Nec Fasc checkpoint Flashcards
- What are some of the most common bacteria isolated in cases of necrotizing fasciitis?
a. Step pyogenes; Staph Aureus;
b. Other species; Aeromonas hydrophilia, bacteroides, clostridium perfringes, enterobacteriaceae, proteus, pseudomonas, vibro vulificus
- Why are diabetics a high-risk group for necrotizing fasciitis? Why are IV drug users?
a. Skin infections can spread rapidly, pts tend not to notice foot injuries.
b. Injecting nec fasc into body
- Why does antibiotic therapy alone frequently fail to stop the progression of necrotizing fasciitis?
a. Do to the vascular damage of the infection the antibiotics cannot make it to the site of infection
- What are Lancefield antigens? Are all streptococci able to be classified under this system?
a. Specific polysaccharides located in the cell wall of streptococci, but not all strep has the antigens, S. pneumoniae does not, nor does S. viridians
- Where is S. pyogenes commonly found in humans? Is it considered normal flora?
a. Transiently found on the skin and can colonize the throat, never normal flora
- True or False: S. pyogenes is the most common cause of pharyngitis.
a. No, viral is most common
- Briefly, what is post-streptococcal glomerulonephritis and after which two types of GAS infections does it commonly occur?
a. Complication of clearance from S. pyogenes
- What is the function of the M protein and how does it facilitate GAS infections?
a. Protein that extends on surface of bacteria that inhibits phagocytosis and activation of complement. Strains without M protein are not virulent
- Which function of the innate immune system does anti-C5a peptidase inhibit?
a. Blocks compliment activation
- Between the two, which is antigenic: streptolysin O or streptolysin S? Which is inactivated in the presence of oxygen?
a. Streptolysin S is Stable in the presence of oxygen
- Briefly describe the function of streptokinase, deoxribonuclease, and hyaluronidase and how they promote GAS infections.
a. Streptokinase is a fibrinolysin
b. Deoxyribonuclease and hyaluronidases are essential for tissue invasion
i. Splits hyaluronic acid deep penetration
ii. Destruction of cells releases large amounts of DNA which gets broken down
- What is the pathogenic mechanism behind streptococcal pyogenic exotoxins (Spe)? Which bacteria produces a similar toxin?
a. Superantigen similar to S. Aureus
- What two toxin-mediated diseases are caused by Spe?
a. TSST-1 and scarlet fever
- What are some of the common clinical manifestations of toxic shock syndrome?
a. Hypotension, multiorgan involvement, renal, coag, liver, respiratory distress, generalized rash
- How are streptococcal and staphylococcal TSS different when comparing common complications and patient prognosis?
a. 30% mortality Pyogenessepticemia, 3% aureus
- Antibody titers against which GAS virulence factor is commonly used to establish a history of GAS infections?
a. Anti-streptolysin O
- What types of diseases does Vibrio vulnificus cause?
a. Gastroenteritis, also nec fasc
- How do people typically get infected by Vibrio vulnificus?
a. Eating contaminated seafood or having an open wound exposed to seawater
- What do severe skin infections caused by Vibrio vulnificus look like?
a. Bullous hemorrhagic skin lesions
- What are some of the traits of V. vulnificus that are used to ID it in the lab?
a. Comma-shaped gram negative rods, motile and possess a single polar flagella
b. Oxidase positive, TCBS agar routinely used
- Which agar is used to select for Vibrio species?
a. TCBS
- How is Aeromonas spp. similar to Vibrio spp.? How are they different?
a. Oxidase positive and motile by single polar flagellum
b. Aeromonas will not grow on TCBS, standard rods not comma-shaped
