Extracellular Flashcards
Examples of extracellular bacteria
- Haemophilus influenzae
- Bordetella pertussis
- Pseudomonas aeruginosa
- Streptococcus pneumoniae
- Mycoplasma pneumoniae
What are obligate human pathogens that are transmitted person to person?
All except pseudomonas
Gram- coccobacillus extracellular bacteria; may be encapsulated (types a-f); found only in human respiratory tract (commensal-normal flora)
Haemophilus influenzae
How do you grow H. flu in vitro?
Growing H. flu is fastidious (picky) and requires very rich media with hemin
How is H. flu transmitted?
respiratory droplets
What are the diseases caused by H. flu?
Meningitis Otitis media (common in children)
What vaccines are available for H. flu?
conjugate vaccines (polysaccharide conjugated to a protein carrier)
most important/worrisome disease caused by H. flu (type b); more frequent in young children yet to be vaccinated; quick onset, death can occur rapidly; fever, altered CNS, seizures, coma
meningitis
rare disease caused by H. influenza (type b); swelling of epiglottis that can cause an airway obstruction
Epiglottitis
most common disease caused by H. influenzae (nonencapsulated). why?
Otitis media (middle ear infection)
- Anti-polysaccharide antibody is T-cell independent, and T-cell independent responses are inefficient early in life.
What are the virulence factors of H. flu?
pili (attachment)
LOS (same as LPS)
maybe capsule
What does the capsule of a type b H. influenzae bacteria have?
Polyribosyl phosphate (PRP)
Gram- coccobacillus, extracellular, obligate aerobe that causes Pertussis (whooping cough); found only in human respiratory tract
Bordetella pertussis
How do you grow B. pertussis in vitro?
fastidious, slow, sensitive to inhibitory factors in media
How is B. pertussis transmitted?
respiratory droplets
highly communicable
What is the phase that lasts about 7 days with relatively mild cold-like symptoms, mild cough, rhinorrhea, malais. B. pertussis is most easily detected in this phase.
Catarrhal Phase
What is the phase that lasts 1-4 weeks with severe, forceful, inspiratory gasp coughing, and leukocytosis. B pertussis is hard to detect in this phase
Paroxysmal Phase
What is the phase that can last several weeks with less cough and gradual recovery?
Convalescent Phase
What are the virulence factors of B. Pertussis?
- Pili
- LOS/LPS
- Toxins (exotoxins)
What are the exotoxins produced by B. pertussis
Tracheal Cytotoxin
Pertussis toxin
Adenylate cyclase toxin
Which toxin causes cell wall fragment of the host and induce ciliostasis (kills cilated cells)
Tracheal Cytotoxin
Which toxin results in leukocytosis by impairing lymphocyte entry into lymph nodes
Pertussis toxin
Acellular pertussis vaccines help protect against disease, prevent infection and transmission (True or False)
False: protect against disease but fails to prevent infection and transmission
chemically modified toxin (no longer toxic), but still antigenic; used with Diptheria and Tetanus
toxoid
organism inactivated, but intact; used with Pertussis
Whole cell vaccine (acellular vaccine)
encapsulated gram - rods that can cause sepsis through nosocomial (hospital) infections; highly antibiotic resistant
Pseudomonas aeruginosa
P. aeruginosa is a problem pathogen in patient with ______ because it creates mucoid colonies
CF
Encapsulated, Gram + dipplococci bacteria that causes acute pneumonia most commonly in children, elders, and immunocompromised
Streptococcus pneumoniae
What causes acute pneumonia with rusty, blood tinged sputum, typical, lobar pneumonia followed by upper respiratory tract infections
Streptococcus pneumoniae
Vaccines for S. pneumoniae
Pneumovax 23 for adults
Prevnar 13 for children
Obligate mycobacterium human pathogen that causes chronic walking pneumonia with long incubation period; doesn’t gram stain; smallest known free-living organism
Mycoplasma pneumoniae
How is M. pneumo transmitted?
respiratory droplets
What is required for M. pneumo to cause disease
attachment to respiratory epithelial cells via “attachment organelle”
What is secreted by M. pneumo that acts as exotoxin but is not a toxin?
H2O2
What non-specific serologic test is often positive for M. pneumo?
Cold agglutinins (RBC agglutinated by IgM at 4 celcius)