Viridans Streptococci

Question 1

Viridans Streptococci are sometimes known as?

Answer 1

Oral streptococci.

Question 2

The viridans streptococci are commensals of?

Answer 2

Upper respiratory tract
Female genital tract
GI tract
A large number is present in mouth.

Question 3

Describe the pathogenesis of viridans streptococci?

Answer 3

1. Ability to produce acid especially in s. Mutans is important in dental caries.
2. Production of various carbohydrates with aids in adherence to tooth enamel and gum is important for colonisation.
3. Extracellular dextran production.
4. Fibronectin

Question 4

What is the function of extracellular dextran?

Answer 4

Used for adherence to heart valves and it offers resistance to antimicrobial therapy.

Question 5

What is the function of fibronectin?

Answer 5

It also mediates adherence to heart valves.

Question 6

What are the clinical features of viridans streptococci?

Answer 6

Endocarditis.
Bacteriemia.. Causes severe sepsis in neutropenic patients.
Meningitis.
Pneumonia.
Sialadenities.
Pericarditis.
Odontogenic infections.

Question 7

What is the diagnosis for viridans streptococci?

Answer 7

Gram positive cocci, catalase negative.

Facultative anerobe.

Most are alpha hemolytic on blood agar but some are non hemolytic.

They are resistant to bile solubility and optochin.

Unable to grow in 6.5% NaCl.

Question 8

What is the treatment for viridans streptococci?

Answer 8

CAI- Penicillin is the treatment of choice. Some other beta lactams like ceftriaxone can be used.

Nosocomical infections- Aminoglycoside + beta lactams.

Vancomycine is used in penicillin allergic pts and penicillin resistant infections.

Question 9

Nosocomial infections are associated with increased resistance to penicillin and other beta lactams and often resistance to aminoglycoside.

T/F

Answer 9

True.