2/27: mucosal surfaces, enterobacteriaceae-diarrheal diseases Flashcards
Name 3 members of the enterobacteriaceae family that cause diarrhea
- e. coli
- salmonella species
- shigella species
Mucosal surface definition and examples
any surface that interacts with air and has glands that secrete mucous
examples: oral cavity, respiratory tract, repro/urinary tract, GI
What are the defenses of mucosal surfaces?
innate immunity, adaptive immunity and non-specific barriers (the cells themselves, mucous are physical barriers against infection)
E. Coli 0104:H4 OUtbreak
caused by ____
3500 causes, 800 caused by ____
32 people died, surprising because ____
caused by alfalfa sprouts, cucumbers
800 cases associated with hemolytic uremic syndrome
32 death is surpsing because this is rare for e. coli infections
E. Coli 0:26 outbreak
caused by ____
produced ____ (associated with bloody diarrhea)
mortality?
caused by chipotle
produced shiga toxin (associated w/ bloody diarrhea)
50 cases, half hospitalized, nobody died
Why do oral healthcare practitioners care about GI diseases?
they originate in the ORAL CAVITY due to fecal matter contamination
How does it get there? 7 F’s
What are the 7F’s?
how fecal matter contamination enters the oral cavity
feces food fluids fingers fomites fornication
What is an inoculum size?
Low inoculum size range? spread by?
high inoculum size range? spread by?
inoculum size = amount of bacteria it takes to make someone sick (ID, infectious dose)
low ID: 50-100, usually spread by fomites or fingers so it doesn’t take as much
high ID: require millions of organisms to cause disease, so you would need bacteria to be in your food/drink
Name the 5 natural barrier defenses of the GI system
- natural anatomical and physiological properties
- acidity (and change in acidity) (stomach = 1-2, duodenum = 9)
- motility (chime moves through stomach and small intestine quickly, so bacteria need to be able to directly adhere to epithelium or mucous layer)
- mucous layer
- tight junctions hold epithelial cells together, prevent penetration of bacteria
normal flora in GI provides a physical barrier by ____
competing with pathogens for nutrients and oxygen
Name the 6 secretory antimicrobial compounds found in the GI system
- lysozymes
- lactoferrin
- cathelicidin
- alpha defensins
- beta defensins
- secretory Igs
Describe how lysozymes defend against bacterial invasion of GI tract
cleaves NAG and NAM linkage (although the murein isn’t directly exposed in gram Negs it still works)
Describe how lactoferrin defend against bacterial invasion of GI tract
sequesters/hides iron from bacteria
Describe how cathelicidin defend against bacterial invasion of GI tract
disrupts gram pos and gram neg membranes
Describe how alpha defensins defend against bacterial invasion of GI tract
made by ____
create pores in microbes
made by neutrophils and intestinal paneth cells
Describe how beta defensins defend against bacterial invasion of GI tract
made by ____
creates pores in microbes
made by epithelial cells
Describe how Igs defend against bacterial invasion of GI tract
secretes IgA specifically
What are the 3 ways that pathogenic bacteria overcome the innate barrier defenses of GI tract?
- acid resistance
- fimbriae/pilli
- bacterial structures
how does acid resistance help bacteria overcome innate barrier defenses in GI?
how does ID # play a role?
just enough acid resistance to get them through the stomach and into duodenum
microbes with low ID tend to be more acid resistant
How do fimbriae/pilli help bacteria overcome innate barrier defenses in GI?
helps microbe adhere to tissues
How do bacterial structures help bacteria overcome innate barrier defenses in GI?
bacteria can slightly change their cell membranes to evade bactericidal compounds, can incorporate cationic amino acids into cell membrane to reduce effect of cationic antimicrobial peptides
can sequester iron through siderophores
Macrophages are important for mucosa immunity because they recognize _____
TLR4 recognizes ____
macrophages recognize PAMPs and activate and kill many of the microbes
TLR4 recognizes LPS of gram negative bacteria
Describe the enteroibacteriaceae family general info
gram negative
range from coccobacilli to elongated rods
facultative aerobes
don’t form spores
ALL HAVE ENDOTOXIN LPS, some produce and secrete exotoxin
Enterobacteriaceae family all have cell wall components that are antigenic. 3 main types:
- O antigen (outer antigen, LPS)
- K antigen (polysaccharide capsule, not all have)
- H antigen (flagella)
What is a serotype?
Define e.coli O157:H7
variations within a bacterial species due to the difference in cell wall surface antigens
e.coli O157:H7 mean O-antigen LPS is type 157 and H-antigen flagella is type 7
Escherichia coli
most ferment ___
and produce ___
ferment lactose
produce indole
Escherichia coli serotypes are determined by ___ antigens
O, K, H
Most common type of pili on escherichia coli is ____
type 1
Type 1 pili on escherichia coli binds ____
d-mannose on epithelial cells
this has an on/off switch that turns ON in presence of ACID
The p pili on escherichia coli binds ____
digalactoside in urinary tract and in some erythrocytes