Bacterial CNS Flashcards Preview

2020 MHS microbiology unit 2 > Bacterial CNS > Flashcards

Flashcards in Bacterial CNS Deck (40)
Loading flashcards...

what are the types of hemolysis?

  1. alpha
    1. green, aka partial hemolysis
    2. alpha hemolysin partially breaks down RBC, the culture is clear
  2. beta
    1. culture apears clear
    2. breaks down the RBC and hemoglobuin entirely
  3. gamma
    1. the culture just has the growth with out any color change
    2. does not contain hemolysin


gram negative rods


facultative anaerobes

  1. oxidase?
  2. catalase?
  3. required growth factors?


haemophilus influenzae

  1. gram negative rods
  2. non-motil
  3. facultative anearobes
  4. oxidase +
  5. catalase +
  6. reduce nitrates
  7. require preformed growth factors
    1. X(hemin)
    2. V(NAD)


invade bloodstream by breakdown in the tight junctions between epithelial cells

describe the significant subtype.

haemophilus influenza B

  1. type b 
    1. encapsulated strain capable os sytemic invasion
    2. HiB = vaccine against this strain


what are the virulence factors for HiB?

  1. virulence
    1. capsule
      1. most important factor
    2. IgA proteases
    3. fimbriae adherance
    4. LPS- via gram negative rod


strict human pathogen

  1. O2 use
  2. gram
  3. culture
  4. important features


neisseria meningitidis

  1. aerobic, nonmotile, non-spore forming
  2. gram negative, diplococci
  3. chocolate agar
  4. importantt features
    1. catalase +
    2. capnophilic- requires CO2
    3. requires iron-possible reason for being strict human pathogen
      1. competes with human host by binding human transferrin


what are the virulence factors for neisseria meningitidis?

  1. pili (fimbriae)
  2. capsule
  3. transferin - receptor for iron
  4. endotoxin - gram - LPS
  5. IgA protease


transmission from respiritory dropletts, found on mucosal surfaces of nasohparynx and oropharynx

neisseria meningitidis


meningitidis in children and infants



meningitidis found in every age group

Neisseria meningitidis


purpura of skin and mucous membranes

petechial rash


these are all symptoms of meningococcemia



meningitidis from organism that colonizes the nasopharyngeal mucosa

neisseria meningitidis


neisseria meningitidis meningisums include (3)



  1. inflammation of the meninges or subarachnoid hemorrhaging
  2. nuchal rigidity
  3. kernigs sign, brudzinskis sign

altered sensorium- cannot think clearly


Gram + diplococci

  1. hemolytic 
  2. catalase
  3. oxidase
  4. urease
  5. ferments



list two important species taht are catalase  + and -


key virulence factor for invasive streptococcus pneumoniae

polysaccharide capsule


most common cuase of meningitis in adults, second most common cause in children.

transmission through respiratory droplets.

  1. gram
  2. hemolysis
  3. catalase
  4. Ab sensitive test
  5. urease
  6. ferments

streptococcus pneumoniae



What does the protease of the following target

  1. HiB
  2. N. meningitidis
  3. S. pneumonia


  • prblems is the potential of inhibiting beneficial effects of IgG Ab
  • PCR diagnostic assay 
    • require low number of sample to detect bacteria


patient presents to the ER 11 days after eating some ice cream, which was later found to be recalled.

The bacteria was sampled and found to grow on blood agar.

  1. bacteria
  2. gram
  3. O2 demand
  4. Catalse
  5. Oxidase
  6. derived from


CNS invasion of lysteria monocytogenes includes

  1. BBB
  2. WBC
  3. oral mphage

  1. taken up by phagocytosis and can exit the cell and enter the surrounding enviornment. This is an issue if this happens while the cell is in the brain or near.
  2. CNS invasion by one of the three methods
    1. invasion of the endothelial cells of the BBB
    2. transportation of bacteria to the CNS within circulating leukocytes 
      1. phagocyte facilitated
    3. bacteria inoculated into oral tissues through chewing of contaminated food
      1. followed by macrophage phagocytosis which in turn can invade cranial nerves


fifth most common cause of meningitis

  1. risk groups 


bacitracin resistant 

catalase negative

  1. gram
  2. hemolysis
  3. virulence factors-3

streptococcus agalactiae

  1. gram +
  2. beta hemolysis
  3. virulence
    1. capsule
    2. pore forming bet heolysin/cytolysin


affects neonates, infants and older than 60.

gram +

bacitracin resistant

catalase negative

streptococcus agalactiae


how many samples are collected and for who on a CSF analysis

  1. 4 samples 
    1. chemistry/serology
    2. microbiology
    3. hematology
      1. differential
    4. immunological test/protein electrophersis


How does glucose level in CSF analysis affect the following and what does it indicate? -3 

  1. increase WBC + neutrophils a +decreased CSF glucose
    1. bacterial meningitis
  2. increased WBC + lymphcytes + decreased CSF glucose
    1. tubercular meningitis
  3. increased WBC + lymphocytes + normal CSF glucose
    1. viral meningitis


patient CSF presents with

  1. increased WBC
  2. neutrophils
  3. decreased glucose

bacterial mengitis


csf sample presents with the following

  1. increased WBC
  2. lymphoctes
  3. decreased glucose

tubercular meningitis


csf sample show the following

  1. increased WBC
  2. lymphocytes
  3. normal glucose


viral meningitis


harsh acidic enviornment leads to 

  1. what type of colonization
  2. where do microbes colonize?

  1. harsh acid environment leads to low colonization
  2. mucosal lining ofthe stomach is less acidic and acts as a more moderate location for colonization
    1. microbes survive the stomach and colonize the lining


lactobacilli are most likely to found

duodenum and small intestine


what do the species that inhabit the duodenum need to survive?

what are very sensitive to bile salts?

bile salt hydrolase

gram positive are sensitive to bile salts, due to lack of an outer membrane