Gram Negative Rods That Cause Serious Disease

Question 1

There are 5 major gram negative rods that cause serious disease that you must know. What are they?

Answer 1

E. coli
Pseudomonas aeruginosa
Klebsiella
Proteus
Legionella

Question 2

I am a gram negative rod that causes neonatal meningitis

Answer 2

E. Coli

Question 3

Which of the major gram negative rods ferment lactose?

Answer 3

E Coli and Klebsiella

Question 4

What agar helps us determine whether or not something is lactose fermenting?

Answer 4

MacConkey Agar; it turns pink in the presence of a lactose fermenter

Question 5

Of all the gram negative rods to know in this lesson, which are oxidase positive?

Answer 5

Pseudomonas, this is not the only oxidase positive organism you have to know but in terms of the gram negative rods this is the one to know

Question 6

Which of the 5 G- rods that cause major disease produce H2S?

Answer 6

Proteus

Question 7

BCYE is an agar that is ____________ in color and is made specifically for the diagnosis of________________-

Answer 7

black, legionella. They appear white on the black agar

Question 8

This gram negative organism turns MaConkey agar from yellow to pink and has a green metallic sheen on EMB agar

Answer 8

E coli

Question 9

What virulence factor is observed in ecoli that causes neonatal meningitis?

Answer 9

K1 capsular antigen

Question 10

What virulence factor allows e coli to cause UTIs?

Answer 10

they adhere to urinary epithelium; often the P-pilus has adhesin proteins

Question 11

What leads to secretory diarrheal illness with E coli?

Answer 11

exotoxins

Question 12

Why is e coli a risk for causing sepsis in UTIs?

Answer 12

It makes an endotoxin that can lead to severe sepsis

Question 13

This bacteria has a thick capsule, is gram negative, urease positive, and has thick mucoid colonies on blood agar

Answer 13

Klebsiella

Question 14

Urease positive organisms can lead to __________ stones

Answer 14

struvite

These organisms include klebsiella and proteus

Question 15

These two organisms can precipitate the formation of struvite stones

Answer 15

Proteus and klebsiella

Question 16

I am associated with aspiration pneumonia and destroy alveolar spaces, form cavities, and cause the production of blood tinged sputum

Answer 16

Klebsiella

Question 17

Currant Jelly Sputum is pathopneumonic for

Answer 17

klebsiella

recall that ‘rust colored sputum’ is strep pneumo, G+

Question 18

Persons with alcohol use disorder and/or oropharyngeal dysphagia are at increased risk for pneumonia caused by this organism

Answer 18

Klebsiella

Question 19

Lactose fermenting, urease positive, UTIs, struvite stones, aspiration pneumonia, currant jelly sputum

Answer 19

klebsiella

Question 20

These three gram negative organisms are common causes of UTIs

Answer 20

E coli, klebisella, and proteus

Question 21

Magnesium ammonium phosphate

Answer 21

struvite

Question 22

“swarming motility” on blood agar, produces H2S, and creates a black pigment on TSI agar

Answer 22

proteus mirabelus

Question 23

Where is pseudomonas found?

Answer 23

Wherever water is found

Question 24

Produce blue green pigment

Answer 24

pseudomonas

Question 25

Fruity grape like odor

Answer 25

pseudomonas

Question 26

capsulated, motile with flagella, gram negative, oxidase positive, green-blue colonies

Answer 26

pseudomonas

Question 27

Exotoxin A

Answer 27

produced by pseudomonas, inactivates EF-2 (Elongation factor 2 (EF-2) is a protein that helps move messenger RNA (mRNA) through ribosomes during protein synthesis. It is a key part of a cell's translation machinery.) This leads to tissue necrosis.

Question 28

Type 3 secretion system

Answer 28

A "type 3 secretion system" (T3SS) is a complex molecular machine found in certain Gram-negative bacteria that allows them to directly inject proteins, called effector proteins, into the cytoplasm of host cells, essentially acting like a syringe to deliver bacterial virulence factors into the target cell, bypassing the extracellular space; this mechanism is crucial for many bacterial pathogens to establish infection within a host.

Question 29

This delivery system allows pseudomonas to directly deliver exotoxins to host cells

Answer 29

type 3 secretion system

Question 30

What opprotunistic infections does pseudomonas cause?

Answer 30

pneumonias, burn wound infections, hot tob folliculitis, otitis externa, corneal ulcers, and skin infections such as those with diabetics' sneakers.

Question 31

Hot tub folliculitis

Answer 31

pseudomonas

Question 32

How does pseudomonas lead to UTIs?

Answer 32

Indwelling cathetiers; pseudomonas grows biofilms on the plastic

Question 33

Slender pleomorphic gram neative saprophyte, replicates in amoeba

Answer 33

legionella

Question 34

Pneumonia but has hyponeutremia and may have diarrhea

Answer 34

Legionella

Question 35

Pontiac fever

Answer 35

Legionella

Question 36

Do not stain well but can be stained with silver stain. Must be grown on charcoal yeast extract. In humans, replicates in alveolar macrophages and alveolar epithelium

Answer 36

legionella

Question 37

Hypotension in gram negative bacteremia such as that observed in pseudomonal bacteremia is facilitated by what toxin?

Answer 37

Lipid A, an endotoxin present in the lipopolysaccharide of many gram-negative bacterial cell walls, is responsible for hypotension in gram-negative bacteremia. Upon release from the bacterial cell wall (like when the cabteria is lysed by a macrophage or something), lipid A causes activation of macrophages and the complement cascade via TNF-α, IL-1, and IL-6, resulting in the release of additional inflammatory mediators, including nitric oxide and histamine. These mediators cause relaxation of the smooth muscles, inducing vasodilation and hypotension, as seen in this patient. GRAM NEGATIVE SHOCK!

Question 38

This virulence factor is responsible for hypotension in gram negative bacteremia

Answer 38

lipid A; Part of the LPS. it causes activation of macrophages and the complement cascade via TNF-α, IL-1, and IL-6, resulting in the release of additional inflammatory mediators, including nitric oxide and histamine. These mediators cause relaxation of the smooth muscles, inducing vasodilation and hypotension, as seen in this patient

Question 39

These produce nitrites because these organisms have nitrate reductase. So if urine is negative for nitrites, it is unlikely a UTI caused by these organisms.

Answer 39

E coli Klebsiella Proteus A young, sexually active woman presents with features of uncomplicated urinary tract infection. The negative urinary nitrite test indicates infection with a pathogen that does not produce nitrate reductase. Although e coli is the most common cause of UTIs, it produces nitrites. Note that the second most common cause of uncomplicated UTIs in young females is Gram + Staph saprophyticus

Question 40

Patients with a urinary tract infection (UTI), alkaline urine (pH > 8), and an indwelling urinary catheter are most likely infected with ...

Answer 40

Proteus mirabilis, a gram-negative, oxidase-negative rod. Patients with a urinary tract infection (UTI), alkaline urine (pH > 8), and an indwelling urinary catheter are most likely infected with Proteus mirabilis, a gram-negative, oxidase-negative rod.

Question 41

Common cause of indwelling catheter UTI but urine is alkaline

Answer 41

proteus mirabilis

Question 42

Common cause of indwelling catheter UTI but urine is NOT alkaline

Answer 42

pseudomonas

Question 43

Charcoal yeast extract agar (buffered with cysteine and iron) is the medium used to culture and identify

Answer 43

legionella

Question 44

What major virulence factor does klebsiella pneumoniae have to evade host immune defenses

Answer 44

Klebsiella pneumoniae possesses a capsular polysaccharide that acts as an antiphagocytic virulence factor and allows bacteria to evade host immune defenses.

Question 45

Exotoxin A is produced by ______________________________, a gram-negative rod that can cause a lung abscess secondary to pneumonia, especially in patients with alcohol use disorder. However, lung infection by this is typically associated with green-colored sputum, not dark red sputum, due to the production of pyocyanin.

Answer 45

Pseudomonas aeruginosa

Question 46

What virulence factor in E coli is associated with risk for pyelonephritis

Answer 46

Pyelonephritis-associated fimbriae (P-fimbriae) are present on uropathogenic E. coli. a gram-negative rod that causes cystitis and pyelonephritis. E. coli can also cause a lung abscess secondary to pneumonia, but E. coli pneumonia is typically hospital-acquired, and P-fimbriae are not responsible for the pathogenesis of pulmonary infections. Instead, other virulence factors, such as the K capsule, are involved in the pathogenesis of E. coli pneumonia.

Question 47

Pseudomonas aeruginosa secretes exotoxin A, which inactivates elongation factor-2 (EF-2) by ADP-ribosylation. Since EF-2 facilitates the translocation of the growing peptide from the A site to the P site of eukaryotic ribosomes, deactivation of EF-2 causes______________________________________

Answer 47

inhibition of protein synthesis

Question 48

It is the primary virulence factor in gram-negative septic shock, as it induces the release of proinflammatory mediators including TNF-α, IL-1, and IL-6.

Answer 48

Lipooligosaccharide (LOS) is an endotoxin found on the outer membrane of gram-negative bacteria like Neisseria meningitidis. LOS has a lipid A. LPS and LOS are both very similar and can help facilitate shock.

Question 49

Meningococcemia is confirmed by the growth of the organism on ______________________ agar, which is a selective medium that is used to isolate Neisseria species like Neisseria meningitidis.

Answer 49

Thayer-Martin

Question 50

The medium commonly used to isolate P. aeruginosa is ..............

Answer 50

Cetrimide agar