428 



BACTERIOLOGY. 



Of the 18 pseudo-typhoid bacilli isolated, 12 killed guinea 

 pigs when injected intraperitoneally in doses of 2 c.c, 

 whereas the remaining 6 had no effect. Anti-typhoid serum 

 was said to be efficacious in preventing infection by these 

 organisms. A mention may be made, moreover, of the fact 

 that Ohlmacher isolated a bacillus, indistinguishable from 

 that of Eberth, from the Cleveland tap-water. In cadavers 

 buried for 1^2 years only typhoid-like bacteria are said to 

 be present. 



The typhoid bacillus cannot be identified by any one 

 •characteristic. The suspected culture must give most, if 

 not all, of the known reactions of the typhoid germ. These 

 reactions may be grouped together in the following sum- 

 mary: 



1. — Appearance of colonies. 



2. — Active motion. 



3. — Large number of whips, in- 

 cluding giant-whips.. 



4.— Gram's stain negative. 



5. — No gas production. 



■6. — No coagulation of milk- 



7. — No indol reaction. 



-8. — No acid production (lactose 

 media). 



9. — Invisible growth on potato. 



10. — Colonies on Eisner's medium. 



11. — Transparent diffusion on Stod- 

 dart's medium. 



12. — No growth in Uschinsky's fluid. 



13.— Agglutination by diluted 

 typhoid fever serum. 



14. — Pfeiffer's reaction with anti- 

 infectious typhoid serum. 



15. — Pathogenic effects. 



The above characteristics will be found described un- 

 der their respe.ctive heads. The ubiquitous colon bacillus 

 is especially ruled out by the last 11 tests. The colon ba- 

 cillus is less pathogenic and rarely kills guinea-pigs when 

 injected subcutaneously. 



Plate cultures can be made with ordinary gelatin, with 

 Eisner's medium or with a 3-5 per cent, urine gelatin (see 

 •Chapter XIV). The suspected typhoid colonies are then 

 transplanted to other media and subjected to the tests 

 given above. It is advisable to transplant 20 or more sus- 

 picious lookjng colonies into bouillon tubes which are then 

 placed at 39° to develop. A drop or two of each culture 



