Bacterial infections of Mouth and Pharynx

Question 1

what does a sore throat usually show upon exam?

Answer 1

inflammation of pharynx, tonsils, uvula with exudate, cervical lymphadenopathy and fever

Question 2

what are the most common causes of sore throat? what are other alternatives?

Answer 2

virus is most common

also caused by bacteria- strep. pyogenes, c. diphtheria, n gonorrhoeae and h influenzae

Question 3

what percent of pharyngitis is due to group A strep?

Answer 3

30% (streptococcus pyogenes)

Question 4

how is group A strep tested? what are the limitations of the test?

Answer 4

rapid antigen detection- prone to false negatives (not sensitive)
can also culture

Question 5

what are the defining characteristics of group A strep?

Answer 5

gram positive cocci that grow in chains

beta- hemolytic, bacitracin sensitive and react with lancefield group A antiserum

Question 6

what is the reservoir of group A strep. how is it transmitted?

Answer 6

carriers have it in pharynx and skin. transmitted by contact or saliva

Question 7

what are the toxins of group A strep?

Answer 7

streptokinase (tissue lysis), streptodornase (digests DNA), hyaluronidase (digests CT), pyrogenic toxin (fever and toxic shock) and erythrogenic toxin (rash)

Question 8

what is streptolysin and how is it useful?

Answer 8

a substance associated with group A strep that produces hemolysis on blood agar. induces short lived IgM antibody that is diagnostically useful

Question 9

what physical virulence factor does group A strep have?

Answer 9

pilli

Question 10

what are some complications of streptococcal pharyngitis?

Answer 10

tonsillitis, middle ear infection, mastoiditis, meningitis, scarlet fever and rheumatic fever

Question 11

how does mastoiditis arise in strep pharyngitis? meningitis?

Answer 11

an ear infection travels upward into the mastoid air cells. can go from there to the meninges

Question 12

what is the cause of scarlet fever? what are the clinical manifestations?

Answer 12

exotoxin from a bacteriophage of group A strep

skin and tongue rash (strawberry tongue)

Question 13

how is strep throat prevented?

Answer 13

prophylactic antibiotics for patients who have had post strep diseases or tonsillectomy may reduce the risk of future infections

Question 14

what is the treatment for group A strep?

Answer 14

penicillin, amoxicillin, erythromycin or cephalosporins (little resistance). not essential because infection is self limiting

Question 15

what is the progression of rheumatic fever? what is it caused by?

Answer 15

arises 3 weeks after resolution of strep throat with fever, polyarthritis and inflammation of the heart. autoimmune

Question 16

how is rheumatic fever diagnosed?

Answer 16

fever, polyarthritis and heart murmur plus IgM anti streptolysin O antibody. heart lesions and joints are sterile

Question 17

how does carditis from rheumatic fever resolve?

Answer 17

fibrosis of the endocardium or calcification. often has permanent valve distortion with life long risk of endocarditis (give prophylaxis to prevent)

Question 18

what is the treatment for rheumatic fever?

Answer 18

anti inflammatory drugs with replacement of heart valves if necessary

Question 19

how is rheumatic fever prevented?

Answer 19

if there is a prior history, aggressive antibacterial therapy should be given if there is another strep throat infection

Question 20

what bacteria causes dental carries? what identifies them?

Answer 20

streptococcus viridans. alpha hemolytic and optochin resistant

Question 21

what is the biofilm produced on teeth? how do they cause cavities?

Answer 21

bacteria produce carbohydrates that form biofilm. produce acids that demineralize enamel and dentin

Question 22

what are complications of dental caries?

Answer 22

pulpitis, abscesses and cellulitis

Question 23

how are dental caries treated?

Answer 23

decalcified tissue is removed and acute abscess are treated temporarily with penicillin, erythromycin or cephalosporins

Question 24

what is the usual cause of endocarditis? what other organisms can cause it?

Answer 24

usually viridans streptococci. IV drug users and pts with infected IV lines may contract s aureus. alternatively the HACEK group of gram negative rods

Question 25

how is diagnosis of endocarditis confirmed? what clinical features may be present?

Answer 25

confirmed by cardiac exam. may cause splinter hemorrhages under fingernails and in conjunctiva. blood culture may be positive

Question 26

how is endocarditis treated?

Answer 26

prolonged antibiotics. replacement of valves may be necessary but the new valve may become infected

Question 27

how is endocarditis prevented?

Answer 27

antibiotic coverage of dental treatment and catheterization in at risk patients

Question 28

what is peridontal disease? what is the early stage?

Answer 28

chronic inflammation in oral tissues that are in contact with dental plaque. early stage is gingivitis (reversible)

Question 29

what occurs with prolonged gingivitis?

Answer 29

gingiva detach from the tooth creating a pocket where alveolar bone is destroyed. mature plaque is calcified and teeth are eventually lost

Question 30

what organism is responsible for peridontal disease?

Answer 30

not a single microorganism- complex mix of anerobic organisms

Question 31

what is the treatment of peridontal disease?

Answer 31

improvement in dental hygine including regular dental scaling to remove calcified plaque. peridontal surgurey can reduce pockets

Question 32

what is the etiology of diphtheria infection?

Answer 32

infection of pharyngeal mucous membrane causing necrosis and “membrane” with respiratory obstruction

Question 33

what does the diphtheria toxin cause?

Answer 33

causes systemic muscle paralysis- may lead to myocarditis and death (encoded by bacteriophage)

Question 34

how is diphtheria transmitted?

Answer 34

air borne droplets

Question 35

how is diphtheria diagnosed?

Answer 35

by growth of the bacteria on tellurite plates (have to order specially). gram positive rods with clubbed end and internal beads. confirmed to produce toxin by antibody tests or contain toxin gene by PCR

Question 36

how is diphtheria treated?

Answer 36

with antitoxin (asap). penicillin or erythromycin helps with resolution

Question 37

how is diphtheria prevented?

Answer 37

with a vaccine inlcuding toxoid. required for all school children