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Lower respiratory tract infection Flashcards

1
Q

This lecture will come as MCQs or Matching questions in the theory as well as in the OSPE
In OSPE you will find a short history about the case (…child presented with pneumonia, sputum was examined and they show for example the colony asking for the most likely pathogen responsible for it, Gram stain, what is virulence factors, how to prevent it, etc. …) so if they show the optochin disk we can say strep pneumoniae

A
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2
Q

What is meant by the lower respiratory tract infections?

A

They are infections that originates from the carina (from the bifurcation of the trachea and beyond)

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3
Q

What is pneumonia?

A
  • It is a acute inflammatory process of the lung parenchyma due to microbes
  • It is the leading cause of death due to infection (especially <5, >65years)
  • Most of the pathogens that cause pneumonia are normal commensals of the respiratory system (i.e. Streptococcus pneumoniae) and most these are opportunistic pathogens so when there is stagnation it provides medium for the pathogen to multiply and invade the host system causing infection
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4
Q

What are the different classifications of pneumonia?

A

1) Clinical classification

2) Etiological classification

3) Morphological classification

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5
Q

What are the different aspect of the clinical classification of pneumonia?

A

1) Community acquired

2) Hospital acquired

3) Typical pneumonia

4) Atypical pneumonia

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6
Q

What is the etiological classification?

A

1) Bacterial

2) Viral

3) Fungal

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7
Q

What is the morphological classification of pneumonia?

A

1) Lobar (one lobe “localized”)

2) Bronchial (patchy involvement in both lung)

3) Interstitial (when the parenchyma is involved “between the alveoli and parenchyma”)

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8
Q

What is meant by typical & Atypical pneumonia?

A

Typical: Classical pneumonia presents with dyspnea, productive cough with sputum, fever, chest pain, has inflammation, edema, on auscultation and percussion you can identify pneumonia

Atypical: Pathogen present in the lung parenchyma causing the infection but patients does not present with the classical symptoms. Can have slight fever, dry cough but upon investigations we can make a diagnosis of pneumonia

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9
Q

What meant by CAP AND HCAP?

A

1) CAP (Community-acquired-pneumonia): It is the pneumonia that occurs in any patient in the community

2) HCAP (Health-Care-Associated-Pneumonia):

  • Hospital Acquired Pneumonia (pneumonia that develops after 48 hours from being admitted to the hospital
  • Ventilator-associated pneumonia (VAP), HAP that develops in patients who have been intubated and received a mechanical ventilator for at least 48 hours (MRSA/ESBL)

3) Pneumonia in a immunocompromised patient

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10
Q

What are the risk factors for pneumonia?

A

1) Age <2, >65 years old

2) Chronic diseases (asthma, HIV/AIDS)

3) Smoking

4) Environmental factors (air pollution, congested and humid air)

5) People with obstructive or restrictive disorders

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11
Q

What are the common clinical presentation of pneumonia?

A

1) Fever

2) Cough (to remove the sputum from the body that was formed) with or without asthma

3) Shortness of breath

4) Chest pain that gets worse with deep breathing or cough

5) Low oxygen levels in the blood

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12
Q

What is the etiology of pneumonia?

A
  • 80% of pneumonia in infants and children are caused by viruses
  • 80% of the pneumonias in adults are bacterial
  • The etiology of CAP is strongly age dependent
  • Microaspiration of the oropharyngeal secretions is the most common route by which these microbial agents reach the lungs
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13
Q

What is the most common cause of pneumonia in infants & children?

A

Viruses (in 80% of the cases) (RSV mainly “respiratory syncytial virus”)

  • But from the other 20% if it was bacterial (then strep pneumonia is the most common cause)
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14
Q

What is the main organism that causes pneumonia in adults?

A

Bacteria (mainly streptococcus pneumonia)

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15
Q

What is the most common route by which the pneumonia microbial agents reaches the lungs?

A

Microaspiration

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16
Q

What is the most common viral cause of pneumonia?

A

Respiratory syncytial virus (they form a syncytium “fusion of cells”) that affects children less than 2-years old

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17
Q

What is the most common bacterial pathogen that causes pneumonia in children?

A

Streptococcus pneumonia (normal commensal flora)

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18
Q

What is the most common pathogen that causes pneumonia in patients infected with HIV?

A

Pneumocystis jiroveci (fungi)

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19
Q

What are the most common pathogens that causes pneumonia in 2-months to 5-years babies?

A

1) Respiratory syncytial virus

2) Influenza

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20
Q

What is the most common pathogen that causes pneumonia in individuals of age 5-19?

A

1) Mycoplasma pneumonia

2) Chlamydophilla pneumonia

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21
Q

What is the most common pathogen that causes pneumonia in adults?

A

S.pneumonia

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22
Q

What is the most common pathogens that causes pneumonia in (hospital acquired pneumonia or ventilator associated pneumonia)?

A

1) Pseudomonas aeruginosa

2) Staphylococcus aureus

3) Legionella pneumophilla

4) Klebsiella

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23
Q

What is the most common pathogen that causes pneumonia in immunocompromised patients?

A
  • Like the people who takes steroids, have HIV, or patients undergoing chemotherapy
  • P.jiroveci (Pneumocystis jiroveci)
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24
Q

What are the top viruses from most to least that causes pneumonia?

A

1) Respiratory syncytial virus

2) Influenza

3) Coronavirus (COVID-19)

4) Parainfluenza

5) Adenovirus

25
What is the RSV (respiratory syncytial virus)?
- It is a single-stranded, non-segmented, enveloped (outer glycolipid layer-protein coat, from the host cell), RNA virus from the paramyxovirus family - It forms a syncytium (fused cell lining) - They are susceptible to heat, detergents, temp, etc - They are transmitted by close contact to body fluids or blood
26
RSV is the most common cause of what pathologies?
1) Bronchitis 2) Bronchiolitis 3) Pneumonia in children less than 2-years 4) fatal acute respiratory tract infection in infants and young children 5) Hospital acquired "viral" infections - They infect premature infants and children with congenital heart disease and chronic lung disease
27
What is the laboratory diagnostic tests for RSV?
1) Antigen detection (rapid) 2) RT-PCR
28
What is the prophylaxis given to children at high risk and young children for RSV?
Palivizumab
29
What is the treatment for severe RSV infection in hospitalized infants and young children?
Ribavirin
30
Describe the influenza virus
- AKA Flu virus - Segmented RNA, enveloped, from the Orthomyxoviridae family, There are three types: 1) Influenza A: Causes pandemics (as it circulates between man and animals) 2) Influenza-B: Causes outbreaks (man only) 3) Influenza C: Rare, man only - Spreads via close contact droplet - Influenza causes a acute respiratory tract infection, that is considered as a contagious disease - It causes genetic instability (Drifts B and Shifts A)
31
What are the proteins that are released by the influenza virus as a protective mechanism?
- It produces 11 proteins the most important ones are: 1) Hemagglutinin (HA) - It helps in the attachment of the virus to the sialic acid receptors in the respiratory tract (for the attachment and internalization of the virus) - Antibody against (HA) will be protective will block their attachment 2) Neuraminidase (NA) - It is needed for the splitting and releasing (detachment) of the newly formed virus - For the detachment and spreading of the virus
32
How is the influenza virus subtyped?
- Their is 16 subtypes of hemagglutinin and 11 of neuraminidase, the shuffling between them produces different combination for various subtypes - H1N1 & H3N2 are the main one causing pandemic and most common strains of influenza - Bird flu is H5N1
33
What is the clinical presentation of influenza?
1) Central headache 2) Systemic fever 3) Muscle aches 4) Coughing 5) Vomiting 6) Runny nose, sore throat, aches 7) Joint aches
34
What are the preventative measure for influenza?
1) Killed and inactivated quadrivalent (combination of the 4 most common viruses in the area) vaccine is the one used here-safe- can be given to children and in pregnancy - One dose administered intramuscularly
35
What are the different bacteria that causes pneumonia?
1) Streptococcus pneumonia 2) Mycoplasma pneumonia 3) Chlamydophila pneumonia 4) Legionella pneumophila (HAP) 5) Klebsiella pneumonia (HAP)
36
Describe the streptococcus pneumonia bacteria
- Leading pneumonia cause across all age groups especially adults - It is a gram positive diplococci - Catalase negative - Opstochin sensitive and bile soluble - It is encapsulated (via polysaccharide, which is its main virulent factor, that prevents phagocytosis) - Pneumococci are common inhabitant of the mouth
37
What is pneumococcal pneumonia?
- It is a bacteria that is spread endogenously from colonized nasopharynx or oropharynx to the distal sites, mainly after aspiration - It multiplies in the alveolar space at the lower lobes of the lungs - It has a sudden onset, with fever and chills - It produces a productive cough with blood-tinged sputum, and chest pain - children below two and adults above 65 are at high risk of pneumococcal infection, along with patients of hematologic disorders (malignancy, sickle cell disease, etc), because this bacteria is capsulated spleen is must so hat we get rid of it
38
How to diagnose pneumococcal pneumonia in the lab?
- If there is productive cough and you suspect pneumonia you can send the sputum for analysis (sputum is the reprehensive specimen for the LRTI) - It is catalase negative, susceptible to optochin, and soluble in bile 1) Sputum analysis 2) Blood culture 3) Urine antigen detection (because the polysaccharide is filtered by the kidneys) - Gram staining of the sputum is performed, as you can see a lot of gram + diplococci, with many macrophages and neutrophile in pneumonia - Anti-biotic sensitivity test should be done as it is sensitive to penicillin
39
How to prevent pneumococcal pneumonia?
- Recommended for people over 60 years of age, immunosuppressed, diabetic, sickle cell disease patients - Two multivalent vaccines consisting of 23 (Polysaccharide "the main virulent factor of s.pneumonia" PCV-23 not given in children as it does not stimulate memory) or 13 (Conjugate "polysaccharide with protein" PCV-13, with memory so effective in children) serotypes of S.pneumonia capsules are available
40
How to treat pneumococcal pneumonia?
Penicillin-G, erythromycin and new macrolides are alternatives in case of penicillin sensitivity
41
What is the bacteria mycoplasma pneumonia?
- It is the smallest free-living bacteria, that does not have a rigid cell wall containing sterol in their cell membrane - It causes tracheobronchitis and pneumonia (atypical/walking pneumonia) - It infects children between 5-15 years - You see patchy infiltration of the lungs in the x-ray
42
What is the virulence factor of mycoplasma pneumonia?
P1 adhesion, which attaches to the cilia on epithelial cells, which it destroys
43
How does mycoplasma pneumonia spread?
It spreads via respiratory droplets during coughing
44
What is the drug of choice to treat mycoplasma pneumonia?
Erythromycin, doxycycline, or new fluoroquinolones
45
What is chlamydophila pneumonia?
- It is a bacteria that behaves like a virus (Very interesting bacteria that behave like viruses it enters the cell and replicates inside causing many sexually transmitted infections and also can cause eye disorders) - Through its life cycle it transforms from an inactive infectious form (elementary body) to a metabolically active noninfectious form (reticular body (RB)) - It causes atypical pneumonia - We use PCR to diagnose it - Humans get infected with The metabolically inactive infectious type which is just like a spore when inhaled it enters the respiratory epithelium becomes internalized and transforms into a reticulate body then it replicates and the host cell dies and continues to infect new cells.
46
How to treat chlamydophila pneumonia?
Macrolides (erythromycin, azithromycin, clarithromycin) in addition to doxycyclin or levofloxacin
47
What is Klebsiella pneumonia?
- It is a gram-negative bacillus, enterobacteria, with a prominent mucoid appearance of isolated colonies - Causes community/hospital-acquired lobar pneumonia
48
Describe the microscopic photo of Klebsiella pneumonia
It produces a pink lactose fermenting mucoid secretions
49
What is legionella pneumophila?
- Named legionella because it was discovered first in (legion) - It causes both community-acquired and hospital-acquired pneumonia - Its infection has been linked to water distribution - They are slender, pleomorphic gram-negative rods - They are capable of multiplying in alveolar macrophages, and prevent the fusion of phagolysosomes - It is responsible for the legionnaires disease (serous pneumonia) & Pontiac fever (mild flu-like) - transmitted through inhalation
49
What is the gold standard for diagnosing pneumocystis carinii pneumonia (PCP)?
Bronchoalveolar Lavage
50
What is pneumocystis carinii pneumonia (PCP)?
- It is a fungus (pneumocystic jiroveci) - Causes pneumonia in immunocompromised patients - It is present as a bilateral interstitial pneumonia with pleural effusion - Bronchoalveolar Lavage is the gold standard for diagnosis, then comes the GMS-Stain and PCR
51
What is the treatment for pneumocystis carinii pneumonia?
1) Trimethoprim 2) Sulfamethoxazole
52
What is the bacteria that causes pneumonia in immunocompromised patients?
Pneumocystis jiroveci
53
What bacteria causes both community and hospital infections from water systems (both stagnant and warm water)?
Legionella pneumophila
54
Which bacteria can cause hospital or community-acquired lobar pneumonia?
Klebsiella pneumonia
55
which bacteria cause outbreaks in places where there is a water heating system?
legionella pneumophila
56
When do we say that a person has a HAP or VAP?
1) HAP when they develop pneumonia 48 hours after being administered to the hospital 2) VAP when they develop pneumonia after being intubated for 48 hours at least
57
How to prevent VAP?
- It accounts for 20% of all nosocomial infections, with a crude mortality rate of 70% 1) Elevate the head so that gravity reduces the stagnation 2) Clean the mouth using chlorhexidine as most pneumonia comes from the mouth 3) DVT increases the risk of developing pneumonia so give DVT prophylaxis 4) Daily sedation assessment - These will reduce the risk of VAP by 45%

Y2S1-Microbiology-CVS (3 decks)

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