RTI IV Flashcards
describe MERS vs SARS
- MERS = URT AND LRT involvement (SOB), GI symptoms, lung parenchyma
- SARS = mainly LRT (not commonly URT)
list the clinical symptoms of H. influenzae
- clinical symptoms:
- otitis media, pneumonia, epiglottitis, meningitis
what is the most common cause of epiglottitis?
H. influenzae = most common cause of epiglottitis; swelling of epiglottis and supraglottic tissues due to bacterial infxn
also associated: S. pneumoniae
H. influenzae is (G+ve/G-ve) and is ____ (shape)
H. influenzae is G-ve and is a coccobacillus
H. influenzae is serotyped according to ____; type b is particularly associated with _____
H. influenzae is serotyped according to capsule (a to f);
type b is particularly associated with invasive disease and therefore has a vaccine for it (Hib)
the _____ on H. influenzae attaches to sialic acid-containing mucin oligosaccharides
the P-2 outer membrane protein on H. influenzae attaches to sialic acid-containing mucin ol igosaccharides
the LPS of H. influenzae impairs _____
the LPS of H. influenzae impairs ciliary function, endotoxin
describe the capsule of H. influenzae (function and composition)
antiphagocytic capsule is composed of polyribose ribitol phosphate (PRP)
H. influenzae is coagulase (positive/negative) and catalase (positive/negative)
H. influenzae is coagulase negative and catalase positive
describe the culture of H. influenzae
- culture requires chocolate agar (blood cells in lysed form) with X and V growth factors
- X factor = acts as hemin
- V factor = nicotinamide adenine dinucleotide (NAD)
describe what is seen
describe epiglottitis seen in H. influenzae
describe tripod positioning and what it is seen in
describe the Sketchy
Moraxella catarrhalis is (G+ve/G-ve) and _____ (shape)
Moraxella catarrhalis is G-ve and diplococcus
Moraxella catarrhalis is a common cause of ____ in children and _____ in elderly
Moraxella catarrhalis is a common cause of otitis media in children and acute exacerbation of COPD in elderly
describe the pathogenesis of Moraxella catarrhalis in otitis media
- initial step = colonization of nasopharynx
- migration from nasopharynx to middle ear through eustachian tube
- migration usually precipitated by viral URI
describe the pathogenesis of Moraxella catarrhalis in acute exacerbation of COPD
- altered mucociliary fxn
- airway colonization and infxn
- triggered b acquisition of new strains
describe the diagnosis of Moraxella catarrhalis
- lab diagnosis:
- G-ve diplococcus
- blood and chocolate agar: round, opaque colonies
- hockey puck sign (colonies move when touched without disintegrating)
- colonies take pink color after 48 hours
-
differentiate from Neisseria by:
- MC = DNase +ve, Nitrate reduction +ve
how is it possible to differentiate between Moraxella catarrhalis and Neisseria?
MC = DNase +ve and nitrate reduction +ve
Moraxella catarrhalis produce ___ which make them resistant to ____
Moraxella catarrhalis produce B-lactamses which make them resistant to penicillins
list the molecular mechanisms that contribute to the pathogenesis of Moraxella catarrhalis
- molecular mechanisms
- adherence to resp. epi.
- intracellular invasion
- complement resistance
- biofilm formation
- induction of inflammation
- as a co-pathogen
describe the symptoms of flu in adults
- rapid onset after short incubation of 1-4 days
- sudden malaise and headache
- abrupt rise of fever, chills, severe muscle aches, loss of appetite, non-productive cough
- recovery complete in 7-10 days
describe the symptoms of the flu in children
- same as those in adults, plus:
- higher fever
- GI symptoms (vomiting, abdominal pain)
- earache (otitis media)
- muscle pain and sometimes swelling
- croup often but not always
- febrile convulsions (children under 3 = rare)
describe flu vs. cold
name the rare neurological syndromes associated with influenza
- Guillain Barre syndrome
- encephalitis
- Reye syndrome in children: made worse by aspirin and aspirin-containing drugs
describe the biology of influenza virus
- family = orthomyxovirus
- enveloped
- 7 or 8 segments of negative sense ssRNA
- 8 = A and B
- 7 = C
the M2 protein (ion channel) is found ONLY in influenza __
the M2 protein (ion channel) is found ONLY in influenza A
describe the unique features of influenza virus
describe the origin of influenza A, B and C
2 lineages of influenza ___ circulate in the population; Victoria-like and Yamagata-like
2 lineages of influenza B circulate in the population; Victoria-like and Yamagata-like
hemagluttinin (H) aids the virus in _____
while
neurominidase (N) aids the virus in _____
hemagluttinin (H) aids the virus in adhering to resp. tissue
while
neurominidase (N) aids the virus in penetrating resp. tissue
describe the role of hemagluttinins in influenza A
-
major antigen against which neutralizing antibodies are directed
- highly variable: responsible for evolution of new strains
- requires cleavage to be active:
- carried out by cellular proteases
- proteases probably define tissue tropism
influenza pathogenesis: ____ occurs at the onset of symptoms or just before the onset of illness (0-24 hours)
influenza pathogenesis: viral shedding occurs at the onset of symptoms or just before the onset of illness (0-24 hours)
influenza pathogenesis: systemic symptoms are caused by _____ while local symptoms result from ______
influenza pathogenesis: systemic symptoms are caused by interferon and cytokine response while local symptoms result from epithelial damage, including ciliated mucus-secreting cells
influenza pathogenesis: ____and ____ response play important role in immune resolution and immunopathogenesis
influenza pathogenesis: interferon and cell-mediated immune response (NK and T cells) response play important role in immune resolution and immunopathogenesis
the HA and NA of influenza A virus can undergo _____ and ______
the HA and NA of influenza A virus can undergo major (reassortment: shift; A only) and (mutation: drift; both A and B)
describe antigenic drift vs. antigenic shift
antigenic drift is seen in strains ____ while antigenic shift is seen in strains ____
antigenic drift is seen in strains A, B, C (less frequent)while antigenic shift is seen in strain A only
describe lab diagnosis of influenza
- serology: 4-fold rise in the antibody titer between acute and convalescent phase sera
- detection of viral nucleic acids via RT-PCR or hybridization
describe the role of amantadine and rimantadine
- inhibit uncoating of influenza A; only target is M2 protein
- no effect on influenza B or C
describe the role of Zanamivir and Oseltamivir
- inhibit neuraminidase: without this, virus binds to its own sialic acid and forms useless clumps → blocks release
- works on influenza A and B, not C
Aspergillus sp. causes acute ___ in severely immunocompromised patients (e.g. ____)
Aspergillus sp. causes acute pneumonia in severely immunocompromised patients (e.g. neutropenia)
the 3 symptoms of Aspergillus are….
- deadly invasive pneumonia
- hemoptysis
- high mortality
