Respiratory Infections 5

Question 1

Pneumonia classification: type of microbe

Answer 1

• Typical = Gram Positive and Gram Negative Bacteria

* Atypical = Viruses, Atypical Bacteria, Fungi, Parasites

Question 2

Pneumonia classification: exposure

Answer 2

Community acquired pneumonia
Nosocomial
- hospital acquired pneumonia: >48 hours post-admission
- ventilator associated pneumonia: >48 hours intubation
- Healthcare Associated Pneumonia HCAP <3 months post healthcare facility (hospital, long term care facility)

Question 3

Pneumonia Classification: source of microbe

Answer 3

Aspiration Pneumonia: microbes originate from GI tract (vomiting, impaired gag reflex, intubation)

Question 4

Broncho-pneumonia/Lobar

Answer 4

typical pneumonia with focal densities

Question 5

Interstitial pneumonia

Answer 5

atypical pneumonia with diffuse, hazy infiltrates

Question 6

Acute Exacerbated Chronic Bronchitis

Answer 6

reactivated inflammation in patient with chronic lung condition (CF, COPD)

Question 7

Necrotizing/Cavitary Pneumonia

Answer 7

focal liquification, region of decreased opacity due to necrosis

Question 8

Viral pneumonia

Answer 8

• normal or increased lymphocytes
• tachypnea and wheezing
• no pleuritic Chest pain
• no CNS features
• hyperinflation with bilateral interstitial infiltrates

Question 9

Bacterial pneumonia

Answer 9

• high fever and chills
• dyspnea and productive cough
• pleuritic chest pain
• anxiety and delirium
• lobar consolidation +/- pleural effusion
• increased granulocytes

Question 10

Most common viral causes of atypical pneumonia

Answer 10

SARS-CoV2

Influenza

Question 11

SARS-CoV2: Biology

Answer 11

Family - Coronaviridae
SARS-CoV2
=Severe Acute Respiratory Syndrome Coronavirus 
• Enveloped ss(+)RNA virus
• Spike protein – vaccines
• RDRP–antivirals

Question 12

How to diagnose SARS-CoV2

Answer 12

• Rapid Antigen ELISA, lateral flow
  * Suggestive of active
• NAAT (RT-PCR)
  * Confirmatory for active infection
• Serology - EIA
• IgM -> Suggestive of active infection
• IgG -> Anti-nucleocapsid is indicative of past infection

Question 13

Transmission of sars cov2

Answer 13

Aerosol droplet, Airborne

Question 14

Who is high risk for sars cov2

Answer 14

• Unvaccinated ~97x risk of death
• Elderly,Hypertension,Obesity,Diabetes
Smokers, people with other respiratory illnesses

Question 15

Prevention against sars cov2

Answer 15

Moderna,Pfizer
• mRNA subunit vaccines encoding Spike protein
• Require 2x doses to yield high efficacy
• Booster is recommended post-Omicron

Johnson-Johnson,AztraZeneca
• AdenovirusvectorswithsubunitDNASpikeprotein

Question 16

Shift

Answer 16

Sudden phenotypic change of virus from gene rearrangement with co-infection with 2 strains

Question 17

Drift

Answer 17

Gradual accumulation of random point mutations

Question 18

Alpha, Delta and Omicron BA.1 and Omicron BA.2 emerged from which process

Answer 18

Drift

Question 19

New strains of Omicron XE, XR, etc. emerged from

Answer 19

Shift gene recombination events with Omicron BA.1 and Omicron BA.2

Question 20

SARS-CoV2 Pathogenesis part 1

Answer 20

Spike Protein binds to ACE2 host receptor

Question 21

SARS-CoV2 Pathogenesis part 2

Answer 21

2. Viral replication
   Virus initially downregulates Interferon-α
   Virus replicates in interstitial tissue, Syncytia formation
   Virions spread systemically, replicating in CD4+ T cells, cardiac, hepatic, renal tissue

Question 22

SARS-CoV2 Pathogenesis part 3

Answer 22

• cytokine storm
• bradykinin activation
• Vascular damage accumulates on major organs

Question 23

What’s this showing

Answer 23

SARS-CoV2: Pathogenesis Syncytia Formation

Question 24

What is a syncytia

Answer 24

A single cell or cytoplasmic mass containing several nuclei, formed by fusion of cells or by division of nuclei

Question 25

Clinical Presentation: COVID-19

Answer 25

* Onset~3-14days * Loss smell (anosmia) * Loss of taste (ageusia) * Interstitial pneumonia progressing to Acute Respiratory Distress Syndrome ARDS is most common cause of mortality * Viral replication in any tissue with ACE2R plus immune-mediated inflammation can cause multi-organ tissue damage

Question 26

What is seen on COVID-19 Imaging

Answer 26

* Ground-glass opacities are most common. | * Consolidation can be observed, esp. with superinfection

Question 27

COVID-19 Complications

Answer 27

* Interstitial Pneumonia -> ARDS -> Death * Secondary Bacterial Pneumonia Superinfections * Sepsis, Coagulopathy * Multi-System Inflammatory System in Children (MIS-C) * Long COVID aka Post-Acute Sequalae SARS-CoV2 Infection (PASC)

Question 28

Influenza: Biology

Answer 28

* Family–Orthomyxoviridae * Enveloped * Segmented ss(-)RNA * Haemagglutinin (HA) glycoprotein * Viral Attachment Protein * Neuraminidase (NA) surface enzyme * Release of new virions by sialic acid cleavage * Based on Matrix (M-protein) and nucleoproteins * Rapid Antigen test can determine Type A/B

Question 29

Influenza replication

Answer 29

- Hemagluttanin does attachment: binds sialic acid - virus enters by endocytosis - M2 - uncoating - segmented ss(-)rna is replicated by RNA dependent RNA polymerase - neuraminidase cuts sialic acid releasing the virus

Question 30

Type A Influenza

Answer 30

Zoonotic! • More pathogenic than Type B or C. • Reservoir: humans, birds, swine, horses, seals. • Antigenic Shift cause pandemics (ex. Swine flu H1N1 in 2009) • Antigen Drift cause localized annual epidemics

Question 31

Type B and Type C influenza are human-restricted cause milder symptoms and undergo __________ only

Answer 31

Antigenic drift only

Question 32

How is Influenza transmitted

Answer 32

Aerosol droplet: human-to-human, animal-to-human (Bird & Pig)

Question 33

Influenza type A H1N1 has tropism for

Answer 33

humans, pigs, horses and ducks

Question 34

What caused the global swine Flu Pandemic

Answer 34

Genetic reassortment shift events * A host animal was co-infected with more than 1 strain and the new virions are packaged with a new combination of genome segments. * Introduction of new HA type (H1) on human-adapted virus to immunologically-susceptible population = pandemic

Question 35

Influenza Virus Prevention

Answer 35

Annual drift necessitates yearly booster Live, attenuated nasal spray • Induces strong IgA response • Recommended for > 2 years, < 50 years Killed, Inactivated shot • Induces IgG response • Recommended for health care workers, age extremes, immunocompromised

Question 36

Influenza Virus Pathogenesis

Answer 36

* Influenza HA targets sialic acid on mucus secreting, ciliated cells and replicates in respiratory tract * Infection in lower respiratory tract leads to cytokine storm and desquamation (shedding) of bronchial epithelium cells * Virus infection facilitates primary viral pneumonia and onset of secondary bacterial infections (most common cause of Flu-associated death)

Question 37

Clinical presentation of the flu

Answer 37

* Preceded by or with a cold * Dry sputum cough * Dyspnea * High fever * Intense muscle pain * GI symptoms are more common in children

Question 38

Influenza Complications

Answer 38

Secondary Bacterial Superinfections including sinusitis, otitis media (children), typical bacterial pneumonia (elderly) = MOST COMMON CAUSE of “Flu-associated” deaths

Question 39

COVID-19 and Flu prognosis

Answer 39

▪ Can be range from mild to life-threatening, especially hypoxia ▪ Approximately 1/3 COVID-19 patients experience symptoms for months ▪ Antivirals for Influenza will shorten the course if administered <24 hours after onset

Question 40

Is it COVID, Common Cold or Flu?

Answer 40