gram negative rods

Question 1

after identifying that a bacteria is a gram negative rod what is the next step in lab diagnosis ?

Answer 1

find out if it is lactose fermenting or not by usingg mackonkey agar

Question 2

most gram negative rods are resistant to ?

Answer 2

penicillin and vancomycin

Question 3

what type of patients are most commonly infected by klebsiella ?

Answer 3

people with impaired host defense so alcoholics, diabetics

Question 4

what is the usual case of klebsiella infection ?

Answer 4

usually happens due to the aspiration of GI contents and causes lung abscess which is anchovy coloured on aspiration

Question 5

what type of pneumonia is massociated with klebsiella ?

Answer 5

lobar pneumonia
classically makes a red currant jelly sputum

Question 6

what are the virulence factors associated with e coli ?

Answer 6

fimbrae - which usually cause UTIs
k capsule - K1 capsular antigen which cause meningitis in babies , inhibits phagocytosis

Question 7

what is the most likley source of Ecoli bacteremia ?

Answer 7

UTI infection by E coli

Question 8

what are the four different E coli diarrheal illnesses ?

Answer 8

enteroinvasive
enterotoxigenic
enteropathogenic
enterohemorrhagic

Question 9

what is the clinical picture associated with enteroinvasive E coli ?

Answer 9

EIEC is invasive and clinically similar to shigella but no toxin is made

Question 10

what are the two toxins associated with enterotoxigenic e coli ?

Answer 10

heat stable and heat labile exotoxin
no inflammation or necrosis

Question 11

which type of e coli is associated with travellers diarrhea ?

Answer 11

ETEC
shows watery diarrhea
no inflammation or invasion

Question 12

what is the problem with enteropathogenic e coli ?

Answer 12

no toxin or inflammation
just prevents absorption
blunting of the villi decreases the absorption
this usually happens in children

Question 13

does EHEC ferment sorbitol ?

Answer 13

no

Question 14

what are the mechanisms of action associated with nthe toxin in EHEC ?

Answer 14

toxin mediated
doesnt invade the cell
produces shiga like toxin

Question 15

what is the toxin effect of EHEC ?

Answer 15

endothelium swells , vessel lumen narrows
deposition of fibrin
hemolysis and inflammation

Question 16

what is the feared complication of EHEc ?

Answer 16

HUS

Question 17

what s the triad in HUS ?

Answer 17

hemolytic anemia
thrombocytopenia acute renal failure
Acute renal failure

Question 18

what is the oset of HUS in relation to te diarrhea in EHEc ?

Answer 18

HUS usually happens 5-7 days later

Question 19

what is the driving factor in gram negative sepsis ?

Answer 19

endotoxin LPS and Lipid A

Question 20

what are the common scenarios associated with gram negative sepsis ?

Answer 20

insertion of a catheter in a
elderly patient

Question 21

what are the features of diarrhea in
invasive infections
toxin mediated disease
protozoal infection ?

Answer 21

invasive infection - fecal leukocytes and RBCs
toxin mediated disease - mucous epithelial cells
protozoal infection - stool ova

Question 22

why is enterobacter resistant to many antibiotics ?

Answer 22

because of the presence of extended spectrum beta lactamases

Question 23

what is enterobacter usually treated with ?

Answer 23

carbapenems

Question 24

what are the two types of salmonella ?

Answer 24

salmonella typhi - cause typhoid fever
non typhoid strains - invasive gastroenteritis

Question 25

what is the classic cause of osteomyelitis in sickle cell patients ?

Answer 25

salmonella

Question 26

what is the cellular response in association with salmonella ?

Answer 26

mainly monocytes

Question 27

how is salmonella differentiated fro shigella ?

Answer 27

with a triple sugar iron test where the media turns black with salmonella but not with shigella

Question 28

what are the classic features of typhoid fever ?

Answer 28

1- rose spots on trunk and abdomen 2- pulse temperature dissociation ( high fever slow pulse ) 3- can hide i nthe gall bladder and cause a carrier state

Question 29

what is the treatment for typhoid fever ?

Answer 29

ceftriaxone and fluoroquinolone

Question 30

what drugs are contraindicated for diarrhea in salmonella ?

Answer 30

loperamide

Question 31

what cells are invaded by shigella ?

Answer 31

m cells in peyers patches

Question 32

what is the difference in terms of spread between salmonella and shigella ?

Answer 32

salmonella spreads in the blood stream whilst shigella spreads from one cell to the other

Question 33

what is the cellular response associated with shigella ?

Answer 33

PMN

Question 34

what are the similarities between shigella and salmonella ?

Answer 34

both are gram negative rods both cause bloody diarrhea and both are invasive

Question 35

what bis the cell to ell spread in shigella called ?

Answer 35

macropinocytosis

Question 36

what appearance does proteus have on agar ?

Answer 36

bulls eye appearance

Question 37

which bacteria is associated with struvite kidney stones ?

Answer 37

proteus

Question 38

what is the most common causative organism associated with VAP ?

Answer 38

psedomonas aeruginosa

Question 39

what pigment and odor does does pseudomonas produce ?

Answer 39

blue green pigment called pyocyanin sweet grape like odor

Question 40

what environment is most likely associated with pseudomonas aerigonsa ?

Answer 40

water sources

Question 41

what are the toxins associated with pseudomonas ?

Answer 41

PEEP endotoxin LPS phospholipase C which degrades the cell membrane exotoxin A which causes adp ribosylation of E2F

Question 42

what is the cause of pneumonia in patients with cystic fibrosis ?

Answer 42

pseudomonas aerigonsa and the mucoid polysacchride capsule which may contribute to the chronic pneumonia

Question 43

what bacteria are burn victims more susceptible to ?

Answer 43

pseudomonas aerugonsa

Question 44

what water associated infections does pseudomonas cause ?

Answer 44

otitis externa hot tub folliculitis

Question 45

what is the causative organism of mosteomyelitis in IV drug abusers ?

Answer 45

pseudomonas

Question 46

what are the manifestations of pseudomonas bacteremia ?

Answer 46

ecthyma gangrenosum black necrotic ulcers on the skin

Question 47

what is the classic case associated with ecythma gangrenosum ?

Answer 47

neutropenic cancer patient that is hospitalized and develops black lesions on the chest or back

Question 48

what cancer is associated with h pylori ?

Answer 48

MALT lymphoma

Question 49

what stain and medium is used for legionella ?

Answer 49

silver stain buffered charcoal yeast extract agar with iron and cysteine

Question 50

how is someone infected by legionella ?

Answer 50

inhaled bacteria outbreaks in nursing homes hotels with contaminated water

Question 51

what are the symptoms of legionella ?

Answer 51

watery diarrhea with pneumonia hyponatraemia ( confusion) no bacteria on gram stain

Question 52

what is the mild form of legionella ?

Answer 52

pontiac fever , no respiratory complaints