Micro - Respiratory

Question 1

Upper Respiratory Tract Infections

Answer 1

otitis externa, sinusitis, rhinitis, pharyngitis, epiglottitis, laryngitis

Question 2

Lower Respiratory Tract Infections

Answer 2

bronchitis, bronchiolitis, pneumonia

Question 3

Respiratory Defenses

Answer 3

1. Mucociliary lining of nasal cavity
2. Change of direction of airway (pathogens get trapped in mucous layer)
3. Ciliary Elevator
4. Normal flora competition
5. Alveolar macrophages (innate immune system)
6. IgA (acquired immune system)

Question 4

2 Major obstacles organisms must overcome

Answer 4

1. Avoid/survive mucus layers

2. Avoid phagocytosis and survive

Question 5

Turbinate Bones

Answer 5

“Baffle plates”

covered with mucus –> air swirls as it passes over –> pathogens come into contact with mucus covered passages

Question 6

Mucociliary Elevator

Answer 6

1. mucus-producing goblet cells
2. ciliated epithelium
   * smoking paralyzes the cilia –> smoking cessation can lead to regrowth of cilia

Question 7

Normal flora of respiratory tract

Answer 7

Upper - lots

Lower - NONE –> considered sterile

Question 8

Pathogen initiation of disease

Answer 8

1. Must be sufficient dose of microorganisms
2. infectious particles must be airborne
3. airborne particles must be viable in air
4. organisms must be deposited on tissue susceptible to infeciton

Question 9

Rhinitis

Answer 9

Common cold - generally no fever
Nasal stuffiness, sneezing, headache, tiredness, lacrimation, sore throat
Usually seen in winter, spread person-person
- symptoms peak 2-5 days post infection, resolved by 14 days
- supportive therapy

Question 10

Rhinovirus

Answer 10

#1 cause of rhinitis
RNA virus --> icosahedral --> non-enveloped --> ss(+)non-segmented(IV) --> picornaviridae
infects nasal passages following attachment to ICAM-1 --> localized inflammation and lytic infection --> ciliated epithelial cells are destroyed
- break in barrier may lead to secondary infection by normal flora

Question 11

Parainfluenza

Answer 11

RNA virus –> helical capsid –> enveloped –> ss(-)non-segmented(V) –> paramyxoviridae
F-protein –> forms multinucleated cells
Hemagglutinin –> interacts with salic acid –> endocytosis
Neuroaminidase –> envelope protein responsible for cleaving HA bound to salic acid –> viral spread

Question 12

Coronavirus

Answer 12

RNA virus –> helical capsid –> enveloped –> ss(+)non-segmented (IV) –> coronaviridae
Can cause SARS –> rapidly progressive pneumonia

Question 13

Mastadenovirus

Answer 13

DNA virus –> icosahedreal nucleocapsid –> non-enveloped –> DS linear DNA (I) –> adenoviridae
most common viral cause of conjunctivitis

Question 14

Rhinosinusitis

Answer 14

inflammation or infection of mucosa of nasal passages and atleast 1 paranasal sinuses
2 most common causes = S. pneumoniae and H. flu
Sx: sneezing, rhinorrhea, congestion, post-nasal drip, aural fullness, facial pressure, headache
Fungal rhinosinusitis –> RARE, aspergillus fumigatus (immunocompromised)
- antibiotic treatment for bacterial causes

Question 15

Strep pneumoniae

Answer 15

gram (+) diplococci –> catalase (-) –> alpha hemolytic –> bile-esculin negative –> optochin susceptible
Capsule, IgA proteases
Major cause of community acquired pneumonia

Question 16

H. influenzae

Answer 16

gram (-) –> coccobacilli, pleomorphic –> X & V factors

IgA protease, capsule –> avoids phagocytosis

Question 17

Pharyngitis

Answer 17

Majority caused by viruses (conjunctivitis, cough, hoarseness)
Strep pyogenes is most common bacterial cause (severe pain with swallowing)
Sx: fever, sore throat, edema, hyperemia of tonsils
Rapid strep test tells if bacterial –> culture takes 1-2 days
needs to be treated within 9 days to prevent glomerulonephritis or rheumatic fever

Question 18

Strep pyogenes

Answer 18

gram (+) cocci –> catalse (-) –> beta-hemolytic –> bacitracin sensitive
attaches to mucosal epithelial cells with M-protein, lipoteichoic acid, and protein F
Capsule (hyaluronic acid) –> prevents phagocytosis
Protease and Hyaluronidase –> invasion
Streptokinase –> plasminogen to plasmin (fibrinolytic)

Question 19

Scarlet Fever

Answer 19

certain strains of s. pyogenes
Streptococcal Pyogenic Exotoxins –> SpeA, SpeB, SpeC, SpeF
encoded by lysogenized bacteriophage
“strawberry tongue”

Question 20

Corynebacterium diphtheriae

Answer 20

gram (+) bacilli –> non-spore forming –> non-motile
produces AB toxin (B=binding, A=enzymatic activity)
toxin A –> acts against EF-2 (inhibits translation –> cellular death) –> airway blockage
DON’T disrupt the capsule –> pathogen will gain access to blood
Dtap and Tdap

Question 21

Croup (laryngotracheobronchitis)

Answer 21

Fever, restlessness and shortness of breath
Mild URI and cold-like symptoms (winter time)
“Bark-like” cough with respiratory stridor (at night)
Symptoms peak 3-5 days and resolve 4-7 days
Caused by parainfluenza, influenza, and respiratory syncytial virus

Question 22

Respiratory Syncytial Virus (RSV)

Answer 22

helical nucleocapsid –> enveloped –> ss(-) nonsegmented –> paramyxoviridae –> pneumovirus
F-protein causes fusion of cells into “syncytium”
Attaches to epithelium via protein G

Question 23

Most common cause of pneumonia in neonates?

Answer 23

Strep agalactiae (group B strep)
E. coli

Question 24

Adult pneumonia causes?

Answer 24

18-40 yrs (Mycoplasma pneumoniae, chlamydia, strep pneumoniae)
40-65 yrs (S. pneumoniae, H. flu, Legionella, virus)
+65 yrs (S. pneumo, gram (-) rods, H. flu)

Question 25

Most common cause of meningitis in +60 yrs?

Answer 25

S. pneumo, Gram (-) rods, listeria

Question 26

Most common cause of meningitis in kids

Answer 26

S. pneumo, N. meningitidis, H. flu type B

Question 27

Coxsackievirus A/B

Answer 27

RNA --> icosahedral --> non-enveloped --> ss(+) (IV) --> picornaviridae --> enterovirus fecal-to-oral transmission

Question 28

Influenza C virus

Answer 28

RNA --> helical --> enveloped --> ss(-) (V) --> orthomyxoviridae Infects through Hemagglutinin --> salic acid and also neuroaminidase --> cleaves binding for viral spread

Question 29

Immune response to infection?

Answer 29

IL-1 and IFN-gamma

Question 30

Moraxella catarrhalis

Answer 30

2nd most common cause of bacterial pneumonia in patients with COPD Pili, endotoxin, capsule

Question 31

Bronchitis

Answer 31

LRI - cough (hacking with sputum), fever, chest pain prior to onset, typically common cold CXR doesn't reveal bronchitis typically self limiting --> if longer than 14 days then antibiotic may be needed

Question 32

Bacterial causes of bronchitis

Answer 32

Mycoplasma pneumoniae | Chlamydia pneumoniae

Question 33

Mycoplasma pneumoniae

Answer 33

not gram (+) or (-)

Question 34

Chlamydia pneumoniae

Answer 34

not gram (+) or (-)

Question 35

Bronchiolitis

Answer 35

no alveolar involvement --> inflammation of bronchiole wall, typically in kids <1 yr because of tiny airways RSV is main organism

Question 36

Pertussis (whooping cough)

Answer 36

2 Phases 1. after 3-21 day incubation period --> Catarrhal stage, lasts 1-2 weeks with cold symptoms (runny nose) 2. Paroxysmal stage --> severe uncontrollable coughing, can result in spasms, bursting blood vessels, vomitting Recovery phase (convalescent stage) --> bacteria no longer cause ongoing symptoms --> epithelial cells recoverying (takes weeks to months)

Question 37

Bordatella Pertussis

Answer 37

gram (-) --> coccobacilli (pleomorphic) --> growth on bordet-gengou medium AB toxin --> B-binding, A-enzymatic activity that increases cAMP --> massive overproduction of mucus --> cough tracheal cytotoxin

Question 38

Influenza virus

Answer 38

RNA virus --> helical --> enveloped --> ss(-) segmented (V) --> orthomyxoviridae 8 segments RNA polymerase --> no self-check --> lots of mutations --> constantly mutating Hemagglutinin binds sialic acid --> neuraminidase cleaves to assist in invasion Neuraminidase has HIGH rate of mutation so immune system has trouble gaining immunity

Question 39

Antigenic Shift

Answer 39

occurs when major changes in antigens occur due to gene reassortment in influenza virus

Question 40

Antigenic Drift

Answer 40

occurs when minor changes in antigens occur due to gene mutation in influenza virus reason for the need of flu shot every year

Question 41

Pneumonia

Answer 41

inflammatory condition in which fluid fills alveoli most common cause = Strep pneumoniae Typical - Sudden onset of fever, chills, dyspnea, productive cough, crackles of lungs Atypical - gradual onset of non-productive cough, headache, sore throat, dyspnea, fever

Question 42

CXR use?

Answer 42

CXR will show infiltrates for pneumonia. | CXR is also used to exclude pneumonia and therefore diagnose bronchitis/bronchiolitis

Question 43

Nosocomial pneumonia

Answer 43

gram (-) rods, staph aureus

Question 44

Pneumonia in immunocompromised

Answer 44

``` Gram (-) rods Streptococcus pneumoniae Fungi Filamentous bacteria Pneumocystis jiroveci Viruses ```