RTI IV Flashcards by Neil Mehta

describe MERS vs SARS

MERS = URT AND LRT involvement (SOB), GI symptoms, lung parenchyma
SARS = mainly LRT (not commonly URT)

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list the clinical symptoms of H. influenzae

clinical symptoms:
- otitis media, pneumonia, epiglottitis, meningitis

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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

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H. influenzae is (G+ve/G-ve) and is ____ (shape)

H. influenzae is G-ve and is a coccobacillus

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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)

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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

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the LPS of H. influenzae impairs _____

the LPS of H. influenzae impairs ciliary function, endotoxin

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describe the capsule of H. influenzae (function and composition)

antiphagocytic capsule is composed of polyribose ribitol phosphate (PRP)

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H. influenzae is coagulase (positive/negative) and catalase (positive/negative)

H. influenzae is coagulase negative and catalase positive

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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)

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describe what is seen

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describe epiglottitis seen in H. influenzae

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describe tripod positioning and what it is seen in

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describe the Sketchy

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Moraxella catarrhalis is (G+ve/G-ve) and _____ (shape)

Moraxella catarrhalis is G-ve and diplococcus

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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

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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

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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