E. coli, shigella, salmonella, opportunistic enterobacteriacae Flashcards
Overall characterisitics?
Gram - rods Facultative anaerobes Oxidase negative Reduce nitrates to nitritie (Dipstick UTI) Motile except EIEC, shigella, klebsiella
K antigens found where?
Capsule polysaccharide
H antigens found where?
Flagella
O antigens found where?
LPS O side of gram negative
UTI?
E coli
Fecal samples cultured on what? Why?
MacConkey
blue: inhibits gram +
Lactose: red or pink=ferment
Lactose fermenters?
Pink on macConkey
Non-fermenters of lactose?
same color as macConkey
Slant agar color breakdown?
Yellow: ferment lactose makes acid (yellow)
Black: iron metabolism by hydrogen sulfide
Gaps: hydrogen gas
Treatment of enterobacteriacaeao?
rehydration
No need for antibiotics, unless bloody diarhea
Dysentary is what?
Bloody diarhea
What percent of diarrhea is caused by viruses?
90%
> 10-14 days is likely what?
Parasites: giardia
Chronic diarhea infection, think what?
HIV
E coli outside colon?
UTI
Sepriciemia and meningitis in neonates
HUGE killer in 3rd world
E coli virotypes?
EPEC: generic diarhea EHEC: hemoragic diarhea ETEC: toxic EIEC: invasive Aggregate ecoli:
EPEC virulence?
Type II secretion: injects its own receptor protein, changes locks to let itself into living on cell
Encodes a pedestal
Watery diarhea
EHEC virulence?
like EPEC +
O157:H7
Shiga toxin: bloody diarhea
EHEC mode of transmission?
Undercooked beef
Fruits, juices, vegetables
Human to human
EHEC presentation?
Little fever
Acute cramps
Watery diarhea>bloody within 24 hours
EHEC diarhea lasts how long?
8 days
hospitalization often necessary
Shiga toxin MOA?
INFLAMMATION AB toxin Cleave 28S RNA of ribosome Kills cell by destroying protein production Lysogenic phage encoded
What is LEE?
DIARRHEA Locus of enterocyte effacement PAI: type III secretion system delivers receptor to host cell pedestal formation diarhea
Shiga toxin can do what in children?
Hemolytic uremic syndrome via killing cells
What is color of EHEC O157:H7 on sorbitol MacConkey?
White (other STEC and e coli are red/pink)
Tx for EHEC?
NOT ANTIBIOTICS!!!
stress bacteria can increase Shiga toxin production, leading to HUS
FLUID REPLACEMENT, blood transfusion
O157:H7 cannot use what?
Sorbitol : diagnosis
ETEC virulence factors?
Traveler’s diarhea
CFA 1 or 2: attachment
LT: heat labile toxin: choLera toxin mode
ST: heat stable toxin: not AB: hormone like
EIEC is like what?
Shigella
Lactose -
non-motile
dysentery
EIEC is unique in what way?
Intracellular: makes tails and pushes into next cell
EPEC is what?
Generic… no toxins… ust watery diarhea
K1 antigen e coli causes what?
Neonatal meningitis
UPEC is what?
UTI e coli (90%)
UPEC virulence factor?
P fimbriae: PAP villi
K capsule
Which e coli is most common in the US? Why?
EHEC: O157:H7
We eat more BEEF
Salmonella culture means what?
Infection: not normal flora
What does salmonella typhi cause?
Not GI: typhoid fever
Salmonella culture?
Gram - Lac - Glu + gas+ : cracks H2S
How do we tell difference between E coli and salmonella on MacConkey?
White colonies, not Pink
Two main salamonellosis bugs?
s. enteriditis
s. typhimurium
from: meat, dairy, eggs, pet turtles, reptiles, humans
Salmonella virulence factors?
PAI type III secretion system injects: M cell target Membrane "ruffles" endocytose bacteria Bacteria cross basal membrane Enter lamina propria Kills macrophages Inflammation
What does salmonella invade?
M cells
Lamina propria
What is the timeline differences for toxins, viruses, bacteria?
Toxins: 3-4 hours
Virus: quick
Bacteria: 20+ hours to establish
Salmonella can disseminate to where? in who?
HIV, sickle cell kids: elderly and young
Osteomyelitis (sickle)
Bacteremia (HIV, cancer patients)
Endocarditis
Renal problems
s. Typhus enters blood how?
M cells Survive in macrophages Spread to mesenteric lymph nodes Ruptured spleen Vi capsule inhibits neutrophil uptake Sepsis
Perforations of GI tract at necrotic Peyer’s patches can lead to severe hemorrhage
Presentation: Insidius rising fever with headache, abdominal pain, slow pulse, mental confusion, ruptured spleen or intestine
Typhoid fever
Tx for typhoid fever?
Ceftriaxone
Oral vaccine for travelers to endemic areas
Three types of shigella and where?
s dysenteriae: central and south america: high Stx
high fatality rate
HUS
s sonnei: US, children, 70% of cases in US
less bloody, more watery
s flexneri: most common worldwide, 2nd in US
Gay men STD
Shigella is most common in who?
Children, institutions, gay men
Shigella culture?
Gram -, non motile rod Lac- Glu + no gas no H2S leukocytes prominent in stool
Presentation: acute bloody diarrhea in kid/gay man
Shigella
S. sonnei is notable for what?
Less bloody, more watery
Yersinia mimics what?
Appendicitis
Klebsiella buzzwords?
Alcoholics
Currant jelly sputum
Proteus and Morganella buzzwords?
UTI