Micro - - URT Flashcards
methods cause disease - bacteria
toxin
host immune response
bacterial proliferation and invasion
methods cause disease - virus
cytopathic effect
host immune response
tumorigenesis
URTI
otitis externa/media, rhinitis, pharyngitis, epiglottis, laryngitis, croup, sinusitis
LRTI
bronchitis, bronchiolitis, influenza, pneumonia, TB
Anatomical features to defend against infection
Mucociliary lining of the nasal cavity, mucus contains antimicrobial compounds lysozyme and lactoferrin, and secretory IgA antibodies.
Change of direction of the airway from the sinuses to the pharynx
Alveolar macrophages eliminate microorganisms in the lungs
The ciliary elevator
Normal flora competition (Staphylococci)
obstacles to infection
Avoid/survive the mucus layers of the URT which would eventually lead to swallowing of the pathogen.
Must also avoid phagocytosis or be able to survive and/or multiply in the phagocytic cell.
Colonization facilitated by
adherence factors and immune evasion factors of the pathogenic microorganism.
Rhinitis pathogen
Usually rhinoviruses
adenovirus, coronavirus
rhinovirus characteristics
RNA - icosahedral nucleocapsid - nonenveloped - ss(+) nonsegmented (IV) - picornaviridae - rhinovirus
RNA - icosahedral nucleocapsid - nonenveloped - ss(+) nonsegmented (IV) - picornaviridae
rhinovirus (common cold 40-50%)
coronvirus characteristics
RNA - helical nucleocapsid - enveloped - ss(+) nonsegmented (IV) - coronaviridae - coronavirus
RNA - helical nucleocapsid - enveloped - ss(+) nonsegmented (IV) - coronaviridae
coronavirus (common cold 10%)
Influenza C virus characteristics
RNA virus - helical nuclecapsid - enveloped - ss(-) segmented (V) - orthomyxovirus - influenza (A, B, C)
C causes colds
RNA virus - helical nuclecapsid - enveloped - ss(-) segmented (V) - orthomyxovirus
Causes colds
Influenza C
Coxsackievirus A + B characteristics
RNA - icosahedral - nonenveloped - ss+ nonseg (IV) - picornaviridae - enterovirus - cox a/b
RNA - icosahedral - nonenveloped - ss+ nonseg (IV) - picornaviridae - enterovirus
cox a/b
parainfluenza virus characteristics
RNA - helical - env - ss(-) non (V) - paramyxovirus - parainfluenza
RNA - helical - env - ss(-) non (V) - paramyxovirus -
parainfluenza
adenovirus characteristics
DNa - icosahedral - nonenv - DS linear DNA (I) - adenoviridae - mastadenovirus
bugs for the common cold
rhinovirus
coronavirus
influenza C, cox A/B, parainf, adenovirus (summer + conj)
Most cases of sinusitis caused by
viruses
viral sinusitis resolves in
5-7 days, no med tx
viral sinusitis may predispose to
bacterial sinusitis (after cold, dental extractions, allergic rhinitis)
dx bacterial rhinosinusitis
beyond 7 days in adult, facial swelling or tooth pain
children - over 10-14 days or fever over 102, facial swelling/pain
common causes CA acute bacterial rhinosinusitis
Strep pneumo
H. influenzae
other: s. pyogenes, S. aureus, m. catarrhalis
fungal sinusitis
rare - after abx don’t work
aspergillus fumigatus (mechanical removal)
sinusitis tx
nasal saline washes and steam!
mapap, decong, mucolytics?
abx tx = augmentin (amox) or azithro
mechanism augmentin
Inhibit cross-linking of peptidoglycan by transpeptidase (D-al-D-al spot)
+ clavulanate = block penicillinase
mechanism azithromycin
MACROLIDE
Bind 23S of 50S to prevent translocation - Binds to 50S ribosomal RNA near the peptidyltransferase center blocking peptide chain elongation.
most common cause pharyngitis
viruses cause 90% adults, 75% kids (rhino, corona, adeno, parainflu, influ A/B, RSV, EBV)
bacteria - s. pyogenes
virulence factors S. pyo for pharyngitis
when S. pyogenes attaches to the mucosal epithelial cells using its M protein, lipoteichoic acid, and fibronectin-binding protein (protein F). Capsule is composed of hyaluronic acid (HA) and prevents phagocytosis by macrophages. Invasion virulence factors include protease and hyaluronidase.
symptoms pharyngitis viral and bact
Fever, sore throat, edema, and hyperemia of the tonsils and pharyngeal walls
viral pharyngitis sxs
Conjunctivitis Cough Hoarseness Inflammation of the mucus membrane Diarrhea
bac pharyngitis sxs
5-15 yo
fever, severe pain
Ha, N/V, abdomnal pain
red tonsils w/o exudate and enlarged tender cervical lymph nodes
NOT definitive
tx S. pyo pharyngitis
antibiotics (penicillin or erythromycin for those allergic to penicillin) to block the development of glomerulonephritis and rheumatic fever.
dx S pyo phar
rapid strep test (antigen detection)
culture takes 1-2 days but is most accurate
s. pyo characteristics
Gram + cocci catalase - B hem bacitracin sensitive Group A - S. pyogenes
Gram + cocci catalase - B hem bacitracin sensitive Group A
S. pyogenes
other disease associated with S. pyogenes pharyngitis
Scarlet fever
exotoxins ssa, speA, speC (superantigens)
S. pyo uses ______ to get rid of oxgyen radicals
peroxidase (makes 2H2O but no O2 so no bubbles like catalase)
Diptheria causes
pharyngitis
symptoms unique to diptherria
thick grey membrane covering back of through