Chapter 11 Flashcards

Spore Forming Gram Positive Bacilli: Bacillus and Clostridium

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1
Q

Bacillus: General Characteristics

A

large
aerobic
gram +
long chains

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2
Q

Bacillus: Typical Morphology

A

3-4*1
square ends
centeral spores

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3
Q

Bacillus: Culture

A

round
“cut glass” apearence
common hemolysis in B. cereus + saprophytics
gelatin liquefier

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4
Q

B. anthracis: Pathogenesis

A
cutaneous
inhalation (woolsorters' disease)
gastrointestinal
injection
gelatinous edema, spread via lymphatics
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5
Q

B. anthracis: Virulence Factors

A

poly-gamma-D-glutamic acid capsule (plasmid: pXO2) (no disease without capsule)
PA (protective factor , membrane channel)
EF (edema factor , adenylate cyclase)
LF (lethal factor , impairing immunity)
(pXO1)

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6
Q

Bacillus in immunocompromised

A
meningitis
endocarditis
endophthamitis
conjunctivitis
acute gastroenteritis
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7
Q

B. anthracis: Clinical Findings (Cutaneous Anthrax)

A

pruritic papule 1-7 days , vesicle , necrotic ulcer (centeral black eschar)
lymphangitis
lymphadenopathy
fever
malaise
headache
20% sepsis –> meningitis
no antibiotic therapy (only prevents dissemination)
after 7-10 days eschar fully developed and heals by granulation with scar

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8
Q

B. anthracis: Clinical Findings (Inhalation Anthrax)

A

spores phagocytosed in lungs , mediastinal lymph nodes , hemorrhagic mediastinitis , sepsis
up to 6 week incubation
marked hemorrhagic necrosis
mediastinal edema (visible widening on radiographs)
substernal pain
hemorrhagic pleural effusion
cough
sepsis –> hemorrhagic meningitis/hematogenous spread to GI tract –> bowel ulcer

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9
Q

B. anthracis: Clinical Findings (Gastrointestinal Anthrax)

A

abdominal pain
vomiting
bloody diarrhea

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10
Q

B. anthracis: Clinical Findings (Injection Anthrax)

A

extensive , painless , subcutaneous edema (no eschar)

hemodynamic instability

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11
Q

B. anthracis: Diagnostic Lab Tests

A

immunofluorscent
blood agar: nonhemolytic , white-gray , tenacious , rough , ground-glass appearance , medusa head
capsule: bicarbonate with 5-7% CO2 medium
always nonmotile (B cereus: swarming)
definitive: lysis with anthrax gamma-bacteriophage , fluorscent Ab , PCR
ELISA not + in early disease

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12
Q

B. anthracis: Immunity

A

vaccine: cultures grown in 42-52 c for several months , AVA BioThrax (unencapsulated toxigenic with PA absorbed to AlOH3)

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13
Q

B. anthracis: Treament

A
ciprofloxacin
penicillin G
doxycycline
erythromycin
vancomycin
Bioterorrism: prophylaxis + ciprofluxacin / doxycycline for 60 days
Raxibacumab: PA inhibitor
AIGIV: PA inhibitor , polyclonal antiserum
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14
Q

B. cereus: Emetic Food Poisoning

A
fried rice , milk , pasta
nausea
vomiting
abdominal cramps
diarrhea
self-limiting (within 24 hours)
emetic toxin: plasmid-encoded preformed cyclic peptide
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15
Q

B. cereus: Diarrhael Food Poisoning

A
meat , dishes , sauces
1-24 hours incubation
profuse diarrhea
abdominal pain and cramps
vomiting (uncommon)
fever (uncommon)
eterotoxin: fluid accumulation in small intestine
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16
Q

B. cereus: Pathogenesis

A

eye infections: severe keratitis , endophthalmitis

systemic: endocarditis, catheter-associated bacteremia , CNS infection , osteomyelitis , pneumonia

17
Q

B. cereus: Treatment

A

non-food borne infections: vancomycin , clindamycin + aminoglycoside
wound infecrion: ciprofloxacin

18
Q

B. cereus: Resistance

A

penicillins , cephalosporins