Becterial Pneumonias Flashcards

1
Q

Bacterial pneumonia most common pathogens

A

All of these pathogens enter the respiratory system via inhalation, aspiration of systemically via blood.

Streptococcus pneumonia
- most common in adult

Haemophilus influenza type B
- most common in adult

Legionella pneumothorax

Klebsiella pneumoniae

Pneumocystis jirovecii (fungal pathogen usually seen only in immunosupression)

Mycoplasma pneumoniae
- more common in adults

Note: staph aureus does not produce pneumonia

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2
Q

Is most pneumonia viral or bacterial?

A

Viral is far more common

This is especially true in children
- RSV and HRV combine for almost 50% of all childhood pneumonia

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3
Q

Hospital pneumonia catagories

A

Based on how they got the disease (all tend to be more rare infections)

1) Are HIV positive
- pneumocystis jiroveci
- mycobacterium

2) immunocompromised through drugs
- aspergillosis
- mycobacterium

3) ventilation assistance
- kiebsellia
- serrata
- aeruginosa

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4
Q

What is imperative to do when you suspect problematic pneumonia (bacterial)

A
  • Gram stain
  • culture the sputum that is present
  • serology

Also begin empirical treatments until specific pathogen is known

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5
Q

Complement fixation test

A

Determines what antibodies a patient has in their body

Procedure:

1) patient serum is mixed with specific pathogenic antigens
2) compliment and RBCs are then added tot he mixture
3) if patient DOES have antibodies = compliment binds to antigen/antibody complex and NO RBC LYSIS/ reactive
4) if patient DOESNT have antibodies = compliment binds to the RBC and RBC LYSIS/nonreactive

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6
Q

Types of ELISA refresher

A

Direct ELISA

  • used when you want to know if a patient has a specific antigen
  • mix patient sample with primary antibody conjugate that is labeled fluorescently

Indirect ELISA

  • used when you want know if a patient has a specific antibody
  • mix patient sample with secondary antibody conjugate (artificial antibody that is labeled and is made to bind to natural antibodies)

Sandwich ELISA

  • use when you want know if a patient has a specific AB:AG complex
  • mix patient sample with secondary antibody conjugate (artificial antibody that is labeled and is made to bind to natural AB:AG complexes)
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7
Q

Mycoplasma pneumonia

A

Primary cause of “walking pneumonia”
- Pulse-temperature dissociation is present (fever w/ no increased pulse) w/ very mild symptoms

Lack cell walls (cant use B-lactams)

Smallest free-living organisms

need PCR for definitive diagnosis

Hard to culture (use eatons agar if you must)

Generates own ROS and use gap junctions to move into cells

  • Can show hemolytic anemia*
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8
Q

Stevens-Johnson syndromes

A

Widespread Epidermal damage caused by the production of self-reactive CD-8 cytotoxic T-cells

Causes:

  • mycoplasma pneumoniae
  • HSV
  • exposure to certain medications if you have hypersensitive (or not sometimes)
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9
Q

Hemolytic anemia

A

Body mistaken creates self-reactive antibodies to its RBCs in cold temperatures
- diagnosed via cold-agglutination testing

Is often associated with mycoplasma pneumoniae and legionnaires diseases

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10
Q

Streptococcus pneumoniae specifics

A

Accounts for 60% of all bacterial pneumonia

  • most common pathogen in secondary infections after viral infections
  • high rates in alcoholics and drug abusers
  • produces rusty sputum (mild hemoptysis)

Gram positive diplococci w/ capsule

Forms biofilms

A-hemolytic
- partially hemolytic (looks green)

Tests:

  • optochin (+)
  • catalase (-)
  • coagulase (-)
  • pneumolysin (+)
  • quellung (+)
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11
Q

Complications in streptococcus pneumoniae

A

Bacteremia

Sepsis

Meningitis

Pneumococcal endocarditis

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12
Q

Legionnaires disease specifics

A

Legionella pneumophila is the causative agent
- most common in thick,moist air infections (poor AC units, Hot tubs, showers etc.)

Aerobic intracellular pathogen

Gram-negative and stains poorly

  • need to use silver staining W/ BYCE (buffer charcoal yeast extract) agar
  • BYCE has no hydrogen peroxide (since hydrogen peroxide is instant death to this bacterium)

Major virulence factor = metalloprotease secretion
- inhibits phago-lysosome and breaks down zinc

  • to best detect use urinary antigen tests*
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13
Q

Pontiac fever and atypical legionella pneumonia

A

Both are atypical forms of pneumonia caused by legionella pneumophila

Atypical:

  • severe pneumonia w/ little to no inflammation of the bronchioles/upper airways
  • hyponatremia is common
  • not self-limiting

Pontiac fever

  • less severe pneumonia that only shows a fever and arthralgia
  • self-limiting
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14
Q

Pseudomonas aeruginosa specifics

A
  • ALWAYS GROWS GREEN*
  • also shows a grape-like odor

Gram (-) rods

Found in all places, especially in hospitals
- most patients are asymptomatic, and usually only express symptoms if they are immunosuppressive

VERY common in CF patients and people w/ ventilator assistance

  • roughly 80% of all CF patients have pseudomonas by age 25 in their lungs
  • if untreated causes necrotizing pneumonia

Tests:

  • catalase (+)
  • oxidase (+)
  • hemolysin (+)
  • leukocidin (+)
  • elastase (+)
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15
Q

Virulence factors in pseudomonas aeruginosa

A

Exotoxin A
- inactivates elongation factor 2 in hosts which halts cell protein synthesis

Mucous exoploysaccharide
- helps form biofilms

Phospholipids C
- lysis of cell membranes

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16
Q

Presentations of pseudomonas aeruginosa

A

Sepsis

Soft tissue wounds

  • will look green w/ grape smell
  • looks gangrenous most of the time
  • very high incidence in burn wounds

Eyes

  • causes extreme rapid pain if in the eyes
  • vision loss will occur if untreated

Endocarditis

17
Q

Haemophilus influenza (type B)

A

Gram (-) rod

DOESNT CAUSE FLU
- type A does this

Only grows on chocolate agar w/ factors V and X present

Can produce epiglottis, meningitis and otitis media on top of pneumonia
- rates are stupid low due to vaccines

18
Q

Klebsiella pneumoniae specifics

A

Gram negative anaerobic rod w/ capsule

Found in flora of the mouth and GI normally and doesn’t actually cause damage unless it gets into the wrong places or you are any of the following susceptible populations 
- alcoholic 
- diabetic 
- immunocompromised 
(Because of this its very rare) 
  • shows currant jelly sputum (bright red mucus sputum infections*
  • also may show lobar pneumonia w/ lung abscesses
Tests:
- urease (+)
- lactase (+) on Macconkey agar 
- Beta-lactamase (+)
(cant use B-lactams, must use cephalosporins)
19
Q

Moraxella catarrhalis specifics

A

Aerobic Gram (-) diplococci

Not common except in the following

  • lung cancer
  • COPD
  • children younger than 2
  • elderly (>65yrs)
  • immunosupression

Causes pneumonia and URIs that spreads via respiratory droplets

20
Q

Burkholderia cepacia (BCC)

A

Gram negative rods w/ capsule

Is catalase positive

Most commonly found in CF patients
- this is due to it being the #1 most common co-infection w/ pseudomonas aeruginosa infections

Very dangerous and rapidly mutates
- very antibiotic resistant

  • this often tested in CF patients just regularly*
21
Q

Pneumocystis jirovecii

A

Fungus that likes to live in alveoli
- always asymptomatic in healthy patients

Dangerous in HIV cases

Have foamy alveolar casts w/ disc-shaped yeast upon microscopic examination

Shows ground glass opacities on CTs

Symptoms (very rapid onset)

  • tachypnea
  • fever
  • cough
  • respiratory distress
22
Q

Zoonotic pathogens that can cause pneumonia

A

Chlamydia psittaci

  • spread by parrots and pigeons
  • have elementary (infections) and reticulate (replication) bodies

Histoplasma capsulatum
- spread via rare fungus on animals