Bacterial and Viral GI Infections (Quiz 2) Flashcards
what feature of GI bacteria allows them to live in the stomach and survive stomach acid
- those without envelopes (have sturdy capsids)
- secretion of enzymes to buffer pH (H. pylori & urease)
- inherent acid resistance (Shigella spp.)
how does bacterial overgrowth syndrome occur
symptoms it can cause
- decrease amount of acidity in the stomach
- increase number of microbes
- grow further into the stomach/small intestine
- vitamin deficiencies
- fat malabsorption
- malnutrition
which classification of enteric bacterial pathogens is caused by facultative intracellular pathogens and relies on invasion of host cells
examples and gram stain
- enteroinvasive
- Salmonella enterica (gram -)
- Shigella (gram -)
- Yersinia enterocolitica
- Campylobacter jejuni (gram -)
- Listeria monocytogenes (gram +)
- Enteroinvasive E. coli
ENTEROINVASIVE BACTERIA ARE CLESSY
which classification of enteric bacterial pathogens is caused by bacteria that produce enterotoxin and invasion does NOT play a role in disease
examples and gram stain
- Enterotoxic
- Vibrio cholerae (gram -)
- ETEC
- C. diff
VEC
which classification of enteric bacterial pathogens is caused by bacteria that destroy epithelium and invasion does NOT play a role in disease
example and gram stain
- Enteropathogenic
- EPEC (gram -)
- EHEC (gram -)
- H. pylori
HEE!
which classification of enteric bacterial pathogens does invasion play a role in disease
- Enteroinvasive
rice water stool associated with which bugs
- V. cholerae, ETEC
they secrete bacterial toxins
Typhoid group of Salmonella enterica affects what species
what about nontyphoid salmonella enterica
- humans only
- animals and humans
Salmonella enterica serovar typhi is a _________ pathogen
states of typhoid fever
where does it colonize?
describe its infection
- obligate human
- carrier state with shedding of bacteria
- biliary duct
- starts out as GI infection and disseminates to other organs in a systemic infection
infectious dose of S. enterica typhoid variant
what about non-typhoid
- low
- high
are antibiotics recommended as treatment for S. enterica typhi
which ones?
what about non-typhoid variants
- yes
- Ciprofloxacin or Ceftriaxone
- no
where does Shigella colonize
how?
motility patterns of Shigella spp
any animal reservoirs?
how is it transmitted
treatment
- lower intestine of humans
- acid resistant
- nonmotile
- no animal reservoirs
- person-person
- rehydration +/- Antbiotics
where would you find:
S. sonnei
S. flexneri
S. dysenteriae
- US and developed world
- developing world
- epidemics
why do we generally not give people with shigellosis antibiotics
which antibiotic
- can cause hemolytic uremic syndrome
- ciprofloxacin
Shiga toxin of S. dysenteriae and EHEC
where is its G3b receptor expressed
- A+B toxin
- blocks absorption of glucose, electrolytes, and amino acids
- associated with development of HUS
- endothelial cells of intestine, kidney, and brain
C. jejuni requires what kind of agar to grow
- charcoal
what is the most common bacterial cause of diarrheal disease in the US
shape
what is its infectious dose
treatment
- Campylobacter
- cork-screw rod
- low infectious dose
- rehydration
which bacteria grows at refrigerator temp
hosts
treatment for invasive infections
- Listeria monocytogenes
- range of hosts, humans, birds, fish
- IV antibiotics (ampicillin and gentamicin) for 14-21 days
motility pattern of L. monocytogenes
- actin-based
- propels from one cell to another using host actin so it doesn’t have to enter extracellular environment
how Listeria is spread
common objects?
- foodborne
- mother-child
- dairy
- processed meats
what population do we worry about with listeria
why
- pregnant women
- they may have mild flu-like symptoms but can cause series defects for their baby like miscarriages, stillbirth, and pre-term labor
- can also cause CNS infection in neonates
where do you normally find Vibrio in the environment
any infected animal hosts?
important shape of vibrio
transmission by
- fresh, brackish or marine water
- on shells of crustaceans
- no (humans only)
- comma-shaped rod
- contaminated water or food
how do cholera toxin and ETEC labile toxin work
- A+B toxin
- activates adenylate cyclase which results in secretion of electrolytes and water resulting in profuse, watery diarrhea
what do Enterotoxigenic E. coli do
- deliver enterotoxin
what do Enteropathogenic E. coli do
- adhere to and damage epithelium, but don’t invade
what do Enteroinvasive E. coli do
- invade, escape phagosome, and spread to adjacent cells
what do Enterohemorrhagic E. coli do
- deliver shiga toxin
what enteric viruses has
dsRNA, segmented
dsDNA virus
ss+RNA viruses
- rotavirus
- adenovirus
- norovirus
- astrovirus
- enteroviruses
how do enteric viruses differ from enteroviruses
- with enteroviruses, infection and disease occurs in other sites after GI replication
what are the enteric viruses
- rotavirus
- norovirus
- astrovirus
- adenovirus
what are the enteroviruses
- poliovirus
- coxsackievirus
- hepatitis A
which virus has a viral protein that acts like an enterotoxin
what viral protein
what does it do
- rotavirus
- NSP4
- affects Ca2+ flux in uninfected enterocytes
Rotavirus mostly affects what age group
- 6 mo - 2 years
seasonal epidemic of rotavirus
- fall - SW
- spring - NE
treatment of rotavirus
- rehydration
is there a vaccine for rotavirus?
which ones?
- yes, there are two
- Rotarix
- RotaTeq
which virus is the most common cause of viral gastroenteritis in adults and adolescents
what part of the body does it infect
treatment
- norovirus
- villi in jejunum
- rehydration
importance of poliovirus
- can cause poliomyelitis - inflammatory disease of gray matter in spinal cord
which polio vaccine is the inactivated vaccine
what kind of antibody response does it generate?
what does it protect against
- Salk
- IgG; no IgA induced
- paralytic polio
which polio vaccine is the oral polio live vaccine virus
what antibodies does it stimulate
do we use it in the US? Why?
- Sabin
- oral and duodenal IgA, serum IgG
- why? Can mutate back to neurovirulence
what does Coxsackie virus cause
- hand-foot-mouth disease
non-polio enterovirus infections are generally during which seasons
where are they normally found
- summer to fall
- water supplies
two types of damage for enteric GI pathogens
- inflammatory
- secretory diarrhea
what bacteria will grow on Lactose MacConkey agar
- gram negatives
how does Salmonella enterica survive gastric passage
- acid-tolerant
Salmonella enterica affects what species
Salmonella bongori affects what species
- mammals and reptiles
- replies only
which virus are outbreaks more common in infants or elderly
- astrovirus
