Bacterial Pathogens of the Respiratory Tract Flashcards by Amin Bemanian

In what ways do bacteria enter/spread into the lower respiratory tract?

Direct ihalation
Aspiration of upper airway contents
Spread along mucous membrane sufrace
Hematogenous spread
Direct penetration (intratracheal tube)

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What are the defense barriers to bacterial infections?

Ability to filter particles based on size
Mucociliary elevator
Respiratory tract secretions
Localized immune cells and responses

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What are the common bacterial pathogens (discussed in this lecture)?

Bordetella pertussis
Corynebacterium diptheriae
Neisseria meningitidis
Streptococcus pyogenes
Staphylococcus aureus
Streptococcus pneumoniae
Haemophilus influenzae
Mycoplasma pneumoniae
Pseudomonas aeruginosa
Legionella pneumophila
Mycobacterium tuberculosis

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Which bacteria are gram positive? Of these which have coccus and which have rods?

Gram positive
- Coccus
  - Staphylococcus
  - Streptococcus
- Rods
  - Corynebacterium

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Which bacteria are gram negative? Of these, which have coccus, which have coccobacillus and which have rods?

Gram Negative Bacteria
- Coccus
  - Neisseria
- Rod
  - Pseudomonas
  - Legionella
  - Haemophilus
- Coccobacillus
  - Bordetella

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Which bacteria are acid fast with rods?

Which bacteria is pleomorphic and has no cell wall?

Acid Fast (Rod) - Mycobacterium

No cell wall (Pleomorphic) - Mycoplasma

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Streptococcus pyogenes

Morphology:
Disease:
Virulence Factors:
Vaccine?:

Streptococcus pyogenes

Morphology: Gm +; cocci in chains
Disease: Strep throat, scarlet fever
Virulence Factors: ß-hemolytic, hyaluronic capsule, M protein
Vaccine?: No

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Streptococcus pneumoniae

Morphology:
Disease:
Virulence Factors:
Vaccine?:

Morphology: Gm +; cocci in chains
Disease: Otitis media, sinusitis, pneumonia
Virulence Factors: α-hemolytic, polysaccharide capsule, pneumolysin
Vaccine?: Yes

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Staphylococcus Aureus

Morphology:
Disease:
Important virulence factors:
Vaccine?:

Staphylococcus Aureus

Morphology: Gm+; cocci in clusters
Disease: Upper RT infections, pneumonia
Important virulence factors: Polysaccharide capsule, protein A, lots of toxins
Vaccine?: No

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Neisseria meningtidis

Morphology:
Disease:
Important virulence factors:
Vaccine?:

Neisseria Meningtidis

Morphology: Gm -; Diplococci
Disease: Pharyngitis, pneumonia
Important virulence factors: Polysaccharid capsule, pilin, endotoxin
Vaccine?: Yes

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Haemophilus Influenzae

Morphology:
Disease:
Important virulence factors:
Vaccine?:

Haemophilus Influenzae

Morphology: Gm-; plemorphic, short rods
Disease: Otitis media, sinusitis, pneumonia, epiglottitis
Important virulence factors: Nonencapsulated and encapsulated, several adhesins
Vaccine?: Yes

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Mycobacterium tuberculosis

Morphology:
Disease:
Important Virulence Factors:
Vaccine?:

Mycobacterium tuberculosis

Morphology: Acid fast rods
Disease: Tuberculosis
Important Virulence Factors: Acute/latent infections, lipid-rich cell envelope
Vaccine?: Yes

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Legionella pneumophila

Morphology:
Disease:
Important Virulence Factors:
Vaccine?:

Legionella pneumophila

Morphology: Gm -; rods
Disease: Legionairre;s disease; pontiac fever
Important Virulence Factors: Opportunistic, numerous enzymes
Vaccine?: No

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Pseudomonas aeruginosa

Morphology:
Disease:
Important Virulence Factors:
Vaccine?:

Pseudomonas aeruginosa

Morphology: Gm-; rods
Disease: Otitis media, pneumonia
Important Virulence Factors: Opportunistic, numerous enzymes, forms biofilms
Vaccine?: No

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Mycoplasma pneumoniae

Morphology:
Disease:
Important Virulence Factors:
Vaccine?:

Mycoplasma pneumoniae

Morphology: Does not stain; pleomorphic
Disease: Tracheobronchitis, pneumonia
Important Virulence Factors: Lacks cell wall, P1 adhesin
Vaccine?: No

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Corynebacterium diptheriae

Morphology:
Disease:
Important Virulence Factors:
Vaccine?:

Corynebacterium diptheriae

Morphology: Gm + rods in club or v-shape
Disease: Diptheria, pseudomembrane in RT
Important Virulence Factors: Deptheria toxin, local and systemic infection
Vaccine?: Yes

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Bordetella pertussis

Morphology:
Disease:
Important Virulence Factors:
Vaccine?:

Bordetella Pertussis

Morphology: Gm -; pleomorphic, coccobacillus
Disease: Pertussis
Important Virulence Factors: Pertussis toxin, pertactin, FHA
Vaccine?: Yes

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What are some strategies used by RT pathogens to adhere to and/or invade tissues?

Pili

Fimbriae

Adhesins

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What are some factors that inhibit or neutralize host defense mechanisms?

What are some toxins that alter/inactivate host cell functions?

What are some factors that inhibit or neutralize host defense mechanisms?

Proteases, capsule

What are some toxins that alter/inactivate host cell functions?

Ribosylate G-proteins and EF-2, phospholipases

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What are the three distinct phases of pertussis (Bordetella pertussis)?

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Catarrhal - initial 1-2 weeks of infection
Paroxysmal - most severe symptoms (cough)
Convalescence - symptomology due to pertussis toxin

For bordetella pertussis, adults are often ______ ______ because it is a disease of the ______

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Asymptomatic carriers

Young

What is the mechanism of B. Pertussis elicitation?

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Bacteria binds to ciliated epithelium
PTx alters adeylate cyclase activity
1. ADP ribosylates G
2. Elevates cAMP production
3. Increases secretions and mucus production
Damage to the mucociliary escelator → Whooping cough

C. Diptheriae is often arranged in ______

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pallisades

What is the function of diptheria toxin (DTx)?

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ADP-ribosylates EF-2

Produces pili required for bacterial colonization of upper RT

What is the C. Diptheriae mechanism of disease elicitation?

1. Pili mediate adherence to respiratory epithelium 2. Extensive bacterial replication at surface epithelium 3. Two stages: invasion and toxigenesis

What makes up the vaccine for C. Diptheria?

Formalin inactiavted diptheria toxin

Neisseria meningitidis is a common inhabitant of the \_\_\_\_\_\_\_\_\_\_

nasopharynx

What are the functions of the N. meningitidis virulence factors? ## Footnote Capsule: Type IV pili: Endotoxin: Lipooligosaccharide:

Capsule: Prevents phagocytosis and complement fixation Type IV pili: Allow colonization of the nasopharynx Endotoxin: Responsible for most clinical manifestations Lipooligosaccharide: Has endotoxin activity

The N. meningitidis vaccine works against which serotypes? At what age are the different vaccines administered?

Developed agains serogroups A, C, Y, and W135 Adminstered to individuals \> 2yrs old MCV4-conjugate vaccine = 55yrs and younger MPSV4-capsule vaccine = 55yrs and older

Streptococcus pyogenes is catalase - \_\_\_\_\_\_

negative

Describe the diseases associated with Streptoccocus pyogenes

Pharyngitis: redness and edema of the mucous membranes, fever, purulent exudate, tonsilitus Scarlet fever: streptococcal pharyngitis and an erythematous punctiform rash

S. Pyogenes surface proteins (M protein, F protein, LTA) promote...

Adherence in pharynx

Besides gram stain, how can Streptococcus be tested for?

Rapid antigen detection test

How is staphylococcus aureus aqcuired?

Acquired via aspiration of oral secretions or hematogenous spread from distant infection side

What are the functions of the following S. aureus virulence factors? ## Footnote LTA: Protein A: Coagulase:

LTA: Binds to epithelial cells (fibronectin) Protein A: Binds Fc receptors to inhibit antibody-mediated clearance Coagulase: converts fibrinogen to fibrin

What is the function of pneumolysin in S. pneumoniae?

Destroys ciliated epithelial cells Activates alternative complement pathway Suppresses phagocyte oxidative burst

_S. Pneumoniae vaccines_ When do you deliver the two types of vaccines?

Adults and children \> 2yrs - immunize with vaccine containing 23-different capsular polysaccharides For children \< 2yrs - immunize with 13-valent conjugated vaccine

H. Influenzae requires ___ and ____ for growth?

heme; NAD

How does H. Influenzae attach to respiratory epithelium?

Pili and OMPs (Outer membrane proteins)

Which type of H. Influenzae has a vaccine?

H. Influenzae type B

What delicious breakfast food does mycoplasma pneumonia resemble on agar medium?

fried-egg like appearance

What is the M. pneumoniae mechanism of disease elicitation?

1. Associates with upper airway epithelial cells through major adhesion (P1) 2. Local accumulation of toxic metabolites 3. Binding destroys cilia and inhibits clearance by normal mechanisms - shedding of bacteria in respiratory secretions 4. Inflammatory response enhances cell damage

Pseudomonas aeruginosa is most associated with lung infections of _____ \_\_\_\_\_\_ patients

cystic fibrosis

The _______ of P. aeruginosa allows the bacteria to resist immune-mediated clearance

biofilm

What are the functions of endotoxin and pyocyanin for P. aeruginosa?

Endotoxin: elicits septic shock Pyocyanin: Pigments that induce release of ROI (reactive oxygen intermediates)

Legionella is typically detected by ....

Fluorescent antibody stain

Between Pontiac fever and Legionnaire's disease, which is more severe?

Legionnaire's disease

Mycobacterium tuberculosis has a thick waxy cell wall containing ______ \_\_\_\_\_ and \_\_\_\_\_\_\_\_\_\_\_\_\_\_

mycolic acids and lipoarabinomannan

Where does mycobacterium persist? What are its virulence factors and what do they do?

Persists within host generated granulomas * Mycolic acids and liparabinomannan -prevents damage by host compounds encountered within granuloma * Cord factor - inhibits PMNs

Bacterial Pathogens of the Respiratory Tract Flashcards

(49 cards)