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microbio final > lecture 14-15 respiratory tract infections - CH 16 > Flashcards

lecture 14-15 respiratory tract infections - CH 16 Flashcards

1
Q

upper respiratory tract

A

mouth, nasal passages, paranasal sinuses, pharynx, and epiglottis

  • warms, humidifies, and filters air
  • innate immunity in the form of mucus and cilia
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2
Q

lower respiratory tract

A

larynx, trachea, bronchi, bronchioles, lungs, and alveoli

  • directs air to the lungs (site of gas exchange)
  • innate immunity in the form of mucociliary escalator and alveolar macrophages
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3
Q

-itis

A

the inflammation and swelling of the corresponding upper/lower respiratory structure

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4
Q

croup

A

laryngotracheobronchitis (combined inflammation of the larynx, trachea, bronchi, and bronchioles) caused mainly by viruses; characterized by a barking cough and stridor

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5
Q

stridor

A

wheezing or loud breathing associated with a blocked or narrowed airway

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6
Q

pneumonia

A

inflammation of the alveoli, which are the small air sacs in the lungs where gas exchange occurs

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7
Q

dyspnea

A

shortness of breath

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8
Q

acute respiratory infection

A

aka common cold

  • rhinoviruses and coronaviruses cause 6-80% of common colds
  • spread through contact, respiratory droplets, fomites
  • SYMPTOMS: sudden onset sore throat, runny nose, sneezing, fatigue, discolored mucus at later stages
  • usually self-limiting. no need for antibiotics
  • con progress to a sinus infection, ear infection, or a lower respiratory tract infection (causing pneumonia)
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9
Q

SARS (severe acute resp. syndrome)

A

caused by a human coronavirus, SARS-CoV

  • zoonotic disease (originated in bats, spread from civets to humans)
  • induces severe respiratory distress, predominant in older males
  • like other coronaviruses, a positive strand, enveloped, helical, nucleocapsid RNA virus
  • has 4 major proteins
  • peaked in 2003, caused ~8000 infections worldwide. did not have asymptomatic spread. not seen after 2004
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10
Q

MERS (middle eastern respiratory syndrome)

A

caused by a human coronavirus, MERS-CoV, first identified in Saudi Arabia in 2012

  • zoonotic disease (spread in bats, spread from camels to humans)
  • similar symptoms to SARS
  • *very high mortality rate of 34%)
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11
Q

COVID-19

A

novel, coronavirus disease first identified in Wuhan in 2019 caused by SARS-CoV2 virus

  • originated in bats, intermediate species not known
  • pandemic
  • asymptomatic in 25% of those infected
  • minor disease in 80% (fever, cough, fatigue can last few weeks)
  • severe disease in 2% of cases (rapid onset of pneumonia, respiratory distress needing O2 supplementation and ventilation)
  • large scale organ damage seen in a subset of patients; result of excessive immune activation
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12
Q

SARS-CoV2

A
  • like other coronaviruses (a positive strand, enveloped, helical nucleocapsid RNA virus)
  • virus binds to ACE2 receptors on epithelial cells of lungs and gut to enter into host cell. synthesizes viral RNA polymerase to make copies of its genome
  • replication inhibitor, Remedesivir used to treat severe infections
  • monoclonal antibodies treatment; to neutralize virus binding and reduce viral load
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13
Q

respiratory syncytial virus (RSV) infections

A
  • leading cause of acute lower respiratory tract infection in children under 5 worldwide
  • estimated it kills between 66,000-199,000 children per year
  • top cause of bronchitis and pneumonia in children under 1
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14
Q

influenza

A
  • begins in upper res tract
  • 1-4 day incubation period
  • SYMPTOMS begins very quickly (headache, chills, dry cough, body aches, fever, stuffy nose ,and sore throat)
  • extreme fatigue can last a few days or weeks
  • CAUSATIVE AGENT: influenza virus
  • ## cause of repeated epidemics and pandemics
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15
Q

influenza virus

A
  • enveloped RNA virus family of orthomyxoviruses
  • has 2 main antigens on spikes (hemagglutinin HA and neuraminidase NA) that allow for entry and escape of virus from host cell
  • 3 different subtypes: A B C
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16
Q

influenza A

A

undergoes frequent mutation, causes most epidemics and pandemics.

  • deaths often due to secondary bacterial pneumonia
  • animals and birds act as reservoirs
  • spanish flu of 1918: record numbers of 15-34 year old died
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17
Q

influenza B

A

undergo antigenic variation at a slower rate.

  • limited geographical epidemics
  • can only infect humans
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18
Q

influenza C

A

lacks NA (neuraminidase)

  • limited infectivity
  • not often recognized as influenza
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19
Q

antigenic variation

A

rapid mutation in HA and NA antigens that prevent a robust adaptive immune response

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20
Q

antigenic drift

A

mutations in HA and NA that results in significant difference in the epitopes expressed on the surface of virus
- this reduces effectiveness of previously generated antibodies

21
Q

antigenic shift

A

from gene reassortment due to genome exchanges between coinfecting viruses
- new viruses emerge

22
Q

influenza vaccines

A
  • flu vaccines are the best option to prevent and limit influenza
  • new vaccines are created every year
  • vaccine effectiveness varies from year to year due to antigenic variation
23
Q

inactivated viral strains in flu vacccine

A

injectable vaccines

24
Q

attenuated viral strains in flu vaccine

A

nasal mist vaccine, less effective

25
Q

tuberculosis

A 
Mycobacterium tuberculosis
- 4th leading cause of death
- untreated tb progresses slowly
- only 5% of infected people actually develop a clinical case of tb
- patients with active tb can transmit the disease to others
DIVIDED INTO
- primary
- secondary
- disseminated (extrapulmonary)
26
Q

Mycobacterium tuberculosis

A
  • extremely slow growing (12-18 hr. generation time)
  • has thick cell wall made of waxes and mycolic acids (prevents rapid exchange of nutrients with environment and also offers protection from killing by immune cells)
  • grows inside macrophages
  • acid-fast staining
  • takes up to 2 weeks to grow in culture
27
Q

primary tuberculosis

A
  • asymptomatic or accompanied by mild fever
  • after 3-4 weeks, immune system mounts a cell-mediated response (large influx of WBC into lungs)
  • tubercles
  • bacteria are contained within granulomas (can stay there for decades)
28
Q

tubercles

A

nodules filled with enlarged, fused macrophages surrounded by leukocytes and connective tissue that walls off the bacteria from rest of body (also called granulomas)

29
Q

secondary (reactivation) tuberculosis

A

-live bacteria remain dormant and become reactivated years later due to weakened immune system
- CHRONIC TUBERCULOSIS
(tubercles burst open and bacteria are released into lymph)
(severe symptoms: violent coughing, greenish or bloody sputum)

30
Q

extrapulmonary tuberculosis

A
  • outside of lungs; lymph nodes, kidneys, long bones

- more common in immunosuppressed patients and young children

31
Q

diagnosis of TB

A
  • Mantoux tuberculin skin test (performed by an intradermal injection of tuberculin purified protein derivative PPD into forearm; site is inspected for induration; size is measured)
  • DOES NOT distinguish between an active vs latent TB infection
  • patients who have been vaccinated against TB can have a false positive skin test result
  • previously diagnosed patients should instead be tested with (molecular diagnostics OR interferon gamma release assay)
32
Q

pneumonia

A
  • inflammatory condition of lung
  • fluids fills alveoli
  • begins with URT symptoms (runny nose, congestion, headache, fever)
  • onset of lung symptoms follows (chest pain, fever, cough, discolored sputum)
33
Q

healthcare-acquired pneumonia

A

pneumonia that develops at least 48 hours after admission to a healthcare facility

34
Q

community-acquired pneumonia

A

pneumonia that has developed in a patient who was not recently hospitalized or admitted to some other healthcare facility

35
Q

lobar pneumonia

A
  • bacteria colonize lobes of the lungs
  • pleurisy (inflammation of membrane) is a common symptom
  • consolidation (fibrin deposits) blocks air spaces
36
Q

bronchial pneumonia

A
  • bronchi and spreads to alveoli
  • usually secondary to other viral infection
  • lacks fibrin deposits
37
Q

classical or typical pneumonia

A

signs of consolidation

38
Q

atypical pneumonia

A

bacterial pneumonia that is not characterized by signs and symptoms of consolidation, have dry cough

39
Q

streptococcus pneumoniae

A

gram-POS, encapsulated diplococcus of the Group B streptococci

  • significant concern in individuals < 5 years and > 65 years
  • pneumococcal conjugate vaccines
40
Q

hemophilus influenzae

A

gram-NEG, encapsulated, commonly occurs in children < 6 in developing countries.
- greater than 90% developed country children have been vaccinated with Hib conjugate vaccine

41
Q

mycoplasma pneumoniae

A
  • one of the smallest self-replicating organisms, lack a cell wall
  • lives inside host cells
42
Q

whooping cough (pertussis)

A

CAUSATIVE AGENT: Bordatella pertussis

  • gram-NED, encapsulated, coccobacillus
  • 2 distinct symptom phases (catarrhal and paroxysmal stage)
  • followed by a long recovery (convalescent) phase (complete recovery requires weeks or months; other microorganisms can more easily cause secondary infection)
43
Q

catarrhal stage

A
  • after incubation from 3-21 days
  • appears as cold symptoms (runny nose)
  • lasts 1-2 weeks
44
Q

paroxysmal stage

A
  • severe and uncontrollable coughing
  • violent coughing spasms
  • result in burst blood vessels in the eyes and vomiting
45
Q

diphtheria

A

symptoms initially experienced in the upper respiratory tract
SYMPTOMS: sore throat, low-grade fever; pseudomembrane forms on the tonsil or pharynx due to deposits of bacteria, damaged epithelial cells, fibrin, and blood cells
- often fatal, suffocation; leading cause of death in children under 5 till a century ago
- sequelae (damage/ complications) INCLUDE: myocarditis seen in 20% cases, paralysis

46
Q

Corynebacterium diphtheriae

A

bacteria with toxin producing prophage

  • if strain lacks prophage, it is not pathogenic
  • toxin affects protein synthesis (kills host cells throughout the body)
  • bacteria rarely found beyond upper respiratory tract
  • DPT vaccine: diphtheria toxoid (inactivated toxin); adults need booster doses
47
Q

strep throat

A

STREPTOCOCCAL PHARYNGITIS

  • caused by Group A streptococcus
  • often found as normal flora of URT and skin
  • inflammation of the throat, swollen cervical lymph nodes, exudate in throat/tonsils, cough is absent in most cases
  • can be treated by penicillin-based drugs or macrolide drugs for patients allergic to penicillin
48
Q

scarlet fever

A
  • caused by lysogenized S. pyrogenes strains, that gained the ability to produce an erythrogenic toxin
  • occurs in <10% of streptococcal pharyngitis cases
  • red rash that spread from face and neck to rest of the body
  • due to inflammation in response to toxin

microbio final (4 decks)

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