Bac Infections Of Mouth/Oropharynx

Question 1

What is another name for group A strep?

Answer 1

Streptococcus pyogenes

Question 2

General features of Streptocci

Answer 2

G(+) chains, classified by Lancefield Group and hemolysis on blood agar plates

Question 3

How can you determine a gram positive cocci is streptococci?

Answer 3

If you add hydrogen peroxide to the G(+) cocci and the bacteria are catalase(-), you have confirmed streptococci.

Question 4

Culture features of GAS

Answer 4

G(+) cocci, chains, beta-hemolytic

Question 5

What are the virulence factors of GAS?

Answer 5

Pili (encoded by path. island), toxins

Question 6

What are the five GAS toxins and their effects

Answer 6

Streptokinase (Tissue lysis), Streptodornase (Digest DNA), hyaluronidase (Digest connective tissue), pyrogenic toxin (fever, superantige, toxic shock), erythrogenic toxin (Skin rash)

Question 7

Which GAS hemolysin is of diagnostic use? Is it a virulence factor?

Answer 7

Streoptolysin O is highly antigenic and induces short-lived IgM response; It is NOT a virulence factor. People with strep infections do not get anemia!

Question 8

GAS reservoir

Answer 8

Pharynx and skin

Question 9

Streptococcal pharyngitis complications

Answer 9

Tonsilitis, peritonsilar abscess, Ludwig’s angina; Mastoiditis; Otitis Media; Meningitis; Scarlet Fever; Rheumatic Fever

Question 10

What is Ludwig’s Angina?

Answer 10

Life-threatening cellulitis/infected connective tissue of the floor of the mouth

Question 11

What is Scarlet Fever?

Answer 11

Skin rash and tongue rash (strawberry tongue) caused by pyrogenic exotoxin encoded by bacteriophage that carries gene for erythrogenic toxin caused most commonly by GAS (S. pyogenes)

Question 12

What is Rheumatic Fever?

Answer 12

Autoimmune condition with fever, polyarthritis, and inflammation of heart that causes permanent damage

Question 13

How is GAS transmitted?

Answer 13

Direct contact

Question 14

How is GAS diagnosed?

Answer 14

Culture shows growth on blood agar, zone of beta-hemolysis, bacitracin sensitivity and PYR-positive (Only common beta-hemolytic bug that is PYR positive)

Question 15

GAS prevention

Answer 15

No vaccines, prophylactic ABs, treat carriers

Question 16

GAS Tx

Answer 16

Systemic Penicillin G or erythromycin

Question 17

Another name for Viridans streptococci?

Answer 17

Streptococcus viridans

Question 18

Identification of S. Viridans

Answer 18

No Lancefield group. Blood agar -> Alpha-hemolytic -> optochin resistant and bile insoluble -> S. viridans

Question 19

S. viridans associated diseases and Tx

Answer 19

Dental caries (cavities) -> abscess/cellulitis; Bacteremia and possible sepsis Treated by tooth extraction, penicillin/erythromycin

Question 20

What situations would one prophylactically treat a patient to prevent S. viridans infection?

Answer 20

Administer antibiotics at time of dental Tx

Question 21

Culture findings of Corynebacterium diphtheriae

Answer 21

G(+) rods with clubbed ends and internal beads

Question 22

Virulence factors of C. diphtheriae

Answer 22

Diphtheria toxin encoded on bacteriophage

Question 23

C. diphtheriae transmission

Answer 23

Air-borne droplets

Question 24

Disease associated with C. diphtheriae

Answer 24

Diphtheria - infection of pharyngeal mucous membrane causing necrosis and pseudomembrane formation. Systemic release of toxin causes muscle paralysis, myocarditis and death.

Question 25

C. diphteriae Dx

Answer 25

Growth on tellurite (Tellurium Oxide) plate, Ab test to toxin, Toxin gene ID by PCR

Question 26

C. diphteriae Tx

Answer 26

Equine antitoxin ASAP, mechanical ventialation (in case of anaphylactic response to equine antitoxin) Penicillin, Erythromycin

Question 27

C. diphtheriae prevention

Answer 27

DTaP vaccine (diphtheria, tetanus, pertussis); Diphtheria vaccine required for all school children in NY

Question 28

What is the M protein?

Answer 28

A virulence factor for GAS. Cross Abs for M protein bind to the heart and cause Rheumatic fever.