bacterial infections of URT

Question 1

normal flora of nares

Answer 1

S epidermidis
S aureus
Corynebacterium spp.

Question 2

normal flora of nasopharynx

Answer 2

Streptococcus:
Viridans group (S mutans, mitis, milleri, salivarius)
Moraxella catarrhalis
Bacteroids
S pneumoniae
H influenzae
N meningitides

Question 3

M protein

Answer 3

causes degradation of C3b (opsonin) –> antiphagocytic

essential for virulence

Question 4

Streptococcal pyrogenic exotoxins (SPEs)

Answer 4

super antigens responsible for scarlet fever, toxic shock syndrome, and necrotizing fasciitis
only scarlet fever preceded by strep throat symptoms
nine proteins
cause fever, rash, T cell proliferation, B cell suppression

Question 5

is scarlet fever or acute rheumatic fever caused by inflammatory response?

Answer 5

acute rheumatic fever

Question 6

do SPEs cause scarlet fever or acute rheumatic fever?

Answer 6

scarlet fever

Question 7

will cultures for acute rheumatic fever show S pyogenes?

Answer 7

no, onset ~3 weeks after initial infection
host has fought off infection
disease caused by inflammatory response to infection

Question 8

diseases associated with S pyogenes

Answer 8

Streptococcal pharyngitis
Scarlet fever
Acute rheumatic fever
Streptococcal toxic shock syndrome
Post-streptococcal infection sequelae (acute glomerulonephritis)

Question 9

diagnosis of Strep pharyngitis

Answer 9

culture of posterior pharynx and tonsils

blood agar plates –> beta hemolysis

Question 10

treatment of Strep pharyngitis

Answer 10

10 day course of penicillin or erythromycin

Question 11

symptoms of scarlet fever

Answer 11

desquamation of hands, redness of skin, white coating on tongue

Question 12

symptoms of acute rheumatic fever

Answer 12

fever, joint pain, chest pain, rash, nodules, jerky movements

Question 13

acute glomerulonephritis

Answer 13

post-streptococcal infection sequelae
1-4 weeks after strep pharyngitis, or 3-6 weeks after skin infection
seen in children
deposition of antigen-antibody complexes in glomeruli –> inhibition of filtration
symptoms: edema, HTN, hematuria, proteinuria, decreased serum complement levels

Question 14

epidemiology of strep pharyngitis

Answer 14

respiratory droplets
if untreated, can be carried for weeks
anal carriers –> nosocomial infection
can spread by food contaminated by carriers

Question 15

diagnosis of strep pharyngitis

Answer 15

culture –> blood agar –> beta hemolysis

Question 16

treatment of strep pharyngitis

Answer 16

10 days penicillin or erythromycin

Question 17

symptoms of diphtheria

Answer 17

mild sore throat, slight fever, high fatigue, dramatic neck swelling, whitish gray membrane to tonsils/throat/nasal cavity

Question 18

organism that causes diphtheria

Answer 18

Corynebacterium diphtheriae

Question 19

Corynebacterium diphtheriae

Answer 19

gram + rod
non spore forming
Chinese letters

Question 20

treatment of diphtheria

Answer 20

a

Question 21

symptoms of pinkeye

Answer 21

tears, conjunctival redness, photophobia, EYELID SWELLING, PUS

Question 22

organisms that cause pinkeye

Answer 22

Haemophilus influenzae
Streptococcus pneumoniae
Moraxella lacunata
Enterobacteria
Neisseria gonorrhoeae

Question 23

pathogenesis of pinkeye

Answer 23

airborne respiratory droplets or rubbed in eye from contaminated hands
organisms resist lysozyme
symptoms induced by inflammatory response to organisms

Question 24

treatment of pinkeye

Answer 24

gentamicin or ciprofloxacin drops

Question 25

organisms that cause otitis media and sinusitis

Answer 25

Haemophilus influenzae
Streptococcus pneumoniae
MCAT

Question 26

treatment of otitis/sinusitis

Answer 26

ampicillin

Question 27

diseases caused by Streptococcus pneumoniae

Answer 27

otitis media
sinusitis
lobar pneumonia
meningitis

Question 28

Haemophilus influenzae

Answer 28

small pleomorphic gram negative rods or coccobacilli
facultative anaerobes
fermentative

Question 29

diseases caused by H parainfluenzae and non-encapsulated H influenzae (which colonize URT)

Answer 29

otitis media, sinusitis, bronchitis, pneumonia

Question 30

disease caused by encapsulated H influenzae serotype B

Answer 30

meningitis, epiglottitis, cellulitis in unvaccinated children

Question 31

Chlamydia spp

Answer 31

small obligate intracellular parasites
differ from other bacteria in development cycle:
inactive infectious elementary bodies + active noninfectious reticulate bodies

Question 32

Chlamydia trochamitis pathogenesis

Answer 32

direct destruction of host cells during replication + host inflammatory response
organisms gain access via abrasions/lacerations
granuloma formation

Question 33

diseases caused by Chlamydia trochamitis

Answer 33

trachoma
adult inclusion conjunctivitis
neonatal conjunctivitis
infant pneumonia