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Microbio Block 1 > Aerobic G+ Bacilli > Flashcards

Aerobic G+ Bacilli Flashcards

1
Q

Three classifications of G+ rods & aerobic examples of each

A

Spore-forming: Bacillus sp.
Non spore-forming: Listeria & Erysipelothrix (uniform shape), Corynebacterium (irregular shape)
Acid-fast: no aerobic examples

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2
Q

B. anthracis: main targets of infection

A

Herbivores; humans are accidental hosts (no human-human transmission)

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3
Q

Cutaneous anthrax symptoms

A

Painless papule progresses to ulceration with surrounding vesicles, eschar; painful lymphadenopathy, edema; may dev systemic signs

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4
Q

GI antrax symptoms

A

Ulcers at site of invasion leading to regional lymphadenopathy, edema, sepsis

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5
Q

Inhalation anthrax symptoms

A

Initially nonspecific, then rapid sepsis with fever, edema, mediastinal lymphadenopathy, meningeal symptoms in ½ pts; will die unless imm tx
*Endospores can remain latent in nasal passages/ lower airways

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6
Q

Virulence factors of B. anthraces, functions, location of genes

A 
All on plasmid pXO1
Protective Ag: binds cellular receptor on many cells
Edema factor + PA = edema toxin
Lethal factor + LF = lethal toxin
Polypeptide capsule
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7
Q

How does protective Ag work in B. anthracis?

A

Binds cell surface receptor and acts as a carrier to move EF or LF into cell in acidic endosome

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8
Q

Lethal factor mechanism

A

Zn-dep metalloprotease, binds MAPKK, cleaving it and interrupting its signaling -> cell death

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9
Q

Edema factor mechanism

A

Calmodulin-activated AC exotoxin, binds calmodulin and this complex converts ATP to cAMP -> increased intracellular Ca2+ and cell death

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10
Q

Possible routes of exposure to anthrax

A

Zoonotic infection: exposure to infected cows, goats or animal products like hide, goat hair, wool
Bioterrorism agent

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11
Q

Prevention of B. anthracis

A

Vaccinate animals and humans in endemic areas, who work with animal products imported from those areas, and military personnel

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12
Q

B. cereus: where found, & why

A

Soil organism, spores ubiquitous throughout environment
Spores resist pasteurization and gamma radiation, so found in pasta, rice, milk products, grains, spices, vegetables, meat, chicken, sea food

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13
Q

B. cereus diseases

A

Gastroenteritis: emetic illness & diarrheal illness
Ocular infections secondary to trauma
IV line or CNS shunt infxns
Endocarditis

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14
Q

Features of B. cereus emetic vs. diarrheal illness

A

Emetic: 1-6 hr post ingestion; for 8-10 hours; fried rice, cream, milk products, pasta, reconstituted infant formula
Diarrheal: 8-16 hours post ingestion; profuse watery diarrhea for 20-36 hours; meat and veggies

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15
Q

Virulence factors of B. cereus

A

Heat stable enterotoxin causes emetic form of disease

Heat labile enterotoxin causes diarrheal form of disease (AC/cAMP system)

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16
Q

Listeria monocytogenes physical characteristics

A

G+ short rods, weak beta-hem, low temp growth, facultative intracellular growth, ubiquitous within env/soil, outbreaks assc. with contaminated food

17
Q

Intracellular growth mechanism of L. monocytogenes

A

Phagolysosomal uptake and lysis, replication, actin-propelled protrusion into adjacent cell

18
Q

L. monocytogenes in utero diseases & mechanism

A

Early-onset, invasion of placental endothelium

Stillborn, abortion, or granulomatosis infantiseptica (disseminated abscesses/ granulomas), septicemia, pneumonia

19
Q

L. monocytogenes late-onset diseases

A

Benign colonization of skin, nasopharynx, umbilical stump

Meningitis

20
Q

Epidemiology of L. monocytogenes

A

70% cases in immunosuppressed
Infxn from domestic animals/birds, soil/water/sewage, contaminated food (raw milk, veg, fish, poultry, meat, sea food, refrig. col cuts)

21
Q

High risk populations for listeriosis

A

Neonates, pregnant women, elderly, immunocompromised

22
Q

L. monocytogenes virulence factors & mechanisms

A

Internalin - adherence to cells (binds E-cadherin on enterocytes/M cells)
Listeriolysin O & phospholipases (act at low pH of phagolysosome to release bacteria into host)
ActA - catalyzes assembly of actin until bacterium expelled through cell membrane into adj cell

23
Q

Erysipelothrix rhusiopathiae characteristics

A

Non spore-forming, slender G+ rod
Worldwide in swine, turkey, cattle, fish, and decomposing organic matter; occupational disease of butchers, farmers, vets, meat processors

24
Q

E. rhusiopathiae diseases

A

Localized skin infxn: raised edge & central clearing, self-limited (2-4 w), more severe w/ hemorrhagic bullae & regional lymphadenopathy
Systemic infxn in immunocompromised: bacteremia, sepsis, endocarditis, myocardial abscesses, septic arthritis

25
Q

E. rhusiopathiae virulence factors

A

Capsule to enhance replication in MF, protection from phago
Neuraminidase for attachment, cellular invasion
Hyaluronidase

26
Q

Corynebacterium diphtheriae characteristics

A

Small, irregularly-sharped (club), G+ rods

Often attached after cell division = pleomorphic, like Chinese characters

27
Q

C. diphtheriae: where found & how transmitted

A

Humans are the only reservoir: maintained in oropharynx or skin of carriers (immune or vaccinated)
Transmission by resp droplets or skin contact
Uncommon in U.S. bc vaccine (more common in poor/urban areas)

28
Q

C. diphtheriae cutaneous disease

A

Chronic, nonhealing ulcer d/t colonization of skin and invasion of subcutaneous tissue via skin breaks

29
Q

C. diphtheriae nasopharyngeal disease

A

Exotoxin destroys local tissue -> malaise, sore throat, exudative pharyngitis; *pseudomembrane of dead cells, bacteria, fibrin, lymphocytes can lead to death by obstruction of airway or toxemia d/t myocardial/neuro damage

30
Q

C. diphtheriae virulence factor

A

Diphtheria toxin: two polypeptide protein A-B exotoxin produced at site of infxn, blood dissemination

31
Q

A vs. B polypeptide in diphtheria toxin

A

A: catalytic region that shuts off host protein synthesis by binding eEF-2 on small ribosomal subunit
B: receptor-binding region to bind surface HB-EGF of heart, nerve, other cells & translocation region to help move toxin into cell

32
Q

Location of diphtheria toxin gene

A

Lysogenic bacteriophage encodes tox gene

33
Q

Prevention for diphtheria

A

Vaccine with diphtheria toxoid (formalin treatment of exotoxin) given with pertussis, tetanus Ags to induce Abs that neutralize the binding and activity of the exotoxin

34
Q

Treating diphtheria

A

Antitoxin (Ab to exotoxin), passive immunity via maternal IgG in newborns, antibiotics (penicillin, erythromycin), remove pseudomembrane

35
Q

Corynebacterium jeikeium: who affects, diseases

A

Opportunistic, in immunocompromised
Comm and hosp-acquired bacteremia/sepsis, endocarditis, meningitis, ventriculitis, pneumonia, pyelonephritis, osteomyelitis

36
Q

Resistance in C. jeikeium

A

Multi-drug resistant (beta-lactams, ahminoglycosides, variable to macrolides, tetracyclines, rifampin, Qs)
Chromosomal-assc resistance

Microbio Block 1 (14 decks)

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