Exam 4: gram - rods Flashcards
The bacterial group of gram negative rods are also known as ___
the enteric, because they cause digestion issues
The enterobacteriacae family contains what bacteria?
E. coli k. pneumoniae enterobacter serratia proteus salmonella shigella
What three gram negative rods are considered coliforms?
E coli
K pneumoniae
enterobacter
How are coliform bacteria defined?
- facultative anaerobes
- ferment lactose
- gram negative
- non-endospore forming
- rod shaped
What is the pathogenesis of E-coli?
septicemia, UTI, meningitis, gastroenteritis
severity is dependent on which strain of E. coli
Why is there such great serological variation in E coli?
they transfer DNA via conjugation and transposons.
lysogenic conversion allows “swapping” of virulence factors
How is E-coli diagnosed?
produces green metallic sheen on EMB agar, use IMViC to distinguish from enterobacter
There are 4 different strains of E coli that cause gastroenteritis. what are they?
- enterotoxin producing E. coli (ETEC)
- enteroinvasive E. coli (EIEC)
- enteropathogenic E. coli (EPEC)
- enterohemorrhagic E. coli (EHEC)
Which strain of E. coli causes “traveller’s diarrhea”?
enterotoxin producing E. coli
Which strain of E. coli invades the intestinal cells and has its main virulence factor encoded on plasmid that is shared by Shigella and E. coli?
enteroinvasive E. coli
Which strain of E. coli does NOT invade intestinal cells but rather adheres to them by adhesins coded on plasmid that destroy microvilli on intestinal cells where microbe attaches?
enteropathogenic E. coli
Which strain of E. coli produces verotoxin which blocks the protein that functions to prevent the cell from undergoing apoptosis which causes severe abdominal pain, bloody diarrhea and can lead to hemolytic uremic syndrome (HUS)?
enterohemorrhagic E. coli
How are strains of Klebsiella pneumoniae classified?
by their capsule proteins
Klebsiella penumoniae is the second most common cause of ____ in hospitalized patients and _____ in infants?
sepsis, septicemia
What is the most common species of enterobacter and what does it cause?
enterobacter aeruginosa causes UTI
What is unique about enterobacter aeruginosa?
it produces ornithine decarboxylase
What common opportunistic pathogen in hospitalized patients causes pneumonia, bacteremia and endocarditis and is characterized by a red pigment?
serratia
What opportunistic pathogen is characterized by a swarming behavior on agar and presence of urease enzyme that breaks urea to produce a sherry red color?
proteus
What pathogen most commonly causes typhoid (AKA enteric) fever?
salmonella typhi
After recovering from typhoid fever, humans can harbor the bacteria where?
gallbladder
How is salmonella transmitted?
oral-focal route, food/water contaminated with feces
What does it mean to say that salmonella bacteria are facultative intracellular parasites.
during invasion, the bacteria are phagocytize by monocytes but survive and divide inside the monocyte
salmonellosis starts ______ after exposure and only a low infective due is required to cause disease.
1-3 weeks
In typhoid fever, salmonella initially invades intestinal cells and then moves to _____ and other organs, especially _____.
lymph nodes, spleen
