4-Upper Respir Tract Bacteria Flashcards
upper respiratory tract has
conjuctiva + nasolacrimal ducts + middle ear + eustachian tube + nares + nasal cavity + pharynx + sinuses + larynx + epiglottis
URT defenses
- ciliated epi in conductive airway
- mucocillary escalator- impaired by viral infection, smoke, alc, narcotics
normal microbiota in nasal cavity
- staph epidermidis
- staph aureus (MRSA esp healthcare workers)
- corynebactterium spp
nasopharynx microbiota
- Strep pneumoniae
- moraxella catarrhalis
- notypeable haemophilius influenze
main ones causing dz, all are opportunistic
pharyngitis
inflam of pharynx
-usually viral but can be strep pyogenes or cornyne (less common)
streptococci classifications
gram + cocci in chains + catalase neg
- lancefield serogrouping (A-H)- cell wall carb antigens
- hemolysis- alpha, beta, gamma
- biochem properties
strep pyogenes diseases
aka group A strep (GAS)
1. pharyngitis
2. sequelae (scarlett fever, rheumatic fever, rheumatic heart dz)
strep throat clinical presentation
- swollen tonsils and uvula (anterior cervical lymphadenopathy)
- edema and erythema of pharyngeal
- pus (tonsillar exudate)
- pain/diff swallowing
- fever
spreads by sneezing and coughing, food contaminated by respir droplets
will spont resolve in a week
pharyngitis from S. pyogenes
pyogenes virulence factors
- M protein- degrades complement
- capsule hyaluronic acid- inhibits phagocytosis
- strep pyogenic exotoxins- scarlett fever, toxic shock, necrotizing fascilits
diagnose pharyngitis
- absence of viral pharyngitis (no cough or runny nose, diarrhea)
- anterior cervical lymphadenopathy
- high temp +100.4
- tonsillar exudates/swelling
rapid strep test for lancefield group A antigen + follow up culture
pharyngitis treatment
usually antibiotic therapy for S. pyogenes
-avoid crowds
non suppurtive complications pharyngitis
- scarlett fever
- acute rheumatic fever
- strep toxic shock
- poststrep glomerulonephritis
- PANDAS (peds autoimmune neuropsychiatric)
from S. pyogenes
scarlet fever - pyogenes
mostly in kids after GAS pharyngitis
-sandpaper rash + strawberry tongue
-no systemic spread only in throat bc exotoxins produced at site of infection
treat antibiotics
acute rheumatic fever
pyogenes
two types
1. acute febrile illness- weeks after GAS infections
-arthritis in large joints, carditis/valvulitis, fever
2. neurologic illness-months after GAS infection
-sydenham chorea, no fever or joint symps
acute rheumatic fever treatment
- antibiotics for GAS or recurrent active infection
- anti-inflammatory for arthritis
- manage heart dz/failure
acute rheumatic fever mechanism
antibodies and T cells activated vs GAS during infection then cross react with host proteins = autoimmune mediated damage
-molecular mimicry
GAS infection absent in new acute rheumatic fever cases
diptheria pharyngitis
unique type of pharyngitis from cornye diphtheriae
-toxin mediated
low grade fever + mild sore throat + bull neck (super swollen lymph nodes) + pseudomembrane formation on oro/naso/laryngopharynx
-if untreated lead to kidney fail, myocarditis, death
-pseudomembrane pieces can cause suffocation
diptheria exotoxin
AB exotoxin carried on lysogenic bacteriophage
-stops protein syn via ADP ribosylation of elongation factor 2
local and systemic manifestations
how diptheria spreads
aerosol
respir droplet contamin of fomites
-rare in US
treating diptheria
IV diph antitoxin
-airway management to prevent suffocation
-antibiotics
prevent with DTaP vaccine
epiglottitis
inflamm swelling of epiglottis
1. acute = haemophilus influenzae serotype B > airway obstruction, high fever, stridor, drooling, muffled voice, severe sore throat, toxic facies
2. subacute = sore throat, diff swallowing, low grade fever, GAS (pyogenes, aureus, pneumoniae)
haemophilus influenzae strains
- typeable strain has capsule (polysac of PRP) types A-F
-B is most dangerous (HiB) - nontypebale no capsule (NTHi)
HiB virulence factors
IgA protease
PRP capsule makes antiphagocytic
mostly pediatric esp if unvaccination/improperly vac
spread by drolpets
HiB treatment
dx by culture and gram stain (looks like chocolate/brown)
-antibiotic therapy but if untreated then death
-prevent by conjugate vaccine but not protect against typeable
otitis externa
infection and inflamm with auditory canal
-swimmers ear
pseudo aeruginosa, staph aureus
-fungi can also cause (candida albicans, asperigillus)
antibiotic ear drops to treat
acute otitis media
inflamm of middle ear
-childhood dz huge economic burden and #1 cause of office visits, antibiotics, hearing loss, and surgery with anesthesia for kids
why kids more sensitive acute otitis media
eustachian tube is short, floppier, more horizontal
acute otitis media bacterias
- strep pneumoniae- normal microbiota, ‘the pneumococcus’
- NTHi
- moraxella catarrhalis
acute otitis media presentation
- unexplained crying
- pulling at ears
- otorrhea- pus out ear canal
- GI
- concurrent/preceding viral URTI
acute otitis media risk factors
-second hand smoke
-daycare attendance
-seasonality (winter)
treatment acute otitis media
- antibiotics (amoxicillin)
- watchful waiting if non severe, older than 2
- severe recurrent cases need antibiotics and tympanostomy
prevent by vac for pneumococcal AOM somewhat effective (pneumococcal polysac 23 valent or 13 valent conjugated to diphetheria toxoid)
sinusitis/rhinosiusitis
inflamm of paranasal sinuses or nasal cavity
strep pneumoniae
NTHi
moraxella catarrhalis
same as otitis media
sinusitis dx
bacteriology etiology if 10+ days, severe symptoms after 3 days, following an improving viral URT
treat with waiting or antibiotics in severe/worsening
conjunctivitis
pink eye aka inflamm of conjunctiva
bacterial = purulent discharge
-also viral, allergic, non allergic etiologies
acute conjunctivitis
- common bacterial- eye or nasal secretion from infected
aureus, pneumoniae, NTHi, moraxella - hyperacute- genitals to eyes
neisseria gonorrhoeae
chronic conjunctivitis
- adult inclusion- genitals to eyes, STI strains,
- trachoma- eye or nasal secretions, non STI stains
both from chlamydia trachomatis
neonatal conjunctivitis
- neonatal inclusion- birth canal, STI strains, mucopurulent discharge
C. trachomatis - gonococcal conjunctivitis- birth canal
N. gonorrhoeae
chlamydia characteristics
medially relevant species
1. chlamydia trachomatis
2. chlamydia psittaci
3. chlamydia pneumoniae
very small obligate intracellular bacteria
chlamydia life stages
- elementary bodies- metabolic inactive, infectious
- reticulate bodies- metabolic active, noninfectious
chlamydia trachomatis pathogenesis
direct destruction of host cells during rep = collateral damage from host infalmm resp
treating conjunctivitis
adult and neonatal inclusion forms
-antibiotics via ophthalmic drops, ointment, oral
