45. Salmonella 



With the exception of a few well recognized types such as 

 Salmonella gallinarum and Salmonella pullorum, species or types 

 of Salmonella are generally motile and flagellated. The flagellation 

 of a large number of strains of a large variety of types have been 

 studied over a period of several years. Most of the strains studied 

 were supplied by Dr. MacDonald Fulton of the Stritch School of 

 Medicine, Loyola University, Chicago, Illinois. Several others 

 came from the Illinois State Health Laboratory, Chicago, and a 

 few from diverse sources. 



Flagellar Characteristics 



All types of flagellated Salmonella appear to have the flagella 

 peritrichously arranged. By far the most common shape of the 

 flagella is normal with wavelengths varying between 2.4 and 2.7 

 microns ( see Table XI ) . Curly variants are encountered occa- 

 sionally and appear to be genetic mutants of the normal. In some 

 types such as Salmonella wichita the curly variant appears very 

 stable, while in other types such as Salmonella fijphimuriitm it 

 appears much less so. Lowering the pH of a suspension does not 

 cause a change from normal to curly as with Proteus strains. 

 Other shapes such as coiled and straight have only been observed 

 in odd flagella among otherwise normal types. By careful observa- 

 tion of a large number of organisms a few strains of S. typhi- 

 murium have shown a rare curly flagellum among the normal 

 flagella and also a rare flagellum partly curly and partly normal 

 (Fig. 47c). One strain of S. typhimiirium, supplied by the Illinois 

 State Health Laboratory, showed normal flagella but no motion. 

 The paralyzed flagella of this strain were perfectly normal anti- 

 genically and developed both antigenic phases (i: 1,2,3). The 

 change of antigenic phase in the diphasic types of Salmonella 

 does not appear to be associated with any significant change of 

 flagellar wavelength. In Fig. 48 is shown an interesting filamentous 

 form of Salmonella typhimiirium. 



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