Protozoa of the Digestive and Urogenital Tracts 569 



centrifuged. Washing is continued until the supernatant fluid is clear. 

 The sediment is then examined for Protozoa. For concentration of cysts 

 only, the zinc-sulphate flotation method (59) is usefvxl. 



Culture methods. In the detection of mild infections, culture methods 

 may be successful when direct examination of stools is negative. A variety 

 of culture media^ have been developed and a number of them have 

 proven useful in diagnosis. Craig (40) has pointed out that in the use of 

 culture media for E. histolytica, individual experience with a medium 

 probably counts as much in the long run as the particular type of culture 

 medium. 



The effectiveness of culture methods for detecting E. histolytica in 

 stools containing cysts has been increased by adding streptomycin to the 

 medium. The retardation of bacterial growth, as well as that of Blasto- 

 cystis hominis, apparently facilitates growth of the amoebae after excyst- 

 ment (153). Perhaps the most satisfactory diagnostic medium will prove 

 to be one which inhibits growth of bacteria more or less completely. The 

 development of such a mediimi should be possible when more is known 

 about the growth requirements of the intestinal amoebae and flagellates. 



Complement-fixation. The practical application of complement-fixa- 

 tion to diagnosis of amoebiasis was first reported by Craig (37, 38). Fol- 

 lowing the introduction of a commercially prepared antigen, this test is 

 being used on a progressively wider scale. Complement-fixation seems to 

 be of value in the diagnosis of mild primary amoebiasis, and with certain 

 modifications, in the detection of early hepatic amoebiasis (Chapter 14). 



Trichomonas vaginalis 



The examination of an ordinary wet preparation or hanging-drop 

 is often adequate for the detection of T. vaginalis. In the diagnosis of 

 mild infections, in following the effects of treatment, and in detecting 

 trichomonads in centrifuged urine specimens, culture methods (18, 109, 

 148) are more efficient. Some of the more recently developed media (83, 

 84, 154, 161) are designed for growth of T. vaginalis in bacteria-free cul- 

 tures. The medium of Kupferberg, Johnson, and Sprince (107), now 

 available commercially, requires only the addition of serum and penicillin 

 for diagnostic use. 



LITERATURE CITED 



1. Adams, A. R. D. 1946. Trap. Dis. Bull. 43: 613. 



2. Alexander, F. D. and H. E. Meleney 1935. Amer. J. Hyg. 22: 704. 



3. Anderson, H. H. and .'\. C. Reed 1934. Amer. J. Trop. Med. 14: 269. 



^ Satisfactory culture media have been described for the following intestinal Protozoa 

 of man: flagellates — Chilomostix mesnili (9, 21, 24, 63, 70, 75), Retortomonas intestinalis 

 (17, 70, 75), Pentatrichomonas hominis (9, 63, 70, 75, 148, 174), Tricercomonas intes- 

 tinalis (70); amoebae — Dientamoehn fragilis (9, 49); Endolimax nana (9, 51), Entamoeba 

 coli (9, 48, 51, 148), E. histolytica (9, 23. 32, 36, 51, 63, 127, 138, 144, 148), lodamoeba 

 biltschlii (9); dliates—Balantidiutn coli (11, 80, 139, 148). 



