GI 1 Flashcards
what happens as you move lower and lower down the gastrointestinal tract
you get less and less oxygen hence you have anaerobes in the GI tract
at what age does the GI of an infant resemble that of an adults
2
when do you see microbes in the stomach
when person has gastritis/duodenal ulcers because they take antacids which neutralizes the acid in the stomach –> colonization of bacteria
with growth of teeth, what microbes do you start to see
s. sanguis and s. mutans (seen on dental plaques)
s. salivarius
where do you see the largest amount of bacteria
large intestine
some anaerobes you will find in the large intestine
Bacteroides, Bifidobacterium, Eubacterium, Peptostreptococcus & Clostridium Plus Enterobacteriacea
what organisms are involved in dental caries
lactobacillus spp and strep spp
how does lactobacillus work
lactobacillus in plaque metabolizes sugars to form lactic acid which destroys the enamel of teeth
organisms involved in periodontal disease
anaerobic bacteria
how do people tend to get esophagitis
usually the non infectious route due to gastroesophageal reflux disease
though infectious route of getting esophagitis is uncommon, what types of people get it this route
chemo, transplant, HIV
what are the etiological agents in infectious esophagitis
- Candida albicans, CMV, HSV
- Rare: Mycobacterium tuberculosis, Mycobacterium avium complex, Cryptococcus neoformans, Histoplasma capsulatum, Actinomyces, Cryptosporidium, Pneumocystis jirovecii, VZV, EBV
for esophagitis, how do you differentiate between
candida: predominant pathogen
CMV - “shallow” ulcers
HSV - volcano ulcers
how do you diagnose esophagitis
endoscopy
brushing and biopsy
what are the upper GI infections
oral disease (dental caries and periodontal disease) and esophagitis
at risk population for lower GI infections
children under 5 years old
elderly
immunocompromised
what is FDA ranking of food hazards
- Microbial contamination
- Naturally occurring toxicants
- Environmental contaminants (e.g., metals)
- Nutritional problems (i.e., malnutrition, undernutrition)
- Pesticide residues
- Food additives
biggest cause of gastroenteritis
norwalk virus
these 3 microbes are also major causes of gastroenteritis and are routinely checked for in stool
campylobacter
salmonella
shigella
also a major cause of gastroenteritis, this microbe is checked for if bloody stool
STEC O157:H7
two big known causes of food borne illness outbreaks in US from 2006-2010
norovirus
bacteria
characteristic of foods that most likely cause food poisoning
highly nutritious and are neutral in pH
food borne diseases that have extremely long incubation period
hep A and listeria monocytogenes (both over 2 weeks)
food borne diseases that have short incubation period
staph aureus, vibrio parahaemolyticus, clostridium perfringens (all within a day)
how do you differentiate between food borne and food poisoning
the incubation period with food poisoning taking shorter before onset of symptoms
microbes involved in food poisoning
toxins from c. botulinum, s. aureus, b, cereus
fungal and marine toxins
difference between food borne and food poisoning
in food borne, you eat the food containing the organism that will lead to the symptoms while in food poisoning you actually ingest the toxin
difference between colitis and enterocolitis
colitis is inflammation of LI
enterocolitis is inflammation of SI and LI
define dysentery
inflammation of GI tract with blood and pus in feces
difference between enteritis and gastroenteritis
enteritis is inflammation of the intestinal mucosa
gastroenteritis is inflammation of stomach and intestinal linings
differentiate between the three types of diarrhea
acute is less than 2 weeks
persistent is between 2-4 weeks
chronic is greater than 4 weeks
if one has gastroenteritis with vomiting as the first symptoms, what are the most likely causative agents in infants and older children.adults
infants - rotavirus
older children/adults - norwalk like virus
food poisoning due to performed toxins
bacterial, fungal, marine/algae involved in food poisoning
bacteria - b cereus, c botulinum, s. aureus
fungi - wild mushrooms (amanita, clitocybe, and psilocybes) and aflatoxin (aspergillus)
marine/algae - ciguatera, scombroid, shellfish
symptom of food poisoning
-usually rapid
vomiting, diarrhea, no fever, no fecal leukocytes
what is the exception to rapid onset of food poisoning
c. botulinum which can take anywhere from 6hrs - 8 days
which food poisoning toxin affects just the CNS
C. botulinum
which food poisoning toxin affects CNS and intestine
s. aureus, b. cereus, mushroom and marine
describe the bacteria that is both coagulase and catalase positive
staph aureus is a gram positive bacteria that is arranged in singles, pairs, and clusters
type of toxin does staph aureus release
ST (heat stable) enterotoxin/exotoxin
enterotoxin and infective does of staph aureus
A, B, C1, C2, C3, D, E, H
10^5-10^8
what is the mode of action for staph aureus
act on gut receptors
stimulate vomiting (vagus and sympathetic nerves)
no adenylate cyclase
symptoms of staph aureus food poisoning
watery diarrhea, headaches, muscular cramping/prostration, nausea, abdominal cramp
most common solution for staph aureus
self limiting so will resolve completely in 24-48hrs
incriminated foods in staph aureus
cooked meat (fish, poultry), bakery foods (cream-filled), dairy produce, fruit, vegetables & salads
when is staph aureus food poisoning commonly seen
in summer
then in nov/dec – holiday period
what is used for diagnosis of staph aureus
baird parker and coagulase test
habitat for staph aureus
human and animal pathogens so on skin
