Micro - Gram Negative Bacteria II Flashcards
enterics
gram negative bacteria part of normal intestinal flora
biochem properties of enterics
ability to ferment lactose
production of H2S
EMB agar
methylene blue inhibits gram positives
those that ferment lactose - deep purple to black
E. coli - metallic green sheen
gram negatives that ferment lactose
E. coli and most of enterobacteriaceae
cannot ferment lactose
salmonella, shigella, pseudomonas aeuriginosa
macconkey agar
bile salts inhibit gram positive
lactose fermenters develop pink-purple coloration
determining fecal contamination of water
presumptive test - test tube with lactose
-if ferment- continue
confirmed test - streak water on EMB
-E. coli should show up metallic green
completed test - green colonies in lactose broth again - if produce acid and gas, know you have E. coli
E. coli
coliform
-normal inhabitant of the intestinal tract
enteric surface antigens
O - differs among organisms
K - capsule
H - bacterial flagella
watery diarrhea without systemic symptoms
no cell invasion
-caused by exotoxin release in GI tract
enterotoxigenic E. coli and vibrio cholera
diarrhea with local white blood cell infiltrates in stool and fever as well as RBCs in stool
invasion of intestinal epithelium has occured
enteroinvasive E. coli, shigella, salmonella enteritidis
diarrhea with fever, headache, and white blood cell count elevation systemically
invasion of lymph nodes and blood stream
salmonella typhi
yersinia enterocolitica
campylobacter jejuni
E. coli cause disease
when get genes for virulence factors
can lead to diarrhea, UTI, neonatal meningitis, gram negative sepsis
montezumas revenge
travelers diarrhea
in adults and children
caused by E. coli
different types of E. coli
named based on virulence factors
enterotoxigenic E. coli
ETEC
travelers diarrhea
heat labile toxin
heat stable toxin
stool like rice water - like cholera
enterhemorrhagic E. coli
EHEC
shiga-like toxin
bloody diarrhea, severe cramps
hemorrhagic colitis
blood diarrhea
caused by EHEC
hemolytic uremic syndrome
anemia
thrombocytopenia
renal failure
EHEC - E coli 0157:H7
from infected hamburger meat
enteroinvasive E coli
EIEC
-same disease caused by shigella
bacteria invades epithelial cells
fever with bloody diarrhea with WBCs
cholera diarrhea
rice water
shigellosis diarrhea
bloody with white cells
pili virulence factor in E. coli
can travel up urethra
- infect baldder - cystitis
- infect kidney - pyelonephritis
most common cause of urinary tract infection
E. coli
usually in women and hospitalized patients with catheters
dysuria, frequency, and feeling of fullness over bladder
UTI
-most common - E. coli
Dx of UTI
greater than 100,000 colonies of bacteria in urine
most common cause of neonatal meningitis
1 - group B strep
2 - E. coli
most common cause of gram negative sepsis
E. coli
due to lipid A of LPS
second is klebsiella
klebsiella pneumoniae
causes sepsis
also UTIs in hospitalized patients with foley catheters
also pneumonia
- especially hospitalized patients and alcoholics
- get associated bloody sputum
thick sputum that looks like red currant jelly with pneumonia
klebsiella
high mortality
proteus mirabilis
very motile
-can break down urea
cross reacing antigens with rickettsia
UTI with alkaline pH
proteus mirabilis
antigens cross react in proteus mirabilis and rickettsia
OX-19, OX-2, OX-K
enterobacter
mobile, gram-negative rod
bright red pigment and causes UTIs, wound infections, and pneumonia
serratia
shigella
four species
- dysenteriae, flexneri, boydii, sonnei
- all non-motile - no flagella
- no lactose fermenting
- no H2S production
differentiate shigella, E. coli, salmonella
shigella - no lactose, no H2S
E. coli - lactose, no H2S
salmonella - no lactose, H2S
dysentery in preschool age children and in nursing homes
shigella
always a pathogen
shigella and salmonella
shiga toxin
causes cell destruction
-inhibits ribosome 60S - no protein synthesis - cell death
Vi antigen
on salmonella
-protects from attack on O antigen by antibodies
salmonella
non-lactose fermenter
motile
produces H2S
lives in GI tract of animals
eat uncooked chicken eggs
salmonella
salmonella typhi
typhoid fever
-carried only by humans
fever, headache, abdomen pain (diffuse or RLQ), diarrhea, rose spots rash on abdomen
typhoid fever
salmonella typhi
carrier of salmonella typhi
stored in gallbladder
-can spread
salmonella choleraesuis
affects lung, brain, bone
no GI involvement
patients with no spleen
difficulty clearing encapsulated bacteria
susceptible to salmonella
sickle cell anemia
prone to salmonella osteolyelitis
bone infection
most common type of salmonella infection
diarrhea
-nausea, abdomen pain, diarrhea (watery or mucous and trace blood)
