THE GENUS ACTINOMYCES 



1!) 



Milk: ( ii'owth scanl or absenl . 



Aerobiosis: ( rrows bo1 h under aerobic and 

 anaerobic conditions, somewhal better aero- 

 bically. 



Temperature: Optimum al 37°C; some 

 growth al 32 ('. 



Pathogenicity: Nonpathogenic. 



Habitat : Human mouth. Considered to be 

 a saprophyte found in the mouth and fre- 

 quently confused with A. israelii. 



8. Actinomyces odontolyticus Batty, 1958 

 (Hatty, 1. .1. Pathol. Bacterid. 75: 155 159, 

 L958). 



Morphology: At first, the organism ap- 

 pears in the form of shorl rods subdivided 

 by one or two transverse septa. Later, these 

 rods gradually elongate 1 until a septate sub- 

 mycelium is produced. At the end of these 

 filaments, globular "initial cells" are pro- 

 duced which germinate to produce a non- 

 septate secondary submycelium, which soon 

 commences to break up. Finally, in a week 

 to 10 days, small spores commence to form 

 singly upon short side branches. The size of 

 the mature spores varies greatly in different 

 strains. 



Appearance of colonies: Colonies are usu- 

 ally few in number with an initial appearance 

 similar to those of a-hemolytic streptococci 

 of comparable age. Later, they develop a 

 dark red hemin-like pigment, easily dis- 

 tinguishable. At and after this stage the 

 colonies are exceedingly difficult to subcul- 

 ture. After prolonged artificial culture the 

 organisms can be submit ured at any stage. 

 Attempts to isolate the organism upon horse 

 serum agar or nutrient agar are usually un- 

 successful, but after several subcultures a 

 profuse growth of small convex nonpig- 

 mented colonies is obtained on both these 

 media. All strains grow equally well under 

 aerobic and anaerobic conditions at all 

 stages in their life cycle; in agar stab cultures 

 a filiform growth is obtained throughout the 

 line of inoculum. ( Irowth in peptone brol h is 

 sparse, but in this medium enriched with 



« 



Figure c>. A. odontolyticus, various stages ol 

 culture development (Reproduced from : Batty, I. 

 J. Pathol. Bacterid. :.">: 155 159, L958 



yeast extract, a characteristic glutinous ropy 

 sediment is produced which disperses to 

 give an even turbidity (Fig. 6). 



\o strain produces catalase, oxidase, in- 

 dole, hydrogen sulfide or acetylmet hylcar- 

 binol; all are methyl red-negative and all fail 

 to ferment fructose, maltose, trehalose, 

 starch, inulin, dextrin, glycogen, xylose, 

 rhamnose, glycerol, dulcitol, and salicin. A 

 few strains ferment sucrose, galactose, arabi- 

 uose, or mannitol, with the production of 

 acid but no gas. About half the -trains pro- 

 duce ammonia from peptone, acidify and 

 coagulate litmus milk, and are tolerant of a 

 concentration of 1 in !()()(» potassium tellu- 

 rite. Some strains hydrolyze urea. None 

 liquefy gelatin, Loeffler's medium, or coagu- 

 lated egg medium. All reduce nitrate to 

 nitrite within 18 hour-. 



