Bacteria Ch16-17 Enteric Bacteria Flashcards
describe enteric bacteria and where are they found
-gram negative bacilli
- human and animal flora
- commensal groups that have become pathogenic due to acquired virulence factors like toxins from plasmids, bacteriophages or pathogenicity islands
which enteric bacteria are motile and what flagella do they have
H-antigen with peritrichous flagella
which enteric bacteria are non motile
shigella, klebsiella, yersinia
what type of surface pili do enteric bacteria have
fimbriae for adherence and sex pili for plasmid conjugation
which enteric bacteria have capsules and what kind
- klebsiella enterobacter and E coli
- K or Vi antigen
the enteric bacteria have LPS with
enterobacterial common antigen and serotype specific O antigen
when bacteria have a toxin like cholera toxin:
get watery diarrhea
when bacteria have a toxin like shiga toxin
get blood in diarrhea
when inflammation and neutrophils what happens to diarrhea
pus in diarrhea = dysentery
how are enteric bacteria transferred
- human to human
- seven F’s: feces, food, fluids, fingers, flies, fomites and fornication
what are the enterobacterial common antigen in LPS
outer and inner core sugars
what is the LPS also known as
heat stable enterotoxin
what does Lipid A do
activates inflammatory responses of macrophages
LPS get shed from______ and is bound by _______.
bacteria; plasma protein
what is the primary basis for serotyping
O-antigen
what are the virulence factors of enterobacteriaceae
- endotoxin
- capsule
- H antigen
- antigenic and phase variation
- sequestration
-antibiotic resistance - type III secretion system
what enterobacteriaceae have endotoxin
aerobic and some anaerobic gram negative bacteria
what does endotoxin (LPS lipid A) do
- complement activation
- induces macrophages to secrete inflammatory cytokines which induces fever, clotting, vascular dilation, smooth muscle contraction, shock, death
what does capsule (K antigen or slime) do
antiphagocytic: ineffective humoral response
what is H antigen
flagella protein (flagellin)
what is pathogenicity island
chromosomal location with multiple virulence factors and toxin genes, readily transferable together by conjugation
what amount constitutes severe watery diarrhea
greater than 20L per day
what is the virulence factor for cholera
cholera like AB- exotoxin heat labile enterotoxin
what bacteria is type III secretion system present in
yersinia, salmonella, shigella
how is e coli transmitted
-person to person
- contaminated food
- human and animal feces
what are the E. coli virulence factors
- heat labile enterotoxin LT
- shiga toxin
what is another name for heat labile enterotoxin LT and whats the mechanism
- Traveller’s diarrhea
- ADP ribosylation of G protein -> cAMP increase -> loss of water + electrolytes -> watery diarrhea
what does the shiga toxin do
inactivation of 60S ribosome subunit by removal of a specific adenine base from a nucleotide of 28S rRNA -> stop translation -> cell death -> bloody diarrhea
what are the symptoms of shigella dysenteriae
diarrhea with blood
- intestinal cell invasion
- apoptosis
- neutrophilia
what is the general treatment for diarrhea
- oral rehydration
- to 1 liter of water add:
- 1/2 teaspoon salt
- 1/4 teaspoon bicarbonate
- 1/4 teaspoon KCL
- 4 tablespoon sugar
what clinical symptoms does enterohemorrhagic E coli strain cause and whats the treatment
- blood diarrhea, hemorrhagic colitis, hemolytic uremic syndrome
- replenish fluids
- antibiotics are contraindicated
what is the clinical symptom of uropathogenic e coli strain
cystitis (bladder infection)
what percentage is e coli of enteric bacteria
70-90%
what is the mechanism of uptake for shigella dysenteriae
-shigellas are taken up by M cell and transported beneath the epithelium. macrophages take up shigellas, die and release the bacteria
- the bacteria enter the inferior and lateral aspects of the epithelial cells by inducing endocytosis. the endosomes are quickly lysed, leaving the shigellas free in the cytoplasm
- actin filaments quickly form a tail pushing the sigella into the next cell
- shigellas mutliply in the cytoplasm and the infection extends to the next cell
- infected cells die and slough off. intense response of acute inflammatory cells, bleeding and abscess formation
- apoptosis
what is the epidemiology of shigella dysenteriae
transmission via fecal oral route; sometimes by fecally contaminated food or water, humans generally the only source
what are the shigella dysenteriae virulence factors and what do they cause
-shiga toxin: bloody watery diarrhea
- cell invasion -> neutrophils -> pus
describe S. enterica
- enteric fever
- human resevoir
- typhoid
- high mortality
what do many salmonella species cause
-gastroenteritis
- foodborne illness
-poultry resevoir
what are the virulence factors for salmonella
- type III secretion induced enteric epithelial uptake via M cells
- intracellular endosome growth in macrophagaes
- through macrophages: invasive into different tissues and organs
- destruction of peyers patches -> intestinal rupture
describe the mechanism of salmonella invasion of intestinal epithelia
-M cell uptake through ruffles: transport through epithelial layer
- electrolyte release to lumen (diarrhea/gastroenteritis)
- release of inflammatory exudate
- transport to lymph nodes/transient bacteremia
what is the mechanism of typhoid fever
- ingestion of S.typhi -> small intestine -> inflammation and ulceration of peyer patches -> diarrhea, hemorrhage and perforation
- AND goes to mesenteric lymph nodes -> thoracic duct -> transient bacteremia -> multiplication in macrophages in liver, spleen, and bone marrow -> bile-> gallbladder -> bile -> small intestine
- galbladder -> cholecystitis, carrier state
- multiplication of macrophages -> speticemia -> fever, kidney and other organs infected
describe vibrio cholerae and where is it found
- gram negative vibrio
- estuaries and marine environments
what are the virulence factors of vibrio cholerae
- toxin co-regulated pilus: adhesion to small intestinal epithelia
- cholera toxin: protein A causes cAMP rise and watery diarrhea
- an additional toxin “ST” can raise cGMP levels with a similar effect
- neuraminidase-increase cholera toxin binding
what is CTX phi
a bacteriophage
where is TCP production induced
within the intestine while production in other environments appears to be minimal
what does TCP stand for
toxin coregulated pilus
what encodes the proteins that comprise cholera toxin
ctxA and ctxB
what is the treatment for cholera
-formalinized whole cell vaccine
- several sodes; partial protection for 2-3 years
what is the common epidemic strain for cholera
serovar O1
what is the new strain of cholera and the new virulence factor
- serovar O139 with capsule
what are the virulence factors for vibrio cholerae
- cholera toxin
- toxin coregulated pili
- toxins
- neuraminidase
what are the clinical features for vibrio cholerae
- severe watery diarrhea
- disease is self limiting as intestinal cells with surface bacteria are shed
what is the treatment for vibrio cholerae
rehydration and electrolytes
what is the epidemiology for vibrio cholerae
-fecal transmission in developing countries
- under cooked coastal crabs
what type of microbe is vibrio cholerae
- aerobic/ facultatively anaerobic
what type of microbe is enterobacteriaeae
aerobic/facultatively anaerobic
describe campylobacter jejune
-gram negative vibrio
- short S or comma shaped rods
-oxidase positive
how is campylobacter jejune transmitted and what disease does it cause
- zoonosis: animal reservoir (intestinal)
- transmission: contaminated food (poultry, milk)
- disease: gastroenteritis, diarrhea, dysentery
how long does it take for campylobacter jejune to resolve without treatment and what type of immunity does it create
-less than a week
- creates protective immunity
what are the virulence factors for campylobacter jejune
- LPS
- capsule
- cytolethal distending toxin
- growth in intestinal tract: invade intestinal epithelial cells or grow below epithelial layer and inflammatory response
does campylobacter jejune cause bacteremia
rarely
what type of microbe is campylobacter
aerobic/facultatively anaerobic
what are the virulence factors for C jejune
-adhesion
- invasion of mucosal epithelia
what clinical symptom does C jejune cause
gastroenteritis
