Microbiology - Soft Tissue Injury

Question 1

C. tetani and C. botulinum are gram (+) anaerobes (rods) normally found:

Answer 1

in the environment ie soil

Question 2

C. difficile, Bacteriodes, Prevotella, and Actinomyces are anaerobes (rods) normally found:

Answer 2

They are normal flora

Question 3

C. difficile causes ______________ after antibiotic use, often nosocomial, change antibiotic and intervene surgically as necessary

Answer 3

pseudomembranous colitis

Question 4

What is the pathogenesis of C. tetani?

Answer 4

Vegetative cells release exotoxin tetanospasmin;
retrograde axonal transport;
Acts as protease, cleaves synaptobrevin (aka VAMP) in inhibitory motor nerves of the central nervous system
Without synaptobrevin, vesicles containing GABA and glycine cannot be released from affected neuron
Loss of central inhibitory activity on motor and autonomic neurons

Question 5

What is the pathogen?

Local rigidity, difficulty swallowing
Often afebrile
Strong muscle spasms/paralysis
Trismus (Lockjaw) 
Risus sardonicus (grimace) 
Exaggerated reflexes
Opisthotonus                                                                                              (strong arching of back)
Fractures, tendon ruptures from spasms
Terminal spore gives “tennis racket” appearance on microscopy

Answer 5

C. tetani

Question 6

How are the botulinum exotoxin and tetanospasmin different/similar in their effect on the nervous system?

Answer 6

For botulinim toxin, Synaptobrevin is the same vesicle associated membrane protein (VAMP) targeted by tetanospasmin; at this different location the major affect is on release of acetylcholine –> flaccid paralysis

Question 7

Floppy baby syndrome results from what infectious agent?

Answer 7

C. botulinum

Question 8

T/F: Laboratory studies like culture are useful for the diagnosis of Botulism.

Answer 8

False

Question 9

C. perfringens is what kind of bacteria?

Answer 9

gram + spore forming rod

Question 10

C. Perfringens produces 20+ toxins. Which is the main player?

Answer 10

Alpha toxin: lecithinase, necrotizing, hemolytic, cardiotoxic

Question 11

What diagnosis is indicated by this finding?

Radiography may show “feathering” pattern of gas in soft tissue

Answer 11

Gas gangrene
C. perfringens
Surgical emergency

Question 12

What is the pathogenesis of C. perfringens food poisoning?

Answer 12

Germinating cells multiply in the small bowel
CPE enterotoxin of Type A strains destroys tight junctions between epithelial cells in gut, causing diarrhea and abdominal pain;
resolves in 24 hours

Question 13

What is the pathogenesis of C. diff?

Answer 13

Germinating cells release Exotoxin A, which disrupts tight junctions, causing intestinal swelling and inflammation

Exotoxin B is the major toxin, disrupts the cytoskeleton by depolymerizing actin, kills the surrounding cells

Question 14

“GNAB” or “AGNB” includes:

Answer 14

Bacteroides, Prevotella, Fusobacter