Bacterial Pathogens of the Respiratory Tract Flashcards
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)
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
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
Which bacteria are gram positive? Of these which have coccus and which have rods?
- Gram positive
- Coccus
- Staphylococcus
- Streptococcus
- Rods
- Corynebacterium
- Coccus
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
- Coccus
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
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
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
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
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
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
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
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
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
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
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
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
What are some strategies used by RT pathogens to adhere to and/or invade tissues?
Pili
Fimbriae
Adhesins
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
What are the three distinct phases of pertussis (Bordetella pertussis)?
- 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 ______
Asymptomatic carriers
Young
What is the mechanism of B. Pertussis elicitation?
- Bacteria binds to ciliated epithelium
- PTx alters adeylate cyclase activity
- ADP ribosylates G
- Elevates cAMP production
- Increases secretions and mucus production
- Damage to the mucociliary escelator → Whooping cough
C. Diptheriae is often arranged in ______
pallisades
What is the function of diptheria toxin (DTx)?
ADP-ribosylates EF-2
Produces pili required for bacterial colonization of upper RT
What is the C. Diptheriae mechanism of disease elicitation?
- Pili mediate adherence to respiratory epithelium
- Extensive bacterial replication at surface epithelium
- 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?
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?
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?
- Associates with upper airway epithelial cells through major adhesion (P1)
- Local accumulation of toxic metabolites
- Binding destroys cilia and inhibits clearance by normal mechanisms - shedding of bacteria in respiratory secretions
- 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