MIP A51: Gram Negative Pathogenic Bacteria Flashcards
True or False: LPS is exclusive to Gram negative organisms
True
How do bacteriaphages commonly recognize bacteria?
O-antigens
What is the function of Protein III in Gram Negative bacteria?
It looks similar to a syringe and was developed from flagella- it secretes proteins across the periplasmic space
What are the pathogenic members of the Gram Negative Cocci and Coccobacilli?
Nisseria, Haemophillus, Bordetella, Rickettsia
What test is used to differentiate Enterobacteriacae from other organisms? What does it test for?
Oxidase test; Tests for presence of cytochrome C oxidase
What are the different surface antigens that are used to type E. coli and other Enterobacteriaceae?
O, H, and K antigens
What is the defining feature of Escherichia coli?
They are lactose positive organisms
What compound does E. coli convert tryptophan to? How can this be detected in the lab?
Converts Trp to indole which can be visualized using Cobas reagent
What is the bacterial cause of Traveler’s diarrhea? How is it transmitted?
Enterotoxigenic E.Coli; Transmitted via the fecal-oral route
What is the pathophysiology of Traveler’s diarrhea?
Enterotoxigenic E. Coli adheres to epithelial cells of SI and secretes ST and LT toxins which cause hypersecretion of fluids and electrolytes by stimulating guanylate and adenylate cyclase
To what does Cholera toxin bind?
GM1 ganglioside receptor on eukaryotic cell membrane
How does Cholera toxin act?
The B subunit binds to the GM1 ganglioside receptor and the A1 subunit irreversibly binds and activates adenylate cyclase
What is EIEC, how does it act in the body, and what does the presentation of its disease look like?
Enteroinvasive E. coli that invades epithelial cells of the intestines and underlying lamina propria, causing inflammation and malaise. Diarrhea starts off watery but then contains blood and mucous
What is EHEC? What toxin does it produce? How does its disease present?
Enterohemorrhagic E. Coli, which secretes Shiga toxin that inhibits protein synthesis in cells. Watery diarrhea and cramps at first, but then bloody diarrhea and hemolytic uremic syndrome
Out of ETEC, EIEC, and EHEC, which would you treat with antibiotics?
EIEC
How does Shiga toxin act in the cell?
AB toxin binds to a ganglioside receptor, is endocytosed, and the A subunit exits the Golgi and modifies tRNA binding site of the 60S ribosome, preventing protein synthesis and causing cell death
What is Hemolytic Uremic Syndrome?
A condition in which blood vessels in the epithelium of glomeruli are damaged by toxins, causin kidney failure and platelet lysis
What is EAggEC? What is its pathophysiology?
Enteroaggregative E. coli; Bacteria adhere t gastric epithelium, aggregate, and release EAST, which causes cell swelling and RBC agglutination and causes persistent watery diarrhea
What is EPEC? What is its pathophysiology?
Uses Type III secretion system to inject toxins into the cell in order for the organism to stick gastric cells irreversibly
What opportunistic infections can be caused by E.coli?
Lung, Wound and other soft tissue infections, and meningitis.
What type of bacteria is Pseudomonas aeruginosa?
A Gram negative, oxidase positive, catalase positive, obligate aerobe
What does P. aeruginosa smell like?
Grapes or wet tacos
What bacterial infection is most likely to present with blue or green pigments on bandages or pus?
P. aeruginosa
How are biofilms produced?
Bacteria lose flagella from Quarum-sensing transcription factor; produced when a high enough bacteria population is present. This is followed by the induction of the production of Algenate- a sugar polymer that keeps immune cells and antibiotics out
What is ecthymic granulosum?
Black necrosis appearing on skin due to systemic spread of bacteria
What are the general classes of P. aeruginosa virulence factors?
Proteases, ADP-ribosyl transferases, pili, cytotoxin (leukocidin); Type III secreted toxins; Rhamnolipids, and Alginate
What bacterial infection causes an “onion skin” morphology?
Burkholderia pseudomallei
What is the bacterial basis of Melioidosis or Whitmore’s disease?
Burkholderia pseudomallei
What are the different variations of Melioidosis or Whitmore’s disease?
Acute localized infection, acute bloodstream infection, pulmonary infection, chronic supportive infection
