Gram-Positive Bacilli

Question 1

3 Types of Gram-Positive Aerobic Bacilli

Answer 1

Bacillus anthracis, Listeria monocytogenes, Corynebacterium diphtheriae

Question 2

2 Bacilli of medical importance (and metabolism)

Answer 2

Bacillus anthracis, Bacillus cereus

Aerobic Gram-positive rods

Question 3

Bacillus anthracis characteristics (morphology)

Answer 3

Grow in chains (“bamboo rods”), spore-forming

Question 4

Bacillus anthracis determinants of pathogenicity

Answer 4

Capsule, anthrax toxin

Question 5

Bacillus anthracis capsule composition and function

Answer 5

D-glutamic acid, antiphagocytic

Question 6

Anthrax toxin description

Answer 6

A-B toxin (A = edema factor, lethal factor, B = protective antigen)

Question 7

A-B toxin: 2 parts

Answer 7

Activity subunit, binding subunit

Question 8

EF function

Answer 8

Edema factor: Adenylate cyclase toxin -> edema and inhibition of neutrophil function

Question 9

LF function

Answer 9

Lethal factor: Zinc protease -> cleave host cell kinase -> macrophage cell death

Question 10

Bacillus anthracis clinical disease

Answer 10

Cutaneous, Inhalation, Gastrointestinal

Question 11

Cutaneous anthrax description

Answer 11

Small red macule -> ulcer (blackened necrotic eschar), usually spontaneously resolve

Question 12

Inhalation anthrax symptoms

Answer 12

Symptoms similar to severe viral respiratory infection - fever, SOB, hypotension

Question 13

Gastrointestinal anthrax mortality rates

Answer 13

Intermediate mortality rates

Question 14

Bacillus anthracis diagnostic laboratory tests

Answer 14

Large number of organisms seen by Gram-stain

Question 15

Bacillus anthracis treatment

Answer 15

Penicillin, ciprofloxacin, doxycycline, monoclonal antibodies against the receptor of PA

Question 16

Bacillus anthracis prevention

Answer 16

Nonliving vaccine with PA as its active component

Question 17

Listeria monocytogenes characteristics (metabolism, transmission, where does it grow)

Answer 17

Facultative (metabolism), foodborne transmission, facultative intracellular pathogen

Question 18

Listeria monocytogenes determinants of pathogenicity

Answer 18

Facultative intracellular pathogen, internalin (adhesin), listeriolysin O (pore-forming toxin), ActA

ILA

Question 19

Listeria monocytogenes clinical disease

Answer 19

Meningitis (elderly, young, immunocompromised), fetal infections, neonatal infections

Question 20

Listeria monocytogenes diagnostic laboratory tests (hemolysis, catalase)

Answer 20

Growth of organism, small smooth colonies surrounded by beta-hemolysis, catalase-positive

Question 21

Listeria monocytogenes treatment

Answer 21

Ampicillin (may be used in combination with an aminoglycoside)

Question 22

Corynebacteria characteristics (shape, what species does it infect)

Answer 22

Aerobic Gram-positive bacilli, may have “club-shape”, nonspore-forming, infects only humans

Question 23

C. diphtheriae determinants of pathogenicity

Answer 23

Diphtheria toxin (Gene carried on phage, A-B toxin)

Question 24

Diphtheria toxin A subunit

Answer 24

ADP-ribosylating EF-2 (inhibit peptide chain elongation in pharyngeal epithelial cells) -> necrosis -> pseudomembrane formation

Question 25

C. diphtheriae clinical disease (how it spreads, mechanism, symptoms)

Answer 25

Diphtheria, Spread by direct contact/droplets, Pseudomembrane formation -\> airway obstruction Symptoms: Sore throat, fever, difficulty swallowing, cough, hoarseness, rhinorrhea

Question 26

C. diphtheria diagnostic laboratory tests (morphology)

Answer 26

Bacteria lie in clusters at acute angles ("Chinese letter" appearance) or in parallel groups ("palisade" appearance)

Question 27

C. diphtheria treatment

Answer 27

Horse antisera against DT, antibiotics

Question 28

C. diphtheria prevention

Answer 28

Diphtheria toxoid vaccine (chemically treated toxin - no longer toxic but retains immunogenicity)

Question 29

Clostridia characteristics (spores)

Answer 29

Gram-positive anaerobic rods, spore-forming

Question 30

4 species of clostridia

Answer 30

Clostridium tetani, C. botulinum, C. perfringens, Clostridioides difficile

Question 31

Clostridium tetani determinants of pathogenicity

Answer 31

Tetanus toxin

Question 32

Tetanus toxin mechanism

Answer 32

A subunit cleaves SNARE proteins required for fusion of synaptic vesicle with neuron membrane, prevents release of inhibitory neurotransmitters

Question 33

Clostridium tetani clinical disease

Answer 33

Tetanus - risus sardonicus

Question 34

Clostridium tetani diagnostic laboratory tests

Answer 34

Terminal spores ("tennis racket" or "drumstick" shaped)

Question 35

Clostridium tetani treatment

Answer 35

Human tetanus immunoglobulin, agents to control muscle spasms

Question 36

Clostridium tetani prevention

Answer 36

Vaccine: tetanus toxoid

Question 37

C. botulinum determinants of pathogenicity

Answer 37

Botulinum toxin

Question 38

Botulinum toxin mechanism

Answer 38

Blocks release of acetylcholine, decreased motor neuron activity

Question 39

C. botulinum clinical disease: 3 types of botulism

Answer 39

Food-borne, wound, infant

Question 40

Food-borne botulism characteristics

Answer 40

Symmetric descending paralysis, cranial nerve involvement, fever is unusual

Question 41

Wound botulism characteristics

Answer 41

Ptosis (upper eyelid droops over the eye), skin abscesses

Question 42

C. botulinum diagnostic laboratory tests

Answer 42

Primarily compatible history and clinical symptoms

Question 43

C. botulism treatment

Answer 43

Neutralize toxin, respiratory support

Question 44

C. perfringens (what does it cause)

Answer 44

Causes gangrene and food-poisoning

Question 45

Clostridioides difficile (what does it cause)

Answer 45

Causes diarrhea associated with antibiotic use

Question 46

Actinomycetes characteristics

Answer 46

Resemble fungi Nocardia species (aerobic) Actinomyces species (anaerobic)

Question 47

2 medically important actinomycetes

Answer 47

Nocardia species, Actinomyces species

Question 48

Nocardia species (description of infections)

Answer 48

Infects individuals with deficient cell-mediated immunity (subacute pneumonia -\> dissemination to CNS or skin and soft tissue, transcutaneous inoculation)

Question 49

Nocardia species (staining)

Answer 49

Partially stain using acid-fast technique

Question 50

Actinomyces israelii - what does it cause, staining

Answer 50

Indolent, suppurative infections, spread contiguously, ignoring tissue planes Not partially acid fast

Question 51

What organism cause this?

Answer 51

Clostridium perfringens (gangrene)