Lecture 9 -- Vibrio, Campylobacter, and Helicobacter Flashcards
differentiate between the growth conditions of vibrio cholerae, campylobacter jejuni, and helicobacter pylori
vibriocholerae = facultative
campylobacter jejuni and helicobacter pylori = microaerophilic
what diseases does vibrio cholereae cause?
cholera (watery diarrhea
state which have urease enzyme between:
vibrio cholereae
campylobacter jejuni
helicobacter pylori
only helicobacter pylori has urease
vibrio are gram _______ and oxidase ____
what conditions do they grow in?
give their shape and general characteristices
vibrio are gram NEGATIVE
facultative anaerobic bacteria
oxidase negative
curved rods with polar FLAGELLA
true or false
vibrio are NEVER commensal
true
in order for a significant vibrio disease to occur, what must happen?
a siginificant number of the vibrio must be ingested
where are vibrio primarily found?
what do they require for growth
in water. require NaCl for growth
cholera is a severe _____ disease
diarrheal
name the toxins of vibrio cholereae
endotoxin – LPS/LOS (bc gram negative)
cholera toxin
explain in detail the cholera toxin – its structure and how it accomplishes its goal
the cholera toxin (A2B5) is carried on a bacteriophage which binds to the vibrio cholereae sex pilli.
this causes the activation of adenylate cyclase which leads to the overproduction of cAMP and an excess of ions leaving the cell. this causes fluid also to exit = diarrhea
the cell dies due to the osmotic pressure
what is the “classical” vibrio cholerae serotype, responsible for 7 major pandemics?
VO1 El Tor
what is a newer strain of vibrio cholerae?
VO139 Bengal
the 1st non-VO1 strain.
cause of major disease in 1992
explain how VO139 Bengal was able to cause major disease in 1992
it gained the ability to make a capsule
this mutation traced to the insertion of a NEW SEQUENCE in the O1 gene. this created a new virulent strain.
caused major disease bc previous VO1 exposure provided no immunity to this new strain
what are the 4 species of campylobacter associated with human disease?
campylobacter….
jejuni
coli
fetus
upsaliensis
explain the growth conditions of campylobacter jejuni
MICROAEROPHILIC – like to grow in low oxygen bc they dont have CATALASE that can inactivate peroxide, superoxide that are only present in high O2 environments
what kind of diseases does campylobacter jejuni cause?
gastroenteritis and septicemia, watery diarrhea, dysentery (infection of the intestines)
EXTRAINTESTINAL INFECTIONS — Guillain-barre syndrome
how can someone get campylobacter jejuni?
carried by animals and also by consuming unpasteurized milk
does campylobacter contain urease?
no
explain the structure of campylobacter jejuni.
gram positive or negative?
thin, curved GRAM NEGATIVE rods
is campylobacter jejuni motile?
YES – has polar flagellum
which is more common — campylobacter jejuni or salmonella?
campylobacter jejuni
what does it mean to say that campylobacter jejuni are zoonotic
they are commonly in animals – along with other campylobacter species
what extraintestinal infections does campylobacter jejuni cause? explain what it is
guillan barre syndrome
autoimmune disorder of the PNS. causes progressive, transient muscle weakness.
explain how guillan barr syndrome is an autoimmune disorder
the antibodies created against the campylobacter jejuni and upsaliensis pathogen attack the peripheral nervous tissue instead
name the campylobacter toxins and their function
CDT and LOS/LPS
CDT = cytolethal-distending toxin (AB2 exotoxin)
has DNase activity and causes cell cycle arrest
LOS/LPS are classic endotoxins to gram negative bacteria
what are the only known bacteria that can survive in the stomach?
helicobacter
explain helicobacter classification
there are 2 groups — gastric and enterohepatic
gastric – helicobacter pylori
enterhepatic – helicobacter cinaedi and fennelliae
which helicobacter causes gastritis, ulcers, and gastric cancer?
the gastric helicobacter – h. pylori
does h. pylori contain urease?
YES — this is used to make ammonia and CO2 from urea which counteracts the acid of the stomach — raises the pH so that h. pylori can survive in the stomach.
VERY UNIQUE
Explain the growth conditions of H. pylori
microaerophilic
where is h. pylori found?
in humans and gastric secretions
how does h. pylori adhere to cell surfaces?
OMPs
flagella are characteristic features of bacteria that infect where?
the stomach
explain the structure of H. pylori
is it gram positive or negative?
curved or spiral GRAM NEGATIVE rods
when mature = coccoid form (spherical)
is H. pylori catalse positive or negative?
positve
is h pylori mobile
YES – highly motile
has flagella
characteristic of bacteria that infect the stomach
what is so dangerous about H. pylori?
they can establish a chronic colonization of the stomach — prone to stomach cancer
explain the enzymes of H. pylori
bacterial acid-inhibitory protein
urease activity
mucinases & phospholipases
does h. pylori have adhesins?
yes – OMPs
to adhere to gastric epithelium
what is the function of mucinases and phospholipases in h. pylori?
mucinases — breaks down mucus membranes in the stomach (necessary for infection)
phospholipases – break down cell membranes
what kind of toxins does h. pylori contain
vacuolating cytotoxin A (VacA) – pore forming exotoxin that causes damage to gastric epithelium. makes vacuoles in the cells
Cag – cytotoxin associated gene (cagA)
-this is delivered by a TYPE 4 SECRETION SYSTEM
-this toxin interferes with p53 (causes programmed cell death)– linked to causing gastric cancer
which kind of bacteria have secretion systems?
only gram negative can have secretion systems
does h. pylori get into the blood
no
the bacterial classifications mentioned earlier (gastric and enterohepatic) are put into these categories based on what?
the site of colonization
what kind of clinical diseases does H. cinaedi and H. fenneliae cause?
gastroenteritis (may be linked to IBS) and can cause bacteremia (pretty rare)
what kind of clinical diseases does H. pylori cause
gastritis (acute or chronic)
ulcers
chronic infection – tissue is replaced by fibrotic growth (risk for cancer)
cancer = MALT lymphoma
