Bacterial Pathogens Flashcards
how can bacteria spread into LRT?
direct inhalation, aspiration, spread along mucous membrane surface, hematogenous, direct penetration
defense barriers?
filtration based on size, mucociliary escalator, respiratory tract secretions, localized immune cells/responses
gram positive bugs in lung? + shapes?
staph (clusters), corynebacterium (rods), strep (chains)
acid fast bacteria?
mycobacterium, rod
pleomorphic bug with no cell wall?
mycoplasma
gram negative bugs, shapes?
neisseria (coccus), bordetella (coccobacillus), pseudomonas, legionella, haemophilus (rods)
streptococcus pyogenes:
morphology, disease(s), virulence factors, and vaccine?
G+ cocci, chains;
pharyngitis (strep throat), scarlet fever;
B-hemolytic, hyaluronic capsule, M protein;
no
streptococcus pneumoniae:
morphology, disease(s), virulence factors, and vaccine?
G+ cocci, chains;
otitis media, sinusitis, lobar pneumonia;
a-hemolytic, polysaccharide capsule, pneumolysin;
yes
staph aureus:
morphology, disease(s), virulence factors, and vaccine?
G+ cocci, clusters;
URI, pneumonia;
polysaccharide capsule, protein A, lots of toxins;
no
neisseria meningitidis:
morphology, disease(s), virulence factors, and vaccine?
G- diplococci;
pharyngitis, pneumonia;
polysaccharide capsule, pillin, makes endotoxin;
yes
H. Influenzae:
morphology, disease(s), virulence factors, and vaccine?
G- pleomorphic, short rods;
otitis media, sinusitis, pneumonia;
nonencapsulated and encapsulated, several adhesins;
yes
mycobacterium tuberculosis:
morphology, disease(s), virulence factors, and vaccine?
acid-fast rods;
tuberculosis;
acute/latent infections, lipid-rich cell envelope
legionella pneumophila:
morphology, disease(s), virulence factors, and vaccine?
G- rods;
legionairre’s disease and pontiac fever;
opportunistic, numerous enzymes;
no
pseudomonas aeruginosa:
morphology, disease(s), virulence factors, and vaccine?
G- rods;
otitis media, pneumonia;
opportunistic, numerous enzymes, forms biofilms;
no
mycoplasma pneumoniae:
morphology, disease(s), virulence factors, and vaccine?
doesn’t stain, pleomorphic;
tracheobronchitis, atypical pneumonia;
lacks cell wall, P1 adhesin;
no
corynebacterium diptheriae:
morphology, disease(s), virulence factors, and vaccine?
G + rods in club or V shape;
diptheria, pseudomembrane (localized infection) in RT;
diptheria toxin, local and systemic infection;
yes
bordetella pertussis:
morphology, disease(s), virulence factors, and vaccine?
G- pleomorphic, coccobacillus;
pertussis;
pertussis toxin, pertactin, FHA, fimbriae;
yes (waning in efficacy)
what do pathogens use to cause dz w/ adherence and/or invasion to/of RT tissues?
pili, fimbriae, adhesins
what do pathogens use to cause dz w/ secretion of tissue damaging enzymes?
lysins, proteases, elastases
what do pathogens use to cause dz w/ factors that inhibit or neutralize host defense mechanisms?
proteases, capsule to prevent complement
what do pathogens use to cause dz w/ toxins that alter/inactivate host cell functions?
ribosylate G-proteins and EF-2, phospholipases
what do pathogens use to cause dz w/ factors that overstimulate the immune response?
superantigens- overactivate MHC
how do pathogen cause dz w/ formation of biofilms?
overproduce polysaccharides (alginate)
important features of bordetella pertussis?
strict aerobe, adheres to cilia in RT, produces pertussis toxin, adhesions include FHA and pertactin and pili, highly infectious and transmittable, disease of young, adults are often asymptomatic carriers
diseases associated with b. pertussis? stages of disease?
whooping cough. 3 phases: catarrhal, paroxysmal, convalescence
mechanism of b. pertussis disease elicitation?
bacteria binds ciliated epithelium, PTx alters adenylate cyclase activity: ADP-ribosylates Gia, elevates cAMP production, increases secretions and mucus. other secreted factors damage mucocilliary escalator. get whooping cough.
important features of corynebacterium diptheriae?
pallisades of G+ rods. produces DTx. ADP-ribosylates EF-2 to inhibit protein synthesis. produces pili.
corynebacterium diptheriae mechanism of disease?
pili mediate adherence; extensive bacterial replication. 2 stages: invasion and toxigenesis
vaccine for diptheria toxin?
formalin inactivated DTx. also carrier for conjugate vaccines (Hib).
Neisseria meningitidis features?
oxidase positive, catalase positive, polysaccharide capsule, produce pili, common inhabitant of nasopharynx of healthy children.
diseases associated w n. meningitidis RT infection?
pharyngitis, pneumonia preceded by respiratory tract infection. often seen with underlying disease or in kids. concern is progression to meningitis
n. meningitidis virulence factors and biologic effects?
capsule: prevents phagocytosis and complement.
pili: allows colonization of nasopharynx.
endotoxin: responsible for clinical manifestations.
LOS: has endotoxin activity
n. meningitidis vaccine important facts?
polysaccharide capsule. polyvalent vaccine vs serogroups A, C, Y and W135. kids over 2. MCV4-conjugate to 55 and younger, MPSV4 capsule to 55 and older
strep pyogenes important features?
GAS. beta hemolytic. has M proteins, hyaluronic acid capsule. multiple virulence factors. catalase negative.
s. pyogenes disease elicitation?
surface proteins (M, F, LTA) promote adherence in pharynx. localized tissue destruction d/t secreted enzymes. scarlet fever is secondary, due to pyrogenic exotoxins (Spe- superantigens, not bacterial dissemination)
streptolysin actions?
streptolysin S and O. lyse leukocytes, platelets and erythrocytes
detection of pharyngitis?
rapid strep test or rapid antigen detection test
staph aureus important features?
catalase positive. produces polysaccharide capsule. coated with protein A. produces many different toxins and cytopathic enzymes.
how does staph aureus cause pneumonia?
very young and elderly with underlying pulmonary disease. via aspiration of oral secretions or hematogenous spread from other site. pulmonary tissue destruction due to secreted enzymes.
strep pneumo important features?
alpha hemolytic. virulent strains produce polysaccharide capsule. more than 90 capsular serotypes.
virulence factors of s. pneumo?
secretory IgA protease, pneumolysin does many things (destroys ciliated epithelial cells, activates alternative complement pathway, and suppresses phagocyte oxidative burst)
s. pneumo vaccine facts?
over 2 y.o. immunize with vac with 23-different capsular polysaccharides. for under 2 yo use 13-valent conjugated vaccine.
h. influenzae features?
requires heme and NAD for growth. invasive species possess polysaccharide capsule, uses pili and OMPs (outer membrane proteins- HMW1, HMW2) to bind resp epithelial cells.
diseases associated with h. flu RTI?
pneumonia, sinusitis, otitis, epiglottitis. non-encapsulated = upper RT. lower RT more with kids or underlying condition.
H. flu virulence factors?
capsule: prevents phagocytosis and complement.
pili: binding.
OMPs: binding.
LOS: endotoxin activity.
Hib vaccine?
polysaccharide capsule. 3 monovalent conjugate vaccines and combination Hib-conjugate vaccines. decreased incidence by 99%.
mycoplasma pneumonia features?
coccoid but can be pleiomorphic. obligate aerobe. slow growing. produces P1 adhesin.
m. pneumoniae mechanism of disease?
P1 associates with upper airway cells, close association causes local accumulation of toxic metabolites, oxidation of lipids. destruction of cilia, inhibited normal clearance. shedding of bacterium in respiratory secretions. inflammatory response enhances cell damage via oversecretion of cytokines (& chemokines)
pseudomonas aeruginosa features?
oxidase +, single polar flagella. form biofilm on surfaces and catheters etc to prevent immune clearance (no phagocytosis). an OPPORTUNISTIC pathogen.
common associated RT infections with pseudomonas?
lung infections of cystic fibrosis patients
legionella pneumophila important features?
grows only on special medium, detected by fluorescent ab stain. opportunistic pathogen. single polar flagella. in water. produces cytotixins, hemolysins, endotoxins, lipases. survives in alveolar macrophages.
diseases associated with legionella?
legionnaire’s disease: severe pneumonia-like symptoms, requires abx. vs pontiac fever: self-limiting flu-like. don’t know why one vs other.
mycobacterium tuberculosis important features?
thick waxy cell wall containing mycolic acids and lipoarabinomannan, survives within granulomas, causes acute or latent infection. 10% acute. but latent can reactivate to cause acute. over-exaggerated host response to infection leads to tissue necrosis.
m. tuberculosis virulence factors?
cord factor: inhibits PMNs, no migration.
