In this slide, I will teach you about gram-positive cocci which streptococcus viridans. I will tell you about its diseases, transmission, pathogenesis, characteristics, lab diagnosis, treatment, and prevention in a short and easy way.

2. Streptococcus Viridans
Gram positive cocci

3. Species
• Streptococcus sanguis
• Streptococcus mutans
• S.mutis
• S.gordoni
• S.salivaruis
• S.anginosus
• S.milleri
• S.intermedius

4. Diseases
• Subacute Endocarditis of mitral valve most commonly.
• S.Sanguis cause it
• Brain abscess,
• Central raises area to necrosis with pus surrounded by erethema
• Dental caries( Tooth decay)
• Bacteria in the mouth make acids that attack tooth's surface, or enamel and
make small hole in a tooth.
• S.mutans cause it.
• Mixed infections with mouth anaerobes and Peptostreptococcus
• Grow Under aerobic or microaerophilic conditions (oxygen at a lower partial
pressure) produce variable hemolysis.

6. Habitat & Transmission
•Habitat
•Oropharynx
•Transmission
•During dental procedures, it enter blood
stream

7. Pathogenesis
• Pyogenic (Pus producing)
• Bactremia from dental procedures spreads it to damage
heart valves
• Form vegetations which protected from host defense
• Glycocalyx
• Composed of poly saccharide enhaces adhesion to heart
valve
• Adhere platlets by dextrans

8. Characteristics
•Gram positive cocci in chains
•a hemolytic colonies
•Incomplete hemolysis of RBCs(Green color)
•No lancefield group
•No capsule

9. Laboratory Diagnosis
• Gram stained smear and culture (Crystal violet)
• Catalase negative
• a hemolytic colonies on blood agar
• Optochin Resistant (Growth not inhibited)
• Colonies not dissolved in bile
• Various Biochemical test for classification into
species

11. Treatment
•Pencillin G or ceftriaxone with or without
aminoglycoside
•Vancomycin alone

12. Prevention
•Pencillin
•To prevent endocarditis
•In patients with damaged prosthetic heart
valves who undergo dental procedures.

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