Bacterial Phys & Pathogenesis

Question 1

scalded skin syndrome is characterized by bullous impetigo, associated with what exotoxin?

Answer 1

exfoliative toxin A (S. aureus)

Question 2

All of the following pathogens produce a potent exotoxin EXCEPT:

A. Clostridium tetani

B. Streptococcus pyogenes

C. Streptococcus pneumoniae

D. Corynebacterium diptheriae

E. Vibrio cholerae

Answer 2

C.

Streptococcus pneumonia is an invasive extracellular organism that does not produce an exotoxin.

Question 3

All of the following are examples of invasive intracellular bacteria EXCEPT:

A. Chlamydia trachomatis

B. Salmonella tyhpi

C. Mycobacterium tuberculosis

D. Haemophilus influenzae

E. Listeria monocytogenes

Answer 3

D.

Haemophilus influenza, along with streptococcal/mycoplasma pneumoniaes, and Neisserias meningitidis/gonorrhoeae are all extracellular bacteria.

Question 4

why do people not develop neutralizing antibodies to tetanus and botulism toxins during illness?

Answer 4

these toxins are too toxic to be immunogenic. vaccines against them consist of toxoids that are biologically inactive forms of toxins.

Question 5

Which of the following statements regarding invasive extracellular organisms is FALSE?

A. they primarily depend on host attachment mechanisms and antiphagocytic capsules for virulence

B. they are responsible for the “itis” diseases: pharyngitis, otitis, urethritis, etc.

C. they usually cause serious disease through extensive inflammation

D. they usually invade through mucosal surfaces

E. immunity against them depends on direct T cell killing or T cells activating macrophages

Answer 5

E.

This is a feature of intracellular bacteria. Immunity against extracellular bacteria depends on opsonic antibodies to their capusles or other cell-surface virulence factors.

Question 6

these two multidimensional bacteria depend on both exotoxins and invasive properties to cause disease, and are usually highly inflammatory (though not always)

Answer 6

Staph aureus & Strep pyogenes

Question 7

Which of the following statements regarding invasive intracellular organisms is FALSE?

A. gram negative intracellular organisms, such as C**hlamydia trachomatis, typically cause high fevers

B. they are responsible for the “osis” diseases: tuberculosis, shigellosis, sarcoidosis

C. must use attenuated vaccines against them to stimulate a complete immune response

D. they usually induce granulma formation

E. immunity against them depends on direct T cell killing or T cells activating macrophages

Answer 7

A.

This is false. even though these bacteria contain LPS/LOS in their cell membrane, they are able to invade host cells without being recognized and lysed by immune cells, which prevents their lipid A from interacting with TLR4 receptors.

Question 8

bacteria use these small, high-affinity iron chelating compounds to steal iron away from transferrin during a bloodstream infection

Answer 8

siderophores

Question 9

a _____ is a group of microorganisms that stick to each other on a surface containing polysaccharide slime layers, extracellular DNA and proteins that enable them to evade the immune system and reduce antibiotic effectiveness

Answer 9

biofilm