Immunology
These are the most abundant WBCs which are the first to arrive at the site of inflammation.
What are neutrophils?
Recruited by resident macrophages to the site of inflammation.
Vancomycin is part of this class of antibiotics.
What are glycopeptides?
Vancomycin binds to D-alanyl-D-alanine residues of peptidoglycan to prevent cross-linking by transpeptidases
This toxin of Clostridium difficile causes cell necrosis and fibrin deposition.
What is toxin B (cytotoxin)?
Fibrin deposition contributes to the formation of pseudomembranes.
This protozoa causes flask-shaped ulcers in the colonic mucosa.
What is Entamoeba histolytica?
Trophozoites invade at one point in the mucosa and cause wider tissue destruction in the submucosa, leading to the flask shape.
These two proteins are released by cytotoxic T cells to kill target cells.
What are perforin and granzymes?
Perforin forms pores in the target cell membrane. Granzymes enter through perforin pores and activate caspases, leading to target cell apoptosis.
Bezlotoxumab is metabolized via this mechanism.
What is protein catabolism?
Broken down via similar mechanism as dietary proteins.
Metabolism and elimination not significantly affected by hepatic or renal impairment.
These are the 4 main pathovars of E. coli
What are enteroinvasive, enterotoxigenic, enteropathogenic, and enterohemorrhagic?
Enteroinvasive invades the intestinal mucosa and causes bloody diarrhea.
Enterotoxigenic produces heat-stabile and heat-labile toxins and causes watery diarrhea without inflammation or invasion.
Enteropathogenic blunts villi and causes watery diarrhea without inflammation.
Enterohemorrhagic produces Shiga-like toxin and causes bloody diarrhea without invasion of host cells.
Enterobius vermicularis (pinworm) is diagnosed using this test.
What is the Scotch tape test?
Eggs are deposited in perianal folds, so adhesive can be applied to perianal skin, placed on glass slide, and visualized under microscope for evidence of eggs.
Aside from MHC-to-TCR binding, this other interaction must occur for T cells to become activated.
What is B7 (CD80/CD86) on APCs binding to CD28 on T cells?
If only MHC-to-TCR binding occurs without co-stimulatory signal, the T cell becomes anergic.
Metoclopramide is an antagonist of this receptor in the GI tract and CNS.
What is dopamine D2 receptor?
Inhibition of dopamine-D2 binding in the GI tract leads to increased ACh activity, resulting in increased esophageal and gastric motility.
Inhibition of dopamine-D2 binding in the chemoreceptor trigger zone of the area postrema in the medulla leads to decreased nausea/vomiting.
This particular strain of E. coli is associated with major outbreaks associated with undercooked beef in high-income countries.
What is O157:H7 (EHEC)?
O157 indicates the specific O antigen of LPS.
H7 indicates the specific H antigen of the flagella.
Cattle are a main reservoir for O157:H7 E. coli.
This protozoa is the most common protozoal cause of steatorrhea (foul-smelling fatty diarrhea).
What is Giardia lamblia?
Giardia trophozoites cause blunting of microvilli and damage of brush border in small intestine, leading to fat malabsorption.
These 2 cytokines are released by activated CD4 Th1 cells.
What are IL-2 and IFN-g?
IL-2 is a CD4 and CD8 T cell growth factor that can also activate B cells and NK cells.
IFN-g activates CD4 Th1 cells, inhibits CD4 Th2 cells, and activates macrophages.
This antibiotic can be used off-label to treat gastroparesis due to its side effect of binding GI motilin receptors.
What is erythromycin?
Erythromycin stimulates smooth muscle contractions via binding to GI motilin receptors.
Part of the macrolide antibiotic class.
Cholera toxin from Vibrio cholera causes rice-water diarrhea via increase of this secondary messenger.
What is cAMP?
Cholera toxin irreversibly activates Gs via ADP-ribosylation to increase cAMP levels, leading to opening of CFTR channels and massive chloride and water secretion into the gut lumen.
What is Schistosoma (S. haematobium)?
Disease is primarily caused by immune reaction to the eggs, not the worm itself.
After maturation, S. haematobium likes to inhabit the veins around the bladder while S. mansoni and S. japonicum like to inhabit the mesenteric veins.
What is IL-5?
IL-5 is secreted by Th2 cells to activate eosinophils against helminths and promote IgA production against GI bacteria.
This antacid can also be used as an osmotic laxative.
What is magnesium hydroxide?
Magnesium ions are poorly absorbed and remain in the colonic lumen, creating an osmotic gradient to draw water into the colon and promote peristalsis.
Used in milk of magnesia formulation.
Salmonella is differentiated from Shigella by the production of this compound.
What is hydrogen sulfide (H2S)?
H2S turns the media black in the triple sugar iron (TSI) test, which is used to differentiate Salmonella from Shigella.
Salmonella is also motile while Shigella is non-motile.
Cryptosporidium is diagnosed using this stain to visualize the oocysts.
What is acid-fast (Ziehl-Neelsen) stain?
Oocyst walls contain lipids and complex carbohydrates that retain the carbol-fuchsin stain.
Mycobacterium tuberculosis and Nocardia are also acid-fast positive.