Bacterial Infections of the Mouth and Pharynx

Question 1

streptococcal pharyngitis

Answer 1

sore throat. inflammation of pharynx, tonsils, uvula, cervical lymphadenopathy and fever. not possible to clinically identify each cause reliably. 30% due to group A strep

Question 2

streptococcal pharyngitis diagnosis

Answer 2

group A strep origin suggested by family or social history. rapid antigen detection assays can work, but are prone to false negatives. bacterial culture shows it. beta hemolytic, bacitracin sensitive and react with lancefield group A antiserum

Question 3

streptococcal pharyngitis reservoir

Answer 3

carriers, in the pharynx and skin. transmission is by contact or saliva

Question 4

group A streptococci toxins

Answer 4

streptokinase (tissue lysis), streptodornase (digests DNA), hyaluronidase (digests connective tissue), pyrogenic toxin (fever, super antigen, toxic shock), erythrogenic toxin (skin rash)

Question 5

streptolysin O

Answer 5

highly antigenic, inducing short lived IgM antibody which can be diagnostically useful

Question 6

complications of streptococcal pharyngitis

Answer 6

tonsillitis -> peritonsillar abcess -> ludwig’s angina

middle ear infections, mastoiditis, meningitis, scarlet fever, rheumatic fever

Question 7

scarlet fever

Answer 7

due to exotoxin encoded by bacteriophage that carries gene for the erythrogenic toxin. skin rash and tongue rash (strawberry tongue)

Question 8

streptococcal pharyngitis treatment

Answer 8

systemic penicillin G, amoxicillin, erythromycin, cephalosporins

Question 9

rheumatic fever etiology

Answer 9

post-streptococcal condition. 3 weeks after resolution of sore throat, get fever, polyarthritis, inflammation of heart leading to permanent deformations. recurrences common

Question 10

rheumatic fever diagnosis

Answer 10

clinical features plus presence of IgM anti-streptolysin O antibody. heart lesions and inflamed joints are sterile. no bacteremia

Question 11

rheumatic fever pathogenic

Answer 11

auto immune. certain M-protein types are more likely to be associated with rheumatic fever (M3, M5). some HLA types are more common in patients. carditis can resolve with fibrosis of endocardium, or calcification with permanent valve distortion

Question 12

rheumatic fever treatment and prevention

Answer 12

anti inflamm drugs. no antibacterial therapy needed. replace heart valves if needed. aggressive anti bacterial therapy in the event of later strep infections

Question 13

dental carries etiology

Answer 13

infection of streptococci viridans. alpha hemolytic. optochin resistant. organisms produce high molecular weight carbohydrates that form biofilm on tooth surfaces. break down sugars to make acid that demineralizes enamel and dentin

Question 14

dental carries diagnosis

Answer 14

dental exam shows early demineralization. lab testing not informative since bacteria are part of normal mouth flora for 100% of people

Question 15

strep viridans virulence factors

Answer 15

extracellular polysaccharides. acids.

Question 16

prevention of dental carries

Answer 16

optimal fluoride concentration of drinking water during dental enamel formation. low sugar diet, and topical fluorides

Question 17

dental carries complications

Answer 17

pulpitis, abcesses, cellulitis. bacteremia and endocarditis may follow dental treatment of susceptible patients.

Question 18

dental carries treatment

Answer 18

remove decalcified tissue. acute abscesses can be treated temporarily with penicillin, erythromycin, or cephalosporins. dental extraction is more effective.

Question 19

endocarditis etiology

Answer 19

previous rheumatic fever causes distortion of endothelium in the heart that leads to turbulent blood flow. sticky bacteria can come into contact with this distorted layer and attach and replicate. infection can be very persistent. . heart vegetations can be foci of infection and metastatic abcesses. valves are gradually destroyed. antibiotics do not penetrate these vegetation. usually caused by viridans. can be staph aureus in druggies

Question 20

endocarditis diagnosis

Answer 20

cardiac exam. satellite infectious foci under fingernails and in conjunctiva due to release of infected material into circulation. blood culture may be positive for organisms

Question 21

endocarditis treatment

Answer 21

prolonged antibiotics and replace heart valve (carries risk of new valve being infected)

Question 22

peridontal disease

Answer 22

chronic inflammation in oral tissues that are in contact with dental plaque. early stage is gingivitis, and is reversible if dental hygiene is improved. gingiva can detach and create a pocket where microorganisms proliferate. as pocket becomes deeper, alveolar bone is destroyed and mature plaque becomes calcified, causing teeth to loosen and fall out. no specific microorganism is responsible. treat with improved dental hygiene or surgery

Question 23

diptheria etiology

Answer 23

infection of pharyngeal mucous membrane causes necrosis and membrane covering pharynx. release of toxins causes systemic muscle paralysis including myocarditis and death in 10-20% of people. mostly childhood disease

Question 24

diptheria virulence factor

Answer 24

diptheria toxin encoded by bacteriophage

Question 25

diptheria transmission

Answer 25

airborne droplets

Question 26

diptheria diagnosis

Answer 26

growth of corynebacterium diptheria on tellurite plates. appearance of gram positive rods with clubbed end and internal beads. lab cultures are confirmed to produce toxin by antibody tests or toxin gene on PCR. smears not useful since there are non-pathogenic strains

Question 27

diptheria treatment

Answer 27

antitoxin given ASAP. penicillin or erythromycin helps resolution

Question 28

diptheria prevention

Answer 28

vaccine. DTaP includes diptheria toxoid. required for all NYS children in school