Upper Respiratory tract Flashcards
Define Mucociliary escalator
important for protection of upper respiratory pathway
- constantly has mucous propelled out of mastoids, middle ear, nasolacrimal ducts, sinuses and his lungs then swallow it
- viral infection/smoke/alcohol/narcotics all slow down or stop mucociliary escalator
- URT pathogen must avoid being caught in the mucociliary escalator and swallowed.
describe normal flora
normal flora of the URT are important
- Some URT tissues are considered sterile
- Ex: mastoid air cells, middle ear, sinuses, trachea, bonchi and bronchioles, alveoli
- CONJUNCTIVA - supposed to be sterile but constantly exposed to organisms in air
What is the normal flora in the Nose
- Staphylococcus epidermidis and Staphyloccus aureus are G+ cocci clusters of facultative anaerobes
- -> 20% of healthy adults carry staphylococcus aureus in the nares (goes up in hospital settings) and can be pathogens
- Corynebacterium spp. are G+ rod, pleomorphic, non spore forming
What are the normal flora in the nasopharynx flora
- Streptococcus are G+ cocci, chains (pathogenic if it is in none normal settings
- moraxella catarrhalis are G- diploid-coccobacillus aerobic
- Bacterioides is a strict anaerobe
What are the seasonal normal flora of the nasopharynx
- -> levels go up in the winter. Can cause disease states if immunocompromised or in appropriate tissue.
- Streptococcus pneumoniae
- haemophilus influenzae
- neisseria meningitides
- moraxella catarrhalis
Describe Streptococcus
- Gram positive cocci in chains
- Catalase negative (differentiates it from staphylococcus
Group A = S. pyogenes -Beta
Group B = S. Agalactiae -Beta
Group D = S. Bovis and Enterococcus faecalis
Alpha-hemolytic group = S. Pneumoniae
What causes Streptococcal Pharyngitis (strep throat)
Streptococcus Pyogenes = G+, grows in chains
- differentiated from other streptococci via colony morphology on blood agar
- Beta-hemolytic
- Group A antigen on cell wall used to ID via Rapid Test
Describe pathogenesis of S. Pyogenes
- contains a wide range of virulence factors, which causes range of diseases.
Define M protein virulence factor of S. Pyogenes
Antiphagocytic
- 80 serotypes that are not cross protective
Define Capsule virulence factor of S. Pyogenes
made up of hyaluronic acid that inhibits phagocytosis
- not in all strains
Define Streptococcal Pyrogenic Exotoxins (SPEs) virulence factors of S. Pyogenes
Super antigens responsible for scarlet fever, toxic shock and necrotizing fasciitis
- ONLY SCARLET FEVER is preceded by Strep throat
- Causes fever, rash, T-cell proliferation, B-cell suppression
- 9 types of SPE’s
Define Scarlet fever
- Occurs during acute illness.
- Causes redness of skin and white coating on the tongue
Define Acute Rheumatic fever
Fever, Joint pain, chest pain, rash, skin nodules, uncontrollable jerky movements
- Caused by acute inflammatory process
Define Acute glomerulonephritis
Post streptococcal infection sequelae
- Primarily a disease of childhood that begins 1-4 weeks after streptococcal pharyngitis and 3-6 weeks after skin infection
- Deposition of antigen-antibody complexes in the glomeruli
- causes edema, hypertension, hematuria, proteinuria, decreased serum complement levels
Treatment of Streptococcal pharyngitis
treated with 10 days of penicillin or erythromycin
- treatment established as late as 9 days after onset will prevent the onset of rheumatic fever
Define Diptheria
Toxin mediated disease caused by Corynebacterium diphtheriae.
- control is accomplished most effectively by immunization by a toxoid
- Causes mild sore throat, slight fever, high fatique and malaise. dramatic neck swelling. Whitish gray membrane forms on the tonsils and throat or in nasal cavity
Describe Corynebacterium diphtheriae
variable shape, non-motile, NON SPORE FORMING, Gram positive rod (chinese letters under microscope.
- All stains release diphtheria toxin = powerful exotoxin which causes disease
Describe the pathogenesis of Diptheria
Not invasive (does not enter blood or tissue)
- released Diphtheria toxin is absorbed by the bloodstream
- Classic gray-white membrane in infected individual is made up of clotted blood, epithelial cells of the mucus membrane and leukocyte infiltrate.
Define Diphtheria toxin
Large protein released from bacteria in INACTIVE FORM.
- cleaved extracellularly into two chains:
1) B chain = binds to the receptor on host cell membrane and the entire molecule is endocytosed.
2) A chain = causes inactivation of elongation factor-2 (EF-2) required for movement of the ribosomes on mRNA - thus HALTING protein synthesis and inducing cell death. - -> A subunit is not consumed and can continue the inactivation process
Define Conjunctivitis
“pink eye” or infection of the eye
- Bacterial = increased tears, conjunctival redness, eyelid swelling, LARGE amounts of pus
- Viral = eyelid swelling and pus are MINIMAL
What are the causative agents of Conjunctivitis
Haemophilus influenzae - small G- rod
Streptococcus pneumoniae - G+ encapsulated diplococcus known as pneumococcus
Describe the prevention/treatment of Conjunctivitis
Prevention: removal of school/daycare setting, handwashing, avoid rubbing eyes
Treatment: gentamicin or ciprofloxacin eyedrops
**antibiotic resistant strains of Haemophilus influenzae and Streptococcus pneumoniae exist.
Describe Otitis Media/Sinusitis
Caused by: - Haemophilus influenze = G- rod - S. Pneumoniae = G+ cocci Can spread to cause meningitis. respond well to ampicillin
Describe Chlamydia trachomatis
Causes trachoma via:
1) direct destruction of cells during replication
2) host inflammatory response.
- -> infection does not confer long-lasting immunity; reinfection induces a vigorous inflammatory response and subsequent tissue damage
Define Trachoma
Caused by Chlamydia trachomatis
- initially patients have follicular conjunctivitis with diffuse inflammation
- then conjunctiva becomes scarred and disease progressess causing eyelids to turn inward.
- turned in eyelids abrade the cornea resulting in corneal ulceration and scarring and eventual loss of vision
Define Adult inclusion conjunctivitis
- acute follicular conjunctivitis that occurs in sexually active adults
- characterized by mucopurulent discharge, keratitism corneal infiltrates and some vascularization
Define Neonatal conjunctivitis
eye infection develop in infants exposed to C. Trachomatis at birth
- Eye lids swell, hyperemia occurs and a copious purulent discharge appears
- corneal scarring, corneal vascularization and increased risk of developing C. trachomatis pneumonia.
Define Chlamydophila pneumoniae
Causes pneumonia, bronchitis and sinusitis
- Most C. pneumoniae are asymptomatic or mild
- Most severe infection involve only one lung lobe
- Cannot be distinguished from other atypical pneumonias such as those caused by Mycoplasma pneumoniae, Legionella pneumophila and respiratory viruses
Define Chlamydophila psittaci
transmitted from parrots to human
- occurs by means of the respiratory tract after which the bactera spread to reticuloendothelial cells of the liver and spleen
- Lymphocytic inflammatory response on the alveolar and interstitial spaces
- patients have edema, thickening of the alveolar wall, infiltration of macrophages, necrosis with possible hemorrhages.
