MMI133_Lecture15

Question 1

flora of the upper respiratory tract

Answer 1

alpha-streptococci (GAS) Strepotococcus pyogenes
like acid pH on mucous membranes

Question 2

viral URT infections

Answer 2

common cold + infectious mononucleosis - kissing disease

Question 3

bacteria URT infections

Answer 3

strep throat + complications
diphtheria
otitis media
epiglottitis
whooping cough

Question 4

what is the most common cause of Pharyngitis?

Answer 4

virus - 40% relative importance

common cold
pharyngitis - sore throat due to inflammed pharynx
corup
mono

Question 5

common cold

Answer 5

caused by >100-200 diff viruses - so no immunity + no vax

30-50% - caused by rhinoviruses
15-20% - caused by coronaviruses - infection spreads easily to sinuses + LRT + middle ear

Question 6

rhinovirus

Answer 6

> 50% of common colds
small, RNA, non-enveloped
100 subtypes
90% bind to ICAM-1 receptor

transmission - direct contact (SHAKING HANDS) + some droplet

doesn’t grow at 37 C, optimal 33C, so restricted to URT
10-12 hrs incubation
self-limiting infection + no antivirals + no vax

Question 7

HHV-4

Answer 7

EBV = Epstein Barr virus
infectious mononucleosis = kissing disease
Mono

DNA, herpesviridae, enveloped, remains LATENT in B cells forever

most people have while very young + mild, most severe in older teens + college
systemic effects on cardiovascular + lymphatic systems
virus shed intermittently from saliva thru life

Symptoms: fever, sore throat, swollen lymph glands in neck, weakness, fatigue, enlarged spleen = no hard physical exertion,

production of heterophile = weird antibodies that agglutinate other mammals RBC, but don’t seem to do anything in our bodies

Ampicillin rash complication - superantigen effect

Question 8

EBV is related to

Answer 8

cancer
Burkitt’s lymphoma + other B cell lymphomas
most common childhood cancer in africa
malaria maybe depressed immunity allows it to be worse?

Question 9

Streptococcal pharyngitis

Answer 9

strep throat

Streptococcus pyogenes Strep group A = beta hemolytic streptococci

on inspection, strep throat cannot be differentiated from other infections = needs lab tests

ALL cases of streptococcus pyogenes pharyngitis need to be treated with antibiotics to prevent sequalae complications
can be rapid tested

Question 10

Scarlet fever

Answer 10

streptococcus pyogenes can produce erythrogenic toxin = makes it red

pinkish-red sandpaper like skin rash + high fever + strawberry tongue

may progress to glomerulonephritis or rheumatic fever

first time you get strep throat with one of the strains producing superantigen erythrogenic toxin you can get Scarlet fever

Question 11

Rheumatic fever

Answer 11

non-infectious complication of Streptococcus pyogenes infection after infection has disappeared

cross reactivity of bact antigens with tissue antigens results in mitral valve damage from immune system

heart valve issues associated with streptococcus pyogenes + strep throat

Question 12

Diphtheria

Answer 12

Corynebacterium diphtheriae
aerobic G+ bacillus (non-spore forming)

bact don’t invade tissues - produce exotoxin which inhibits protein synthesis in host cells and tropism for nerve cells

used to be leading cause of mortality in children in early 1920’s

Question 13

diphtheria toxoid vaccine introduced in

Answer 13

1924

vax drastically reduced incidence of disease in NA + europe - now rare disease

Question 14

symptoms of diphtheria

Answer 14

sore throat, fever, malaise
neck swelling + bull neck
nerve paralysis
white-grey membrane across back of throat - fibrin, dead tissue, bact cells, toxin + neutrophils

Question 15

malaise

Answer 15

general feeling of discomfort, illness, or uneasiness whose exact cause is difficult to identify

Question 16

thick gray membrane = pseudomembrane of diphtheria

Answer 16

covers back of throat
very hard to remove + grows out of tissue + bleeds if try to dislodge it
can prevent breathing + obstructs air passage

Question 17

Corynebacterium diphtheriae is apathogenic/cannot cause disease unless

Answer 17

it is lysogenized or transduced by a bacteriophage whihc transfers the exotoxin gene to it so it can make the toxin

so all isolates of C diphtheriae must be tested for toxin production

bact don’t invade tissues, just expel exotoxin which can diffuse into other areas

Question 18

treatment of diphtheria

Answer 18

antibiotics + antitoxin

vax = effective but older pop may only have effective protection in 20% of cases without boosters

tetanus toxoid usually combined with diphtheria toxoid + pertussis DTaP

cutaneous diphtheria is common in tropics

Question 19

most common causes of bact URTI’s

Answer 19

streptococcus pneumoniae
haemophilus influenzae
moraxella catarrhalis

100% of children in daycares have all 3 in nasopharynx

Question 20

pathogens involved in otitis media/infection of middle ear

Answer 20

streptococcus pneumoniae
haemophilus influenzae
moraxella catarrhalis

Question 21

whooping cough = 100 days cough

Answer 21

bordetella pertussis

small aerobic G- coccobacillus or bacillus
many exotoxins
donesn’t invade tissues but colonizes ciliated respiratory epithelium _ kills cells with tracheal cytotoxin

transmission = DROPLET

Question 22

3 stages of whooping cough

Answer 22

catarrhal = cold like
paroxysmal = gasping cough
convalescence = healing

Question 23

whooping cough is most risky for

Answer 23

infants for broken ribs, pertussis pneumonia, oxygen deprivation to brain

countries with no vax program = important cause of morbidity in children

Question 24

whooping cough pathogenicity

Answer 24

FTA filamentous hemagglutinin for adherence
pertussis toxin systemic effects
tracheal cytotoxin damages ciliated cells

lethal toxin = tissue necrosis
adenylate cyclase = reduces phagocytic activity

Question 25

whooping cough treatment

Answer 25

usually not effective for disease, but can administer antiobiotics to reduce length of infectivity

Question 26

whooping cough vaccine

Answer 26

new acellular vaccine against toxins
combined iwht tetanus + diphtheria in DTaP
5 doses nwe recommendations for revaccinating early teens