Gram Neg Pathogens Pt 2

Question 1

Toxin-Producing Bacterial Pathogens:

1. Bacteria types
2. Infection location
3. Stool effects

Answer 1

1. Vibrio spp., Entertoxigenic E. coli
2. Small intestine
3. Lots of watery stool, no blood, no leukocytes, no tissue damage

Question 2

Main Vibrio species. Causes diarrhea.

Answer 2

V. Cholerae (“Cholera gravis”)

Question 3

Virulence factors of V. Cholerae:

Answer 3

1. Flagella
2. Pili to adhere to mucosal tissue
3. Cholera toxin- phage encoded

Question 4

V. Cholerae gives off Ctx which enters cell and binds to ______, keeping it running, leading to cAMP overproduction and Cl over excreted from cell -> diarrhea.

E. Coli has a similar affect.

Answer 4

Adenylyl Cyclase (AC)

Question 5

Responsible for 30-45% of traveler’s diarrhea. Large infectious dose. Colonization factor antigens (cfa) on fimbrae help with adherence.

Answer 5

ETEC: Enterotoxigenic E. coli

Question 6

ETEC produces 2 toxins responsible for disease:

Answer 6

1. Heat-labile toxin (LT): activates AC (like V. Cholerae)

2. Heat-stable toxin (ST): activates GC -> increased cGMP -> increased Cl release -> diarrhea

Question 7

Treatments for secretory diarrhea:

Answer 7

1. Oral rehydration (sugar, salt, water)

2. Antibiotics can reduce severity

Question 8

______ and _____ are “Hybrid” misfits of toxin-producing bacteria because they infect the lower small and upper large intestines, colonization causes effacing lesions, and the latter causes blood in stool

Answer 8

Enteropathogenic E. coli (EPEC)

Enterohemorrhagic E. coli (EHEC)

Question 9

Hamburger pathogen. Produces shiga-like toxin that can lead to hemolytic uremic syndrome (HUS)

Answer 9

EHEC

Question 10

Intimate Adherence (attaching and effacing lesion) stages:

Answer 10

1. Bundle-forming pili (Bfp) assist in long distance adherence
2. Syringe-like secretion system injects Tir into host cell
3. Tir binds to intimin on E. coli -> pedestal formation

Question 11

_____ causes diarrhea not by toxin production but instead by disruption of absorption/tight junctions

Answer 11

EPEC

Question 12

Most common form of bacterial infection of an organ system (minus mouth), and most frequent cause of doctor’s visits (minus dentists). Mostly caused by E. coli.

Answer 12

Urinary Tract Infection (UTI)

Question 13

Uncomplicated vs. Complicated UTI

Answer 13

Uncomplicated:

1. Normal defense mechanisms intact
2. No recent hospitalizations
3. Disease limited to lower urinary tract

Complicated:

1. Structural abnormality in urinary tract
2. Recent hospitalization
3. Disease probably spreads to kidneys

Question 14

Causes UTI. More severe than E. coli induced UTI.

Answer 14

Proteus Mirabilis (P. Mirabilis)

Question 15

Proteus can be diagnosed by:

Answer 15

Consistently alkaline urine

Urease production

Question 16

UTI Treatments

Answer 16

1. Antimicrobials

2. Trimethoprim-sulfamethoxazole (TMP/SMX)

Question 17

Large, mucous colonies due to large capsule. Related to pneumonia.

Answer 17

Klebsiella

Question 18

Among most prevalent Gram-negative GI bugs. Transmitted by oral-to-oral and fecal-to-oral contact. Slow bacterium. Can lead to many gastric diseases. Treated by proton pump inhibitor to decrease gastric acid secretion.

Answer 18

Helicobacter pylori