pneumococcus- daniels Flashcards
Streptococcus pneumoniae overview
Gram positive cocci
- Diplococci
- Aerotolerant anaerobe
- Non-spore forming
- Encapsulated
what bacteria is responsible for most community-acquired pneumonia?
Streptococcus pneumoniae
over a million deaths a year
Phenotyping Strep pneumoniae
A) alpha-hemolysis
B) gram positive
C) catalase negative
D) OPTOCHIN succeptability- zone of inhibition
Risk factors for establishment of infection by Strep pneumoniae
Viral infection (esp. influenza) Smoking Loss of consciousness (aspiration) Edema (fluid) in lungs for any reason High risk comorbidities, age, and demographics Seasonality (Winter/spring)
what are the 4 stages of pathogenesis (multiplication/spread in lungs)
1) Alveoli fill with fluid
2) Early consolidation phase- neutrophil induced inflammation
3) Late consolidation phase
- -alveoli are filled with neutrophils
- -effected tissue is hard not spongy/healthy
4) recovery phase
- –Macrophages phagocytose debris
- –Normal architecture is re-established
Potential sequelae to pneumonia in adults
Pleural effusion = fluid in the chest outside lungs
Bacteremia –> Meningitis
treatments for Pneumococcus infection
1) Penicillins and other β-lactams
2) Macrolides- Erythromycin, Azithromycin
3) Fluoroquinolones- Levofloxacin
what is the main concern when treating Pneumococcus with Penicillins and other β-lactams?
Resistance is a concern unlike group A Strep
what are Strep pneumoniae vaccines comprised of?
Vaccine products are comprised of polysaccharide antigens (capsular) from multiple strains of S. pneumoniae
Legionella pneumophila- where was it discovered?
Philadelphia, PA 1976 Annual American Legion Convention 221 hospitalizations 34 Deaths CDC outbreak investigation traced to A/C system
Legionella pneumophila overview
1) Gram negative pleomorphic rod
2) Obligate aerobe
3) Fastidious = special conditions for cultivation in lab
* ***Cysteine requirement is identifying characteristic
where is L. pneumophila encountered?
Contaminated water
Environmental aerosols (Not spread by cough)
Multiplication/spread of L Pneumophilia
- Bacteria in alveoli phagocytosed by alveolar macrophages
- Virulent strains multiply within autophagosomes
Damage/Immune response to L. Pneumophilia
Cell-mediated immune response
1) release IFN-gamma
2) Causes iron sequestration
Virulence/Proinflammatory mechanisms
1) survival in macrophages
2) LPS, Flagellin
how to treat Legionalla Pneumophilia infections
Antimicrobial drugs with good intracellular penetration
- Macrolides
- Fluoroquinolones
- Tetracyclines
why is penicillin not used to treat L. Pneumophilia?
because they do not achieve therapeutic concentrations in the macrophages
Bordetella pertussis and parapertussis- overview
A) Gram negative rod
B) Obligate aerobe
C) Cause of whooping cough
D) VERY CONTAGIOUS
Pertussis Encounter, Entry, Spread
A) Adults are believed to be reservoir
B) Nasopharynx colonized
C) Organism accesses trachea/bronchi
D) Ciliary Adherence
which substances allow ciliary adhesion in Pertussis?
Filamentous hemagglutinin (Fha)
Pilli (a.k.a. Fimbriae)
Pertactin (a protein)
Damage - Toxin production for B. pertussis
A) Pertussis toxin and Adenylate cyclase/hemolysin
B) Both upregulate host cAMP
Decreased neutrophil function
also produce endotoxin- like every other G- bacteria
what is the main difference between B. pertussis and P. parapertussis
P. parapertussis does NOT produce pertussis toxin
what is the catarrhal stage of pertussis infection?
A) Catarrhal means really really bad runny nose
B) EXTREMELY CONTAGIOUS
paroxysmal stage
fits of numerous, rapid coughing followed by low “whoop” sound
why is laboratory diagnosis of pertussis difficult?
Fewer organisms shed in paroxysmal phase
Must use deep nasal swab and bacterial culture
Vaccines have what form of pertussis?
acellular pertussis
Bordatella bronchiseptica
1) Part of “kennel cough complex”
2) Very rarely affects human beings
- – HIV and chemo patients
what are the 2 diseases that Mycobacterium spp. can cause?
Tuberculosis and leprosy
what are the 3 forms of tuberculosis?
M. tuberculosis – Highly Contagious
M. bovis
M. avium-intracellulare
Dodgy tattoo artists, plastic surgery, environmental (i.e. contaminated deep wounds) can all lead to what?
Opportunistic Disease caused by rapidly growing mycobacteria (RGM)
Mycobacterium spp. are what?
Acid-fast bacteria
Mycobacterium spp.- overview
1) Obligate aerobes
2) Non-spore formers
3) Thick, waxy cell wall
4) Mycolic acid binds carbol fuscin dye
Immunology of granuloma formation- M. tuberculosis
A) multiplication in Macrophages
B) Activation of CD4+ (TH1)
C) Recruitment of more MΦs
ends up causing “multi-nucleated giant cells”
Intradermal skin test for tuberculosis
A) Use of killed antigen “tuberculin” “PPD”
B) Relies on Delayed Type Hypersensitivity
Activation of specific CD4+
—Local inflammation at injection site
—False +s, False –s possible
M. Leprae overview
A) Granulomatous disease (like TB)
B) Organism prefers lower temperature (skin)
C) Spread via respiratory route
what are the 2 forms of Leprosy
Tuberculoid Leprosy
Lepromatous Leprosy
what are the characteristics of Tuberculoid Leprosy
Milder form of disease
May be self limiting
Very few bacteria present in lesions
what are the characteristics of Lepromatous Leprosy
A) Severe, disfiguring
B) Many organisms in lesions
C) Cell mediated immunity is significantly decreased
how is M. leprae grown for study?
Uncultivable in vitro
-Can inocluate mouse footpad
Armadillos are carriers and may have Lepromatous disease
