Strategies of Bacterial Pathogenesis

Question 1

What was the significance of the sunburn like rash in the case 6 presentation?

Answer 1

Should indicate that the pathogen is either staph or strep

Question 2

What were the 3 bacterial oriented potential causes for the disease in case 6?

Answer 2

Staphylococcal scalded skin syndrome
Staphylococcal toxic shock syndrome
Streptococcal toxic shock syndrome

Question 3

What were the 2 non bacterial potential causes for the disease in case 6?

Answer 3

Drug reaction (toxic epidermal necrolysis)
Reaction to soap, bedding/blankets, or reaction to clothes

Question 4

Why is intradermal separation of skin particularly problematic for infection?

Answer 4

Increases suceptibility to infection, compromised barrier

Question 5

What was the bacteria that was cultured from all the babies who were affected by this skin disease? Where were the cultures obtained from?

Answer 5

Staphylococcus aureus

Throat cultures

Question 6

What are the 3 major causes of staphylococcal toxic shock syndrome?

Answer 6

toxic shock syndrome toxin-1,
enterotoxin B,
enterotoxin C

Question 7

What are the 2 major causes of scalded skin syndrome? WHat is the bacteria responsible?

Answer 7

Exfoliative toxin A
Exfoliative toxin B
Staph Aureus

Question 8

What was the toxin found in all the 5 affected babies and single healthcare worker? How were the toxins matched to each other?

Answer 8

Exfoliative toxin A

Pulse field gel electrophoresis profiles were identical (Run on gel after restriction digest)

Question 9

Where was S. aureus found in the affected infants? How does it cause exfoliative skin disease? What specific subset of babies are suceptible and why?

Answer 9

Only in nose and throat
The toxin leaves the nose and throat, goes to the skin where it cleaves desmoglein 1
Only day old infants, because soon after birth, infants start expressing desmoglein 2

Question 10

What is macular erythroderma? What is papular erythroderma? What is a maculopapular rash?

Answer 10

Sunburn like flat rash
Bumpy rash
Sunburn like and bumpy

Question 11

What is the difference between vesicular, pustular and bullous rash?

Answer 11

vesicular - fmall fluid filled sacs
pustular - pus filled
bullous - large fluid filled sacs

Question 12

What is a petechial rash? What type of infection is it associated with?

Answer 12

Small rose shaped rash associated with gram negative infections

Question 13

What is an eschar rash?

Answer 13

Floor burn like rash that will become a black scab

Question 14

WHat is a uticarial rash? What is the specific process that causes it?

Answer 14

Hives - flat macular rash

Caused by type 1 hypersensitivity

Question 15

An eschar is associated with what type of skin infection? At least as was shown in class?

Answer 15

Cutaneous anthrax

Question 16

What is a primary pathogen vs an opportunistic pathogen?

Answer 16

Primary - Will cause infection if present in the host

Opportunistic - Only if compromised immune system

Question 17

What are 5 pathogens that are associated with exotoxemia (toxins in the blood)?

Answer 17

Tetanus 
Diphtheria 
Cholera
Toxic Shock Syndrome 
Scarlet fever

Question 18

Regarding the immune system, what is an extracellular pathogen? What are 3 examples provided?

Answer 18

Microbes that live outside PMNs and macrophages
Haemophilus influenza
Streptococcus pneumoniae
Neisseria meningiditis

Question 19

Regarding the immune system, what is an intracellular pathogen? What are 3 examples provided?

Answer 19

Microbes that live within the macrophages and PMNs
mycobacterium tuberculosis
Salmonella typhi
Listeria monocytogenes

Question 20

What are 2 extracellular organisms that also produce exotoxemia?

Answer 20

Staphylococcus aureus

Streptococcus pyogenes

Question 21

Antibodies are more likely to work against which type of microbe, extracellular or intracellular? What is the alternative for those “immune” to antibodies?

Answer 21

Work best against extracellular - not 100%, especially against those that cause exotoxemia
Intracell pathogens fought by T-cells activating macrophages