Body Sites (stool) Flashcards
What is an infant’s gastrointestinal tract colonized with?
Normal skin flora
Which types of bacteria are most commonly found in the distal ileum of the GI tract?
Enterics, Bacteroides spp.
Which is the most sparsely populated area if the GI tract?
The upper small intestine
In the adult large bowel, by how much do anaerobes outnumber aerobes?
1000 to 1
T or F? Worldwide, diarrheal disease is 2nd leading cause of death.
True
How is diarrheal disease most often transmitted?
By the fecal/oral route or contaminated food/water
T or F? Acute diarrheal syndromes are not usually self-limiting
False, they usually are.
What are some factors of host defense against GI pathogens?
Acidity of stomach
Normal peristalsis
Mucous layer coating the epithelium (GALT)
Normal flora, preventing colonization by potential pathogens
What are some pathogenic microbial factors of GI pathogens?
Toxins: enterotoxins, cytotoxins, and neurotoxins
Attachment mechanisms
Invasion of the host’s intracellular environment
What are the 4 most common bacteria that cause food poisoning by intoxication?
Staph aureus, Bacillus cereus, Type A. Clostridium perfringens (watery diarrhea) and Clostridium botulinum
What type of diarrhea is described? Fluid & electrolyte balance upset
No Fecal Leukocytes present
Watery diarrhea
What type of diarrhea is described? Cell destruction and inflammation occur
Fecal Leukocytes present
Mucus and blood present
Bloody Diarrhea (Dysentery)
What are the three organisms most commonly found in routine stool culture that may cause watery diarrhea?
Aeromonas, Vibrio cholera, and Yersinia enterocolitica
What are the five organisms most commonly found in routine stool culture that may cause bloody diarrhea?
Aeromonas, Campylobacter spp., Plesiomonas shigelloides, Salmonella spp., and Shigella spp.
Which type of E. coli is most like Shigella?
Enteroinvasive E. coli (EAEC)
Which type of E. coli is known to cause traveler’s diarrhea?
Enterotoxigenic E. coli (ETEC)
What type of E. coli is E. coli O157:H7?
Enterohemorrhagic E.coli (STEC)
What is a wet mount usually used for?
For detection of motile parasites (in a fresh liquid specimen)
What do we use to detect E.coli O157:H7, shiga toxins, and Clostridium difficile toxins A or A/B?
Antigen detection - EIA
Supports the growth of most yeasts and bacteria
Blood agar
Supports the growth of enterics and vibrios
MAC
Used for E coli O157:H7 (NSF)
MAC + sorbitol
Moderately selective for Salmonella and Shigella
HE (or XLD)
Selective media with the following incubation conditions: 42°C in 5% O2, 10% CO2, 85% N2 (microaerophilic)
Campy agar (CVA) - selective for Campylobacter
Incubation conditions for BAP, MAC, MAC-Sorb, HE
35-37°C in ambient air; hold 48 hours
How long does CVA agar incubate for, what does it recover?
72h, Campy
If a Yersinia culture is requested, how would you plate it and grow it?
Room Temp (25C°) BAP+MAC + 35-37°C BAP+MAC
