Lecture 7 - Gram neg bacteria of GI Flashcards
Most infectious GI bacteria are Gram ____, because they need the outer wall to protect against things like bile.
Negative
The difference between Diarrhea and Dysentery is that Diarrhea is comprised of mostly _____ while Dysentery shows more solids and sometimes blood and inflamed tissue.
Fluid
The difference between the infections involved in Watery Diarrhea vs Dysentery/Bloody Diarrhea is that the latter involves an infection of the _____ lining of the intestines, while the former does not. The causative agent for Watery Diarrhea is the ____ released by the bacteria.
Epithelial
Toxins
_______ is among the only bacterial genus that can survive in the stomach. ______ Pylori is implicated in stomach ulcers.
Helicobacter (for both)
As part of the host defenses, _____ is an enzyme found in the nasopharynx that cleaves part of the _______ layer in the cell wall.
Lysozyme
Peptidoglycan
In both the small and large intestines, normal flora and shedding of the _______ are among the host defenses. The small intestine also combats bacterial infection via cells of the Mucosa-Associated Lymphoid Tissue (MALT) and _____, enzymes, and Igs.
Epithelium
Bile
Infection differs from intoxication in that the former requires living _____ to grow and colonize the host, while the latter only requires ingestion of the toxin.
Bacteria
Watery Diarrhea is a non-______ disorder that occurs in the _____ intestine. Dysentery and bloody diarrhea are basically the opposite.
non-Inflammatory
Small
E. Coli belongs to the ______ family of bacteria and can causes diarrhea, _____, and _______ colitis.
Enterobacteriae
Dysentery
Hemorrhagic colitis
Salmonella Enteriditis belongs to the ______ family of bacteria and can cause ______.
Enterobacteriae
Diarrhea
Shigella spp. belong to the _______ family of bacteria and can cause _______.
Enterobacteriae
Dysentery
V. Cholerae belongs to the ______ family of bacteria and can cause _____. It is a facultative anaerobe and is _______ (withstands high salt concentration.) In order for V. Cholera to cause disease, a large inoculum is necessary because it is sensitive to stomach acid. V. Cholerae produces a ______ that causes the disease, rather than the bacteria invading the epithelium.
Vibrionaceae
Cholera (keep in mind Cholera is extremely sever diarrhea.)
Halophilic
Toxin
Campylobacter Jejuni belongs to the _____ family of bacteria and can cause ______.
Vibrionaceae
Diarrhea
Helicobacter Pylori belongs to the ______ family of bacteria and can cause peptic _____.
Vibrionaceae
peptic Ulcers
Cholera toxin is an A-B toxin that ADB-ribosylates the ____ protein, constitutively activating it. This, in turn, activates ______ cyclase –> increase in cAMP production. This leads to a decrease in the uptake of____ ions into the intestinal epithelium. In order to compensate, these cells decrease Na and K absorption, and must expel ______ into the lumen of the intestine in an attempt to maintain isotonicity. This is what leads to massive fluid and electrolyte loss.
Gs protein
Adenylyl cyclase
Cl- ions
H2O
Traveler’s Diarrhea is caused by _____ E. Coli (ETEC –> “T” for “Traveler’s”.) Symptoms are similar to Cholera, but are typically less severe. ETEC produce a ____ labile toxin (can’t withstand high heat) which acts in a similar way to ______ toxin.
Enterotoxigenic E. Coli
Heat labile
Cholera
Dysentery is distinguished from bloody and watery diarrhea in that it is characterized by frequent, but low ____ stool passage, usually with ____, mucus, and _____. Bloody diarrhea is similar, but with high ______, and is very liquidy. Hemorrhagic Colitis is similar to Bloody Diarrhea, except there is no ____ (no leukocytes.) All of these cases involve the _____ intestine, and all involve some form of histopathology.
Volume
Blood
Pus
Volume
Pus
Large
Bacillary (because they’re bacilli) Dysentery (AKA ______), is caused by Shigella sonnei and flexneri. Unlike V. Cholera, these Shigella species are highly infectious, needing only a ______ inoculum. The incubation time is around ___-___ days. Unlike with Cholera and ETEC, Shigella infection should be treated with ______ along with rehydration. It is spread via ____-oral transmission.
Shigellosis
Small inoculum (low number of cells.)
2-4 days
Antibiotics
Fecal-oral
Shigella infect the host’s intestinal ______ by inducing phagocytic uptake into the cell. ____ products is the virulence factor that helps Shigella invade these cells. Once in the cell, the bacteria lyses the phagosome and replicates in the cytosol. The bacteria spread through the epithelium, causing inflammation and ____ –> leads to presence of blood, mucus, and _____ in the stool.
Epithelium
IPA products
Necrosis
Pus
Shigella virulence factors include:
- Type ____ secretion system –> long tube essentially that connects bacterial cell to host cell and allows bacterial toxins to flow into host cells.
- ____ products –> help Shigella invade host cells.
- _____ toxin.
- Type III secretion
- IPA products
- Shiga toxin
Hemorrhagic Colitis is caused by Enterohemorrhagic E. Coli - EHEC (same species that caused _____ diarrhea, but is a different strain, so it causes a different disease.) Hemorrhagic Colitis can present as bloody diarrhea or ______, often with abdominal pain.
Traveler’s diarrhea
Dysentery
Most cases (90-95%) of Hemorrhagic Colitis are self-limiting, but some can progress to ____ ____ syndrome (HUS.) HUS initially presents with decreased ______, feeling tired, and pallid.
Hemolytic Uremic Syndrome
Urination
Pathogensis of EHEC is very similar to ______. The bacteria induce uptake into the epithelial cells, colonize, produce toxins (Shiga-like), can move across and between host cells, and the toxins can enter into the ____ stream. This can lead to death of ______ epithelial cells (causing HUS, which is a result of systemic infection as opposed to local) and CNS epithelial cells.
Shigella
Blood Stream
Glomerular epithelial
Campylobacter enterocolitis is the most common cause of bacterial _______ illness in the US. Campylobacter _____ is responsible for more than 90% of the cases. Cramping in this case can be severe with pain similar to ______. Keep in mind this infection can occur in both the small and large intestine.
Diarrheal
Jejuni
Appendicitis
C. Jejuni is a curved rod with a single polar ______. It is also micro_____.
Flagellum
Aerophilic
Salmonella food poisoning is caused by Salmonella enterica (subspecies enteritidis.) It has a common _____ and flagellum that are important virulence factors. It is found in humans, ____ (especially chickens), and peanut butter. Pathology typically occurs within ____-____ hours after ingestion (keep in mind pathology requires colonization of the bacteria.)
Pilus
Birds
6-24 hours
H. Pylori is a gram negative curved rod that is motile (has a tuft of 4-7 ______.) These help the bacteria move through the ____ layer of the stomach.
Flagella
Mucin
H. Pylori moves toward ____ and carbonate, and is carried via its flagella. It secretes _____ which converts _____ to ammonia and _____. This helps buffer the H+ in the local environment. In order to attach to epithelial cells in the stomach, H. Pylori have adhesins (BabA) that recognize a ______ antigen on the surface of these cells. One of the other virulence factors is Vacuolating Toxin.
Urea
Urease
Urea
Bicarbonate
Carbohydrates
H. Pylori are in some way killing off the epithelial layer of the stomach. This allows ____ to cause damage to the _____ membrane.
H+
Basement
Keep in mind that antacids taken for symptoms of gastric ulcers potentially leaves patients more susceptible to infection by bacteria that would otherwise not survive the normally _____ pH of the stomach.
Low
In order to diagnose H. Pylori as the causative agent for gastric ulcers, a gastric _____ should be performed to identify any ulcers. Then, the bacteria should be isolated from the stomach/around the ulcer and tested for _____ (without which H. Pylori is not pathogenic.)
Biopsy
Urease
Treatment for H. Pylori induced gastric ulcers requires a 3 drug treatment including antibiotics and a _____ pump inhibitor (prevents H+ damage to basement membrane).
Proton pump inhibitor
