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Figure 1: Typticase soy agar w/ & w/o sheep blood (Enlarged View). FIG. 1. Tryptic soy agar with and without Sheep Blood. (Rebecca Buxton, University of Utah, Salt Lake City, UT)

Figure 2: Streptococcus pyogenes (Enlarged View). FIG. 2. Beta hemolytic Streptococcus species seen with transmitted light, Streptococcus pyogenes (Lancefield group A. Also see Figures 28-35). (Rebecca Buxton, University of Utah, Salt Lake City, UT)

Figure 3: Normal respiratory flora with Streptococcus (Enlarged View). FIG. 3. Normal Upper respiratory flora mixed with Streptococcus species. (The presence of beta-hemolytic colonies indicates the possibility of Streptococcus pyogenes infection. Also see Figures 26 and 27). (Rebecca Buxton, University of Utah, Salt Lake City, UT)

Figure 4: Streptococcus pyogenes (Enlarged View). FIG. 4. Same blood agar plate as Figure 2 demonstrating that the beta hemolysis of Streptococcus pyogenes is so complete that print my be read through the resulting transparent medium. (Rebecca Buxton, University of Utah, Salt Lake City, UT)

Figure 5: Normal flora with Streptococcus pyogenes (Enlarged View). FIG. 5. Normal Upper respiratory flora mixed with Streptococcus pyogenes demonstrating production of Streptolysin O. Beta hemolysis is only evident where the agar was "stabbed." (Rebecca Buxton, University of Utah, Salt Lake City, UT)

Figure 6: Normal flora with Streptococcus pyogenes (Enlarged View). FIG. 6. Normal Upper respiratory flora mixed with Streptococcus pyogenes demonstrating production of Streptolysin O. Beta hemolysis is only evident where the agar was "stabbed". (Rebecca Buxton, University of Utah, Salt Lake City, UT)

Figure 7: Streptococcus agalactiae (Enlarged View). FIG. 7. Streptococcus agalactiae (Lancefield group B) viewed with incident light: No obvious hemolysis. (Rebecca Buxton, University of Utah, Salt Lake City, UT)

Figure 8: Streptococcus agalactiae (Enlarged View). FIG. 8. Streptococcus agalactiae (Lancefield group B) viewed with transmitted light: Subtle hemolysis. (Also see Figure 36 and 37). (Rebecca Buxton, University of Utah, Salt Lake City, UT)

Figure 9: Listeria monocytogenes (Enlarged View). FIG. 9. Listeria monocytogenes, removing colonies to see the subtle hemolysis directly beneath the colonies. (Rebecca Buxton, University of Utah, Salt Lake City, UT)

Figure 10: Streptococcus species. FIG. 10. Alpha-hemolytic Streptococcus species "Viridans group" streptococci, including species such as the Streptococcus mutans, mitis, and salivarius groups display alpha hemolysis. (Also see Figures 15,16 and 23-25). (Rebecca Buxton, University of Utah, Salt Lake City, UT)

Figure 11: Streptococcus pneumoniae (Enlarged View). FIG. 11. Alpha hemolysis of Streptococcus pneumoniae (Encapsulated strain, also see Figure 17-20). (Rebecca Buxton, University of Utah, Salt Lake City, UT)

Figure 12: Enterococcus faecalis (Enlarged View). FIG.12. "Gamma Streptococcus": Enterococcus faecalis (24 hours, non-hemolytic). "Gamma streptococci" are usually non-hemolytic after 24 hours of incubation, but many eventually display weak alpha hemolysis. (The genus Enterococcus was once a part of the Streptococcus genus, was considered a "gamma Streptococcus species," and usually reacts as Lancefield group D). (Rebecca Buxton, University of Utah, Salt Lake City, UT)

Figure 13: Enterococcus faecalis (Enlarged View). FIG. 13. The same Enterococcus strain as Figure (12), shown with transmitted light at 48 hours incubation demonstrates the alpha hemolysis of some "gamma streptococci." (See also Figure 38). (Rebecca Buxton, University of Utah, Salt Lake City, UT)

Figure 14: Alpha, Beta and Gamma Streptoccoci (Enlarged View). FIG. 14. Alpha (α), Beta (β) and Non-hemolytic Gamma (γ) streptococci (transmitted light). (Rebecca Buxton, University of Utah, Salt Lake City, UT)

Figure 15: Streptococcus species Viridans group (Enlarged View). FIG. 15. Alpha-hemolytic Streptococcus species ("Viridans group"). (Rebecca Buxton, University of Utah, Salt Lake City, UT)

Figure 16: Streptococcus species Viridans group (Enlarged View). FIG. 16. Alpha-hemolytic Streptococcus species ("Viridans group"). (Rebecca Buxton, University of Utah, Salt Lake City, UT)

Figure 17: Streptococcus pneumoniae (Enlarged View). FIG. 17. In addition to alpha hemolysis, this strain of Streptococcus pneumoniae is producing abundant polysaccharide capsular material evidenced by the mucoid or "oil droplet" appearance on the colonies. (Rebecca Buxton, University of Utah, Salt Lake City, UT)

Figure 18: Streptococcus pneumoniae (Enlarged View). FIG. 18. Streptococcus pneumoniae (encapsulated strain). (Rebecca Buxton, University of Utah, Salt Lake City, UT)

Figure 19: Streptococcus pneumoniae (Enlarged View). FIG. 19. Streptococcus pneumoniae (encapsulated strain). (Rebecca Buxton, University of Utah, Salt Lake City, UT)

Figure 20: Streptococcus pneumoniae (Enlarged View). FIG. 20. Streptococcus pneumoniae (encapsulated strain). (Rebecca Buxton, University of Utah, Salt Lake City, UT)

Figure 21: Streptococcus pneumoniae (Enlarged View). FIG. 21. Streptococcus pneumoniae (encapsulated strain). (Rebecca Buxton, University of Utah, Salt Lake City, UT)

Figure 22: Streptococcus pneumoniae (Enlarged View). FIG. 22. Streptococcus pneumoniae (encapsulated strain). (Rebecca Buxton, University of Utah, Salt Lake City, UT)

Figure 23: Mouth Flora (Enlarged View). FIG. 23. Mixed alpha- and non-hemolytic colonies are typical of normal upper respiratory (mouth) flora. (Rebecca Buxton, University of Utah, Salt Lake City, UT)

Figure 24: Mouth Flora (Enlarged View). FIG. 24. Mixed alpha- and non-hemolytic colonies are typical of normal upper respiratory (mouth) flora. (Rebecca Buxton, University of Utah, Salt Lake City, UT)

Figure 25: Mouth Flora (Enlarged View). FIG. 25. Mixed alpha- and non-hemolytic colonies are typical of normal upper respiratory (mouth) flora. (Rebecca Buxton, University of Utah, Salt Lake City, UT)

Figure 26: Normal respiratory flora with Streptococcus (Enlarged View). FIG. 26. Normal Upper respiratory flora mixed with beta-hemolytic Streptococcus species (S. pyogenes). (Rebecca Buxton, University of Utah, Salt Lake City, UT)

Figure 27: Normal respiratory flora with Streptococcus (Enlarged View). FIG. 27. Normal Upper respiratory flora mixed with beta-hemolytic Streptococcus species (S. pyogenes). (Rebecca Buxton, University of Utah, Salt Lake City, UT)

Figure 28: Streptococcus pyogenes (Enlarged View). FIG. 28. Beta hemolytic Streptococcus species: Streptococcus pyogenes (Lancefield group A). (Rebecca Buxton, University of Utah, Salt Lake City, UT)

Figure 29: Streptococcus species (Enlarged View). FIG. 29.  Beta hemolytic Streptococcus species: Lancefield group C. (Rebecca Buxton, University of Utah, Salt Lake City, UT)

Figure 30: Streptococcus species (Enlarged View). FIG. 30. Beta hemolytic Streptococcus species: Lancefield group C (transmitted light). (Rebecca Buxton, University of Utah, Salt Lake City, UT)

Figure 31: Streptococcus species (Enlarged View). FIG. 31. Beta hemolytic Streptococcus species: Lancefield group C (Large colony types of Lancefield groups A, C, and G can appear very similar on blood agar plates). (Rebecca Buxton, University of Utah, Salt Lake City, UT)

Figure 32: Streptococcus anginossus (Enlarged View). FIG. 32. Lancefield group F streptococci (beta-hemolytic strains of the Streptococcus anginossus group) produce very small (so called "minute") colonies which are beta hemolytic, but because of their size and slower growth, the complete clearing of red blood cells may be difficult to appreciate. (Rebecca Buxton, University of Utah, Salt Lake City, UT)

Figure 33: Streptococcus species (Enlarged View). FIG. 33. Beta hemolytic Streptococcus species: Lancefield group F. (Rebecca Buxton, University of Utah, Salt Lake City, UT)

Figure 34: Streptococcus species (Enlarged View). FIG. 34. Beta hemolytic Streptococcus species: Lancefield group F. (Rebecca Buxton, University of Utah, Salt Lake City, UT)

Figure 35: Streptococcus species (Enlarged View). FIG. 35. Beta hemolytic Streptococcus species: Lancefield group F. (Rebecca Buxton, University of Utah, Salt Lake City, UT)

Figure 36: Streptococcus agalactiae (Enlarged View). FIG. 36. Beta hemolytic Streptococcus species: Streptococcus agalactiae (Lancefield group B). (Rebecca Buxton, University of Utah, Salt Lake City, UT)

Figure 37: Streptococcus agalactiae (Enlarged View). FIG. 37. Beta hemolytic Streptococcus species: Streptococcus agalactiae (Lancefield group B) Hemolysis may be difficult to appreciate, and may never completely clear the cells. (Compare with the complete hemolysis of Streptococcus pyogenes, Figure 4 (also see Figures 7 and 8 ). (Rebecca Buxton, University of Utah, Salt Lake City, UT)

Figure 38: Enterococcus faecalis (Enlarged View). FIG. 38. "Gamma Streptococcus" : Enterococcus faecalis (48 hours, slight alpha hemolysis. Also see Figures 12 and 13). (Rebecca Buxton, University of Utah, Salt Lake City, UT)

Figure 39: Streptococcus bovis (Enlarged View). FIG. 39. Streptococcus bovis (Lancefield group D) may appear very similar to some Enterococcus species. (Rebecca Buxton, University of Utah, Salt Lake City, UT)

Figure 40: Streptococcus bovis (Enlarged View). FIG. 40. Streptococcus bovis (Lancefield group D). (Rebecca Buxton, University of Utah, Salt Lake City, UT)

Figure 41: Streptococcus bovis (Enlarged View). FIG. 41. Streptococcus bovis (Lancefield group D). (Rebecca Buxton, University of Utah, Salt Lake City, UT)

Figure 42: Streptococcus bovis (Enlarged View). FIG. 42. Streptococcus bovis (Lancefield group D). (Rebecca Buxton, University of Utah, Salt Lake City, UT)

Figure 43: Antibiotic sensitivity testing of streptococcal species on blood agar. FIG 43. Antibiotic sensitivity testing of streptococcal species on blood agar. The blood agar plate was divided then inoculated with two organisms using a swab. Bacitracin differentiation disks (~0.04 units of bacitracin) were placed in the center of each inoculation and the plate was incubated for 24 hours at 37°C. (A) Streptococcus mitis (alpha-hemolytic, growth noted by greening of the agar) shows no zone of inhibition indicating resistance to bacitracin. (B) Streptococcus pyogenes (beta-hemolytic, growth indicated by clearing of the agar) shows a zone of inhibition (arrow) around the bacitracin disc indicating sensitivity; the zone of inhibition is still red because the red bllod cells did not lyse. (Tasha L. Sturm, Cabrillo Collete, Aptos, CA)