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247 Cards in this Set

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which bacteria is the most common cause of hospital acquired infection and causes clinical disease in 2% of all patient admissions?
Staph aureus
what is the habitat/reservoir of S. aureus?
normal human flora
hospital environments
in general: diseases S. aureus can cause?
can infect any tissue - a very good opportunist
skin infections
food poisoning
endocarditis
toxic shock syndrome
haemolytic pneumonia
four virulence factors posessed by Staph aureus?
1. techoic acid in cell wall
2. coagulase
3. capsule
4. protein A
regarding S. aurues virulence factors:
function of techoic acid in cell wall?
facilitates adhesion to nasal cells
regarding S. aurues virulence factors:
function of coagulase?
clots plasma
antiphagocytic
protects against antibodies
regarding S. aurues virulence factors:
function of the capsule?
antiphagocytic
regarding S. aurues virulence factors:
function of protein A?
binds and sequesters antibodies by Fc end
Staph aureus can obtain a gene that greatly contributes to it's virulence. what gene is this?
Panton-Valentine leukocidin (PV-leuk)
two diseases caused by the PV-leuk gene?
1. severe community acquired necrotizing boils and skin infections
2. lethal necrotizing hemolytic pneumonia in children
antibiotic of choice to treat Staph aureus?
penicillin
what do we use to treat MRSA?
vancomycin
what about treating VISA and VRSA?
linezolid
quinupritin/dalfopristin (Synercid)
group A strep is also known as?
Streptococcus pyogenes
hemolysis pattern of group A strep?
Beta hemolytic (clear)
group A strep is found in highest concentration in what population?
school children (up to 90% infected)
group B strep is also known as...?
strep agalactiae
hemolysis pattern of group B strep?
Beta hemolysis (clear)
three major virulence factors of Strep pyogenes?
1. capsule
2. adhesins
3. prophages
describe the adhesins specific to strep pyogenes
cell wall techoic acid adheres to many membranes
M protein on pili attaches to host cells
strep pyogenes has superantigens. how are they classified?
pyogenic and non-pyogenic
streptolysins belong to which classification of superantigen?
non-pyogenic
why are polyphages considered important virulence factors seen in strep pyogenes?
they are a major source of strain variation
transmission of strep throat?
airborne or direct contact
presentation of strep throat?
pharyngitis (inflammed mucous membranes)
affects tonsils or middle ear
fever
two possible complications of strep throat?
scarlet fever
rheumatic fever
how long after a strep throat infection will rheumatic fever show up?
1-5 wks
cause of rheumatic fever?
cross reacting antibodies to host directed against heart and neuronal tissue
presentation of scarlet fever
red skin rash
strawberry tongue (red and peeling)
pathogenesis of scarlet fever?
erythrogenic toxin carried by phage: rash is due to hypersensitivity to toxin
what sometimes happens after a strep pyogenes skin infection?
acute glonerulonephritis occurs
cause of acute glomerulonephritis seen ~10-14 days after strep infection?
type III hypersensitivity rxn. (immune complex deposition)
treatment for:
1. regular old strep pyogenes?
2. resistant strep
1. penicillin
2. erythromycin
which bacteria looks like "Chinese letters?"
Corynebacterium diptheriae
Gram status of Corynebacterium diptheriae?
Gram (+)
which stains do we use to see Corynebacterium diptheriae?
methylene blue
Loeffler's medium
Tellurite medium
why does Corynebacterium diptheriae stain irregularly (blotchy)?
it contains "metachromatic granules" (globules of polymetaphosphate)
in Tellurite medium Corynebacterium diptheriae shows up as?
dark brown to black
the toxin released by Corynebacterium diptheriae is a two part toxin. describe the parts and their respective functions
1. B fragment: binds to cells
2. A fragment: inhibitor of host cell protein synthesis
how does Corynebacterium diptheriae cause systemic effects?
the bacteria itself never infects past the throat
- the toxin it releases causes systemic symptoms/damage
describe a "diptheritic membrane"
profuse film in throat
caused by degeneration of epithelial cells
composed of fibrin, dead tissue, WBCs, bacteria
**may interfere with breathing**
in a Corynebacterium diptheriae infection, edema in the neck causes?
"bull neck" symptom
which organs does the toxin of Corynebacterium diptheriae target?
heart
kidneys
nerves
what usually causes death in a diptheria infection?
heart failure or respiratory obstruction
treatment for Corynebacterium diptheriae infection?
ANTITOXIN
(preformed antibodies)
*antibiotics do not help cells already exposed to toxin**
what is the name of the immunization available for Corynebacterium diptheriae?
DTaP
DTaP is reccommended at what ages?
2, 4, and 6 months

then a booster every 4-6 yrs
which organism causes whooping cough?
Bordatella pertussis
characteristics of B. pertussis?
Gram (-) rod
capsule present in vivo
habitat/reservoir of B. pertussis?
humans are the only known reservoir
is Bordatella pertussis easy to grow?
NO! it is very sensitive to the environment (and drying kills it easily)
what is difficult about specimen collection when it comes to Bordatella pertussis?
it is killed by the fatty acids in cotton swabs
(therefore must use calcium alginate throat swabs)
which medium is used to culture Bordatella pertussis?
Regan-Lowe agar
(charcoal+serum overcome fatty acid toxicities in the media)
virulence factors seen in Bordatella pertussis (5)?
1. endotoxin
2. pertussis toxin (most harmful)
3. heat-labile toxin
4. peptidoglycan cell wall fragment
5. adhesins
exactly which endotoxin does Bordatella pertussis have?
LPS
what does pertussis toxin do?
*increases susceptibility to histamine, seratonin, endotoxin
*increases lymphocyte response
when in heat-labile toxin released and what does it do?
released at cell death
necrotic and lethal
general pathogenesis of Bordatella pertussis?
bacteria slip between epithelial cells in URT
-pertussis toxins secreted
-creates hypersensitivity to histamine
-produces fits of coughing
why does the whooping occur in a Bordatella pertussis infection?
whooping comes from the need to breathe quickly and deeply between extended fits of coughing
what are the 4 stages of whooping cough?
1. catarrhal
2. paroxysmal
3. convalescent
4. relapse
which stage of whooping cough actually has the "whoop?"
paroxysmal
(this stage is characterized by an inappropriate response to a small stimulus)
a Bordatella pertussis infection in adults is called?
100 day cough
treatment for Bordatella pertussis infections?
mostly symptomatic relief
antibiotics not very effective (once again the toxin is responsible for the disease)
which type of Bordatella pertussis vacacine is currently being used: cellular or acellular?
acellular
(contains proteins only needed to stimulate immunity)
when can a Haemophilus influenzae infection become a medical emergency?
when it causes epiglottitis
(can expand and obstruct airway)
describe the disease progression seen in pneumonia
1. organism enters lungs
2. alveoli fill with pus and liquid (edema/inflammation)
3. results in reduced air exchange
4. systemic spread via the bloodstream
which type of bacteria is likely to cause:
1. typical pneumonia
2. atypical pneumonia
3. chronic pneumonia
4. pneumonia in newborns?
1. Strep pneumoniae
2. Mycoplasma pneumoniae
3. Mycobacterium tuberculosis
4. group B strep
which type of bacteria is likely to cause:
1. pneumonia in the immunocompromised?
2. community acquired pneumonia?
1. pneumocystis jirovecii
2. Strep pneumoniae, H. influenzae, K. pneumoniae
which type of bacteria is likely to cause primary atypical pneumonia? (2)
1. Mycoplasma pneumoniae
2. Chlamydia pneumoniae
which type of bacteria is likely to cause nosocomial pneumonias? (2)
GRAM NEGATIVE RODS
Klebsiella
Pseudomonas
which type of bacteria is likely to cause opportunistic pneumonia?
Nocarida (plus community acquired bacteria)
which type of bacteria is likely to cause aspiration pneumonia?
anaerobes
Staph aureus
gram negative aerobic rods
which type of bacteria is likely to cause pneumonia in the neonate? (2)
E. coli
group B strep
which organism is likely to cause pneumonia in infants? (2)
Chlamydia trachomatis
RSV
which organism is likely to cause pneumonia in children (1/2-5 yrs)? (2)
RSV
Parainfluenza virus
which organism is likely to cause pneumonia in children (5-15 yrs)?
Mycoplasma pneumoniae
Influenza Type A virus
which organism is likely to cause pneumonia in adults <30? (2)
mycoplasma pneumoniae
strep pneumo
which organism is likely to cause pneumonia in adults >65 yrs?
strep pneumo
H. influenzae
which three bacteria cause rust colored sputum?
Streptococcus pneumoniae
Klebsiella pneumoniae
Legionella pneumophila
which organism is the leading cause of pneumonia in children <3 yrs old?
strep pneumo
characteristics of strep pneumo?
gram (+) diplococcus
large capsule
alpha hemolytic
colonies autolyse in late growth
optichin sensitive
habitat of streptococcus pneumoniae?
strict human parasite
which two tests, when used together, detect 98% of streptococcus pneumoniae cases?
Gram stain
urinary antigen
lcan s. pneumoniae live in a phagolysosome?
NO!
this is the major host defense!
what is the most important virulence factor of strep pneumo and what are its functions?
capsule
- anti phagocytic
- prevents opsonization in absence of an antibody
- antibody against capsule opsonizes bacteria
three important toxins released by strep pneumo?
1. pneumolysin
2. hemolysin
3. adhesin
function of pneumolysin released by Streptococcus pneumoniae?
slows ciliary beating in URT
kills pulmonary epithelial cells
which virulence factor causes alpha-hemolysis on blood agar plates?
hemolysin
function of adhesin released by Streptococcus pneumoniae?
choline binding protein helps bacteria stick to respiratory epithelium.
classic treatment for Streptococcus pneumoniae?
penicillin
treatment for Streptococcus pneumoniae if resistance is seen?
erythromycin
fluoroquinolones
Streptococcus pneumoniae also causes what other diseases? (3)
1. Bacteremia
2. Meningitis
3. Otitis media
characteristics of group B Streptococcus?
gram (+)
chain forming
fastidious
very tiny colonies
hemolytic pattern of group B Streptococcus?
Beta hemolytic
catalase status of group B Streptococcus?
catalase negative
habitat/reservoir of group B Streptococcus?
GU tract
group B Streptococcus causes what diseases? (2)
1. pneumonia in newborns (~50% fatality)
2. meningitis in newborns
in relation to group B Streptococcus: describe the mode of transmission and the time frame in early and late onset disease.
transmitted perinatally
early onset disease - within 24 hrs
late onset disease - 7-10 days
when does the CDC recommend that we screen for group B Streptococcus in pregnant mothers?
between 35th and 37th wk
(then give prophylactic antibiotics - penicillin)
what two test are available to detect group B Streptococcus?
1. Rapid GBS testing
2. IDI-strep assay
characteristics of Klebsiella pneumoniae?
- gram stain
- ferments lactose?
Gram (-) rod
enteric bacterium (related to E.coli)
ferments lactose
habitat/reservoir of Klebsiella pneumoniae?
free-living in soil and water
human intestines
sometimes URT
two major diseases caused by Klebsiella pneumoniae?
1. Pneumonia
2. Urinary tract infections (nosocomial)
describe the pneumonia caused by Klebsiella pneumoniae
includes necrosis of the lungs
when left untreated - 90% fatal!
hard to treat (resistance is increasing)
two virulence factors used by Klebsiella pneumoniae?
1. Pili (adhesins on end of pili adhere to mucosal surfaces - "grappling hooks")
2. capsule (inhibits phagocytosis and intracellular killing)
mechanism of antibiotic resistance seen in Klebsiella pneumoniae?
plasmid-mediated
characteristics of Pseudomonas aeruginosa?
-gram stain
- ferments lactose?
Gram (-) rod
does NOT ferment lactose
why is Pseudomonas aeruginosa blue?
blue due to polycyanin excretion
(polycyanin also gives off "grape juice" smell)
when is Pseudomonas aeruginosa pneumonia most often seen?
in CF patients
characteristics of Legionella pneumophila?
gram?
structure?
Abx. resistance?
Gram (-) rod
single polar flagellum
Beta lactamase positive
does Legionella pneumophila grow easily on medium?
NO - it is fastidious and will not grow on blood agar.
- requires charcoal yeast extract agar, then tiny colonies appear in 3-5 days
habitat/reservoir of Legionella pneumophila?
free living in soil and water
may survive in amoebas
commonly found in stagnant water...
spread by environmental aerosols
three s/s of Legionnaire's pneumonia?
1. high non-remitting fever (103-105 degrees F)
2. shaking chills
3. rigor and severe prostration
Besides pneumonia, Legionella also causes what disease?
Pontiac fever
(mild flu-like illness)
virulence factors of Legionella pneumophila?
1. intracellular parasite
2. MIP
3. Dot/ICM
4. Pore-forming toxins
when we say Legionella pneumophila is an intracellular parasite, what do we mean?
it enters fibroblasts and alveolar phagocytes: it wants to be phagocytosed!
what is MIP?
macrophage infectivity potentiator
helps organism survive initial phagocytosis
what is Dot/Icm?
Type IV secretion system that inhibits phagosome maturation
function of pore forming toxins?
one inserts so bacterium can enter host cell
other inserts so bacterium can exit host cell
three ways to diagnose Legionella pneumophila in the lab?
1. fluorescent antibody
2. increase in antibody titers
3. isolation of organsim via lung biosy
treatment for Legionella pneumophila pneumonia?
erythromycin drug of choice
*should be continued for at least 3 wks. to prevent relapse
characteristics of Mycoplasma pneumoniae?
NO CELL WALL!
very small cell and colony size
what makes Mycoplasma pneumoniae unique among prokaryotes?
cholesterol is required for the membrane
habitat/reservoir of Mycoplasma pneumoniae?
mucous membranes of URT and GU tract
*humans are only known reservoir*
what type of disease does Mycoplasma pneumoniae cause?
primary atypical "walking" pneumonia
describe the disease progression of pneumonia caused by Mycoplasma pneumoniae
-begins as upper respiratory "cold" symptoms
-notorious for sore throat and headache
-chills and fever early on
-violent coughing attacks
-produces only sparse whitish mucous
-bradycardia
age group where Mycoplasma pneumoniae pneumonia is most commonly seen?
ages 5-19
prevalent in concentrated populations (students, army barracks etc)
two virulence factors produced by Mycoplasma pneumoniae?
1. adherence factor
2. toxic metabolites
describe the adherence factor seen in Mycoplasma pneumoniae
-terminal structure at one end of cell
-specifically binds to RBCs, epithelial cells, macrophages
-bacteria hang on to cell
- irritate airways and cause cough
describe the toxic metabolites released by Mycoplasma pneumoniae
-locally produced waste products
-harm host cells
treatment for Mycoplasma pneumoniae pneumonia?
tetracycline and erythromycin
(NOT cell wall inhibitors - remember there is no cell wall!)
characteristics of Mycobacterium tuberculosis?
-gram +
-acid-fast
-slender rods
-aerobic
-catalase (+)
why doesn't Mycobacterium tuberculosis stain well?
it has mycolic acids in cell envelope - these stain well with acid fast stains
is Mycobacterium tuberculosis "hardy"?
YES
very resistant to dehydration
is Mycobacterium tuberculosis fastidious?
YES
hard to grow - must grow on glycerol medium (Lowenstein-Jensen medium)
-grows very slow (weeks)
habitat/reservoir for Mycobacterium tuberculosis?
humans and cattle
describe the pathogenesis of a tuberculosis infection
-one organism can cause disease!
-phagocytosed by an alveolar macrophage
-grows in macrophage, kills it, repeats process
-body reacts and forms a tubercle around infection to "wall it off"
-forms a caseated tubercle
-may remain dormant for years - then - tubercle ruptures and infection begins all over again
of the people that get infected with Mycobacterium tuberculosis - how many of them progress to TB?
only 10%
how is TB diagnosed?
*acid fast organisms in sputum
*auramine-O stain - fluorescent detection, easier to see cells
four virulence factors of Mycobacterium tuberculosis?
1. glycan rich surface
2. cord factor
3. proteasomes
4. mycolic acids
function of glycan-rich surface of Mycobacterium tuberculosis?
inhibits phagocytosis by macrophages BUT ALLOWS PHAGOCYTOSIS by alveolar macrophages
function of cord factor in Mycobacterium tuberculosis?
(rope like growth)
*stimulates macrophage phagocytosis
*induces granuloma formation
*inhibits oxidative phosphorylation
*mitochondria degenerate
function of proteasomes secreted by Mycobacterium tuberculosis?
*degrade cytosolic proteins
*protect against NO
function of mycolic acids found on Mycobacterium tuberculosis?
makes bacteria hard to digest and resistant to drying
(allows cells to remain viable in the sputum for weeks to months)
four drug therapy for TB involves?
isoniazid
rifampin
pyrazinamide
ethambutol
*4 drugs for 2 months OR 2 drugs for 4+ months
vaccine for TB?
YES, but not used in US
called BCG vaccine
describe defense mechanisms used by the lungs according to particle size
1. nasal clearance - large particles
2. tracheobronchial clearance via mucociliary action (3-10 micron particles)
3. alveolar clearance (1-5 micron particles = SMALL)
describe alveolar clearance
dust cells phagocytose
carry it to ciliated epithelium or lymph nodes
bronchopneumonia is also called?
lobar pneumonia
describe bronchopneumonia
-patchy consolidation
-often an extension of pre-existing bronchitis
-frequently basally located
in what age group is bronchopneumonia MC seen in?
the extremes of life
(infancy/old age)
describe lobar pneumonia
acute bacterial infection of a large portion of a lobe or an entire lobe
how are organisms spread in lobar pneumonia?
through pores of Kohn
what organism causes >90% of all lobar pneumonias?
Streptococcus pneumoniae
which organism is #2 in causing lobar pneumonias?
Klebsiella pneumoniae
what are the four stages recognized in untreated lobar pneumonia?
1. congestion
2. red hepatization
3. gray hepatization
4. resolution
what is going on during the congestion stage of lobar pneumonia?
lots of intra-alveolar fluid
few neutrophils
what is going on during the red hepatization stage of lobar pneumonia?
-exudate rich in red cells, fibrin, neutrophils
-lung is firm and liver like
what is going on during the gray hepatization stage of lobar pneumonia?
-disintegration of RBCs
-persistance of fibrin/WBCs
what is the resolution stage of lobar pneumonia characterized by?
resolution and reorganization
clinical s/s of lobar pneumonia?
malaise
fever/chills
productive cough by day 3
rusty sputum
pleuritic chest pain/friction rub
what is the difference between treated and untreated lobar pneumonia?
treated - afebrile within 48 hrs
untreated - sick 10 days, then resolves by lysis or gradual lysis
what three tests are used to diagnose lobar pneumonia?
1. sputum gram stain
2. sputum culture (more accurate)
3. blood culture (also accurate)
what is empyema?
spread of pneumonia infection to the pleural cavity (complication of pneumonia)
abcesses are common with which two bacteria causing pneumonia?
1. Klebsiella
2. Pneumococci
besides pneumonia, what else can cause lung abcesses?
-aspiration of infective material
-antecedent primary bacterial infection
-septic emboli
-neoplasia
by what mechanism does a lung abcess heal?
by secondary intention
aspirations are more common in which bronchi?
right
clinical s/s of a lung abcess
cough
fever
productive sputum
weight loss
clubbing
what are four complications of lung abcesses?
1. extension into pleural cavity
2. hemorrhage
3. septic emboli
4. secondary amyloidosis
where in the lung is viral and micoplasmal pneumonia located?
in the alveolar walls
(small particles)
clinical course of primary atypical pneumonia?
(caused by viruses or mycoplasma)
-begins as URI
-extends to lower respiratory tract
-low mortality
are the pleura usually involved in atypical pneumonia?
NO
s/s of atypical pneumonia?
fever
headache
myalgia
cough
alveolar capillary block
are most cases of pharygitis bacterial or viral?
viral
(Rhino, Adeno, Corona)
most common cause of bacterial pharyngitis?
GABHS
s/s of classic strep throat
winter-spring
children
abrupt onet
fever
headache
tonsil exidate
No URI s/s
treatment goals for strep throat?
prevent rheumatic fever complications
prevent suppurative complications
what does treatment of GABHS NOT prevent?
post-strep glomerulonephritis
first choice antibiotic for GABHS?
penicillin (10d)
if strep throat and allergic to penicillin?
cephalosporin
clindamycin
macrolides (erythromycin, clarithromycin, azithromycin)
which group of antibiotics should not be used to treat GABHS due to resistance?
Tetracyclines (TMP/SMX)
acute otitis media is most often caused by? (3)
1. S. pneumoniae
2. H. influenzae
3. M. catarrhalis
if we choose to treat acute otitis media - what antibiotic do we use?
Amoxicillin
sinusitis is most often caused by a bacteria of virus?
virus
which two bacteria commonly are a cause of sinusitis?
S. pneumoniae
H. influenzae
general clues to tell us if a sinusitis/cold is bacterial?
-symptoms last longer than 7 days
-purulent nasal discharge
-unilateral maxillary/tooth pain
-worsening after initial improvement
treatment strategies for sinusitis?
*all viral/most bacterial: don't treat
*persistent/severe: narrow spectrum antibiotic first
drug of choice in acute otitis media that is resistant to amoxycillin?
augmentin
cefuroxime
what are some symptoms not to ignore in a patient with a URI and/or sinusitis?
-fever longer than 10d
-increasing pain
-eye symptoms
-headache
-stiff neck
Top 3 bacteria causing typical community-aquired pneumonias?
1. Streptococcus pneumoniae
2. Haemophilus influenzae
3. Staphylococcus aureus
Top 3 bacteria that cause atypical pneumonia?
1. Mycoplasma pneumoniae
2. Legionella pneumophilia
3. Chlamydia pneumoniae
in what type of patients are atypical agents (esp. Legionoella) associated with increased mortality?
the elderly
treatment strategy for CAP
-outpatient
-previously healthy
-no recent abx. therapy
Macrolide (Erythromycin, Azythromycin, Clarithromycin)
-or-
Doxycycline
treatment strategy for CAP
-outpatient
- previously healthy
-recent abx therapy in last 3 months
*respiratory FQ
*advanced macrolide + high dose amoxycillin
*advanced macrolide + high dose amoxycillin/claulanate
treatment strategy for CAP
-outpatient
-comorbidity(COPD,CHF,DM,etc)
-no recent abx therapy
*advanced macrolide
*respiratory FQ
treatment strategy for CAP
-outpatient
-comorbidity(COPD,CHF,DM,etc)
-recent abx activity
*respiratory FQ
*advanced macrolide + a Beta-lactam
treatment strategy for CAP
-suspected aspiration with infection
*amoxicillin-clavulanate
*clindamycin
treatment strategy for CAP
-influenza with bacterial superinfection
*Beta-lactam (high dose amox, amox/clav, cefpodoxime, cefprozil, cefuroxime)
*respiratory FQ
treatment strategy for CAP
-inpatient - medical ward
-no recent abx therapy
*respiratory FQ
*advanced macrolide + Betal lactam
treatment strategy for CAP
-inpatient-medical ward
-recent abx activity
*advanced macrolide + beta-lactam
which bug should we worry about in an ICU patient?
Pseudomonas
treatment strategy for CAP
-inpatient/ICU
-recent abx therapy
-Pseudomonas not an issue
*Beta-lactam + advanced macrolide or respiratory FQ
treatment strategy for CAP
-inpatient/ICU
-pseudomonas not an issue
-allergic to b-lactams
*respiratory FQ w or w/o clindamycin
treatment strategy for CAP
-inpatient/ICU
-pseudomonas is an issue
*antipseudonal agent + ciprofloxacin
* antipseudomonal + aminoglycoside + respiratory FQ or macrolide
what are the antipseudomonal agents?(5)
piperacillin
pip/tazo
imipinem
meropenen
defepime
treatment strategy for CAP
-inpatient/ICU
-pseudomonas in an issue
-allergic to beta lactams
*aztreonam + levoflaxacin
*aztreonam + moxifloxacin w/or w/o aminoglycoside
treatment strategy for CAP
-nursing home
*respiratory FQ
*amox-clav + advanced macrolide
an acute cough illness in otherwise healthy adults is known as?
acute bronchitis
how long should acute bronchitis last?
1-3 wks
is acute bronchitis more oftenly caused by a bacteria or a virus?
virus (>90%)
viruses causing acute bronchitis? (6)
1. influenza A/B
2. Parainfluenza
3. RSV
4. coronavirus
5. adenovirus
6. rhinovirus
three bacterial causes of acute bronchitis?
1. Bordatella pertussis
2. Mycoplasma pneumoniae
3. Chlamydia pneumoniae
how is acute bronchitis managed?
Antibiotics are of NO BENEFIT if there is no pneumonia present
in acute bronchitis: when would we consider therapy?
1. pneumonia present
2. outbreaks of M.pneumoniae, C.pneumoniae, B.pertussis
antibiotic regimen to treat B. pertussis?
Macrolide
(except in infants <2wks - treat with erythromycin)
do we treat AECB?
Yes
what do we use to treat AECB?
narrow spectrum antibiotic (doxycycline, amox, TMP/SMX)
what is the most important cause of death in the world?
TB
two virulence factors seen in TB?
1. cord factor
2. LAM (Lipoarabinomannan)
what is cord factor?
secreted by TB cells - causes "serpentine" growth in vitro
what is LAM?
*similar to endotoxin
*inhibits IFN-gamma activation of macrophages
*stimulates macrophage to secrete IL-10 (IL-10 inhibits TB induced T-cell proliferation)
why is compliment activation found on the surface of mycobacteria?
-facilitates phagocytosis without the respiration burst needed for killing
where in the lung does the primary TB infection occur?
usually subpleural between upper and lower lobe
which cells phagocytose mycobacteria?
alveolar macrophages
what happens in the primary TB infection?
*bacteria are transported to the regional (subpleural and hilar) lymph nodes
* T cell immunity usually results in 2-3 wks
*results in calcified scars in the lung and lymph nodes
the calcified scars in the lung and lymph nodes are known as?
Ghon complexes
in the primary TB infection: where do the mycoplasma proliferate?
inside the macrophages and lymph nodes
a minority of primary TB cases don't resolve: instead they?
become progressive pulmonary TB
what occurs to cause a secondary TB infection?
reactivation of the primary TB infection
what percentage of primary TB infections reactivate to form secondary TB infections?
5-10%
where does the secondary TB infection most often occur?
apices
what are the three forms of progressive pulmonary TB?
1. Cavitary fibrocaseous TB
2. Miliary TB
3. TB bronchopneumonia
describe the morphology of cavitary fibrocaseous TB
*erosion of bronchioloes causing cavity formation
*usually remains localized to apex
*may spread to other areas of the lung, or via lymphatics and blood
besides the apices, what other part of the lung is involved in cavitary fibrocaseous TB?
the pleura
(see fibrous pleuritis, empyema, serous effusion)
what are some possible complications of TB infections in the air passages?
1. endobronchial and endotracheal TB
2. laryngeal seeding
3. intestinal TB
Miliary TB is primarily caused via what type of spread?
lymphohematogenous spread
involved organs in miliary TB?
bone marrow
spleen
retina
kidneys
adrenals
testes
Name four organs that are resistant to miliary TB involvement
1. heart
2. striated muscle
3. thyroid
4. pancreas
what are scrofula?
infection of the cervical lymph nodes (in this case due to miliary TB)
what is Pott's disease?
TB infection of the Vertebrae
(fistulas along psoas drain to groin)
name of miliary TB complication in bones?
tuberculous osteomyelitis
which type of progressive pulmonary fibrosis used to be called "galloping consumption," and spreads rapidly through the lung?
tuberculous bronchopneumonia
does tuberculous bronchopneumonia form tubercles?
not really
a Ghon complex is indicative of?
primary TB
what cell type is often found within a caseating granuloma?
Langhan's cells
what would TB look like on an acid fast stain?
small, positive staining bacilli