Gram Negative Rods Enterobacteriaceae Lawrence Flashcards
1
Q
Enterobacteriaceae
A
- metabolically active and a variety of substrates
- primary inhabitanst of lower GI
2
Q
E. coli
A
the most common species
3
Q
Salmonella and Shigella
A
Certain strains of E.coli and Yersinia species are primary pathogens and not part of the normal flora
4
Q
Morphology
A
- medium sized gram negative rods
- many have fimbriae
- most have capsules and /or slime layer
- cell wall
5
Q
Antigenic structures
A
LPS, capsule/slime layer, and flagella are flagella (proteins)
6
Q
classification
A
- many biochemical tests
- facultative anaerobes
- ferment glucose
- reduce nitrates to nitrile
- cytochrome oxidase negative
- the most common members of the intestinal flora ferment lactose promptly in more than 90% of isolates
- many other genera (shigella and Salmonella) are rarely positive
7
Q
Toxins
A
- all posses LPS (endotoxin)
- Some also produce exotoxins
8
Q
Pathogenicity
A
- GI or systemic infections
- most common sites of opportunistic infection: wound and urogenital tract infections
- but may occur at any body site, especially in septicemia
9
Q
E. coli occurrence
A
- causes enteric diseases, septicemis, UTI, and mastitis
- most common isolate of normal flora from opportunistic infections
10
Q
Serotyping
A
fimbrial antigens as F antigens
used to be K
11
Q
Enteric diseases
A
six classes of E. coli
12
Q
ETEC
A
-enterotoxigenic
-cause of diarrhea in infants and travelers
diarrhea without fever
-do not invade, just sit on surface
13
Q
EPEC
A
- enteropathogenic
- watery diarrhea without fever or blood
- lose a lot of the microvilli
- attach to pedestal, type III secretion, inject toxin into the body
- attach, do not invade
14
Q
EHEC
A
- enterohemorrhagica
- bloody diarrhea but no fever
- Attach through the pedestal structure, type three secretion system and attach onto the surface
- They produce a shiga toxin, target is the epithelial cells that line the blood vessels and cause hemorrhage
- attach, do not invade
15
Q
EIEC
A
- enteroinvasive
- penetrate and multiply withinepithelial cells of the colon, causing widespread cell destruction
- lack fimbrial adhesins, LT or ST toxin, and shiga toxin
- cause watery diarrhea with blood and fever and sever pain
- primary pathogen in monkeys
