Gram positive bacteria - rods and branching

Question 1

Which two bacteria are gram+ branching filaments?

Answer 1

Actinomyces and Nocardia

Question 2

Which bacteria is gram+ branching filament and anaerobic?

Answer 2

Actinomyces

Question 3

Which bacteria is gram+ branching filament and acid-fast?

Answer 3

Nocardia

Question 4

Which gram+ branching filament is found in normal oral flora?

Answer 4

Actinomyces

Question 5

Which gram+ branching filament is found in soil?

Answer 5

Nocardia

Question 6

What disease manifestations are associated with Actinomyces?

Answer 6

• oral/facial abscesses that drain through sinus tracts

- yellow sulfur granules

Question 7

What is actinomyces treated with?

Answer 7

Penicillin

Question 8

What disease manifestations is Nocardia associated with?

Answer 8

Immunocompromised: pulmonary infections
Immunocompetant: Cutaneous infxns after trauma

Question 9

What is nocardia treated with?

Answer 9

Sulfonamindes

Question 10

Which gram+ organisms are found in rods?

Answer 10

Clostridium, Bacillus, Listeria, Corynebacterium

Question 11

Which gram+ rods are spore-forming?

Answer 11

Clostridium and Bacillus

Question 12

What are the sub-species of Clostridium?

Answer 12

Perfringens
Difficile
Botulinum
Tetani

Question 13

How are all clostridia classified?

Answer 13

Gram+, spore-forming, obligate ANAEROBIC bacilli

Question 14

What toxin is C. tetani associated with? How does the toxin work?

Answer 14

tetanospasmin, an exotoxin causing tetanus. Tetanospasmin is a protease that cleaves SNARE proteins, preventing release of GABA and glycine neurotransmitters from Renshaw cells in spinal cord.

Question 15

What is the presentation associated with C. tetani?

Answer 15

Spastic paralysis, trismus (lockjaw), risus sardonicus (raised eyebrows and open grin)

Question 16

How can C. tetani be prevented/treated?

Answer 16

Antitoxin
Tetanus vaccine (+ booster)
Diazepam for muscle spasms

Question 17

What toxin is C. botulin associated with? How does the toxin work?

Answer 17

Botulinum toxin; pre-formed, heat-labile toxin. Released upon death of bacteria. Cleaves SNARE proteins, inhibiting release of Ach at the neuromuscular junction.

Question 18

What is the presentation associated with C. botulinum?

Answer 18

Adult botulism: from ingestion of pre-formed toxin. Cranial nerve palsies, muscle weakness, respiratory paralysis
Infant botulism: from ingestion of spores (honey). Floppy baby, constipation.
Wound Botulism: puncture wounds/deep space. No GI prodrome.

Question 19

What is the treatment for botulism?

Answer 19

Anti-toxin, human BIG for infant bot, penicillin, supportive therapy.

Question 20

What is the toxin associated with C. perfringens? How does it work?

Answer 20

12 toxins, including Alpha-toxin, lecithinase, which splits lecithin into phosphocholine and diglyceride

Question 21

What does C. perfringens cause?

Answer 21

Myonecrosis (gas gangrene), and hemolysis.

Question 22

What toxin is associated with C. difficile?

Answer 22

Toxin A: Enterotoxin, binds to brush border of the gut.

Toxin B: Cytotoxin, causes cytoskeletal disruption via actin depolymerization

Question 23

What presentation is associated with C. difficile? What precipitates C. diff infection?

Answer 23

Pseudomembranous colitis –> diarrhea.

Abx use precipitates, esp clindamycin or ampicillin.

Question 24

How to diagnose C. diff?

Answer 24

Detect toxins in stool by PCR

Question 25

How to treat C. diff?

Answer 25

Metronidazole or oral vancomycin. | If recurrent, try fidaxomicin, or fecal transplant.

Question 26

What toxins are associated with Bacillus cereus?

Answer 26

* Spores survive cooking. Keeping rice warm --> germination of spores and enterotoxin formation. - Emetic type: Cereulide, preformed toxin, heat stable. N/V w/in 1-5 hrs - Diarrheal type: Heat labile, similar to e.coli/cholera toxin.: Watery, non-bloody diarrhea and GI pain w/in 8-18hrs.

Question 27

What antibiotics work for B. Cereus

Answer 27

For food poisoning, none (caused by pre-formed toxin). For eradication, resistant to beta-lactam abx. Vanc/clinda. No capsule!

Question 28

What kind of capsule does B. anthracis have?

Answer 28

Polypeptide capsule containing D-glutamate. Anti-phagocytic.

Question 29

What toxin is B. anthracis associated with? How does it work?

Answer 29

Exotoxin: 3 proteins 1. Protective antigen (PA) --> Binding B subunit, allows entry into target cell 2. Edema factor (EF) --> Calmodulin-dependent adenylate cyclase, increases cAMP, impairs neut function and causes massive edema (disrupts water hemostasis) 3. Lethal factor (LF) --> Zinc metalloproteinase that inactivates protein kinase. Stimulates mac to release TNFalpha and IL-1B, which contributes to death.

Question 30

What is the most common presentation of B. anthracis?

Answer 30

Cutaneous anthrax (95%): painless papule surrounded by vesicles --> ulcer w/ black eschar, painless, necrotic. Uncommonly progresses to bacteremia/death.

Question 31

What can inhalation of B. anthracis cause?

Answer 31

Pulmonary anthrax: inhalation of spores causes flu-like symptoms that rapidly progresses to fever, pulmonary hemorrhage, mediastinitis, and death.

Question 32

What is the reservoir of B. anthracis?

Answer 32

Sheep, goats, cattle. (*woolsorter's disease).

Question 33

What is the vaccine for anthrax?

Answer 33

Composed of protective antigen (PA). For high risk individuals.

Question 34

How is anthrax treated?

Answer 34

Cipro/doxy | Raxibacumab (inhalational)

Question 35

What are corynebacterium shaped like?

Answer 35

Club shaped

Question 36

What two cultures do corynebacterium appear on?

Answer 36

Cysteine-tellurite agar: black colonies | Loeffler's medium: gram+ rods, >12 hrs stain with methylene blue--> metachromic (blue and red) granules - Babes-Ernst.

Question 37

What encodes the diphteriae exotoxin?

Answer 37

B-prophage (lysogenic conversion)

Question 38

What is the exotoxin of diphtheriae?

Answer 38

B(binding)-subunit permits entry into cardiac and neural tissue A (actin)-subunit inhibits protein synthesis by inactivating EF2 via ADP-ribosylation.

Question 39

What are the sx of diphtheria?

Answer 39

Pseudomembranous pharyngitis +LAD - gray/white exudate. Myocarditis/AV conduction block/arrythmia Neural involvement: peripheral nerve palsies, GB-like sx, palatal and cranial neuropathies

Question 40

What does the vaccine for diphtheria contain?

Answer 40

Formalin-inactivated exotoxin: antibodies to B-subunit are protective.

Question 41

What are the tests for diphtheria toxin?

Answer 41

Schick test: injection of exotoxin into skin | Elek test: detects toxin - looks for precipitin 45 degree lines.

Question 42

What do listeria look like?

Answer 42

Gram positive non-spore forming rods, have flagella; "rocket tails" that allow intracellular movement and cell to cell spread across cell membranes, avoiding antibody. "Tumbling motility"

Question 43

What is the virulence factor of listeria?

Answer 43

Only gram+ organism to produce endotoxin. Listeriolysin O and phospholipases allow escape from phagolysosomes of macrophages. Hemolysin - heat labile and antigenic.

Question 44

Where is listeria acquired from?

Answer 44

Unpasteurized dairy products, cold deli meats, transplacental transmission, or vaginal transmission.

Question 45

What are the presentations of listeria?

Answer 45

1. Amnionitis, septicemia, and abortion in preggos 2. Meningitis in neonates, elderly, and immunosuppressed 3. Granulomatosis infantiseptica 4. Gastroenteritis in healthy individuals.

Question 46

What is the treatment for listeria?

Answer 46

Ampicillin/trimethoprim/sulfamethoxazole for meningitis