staphylococci. 

 It also occurs in the blood in certain suppurative conditions, 

 in pleurisy and inflammation of the pericardium, and some- 

 times in diphtheria, and therefore it is not peculiar to pneu- 

 monia. 



There is one other point to which attention should be 

 drawn. Fraenkel's organism is said to be frequently pre- 

 sent in the saliva of healthy persons. Pneumonia depresses 

 the resistant vitality of the tissues, and thus affords to the 

 diplococcus present in the saliva an excellent nidus for its 

 growth. 



