URTIs (3) Flashcards
list the URTIs we are required to know
- common cold
- pharyngitis
- croup
- pertussis
- otitis media
- sinusitis
what is the common cold
it is a VIRAL URTI
acute and self limiting
most frequent human illness
seasonal
how is the common cold transmitted
most significant = inoculation of conjunctiva or nasal mucosa in 10 seconds
less significant is infective droplets on mucosa
when and for how long is the common cold infective
viral shedding peaks on the third day (coincides with peak of symptoms)
low level shedding can persist for 3 weeks
what is the incubation period of the common cold
24-72 hours from contact to symptoms
list some viruses that cause the common cold
- rhinovirus
- RSV
- influenza virus
- parainfluenza virus
- adenovirus
- enterovirus (coxsackievirus, echovirus)
- coronavirus
- human metapneumavirus
which viruses usually cause the common cold in october/november
parainfluenza virus
which virus is mostly responsible for the common cold in may/june/july/aug
enterovirus (coxsackievirus and echovirus)
which virus is mostly responsible for the common cold in september and march/april
rhinovirus
which viruses are mostly responsible for the common cold in dec/jan/feb
influenza, RSV, coronavirus, adenovirus
pathophysiology of the common cold
virus deposits on nasal/conjunctival mucosa and attaches to the epithelial cell receptors and damages cells–> this results in activation of host defence and release of CYTOKINE IL8
IL-8 attracts PMNs which increase nasal secretion and decrease mucociliary clearance
severity of symptoms corresponds to IL-8
pathophysiology of rhinovirus (common cold)
release of ALBUMIN and BRADYKININS which cause increased vascular permeability
bradykinins cause sore throat and rhinitis
minimal damage to nasal epithelium (like coronavirus)
pathophysiology of adenovirus and influenza A (common cold)
CYTOPATHIC effect and DESTRUCTION of nasal epithelium
how do you diagnose the common cold
differential
clinical presentation of the common cold
rhinorrhea nasal congestion sneezing sore throat cough low grade fever headache malaise
duration = 10 days (cough may last 2-3 weeks)
Tx of common cold
prevention-based (i.e hand washing)
symptomatic treatment saline irrigation decongestants (dont shorten duration) steam inhalation antipyretic/pain control
what is pharyngitis
one of most common reasons for physicians visits
majority are VIRAL
swelling of the back of the throat/pharynx, between the nostrils and larynx
epidemiology of pharyngitis
peak incidence in winter and early spring
mostly school aged kids
GAS pharyngitis:
- 20-30% in kids//5-15% in adults
- incubation period of 2-5 days
- highly communicable but noninfectious within 24 hours of abs use
- transmission via droplet person to person
viruses that cause pharyngitis
- respiratory viruses
- adenovirus
- influenza virus
- parainfluenza virus - other viruses
- coxsackie virus
- echovirus
- HSV
- epstein barr
bacteria that cause pharyngitis
*Strep pyogenes (GAS) “strep throat”
groups C and G strep N. gonorrhea corynebacterium diphteriae fusobacterium necrophilum arcanobacterium hemolyticum
pathophysiology of GAS pharyngitis + virulence factors
(S. pyogenes)
- URT colonization (highly virulent)
- capsule = compromised of HYALURORIC ACID which has a chemical structure very similar to connective tissue and therefore escapes host defenses and allows for colonization
virulence factors:
- M proteins–> resist phagocytosis
- extracellular exotoxins/hemolysins/invasins–> tissue damage
- streptolysin O –> toxic to variety of cells including myocytes (causes rheumatic fever in 3% of untreated patients)
with what symptoms of pharyngitis do you suspect viral etiology
COUGH
hoarseness conjunctivitis rhinorrhea diarrhea rash
*do not test children and adults with signs and symptoms of viral etiology
when do you suspect GAS as the etiologic agent in pharyngitis (symptoms)
ABSENCE OF COUGH
pharyngeal/tonsillar exudate
tenderness/enlargement of anterior cervical lymph nodes
what might you suspect when pharyngitis in a teen or young adult presents with:
- neck pain
- rash
- Lemierre’s disease (fusobacterium necrophorum)
2. consider arcanobacterium haemolyticum
pharyngitis diagnosis procedure
throat culture (90-95% sensitive for GAS)
rapid antigen test (highly specific; sensitivity 70-90%)
confirmatory culture of RADT is negative in children
Tx of pharyngitis
- viral
- bacterial
- symptomatic
2. if GAS, penicillin (alternative is clindamycin)
what is croup
laryngotracheitis (inflammation of larynx and trachea)
self limiting infection
in what age range is croup most common
3-36 months (rare after that)
in what sex is croup most common
boys
when is croup most common
fall/winter (coincides with parainfluenza, influenza, RSV)
when in the day are croup symptoms most prominent
late evenings and early mornings (leading to ER visits)
is croup viral or bacterial
viral
what types of viruses cause croup
**parainfluenza type 1
RSV adenovirus coronavirus influenza (rare but more severe) measles (in endemic areas) rhino/enterovirus (mild cases)
pathophysiology of croup
viral infection of nasal pharyngeal mucosa–>invasion of respiratory epithelium –> inflammation of CARTILAGINOUS SUBGLOTTIC REGION –> narrowing of trachea –> fibrinous exudates may worsen the narrowing
host factors = genetic predisposition, anatomic narrowing, hyperactive airways
what is the hallmark of croup in infants
barking cough
clinical presentation of croup
infants: barking cough
stridor, cough, hoarseness
in older children, hoarseness is a prominent symptom
typical presentation = sudden onset of symptoms, rapidly progressive, previous Hx of croup
how is croup diagnosed
DDx
Tx of croup
NOT antibiotics because its viral
systemic/nebulized STEROIDS
symptom Tx
severe presentations can require nebulized epinephrine, blow-by O2 if hypoxic
transmission of pertussis
direct contact of inhalation of respiratory droplets
incubation is 7-10 days (or 4-21 depending on source)
what causes pertussis
*Bordatella pertussis
obligate human pathogen
fastidious gram - coccobacilli
other strains of bordatella that can cause pertussis are: B. parapertussis, B. bronchoseptica and B. holmesii (severe)
pathophysiology of pertussis
B. pertussis produces toxic and virulence factors–>
adhesins
tracheal cytotoxin/dermonecrotic toxin
these toxins cause local tissue damage and interfere with host immune mechanisms
endotoxins –> systemic manifestations and lymphocytosis
organisms found in ALVEOLAR MACROPHAGES and CILIATED RESPIRATORY EPITHELIAL CELLS
describe the classical clinical manifestations of pertussis
“whooping cough”
paroxysmal cough
inspiratory whoop
post-tussive emesis
adolescents and adults have milder symptoms (protracted cough, considerable morbidity, important reservoir)
what are the 3 phases of pertussis
- catarrhal (1-2 weeks, most contagious)
- paroxysmal (3-6 weeks)
- convalescent (>6 weeks)
investigations you order depend on lengths of symptoms
cough 3 weeks= B. pertussis PCR
Tx of pertussis
antobiotics = MACROLIDE (azythromycin, clarithromycin, erythromycin) or TMP-SMX
if started in catarrhal phase, Abs reduce duration and severity of the disease and limit transmission (after this phase, only transmission is limited)
vaccination schedule for pertussis
2, 4, 6 months; 18 months; 4-6 years; grade 9
what is otitis media
inflammatory disease of the middle ear
at what age is otitis media most prevalent
infancy
60-80% of kids have episode within first year
80-90% by 2-3 years
in what sex is otitis media most prevalent
boys
what vaccine has reduced the incidence of otitis media
pneumococcal vaccine
risk factors for otitis media
- age 6-18 months
- family Hx
- day care
- lack of breastfeeding
- tobacco smoke/air pollution
- pacifier use
- race/ethnicity
- poverty
what normally causes otitis media
66% of patients have combined viral and bacterial infections
S. pneumo = 50%
H. influenzae = 40-45%
M. catarrhalis>S. pyogenes>staph aureus
viral causes can include: RSV, rhino/enterovirus, coronavirus, influenza virus, adenovirus, human metapneumovirus
what are 2 factors essential to the pathophysiology of otitis media
- antecedent viral URT infection (i.e cold)
- colonization with respiratory bacterial pathogen
inflammatory response to the virus obstructs the ISTHMUS of EUSTACHIAN TUBE–> causes negative pressure
secretions produced by the middle ear accumulate
bacteria colonizing URT access middle ear through aspiration or reflux, and grow in middle ear secretions
suppuration = acute otitis media
how is otitis media diagnosed in infants
nonspecific signs and symptoms
fever is 33-66%
how is otitis media diagnosed in children
otalgia (ear pain)
bulging of tympanic membrane
otorrhea (leak of CSF through ear structures)
hearing loss
complications of otitis media
tinnitus vertigo facial paralysis mastoiditis meningitis
Tx of otitis media
70-80% resolve on their own
if strep. pneumo–> treat with AMOXICILLIN (best coverage for S. pneumo of all oral B-lactams)
watchful waiting, pain relief
what is acute sinusitis
inflammation of paranasal sinuses lasting less than 4 weeks
which sex gets more acute sinusitis
women
which age group gets more acute sinusitis
45-75
what percent of acute sinusitis resolves on its own
70% (Abs often misused)
is viral or bacterial acute sinusitis more common
viral (200X)
which viruses cause acute sinusitis
rhinovirus
influenzavirus
parainfluenza virus
typically resolves in 7-10 days
what percent of acute sinusitis is bacterial
0.5-2% of viral URTI
10% related to dental disease
S. pneumo, H. influenzae, M. catarrhalis
why is imaging not recommended in acute sinusitis diagnosis
because it cant distinguish between bacterial and viral causes
diagnose on Hx and physical
when is bacterial acute sinusitis more likely (symptoms)
- URTI symptoms last for longer than 10 days or worsen after 5-7
AND
- nasal congestion/purulent nasal discharge with facial pain
+/-
- fever/maxillary toothache/facial swelling
Tx for acute sinusitis
70% spontaneous resolution
normal saline irrigation is best option
antihistamines NOT recommended
steroids/Abs not shown to help
