Gram Negative Pathogens Flashcards
7 F’s of fecal transmission to mouth (gram negative mucosal pathogens):
- Feces
- Food
- Fluids
- Fingers
- Flies
- Fomites
- Fornication
For some bacteria, as few as ____ organisms is enough to cause disease. For other bacteria, millions of organisms are needed.
50-100
There is only ____ layer(s) of epithelial cells separating the interior of the body from billions of microbes on mucosal surfaces.
1
Natural anatomical/physiological properties that create physical barrier to microbes:
- Acidity
- Motility
- Mucous layer and underlying glycocalyx
- Tight junctions
Secretory antimicrobial compound that cleaves beta 1,4-glycosidic linkages between NAN and NAG
Lysozyme
Antimicrobial compound with bacteriostatic effects via sequestering iron
Lactoferrin
Antimicrobial compound that disrupts bacterial membranes of Gram neg and positive (and fungi)
Cathelicidin
Antimicrobial compound that creates pores in microbes
Defensins
Microbes with _____ tend to be acid resistant.
Low infectious dose
Bacterial structures that adhere to tissue to resist being shed
Fimbriae/Pili
Recognize microbes via pattern recognition receptors to kill the microbes.
Macrophages
Activation of pattern recognition receptors on macrophages also initiates the ______.
Inflammatory response
The _____ macrophage receptor recognizes LPS on gram negative bacteria
TLR4
Inflammatory cytokines like TNF-alpha can disrupt the _____ of epithelial cells (negative effect of mucosal inflammatory response to bacteria)
Tight junctions
The adaptive immune response is generated in _____
Lymph nodes
Invasive Bacteria Pathogens (cause disease by invading intestinal tissue)
- Salmonella
2. Shigella
Shigella spp. Distinguished by O antigen:
- S. Dysenteriae
- S. Flexneri
- S. Boydii
- S. Sonnei
Shigella inoculum size is ____. Survives stomach by _____. Will multiply/colonize the ____.
Very small
Acid resistance
Colon
Shigella enter ____ cells (phagocytic cells) via outer membrane proteins called _____ to reach the basal surface of the intestinal epithelium and infect it.
M
Invasion Plasmid antigens
Intracellular spread of Shigella is facilitated by ____, an ATPase that causes actin polymerization.
IcsA
This develops in the digestive system when invaded cells die and slough off. (From Shigella producing toxins)
Ulcer
All bacterial species will induce an inflammatory diarrhea with ____ in the stool.
Leukocytes
Causes invasive diarrhea and produces shiga toxin (kills intestinal cells, disrupts Na absorption).
S. Dysenteriae type 1
Two species of Salmonella:
S. Bongori
S. Enterica/Typhimurium (medically important)
Gastroenteritis is caused by Salmonella _____ and S. ____ serotypes.
Typhimurium
Enteritidis
Typhoid fever is caused by S. ____ and S. _____ serotypes
Typhi
Paratyphi
Low pH induces the expression of at least 40 proteins found on _____ of Salmonella
Pathogenicity islands on large virulence plasmids
Enters into lymphatic system and replicates within macrophages throughout the body. Strictly a human pathogen. Asymptomatic carriers (colonized gall bladders).
Salmonella Typhi (Typhoid fever)
Similarities and Differences between invasive enteric pathogens (Salmonella and Shigella)
Similarities:
- Invasive
- Respond to environmental changes
Differences:
- Inoculum size (acid sensitivity)
- Bacteremia (Salmonella)
- Species that cause severe disease very different
Diagnosis/Treatment of invasive enteric pathogens:
- Based on symptoms/stool
- Oral rehydration
- Antibiotics
- Fluoroquinolones or surgical removal of gallbladder, Vaccine. (For Typhoid fever)
