Bacterial Infections of the Mouth and Pharynx

Question 1

Group A Strep characteristics: What can it lead to in

Answer 1

Gram-positive cocci in chains; catalase negative; beta hemolytic, sensitive to bacitracin

Question 2

Structural feature of Group A strep, toxins?

Answer 2

Structural: Pili;
Toxins: streptokinase (tissue lysis), streptodornase (digest DNA), hyaluronidase (break down CT), also pyrogenic toxin (fever, super antigen, toxic shock) and erythrogenic toxin (potential skin rash)

Question 3

Reservoir and transmission of group A strep:

Answer 3

1. Human throat and skin

2. Think of carriers in direct contact with susceptible person, infected patient also

Question 4

Hemolysins in group A strep; which one is antigenic?

Answer 4

are not virulence factors that produce hemolysis on blood agar plates; Streptolysin O (induces short-lived IgM antibody which can be diagnostically useful)

Question 5

For diagnosis of group A strep? Treat? Prevention

Answer 5

1. Rapid office tests with Ab assays (quick but not 100% sens)
2. Swab, culture, gram stain, BACITRACIN SENS (do overnight)
3. Direct exam of smear useless
4. Do not use antibiotics until diagnosis is confirmed;
   penicillin, erythromycin, cephalosporins (treatment not essential as infection is self-limiting and resistance to antibiotics not a big problem);
   NO VACCINE; not recommended to treat carriers and maybe give tonsillectomy

Question 6

Complications of strep A sore throat:

Answer 6

1. Tonsils (tonsillitis with peritonsillar abscess and Ludwig’s angina with swelling under tongue) and floor of mouth
2. Middle ear (inflammation of Eustachian tube and infection in middle ear; can drain with Grommet), then mastoids (mastoiditis: swelling of back of ear and soft tissue swelling; BUT TREAT SORE THROAT AND MIDDLE EAR) and meninges potentially (unusual)

Question 7

Another complication of strep A sore throat?

Answer 7

Skin rash from SCARLET FEVER (erythrogenic toxin); look for the strawberry tongue in Scarlet Fever!!

Question 8

Complication of Group A strep following recovery? Symptoms and lesion?
What strains are more likely to lead to this complication? How does this resolve?

Answer 8

Rheumatic fever (usually dudes, 6-15): occurs about three weeks after strep sore throat; autoimmune with fever, polyarthritis, and inflammation of heart; lesions are STERILE; think IgM anti-streptolysin O Ab, look for endarteritis and Aschoff body;
M3, M5, M13;
distortion of aortic heart valve (due to rheumatic fever)

Question 9

For treatment of rheumatic fever? Prevention?

Answer 9

Anti-inflammatory drugs (aspirin/steroids), replacement of heart valves;
patients with history of rheumatic fever should have aggressive anti-bacterial therapy

Question 10

Viridans strep can lead to _____; list the virulence factors and some characteristics about Viridans

Answer 10

dental caries;
virulence factors: sugar-metabolizing enyzmes;
Alpha hemolytic, optochin resistant;
make high molecular weight carbs to form biofilm on teeth (dental plaque) or acids made (decalcification)

Question 11

To diagnose strep viridans? Prevent? Complications? Treatment?

Answer 11

Dental examinations showing early demineralization;
low-sugar diet with optimal fluoride concentration of drinking water;
abscesses, cellulitis, potentially bacteremia and endocarditis following dental treatment;
acute abscesses to treat with penicillin, erythromycin, or cephalosporins, but treat with dental extraction as more effective

Question 12

Another complication of previous rheumatic fever? What would you look for on exam? Diagnose?

Answer 12

BACTERIAL ENDOCARDITIS (sticky bacteria come into contact with distorted endothelium, with valves being susceptible);
heart vegetations with metastatic abscesses, also splinter hemorrhages under fingernails and conjunctiva;
look at Xrays for dental infections and clinical exam; also blood culture for bacteremia/endocarditis

Question 13

Treat viridans strep?

Answer 13

1. Caries (remove them with root canal filling and extraction; penicillin/erythromycin of limited value)
2. Endocarditis (penicillin/erythromycin to treat, but prolonged with poor prognosis, aka 50% die even with treatment)

Question 14

Periodontal disease is ____ early on and can be ____ with what? Over a period of years, what happens? Any specific organism? Treatment?

Answer 14

gingivitis; reversible, if dental hygiene improves; gingiva can detach from teeth and pocket made where microorganisms proliferate, and deeper alveolar bone can be destroyed;
not really but just a mix of anaerobic organisms;
dental hygiene, dental scaling to remove plaque, or use periodontal surgery

Question 15

Diphtheria: characteristics, diagnosis, treatment, prevention:

Answer 15

Gram pos club-shaped rods, could have the diphteria toxin (local and cardiac necrosis), look for skin and mucous membranes inhabited (thick white/dark gray pseudomembrane covering oropharynx)
Spread: respiratory droplets, direct contact;
Diagnosis: swab nose and throat, NEED TELLURITE MEDIA; think RUSSIA!! Tox gene on pcr
Treatment: antitoxin (equine); penicillin/erythromycin
Prevention: childhood vaccination with diphtheria toxoid, and boosters after 1, 5 years; boosters for adults if going to endemic area like RUSSIA