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Z - Micro 03
Micro 03
Question | Answer |
---|---|
Bacillus - aerobic or anaerobic? | Bacchus - wine - aerobic |
Clostridium- aerobic or anaerobic? | closet - no air - anaerobic |
What is unique about bacillus anthracis? | capsule made of protein -- others are made of polysaccharides |
B. anthracis exotoxin - EF | EDEMA FACTOR. A subunit, action. Increases cAMP --> impairs neutrophil fxn, causes massive edema |
B. anthracis exotoxin - LF | LETHAL FACTOR. Stimulates macrophage release of TNFa and IL-1 |
B. anthracis exotoxin - PA | PROTECTIVE ANTIGEN. B subunit - promotes entry of EF into cells. |
Dysphagia and diplopia, followed by muscle weakness after eating canned foods | Clostridium botulinum, ate the toxin in the food, need to be intubated |
Baby ate honey | Clostridium botulinum, ate spores --> spores in GI tract --> release of toxin in the intestines --> floppy baby --> excellent prognosis |
Spores or toxin in tetanus? | Spores enter the body through skin trauma --> releases toxin called tetanospasmin |
What does tetanospasmin do? | acts on inhibitory Renshaw cell interneurons preventing the release of GABA and glycine, both are inhibitory NT's --> sustained tetanic contractions |
Pt presents with lockjaw -- looks like a big grin | Clostridium tetani |
What is the test for Clostridium difficile? | find TOXIN (not spore) in stool samples |
Mechanism of C. difficile infection | C. difficile makes toxin --> damage superficial layers of the colon (doesn’t invade) --> pseudomembranes |
How to treat C. difficile infection? | Pseudomembranous enterocolitis. Metronidazole and vancomycin -- runs through GI and doesn't get absorbed into bloodstream. |
Pseudomembrane on pharynx - pediatric patient | Corynebacterium diptheriae |
What is the mechanism of damage by Corynebacterium diptheriae? | exotoxin --> interfere with protein synthesis --> damages heart and neural cells |
K+ tellurite culture - black colonies | Corynebacterium diptheria |
Loeffler's medium (can see reddish granules) | Corynebacterium diptheria |
how Corynebacterium diptheria gets its toxin | lysogenic conversion by a temperate bacteriophage |
Listeria monocytogenes - cause of meningitis in two groups | neonates and immunocompromised |
How to confirm bacterial meningitis? | Lumbar puncture: CSF with hi neutrophils, high protein, low glucose, gram stain showing organisms) |
Which organisms cause pseudomembranes? | Clostridium difficile and Corynebacterium diphtheriae |
Gram stain for corynebacterium diphtheriae | G+ rod |
Gram stain for haemophilus influenzae | G- rod |
Gram stain for Moraxella catarrhalis | G- diplococcus |
Gram stain for Pseudomonas aeruginosa | G- rod |
Gram stain for Klebsiella pneumoniae | G- fat rod surrounded by mucoid capsule |
How to see Legionella pneumophila | IF stain or Dieterle silver stain |
IgA1 | Neisseria meningitidis - cleaves IgA in half! |
What bacteria can extract Fe from human transferrin without requiring energy? | Neisseria meningitidis |
What other bacteria can obtain Fe from human transferrin or lactoferrin? | E. coli (Fe-binding siderophore) |
Where does Neisseria meningitidis live on the body? | Nasopharynx |
At-risk groups for Neisseria meningitidis infection | 1. Infants aged 6 months to 2 years (when children don't yet manufacture their own antibodies and mom's abs are not effective anymore), 2. Army recruits in boot camp (carrier rates > 40%) |
What should you suspect if baby <2 or army recruit comes in with petechial rash? | Neisseria meningitidis -biopsy the petechiae and you should see diplococci on gram stain |
If baby has bulging open anterior fontanelle | meningitis in neonates |
Patient is lying supine with leg at 90 angle to trunk. If extension of leg causes pain…. | Kernig's sign --> meningitis. leg is fully bent in the hip and knee, and subsequent extension in the knee is painful (leading to resistance).[3]. This may indicate subarachnoid haemorrhage or meningitis. |
Patient involuntarily lifts legs/arms when head is lifted and patient is restrained from sitting up. | Meningial irriation. Meningitis. Brudzinski's sign |
How to diagnose meningitis? | Spinal tap and seeing the organism in the CSF |
When would you use chocolate agar? | When Neisseria is suspected (it's blood agar that's been heated) |
When would you use Thayer-Martin VCN media? | When Neisseria is suspected. Chocolate agar with abx: vancomycin (kills G+), colistin (kills all G- except Neisseria), nystatin (kills all fungi) |
How to tell N. meningitidis from N. gonorrhea? | N. meningitidis ferments maltose while the other does not (meningitidis has an "m" in the name) |
Man comes in with painful urination and purulent urethral discharge | N. gonorrhea infection. |
How to treat N. gonorrhea infection? | Ceftriaxone. |
How does N. gonorrheal infection in women present? | Asymptomatic urethritis, minimal urethral discharge, dyspareunia (painful intercourse) |
Fitz-Hugh-Curtis syndrome | N. gonorrhea or Chlamydia infection of capsule surrounding liver. |
What is most common type of septic arthritis in young, sexually active individuals? | N. gonorrhea |
What is most common type of septic arthritis in infants? | Haemophilus influenzae |
What causes epiglottitis? | Haemophilus influenzae Type B. |
Under microscope, where would you look for Neisseria? | Inside WBC's |
Why are babies given that eye gel when they are born? | Erythromycin eye drugs to protect against N. gonorrhea and chlamydia (can lead to blindness) |