Gram-Negative Bacilli (Enteric)

Question 1

Enterobacterales characteristics (metabolism)

Answer 1

Facultative anaerobic bacilli and coccobacilli, many are opportunistic pathogens

Question 2

Escherichia coli (what diseases it causes)

Answer 2

UTIs, diarrhea, hospital-acquired pneumonia

Question 3

E. coli determinants of pathogenicity

Answer 3

Alpha-hemolysin, aerobactin, polysaccharide capsule (AAP)

Pore-forming toxin, iron siderophore, reduces phagocytosis

Question 4

E. coli K1 capsule (what it is associated with)

Answer 4

Meningitis and bacteremia in neonates

Question 5

UPEC (what is causes)

Answer 5

Uropathogenic E. coli: UTIs

Question 6

UPEC (types of pili)

Answer 6

Type I pili: Binding in the bladder

P pili: Binding in the upper urinary tract, cause pyelonephritis

Question 7

ETEC (how is it spread)

Answer 7

Enterotoxigenic E. coli: Spread through contaminated food and water

Question 8

ETEC (2 toxins)

Answer 8

Heat labile toxin (stimulates adenylate cyclase in gut epithelial cells)
Heat stable toxin (stimulates guanylate cyclase in gut epithelial cells)

Question 9

EPEC (what it causes)

Answer 9

Enteropathogenic E. coli: Diarrhea in developing countries

Question 10

EPEC (mechanism)

Answer 10

Bundle-forming pili - attach to intestinal epithelium
Intimin - adhesin
Type III secretion system

Question 11

Type III Secretion Systems

Answer 11

Directly inject bacterial proteins into cytoplasm of host cells

Question 12

EPEC Type III Secretion (what does it do)

Answer 12

Loss of normal microvilli structure, pedestal formation, injects Tir (acts as receptor for intimin -> allows for tight adherence)

Question 13

EHEC (what does it cause)

Answer 13

Enterohemorrhagic E. coli: Bloody diarrhea, abdominal pain, usually no or low-grade fever

Question 14

EHEC toxin (and what it is responsible for)

Answer 14

Shiga-like toxin, responsible for HUS (hemolytic-uremic syndrome)

Question 15

E. coli diagnostic laboratory tests

Answer 15

Growth on routine media, biochemical tests (lactose fermentation: MacConkey Agar)

Question 16

ETEC treatment

Answer 16

Rehydration

Question 17

EHEC treatment

Answer 17

No antibiotics

Question 18

Uropathogenic E. coli treatment

Answer 18

Nitrofurantoin, fosfomycin, trimethoprim-sulfamethoxazole

Question 19

Shigella species (what do they cause)

Answer 19

Dysentery (cramps, tenesmus, frequent small-volume, bloody, mucoid stools)

Question 20

Salmonella enterica

Answer 20

Facultative intracellular pathogens, common cause of diarrhea

Question 21

S. enterica serovar Typhimurium (what does it cause)

Answer 21

Typhoid fever

Question 22

Tenesmus

Answer 22

Feeling that you need to pass stools

Question 23

Types of enterobacterales

Answer 23

Escherichia coli, Shigella, Salmonella enterica, Yersinia, Klebsiella pneumoniae, Proteus

Question 24

Gastroenteritis

Answer 24

Stomach virus

Question 25

Hemolytic-uremic syndrome

Answer 25

Condition that affects the blood and blood vessels, results in the destruction of blood platelets, a low red blood cell count (anemia), and kidney failure

Question 26

2 Yersinia species (what do they cause)

Answer 26

Y. enterocolitica (infectious diarrhea), Y. pestis (plague)

Question 27

Myalgias

Answer 27

Muscle aches and pains

Question 28

Beta-lactam antibiotics (4 classes)

Answer 28

Penicillins, cephalosporins, monobactams, carbapenems

Question 29

Which beta-lactam antibiotic is active against most gram-negatives?

Answer 29

Carbapenems

Question 30

ESBL

Answer 30

Extended spectrum beta-lactamases (Cleave cephalosporins and monobactams)

Question 31

Dysuria

Answer 31

Painful or difficult urination

Question 32

Y. pestis DP

Answer 32

Bubo formation, LPS in bloodstream, Bacteria make their way to macrophages in the lungs Type III secretion (paralyze macrophages and neutrophils to prevent phagocytosis), antiphagocytic capsule (F1), Pla cleaves fibrin clots -> facilitates bacterial dissemination

Question 33

Y. pestis CD

Answer 33

Bubonic plague, Pneumonic plague

Question 34

Y. pestis DLT (appearance)

Answer 34

Closed safety pins appearance

Question 35

K. pneumoniae DP

Answer 35

Polysaccharide capsule, siderophores

Question 36

Proteus species characteristic

Answer 36

"Swarming motility" - hundreds of flagella per cell

Question 37

Proteus spp (what do they cause and how)

Answer 37

UTIs, nosocomial infections, urease splits urea into ammonium hydroxide, raises urine pH, promotes formation of "struvite" kidney stones

Question 38

Pseudomonads (metabolism, ferment, where found)

Answer 38

Aerobic Gram-negative rods, cannot ferment glucose (unlike enterobacterales), moist environments

Question 39

P. aeruginosa DP

Answer 39

Pili, exotoxin A, alginate (exopolysaccharide, antiphagocytic), Type III secretion system, quorum-sensing PEATQ

Question 40

P. aeruginosa CD

Answer 40

Opportunistic pathogen, lungs of cystic fibrosis patients, nosocomial infections (pneumonia, UTIs, wound infections), bacteremia and sepsis in neutropenic cancer patients (ecthyma gangrenosum), hot tub folliculitis

Question 41

P. aeruginosa DLT

Answer 41

Produces grape-like odor, fluorescent pigments, oxidase positive

Question 42

Acinetobacter baumannii (what do they cause)

Answer 42

Hospital-acquired infections, 50% isolates resistant to carbapenems

Question 43

Vibrios 2 species and what do they cause

Answer 43

V. cholerae (cause cholera), V. vulnificus (cause gastroenteritis, wound infections following cuts exposed to seawater)

Question 44

Helicobacter pylori (shape)

Answer 44

Gram-negative, slender, spiral-shaped

Question 45

H. pylori (common cause of which disease)

Answer 45

Peptic ulcer disease

Question 46

H. pylori DP

Answer 46

Urease, VacA, Type IV secretion

Question 47

H. pylori DLT

Answer 47

Endoscopy, Serological tests for IgG, antibody tests to detect in stool, urea breath test

Question 48

H. pylori treatment

Answer 48

Proton-pump inhibitor + clarithromycin + amoxicillin/metronidazole

Question 49

Campylobacter (what does it cause)

Answer 49

Gastroenteritis leading to diarrhea

Question 50

Typhoid fever symptoms

Answer 50

Prolonged fever, persistent bacteremia, occasionally a rash consisting of a few pink macules observed

Question 51

Salmonella enterica treatment

Answer 51

Treat typhoid fever and bacteremia: Fluoroquinolones, azithromycin

Question 52

Typhoid fever prevention

Answer 52

Vaccine