Bailey Lecture 2 Gram - Mucosal Pathogens

Question 1

What are the two toxin-producing bacterial genuses?

Answer 1

Vibrio & Entertoxigenic E. coli

Question 2

cholerae, parahaemolyticus, vulnificus, & alginolyticus are all species of what genus?

Answer 2

vibrio

Question 3

What are the two main types of Vibrio cholera?

Answer 3

1) El Tor
2) Classical

Question 4

What antigen did the El Tor strain of cholera mutate?

Answer 4

O1 antigen

Question 5

What ages of people and what percentage of people did the El Tor O139 encapsulated bacteria effect?

Answer 5

it affected all age groups and about 1 in 20 people (5%)

Question 6

What are the 3 virulence factors of V. cholerae?

Answer 6

1) flagella
2) pili (to adhere to mucosal tissue)(shift from saltwater’s high ion concentration to the body’s low ion concentration leads to pili expression)
3) cholera toxin (phage encoded)

Question 7

What is the end effect of V. cholerae and what is it similar to?

Answer 7

In the end, V. cholerae causes an increase in the intracellular cAMP (by way of adenylene cyclase) and an increase in intracellular cGMP in mucosal cells of the intestine causing evacuation of Cl and H2O leading to diarrhea

Question 8

30-45% of cases of traveler’s diarrhea (Mexian) are the direct result of which strain of e. coli?

Answer 8

ETEC (enterotoxigenic e. coli)

Question 9

does ETEC (enterotoxigenic e. coli) have a large or small infectious dose?

Answer 9

large

Question 10

____ on the fimbrae of ETEC (enterotoxigenic e. coli) help it adhere to mucosal tissue

Answer 10

colonization factor antigens (cfa)

Question 11

What two toxins are responsible for the traveler’s diarrhea caused by ETEC?

Answer 11

1) heat-labile toxin (LT)
2) heat-stable toxin (ST)

Question 12

What does heat-labile toxin produced by ETEC activate?

Answer 12

it activates adenylene cyclase resulting in an intracellular increase in cAMP

Question 13

In ETEC, what does ST (heat-stable toxin) activate?

Answer 13

ST causes an intracellular increase in cGMP

Question 14

What types of food typically leads to V. cholerae?

Answer 14

shellfish

Question 15

Match the antibiotic with the infection:

Tetracycline

Flouroquinolones

ETEC

Vibrio infection

Answer 15

tetracycline for vibrio infection and 2nd generation flouroquinolones for ETEC

Question 16

What specific types of bacteria are the “hybrid misfit” strains we have been talking about?

Answer 16

1) EPEC (enteropathogenic e. coli)
2) EHEC (enterohemorrhagic e. coli)

Question 17

What type of e. coli is prevalent in newborns and causes noninflammatory secretory diarrhea?

Answer 17

EPEC (enteropathogenic e. coli), is present in the DISTAL small intestine, has a large infectious dose, has an ABSENCE of traditional endotoxins (such as those found in ETEC) and has a characteristic intimate adherence pattern (aka an attaching and effacing lesion)

Question 18

The following is an image showing the three main steps in EPEC & EHEC adherence which is intimate (AKA attaching and effacing) note that the “syringe” in the second stage is called a type III secretin and that the final result is the bacterium on a pedistal on the cell

Answer 18

Question 19

Since there is no toxin production with EPEC, what is the cause of diarrhea?

Answer 19

the cause is malabsorption of nutrients and water due to the disruptions to the microvilli and epithelial tight junctions as a result of the pedistal formation

Question 20

EHEC has a set of EPEC genes that produce an attaching effacing lesion just like EPEC but is much more dangerous due to what?

Answer 20

the fact that the toxin produced can lead to hemolytic uremic syndrome (bleeding in the urine)

Question 21

What is the primary reservoir for EHEC?

Answer 21

cattle. note that EHEC produces what’s called a “shiga-like” toxin which causes hemorrhagic colitis as well as hemolytic urine syndrome (HUS), causing 250-500 deaths annually

Question 22

EHEC can be diagnosed on an agar plate because it cannot do what?

Answer 22

cannot ferment sorbitol

Question 23

“Other” mucosal surfaces include the urinary tract and the respiratory tract. Which organisms connonly infect each of these respectively?

Answer 23

urinary tract: Proteus species and UPEC

respiratory tract: Klebsiella species

Question 24

What is the most common bodily infection besides those in the mouth?

Answer 24

UTI (most frequent reason for doctor visit) Remember that inflammation in the bladder is termed cystitis

Question 25

Which genus is most responsible for cases of uncomplicated UTIs?

Answer 25

e. coli. (80%). For complicated UTIs, e. coli only account for 20% (enterobacteriaceae such as pseudomonas aeruginosa and serratia accounting for the other 80%)

Question 26

Where will a complicated UTI likely spread?

Answer 26

kidneys (calledpyelonephritis)

Question 27

How to UPEC (uropathogenic e. coli) adhere to uroepithelial cells?

Answer 27

via fimbriae

Question 28

_____ produces aerobactin and hemolysin

Answer 28

UPEC

Question 29

P. mirabilis is a common cause of _____

Answer 29

uncomplicated UTI

Question 30

If you have an abnormal urinary tract structure, you are you more likely to have a UTI from UPEC or from P. mirabilis?

Answer 30

p. mirabilis

Question 31

Is a P. mirabilis UTI or an E. coli UTI more severe?

Answer 31

P. mirabilis

Question 32

What type of protease does P. mirabilis carry?

Answer 32

IgA protease

Question 33

urease does what to the pH of urine?

Answer 33

raises it (note that urease is a virulence factor of P. mirabilis). Bacteria will grow better in a lecc acidic environment but urease is toxic to renal cells. This can lead to the formation of urinary stones

Question 34

In an individual with dysuria (urinary infection), is the bacterial concentration in the urine higher or lower than normal?

Answer 34

Lower (at least with pyuria)

Question 35

What are the best two factors that can help with a proteus UTI infection diagnosis?

Answer 35

1) constantly alkaline urine
2) production of urease

Question 36

What is notable about agar colonies of Klebsiella?

Answer 36

large mucoid colonies due to their large capsule

Question 37

Do Klebsiella have pili?

Answer 37

yes they do, two types

Type 1: important for adherence to urinary tract epithelial cells

Type 3: important for adherence to respiratory tract epithelial cells

Question 38

Do Klebsiella contain enterotoxins?

Answer 38

yes, they are similar to ST & LT and therefore induce secretory diarrhea

Question 39

What does aerobactin do?

Answer 39

it sequesters iron

Question 40

What is the PRIMARY virulence factor for Klebsiella?

Answer 40

the antiphagocytic capsule

Question 41

What type of bacteria is known to transfer via oral to oral contact?

Answer 41

Helicobacter (transmits from fecal-to-oral as well) and is a GI bacteria

Question 42

Is helicobacter a fast or slow bacterium?

Answer 42

it is a slow bacteriumthat is only found in the mucous overlying mucous secreting cells of the stomach

Question 43

What type of bacteria we have discussed are readily killed by gastric acid?

Answer 43

H. pylori. It is an efficient producer of urease, causes epithelial cells to release IL-8, has a cytotoxin associated with peptic ulcer disease, and downregulates somatostatin-producing D-cells

Question 44

Treatment for _____ is intense with many side effects

Answer 44

H. pylori