MMI133_Lecture15 Flashcards
flora of the upper respiratory tract
alpha-streptococci (GAS) Strepotococcus pyogenes
like acid pH on mucous membranes
viral URT infections
common cold + infectious mononucleosis - kissing disease
bacteria URT infections
strep throat + complications
diphtheria
otitis media
epiglottitis
whooping cough
what is the most common cause of Pharyngitis?
virus - 40% relative importance
common cold
pharyngitis - sore throat due to inflammed pharynx
corup
mono
common cold
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
rhinovirus
> 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
HHV-4
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
EBV is related to
cancer
Burkitt’s lymphoma + other B cell lymphomas
most common childhood cancer in africa
malaria maybe depressed immunity allows it to be worse?
Streptococcal pharyngitis
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
Scarlet fever
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
Rheumatic fever
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
Diphtheria
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
diphtheria toxoid vaccine introduced in
1924
vax drastically reduced incidence of disease in NA + europe - now rare disease
symptoms of diphtheria
sore throat, fever, malaise
neck swelling + bull neck
nerve paralysis
white-grey membrane across back of throat - fibrin, dead tissue, bact cells, toxin + neutrophils
malaise
general feeling of discomfort, illness, or uneasiness whose exact cause is difficult to identify
thick gray membrane = pseudomembrane of diphtheria
covers back of throat
very hard to remove + grows out of tissue + bleeds if try to dislodge it
can prevent breathing + obstructs air passage
Corynebacterium diphtheriae is apathogenic/cannot cause disease unless
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
treatment of diphtheria
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
most common causes of bact URTI’s
streptococcus pneumoniae
haemophilus influenzae
moraxella catarrhalis
100% of children in daycares have all 3 in nasopharynx
pathogens involved in otitis media/infection of middle ear
streptococcus pneumoniae
haemophilus influenzae
moraxella catarrhalis
whooping cough = 100 days cough
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
3 stages of whooping cough
catarrhal = cold like
paroxysmal = gasping cough
convalescence = healing
whooping cough is most risky for
infants for broken ribs, pertussis pneumonia, oxygen deprivation to brain
countries with no vax program = important cause of morbidity in children
whooping cough pathogenicity
FTA filamentous hemagglutinin for adherence
pertussis toxin systemic effects
tracheal cytotoxin damages ciliated cells
lethal toxin = tissue necrosis
adenylate cyclase = reduces phagocytic activity
