Lec11 Neisseria and gram negatives Flashcards
(46 cards)
What types of bacteria does spleen play essential defense role?
encapsulated organisms
How can polysacccharide vaccines be altered to create longer lasting immunity? Why?
- by conjugating them to proteins
- this helps because proteins are more immunogenic than protein
What are the visual differences between meningococcus and pneumococcus both of which can cause meningitis?
pneumococcus: gram pos, diplococci
meningococcus: gram neg, kidney bean shaped cocci
Who gets meningitis?
- peak incidence age 6 mo to 2 years
- conditions of overcrowding
- those with splenectomy
- those with late complement deficiencies
Where does neisseria meningitis colonize? how is it transmitted?
- colonized nasopharynx in healthy people
- causes life-threatening infection when reaches bloodstream or CNS
- transmitted by respiratory droplets
What are the virulence factors of N. meningitis?
- secretes IgA protease
- —- allows survival in respiratory tract
- pili
- —- mediate attchement to respiratory epithelium
- Opa and Opc proteins
- —- allow to be engulfed by respiratory cells
- capsule
- — antiphagocytic
- lipooligosaccharide
- — endotoxin that triggers sepsis
What is rash like in mengingococcemia?
- cap appear as petechiae, purpura, or hemorrhagic bullae
- always non-blanching
WHat happens when LPS endotoxin released?
- released when bacterial cell dies
- riggers fatal downstream events
How many serogroups in N mengingitidis? which are most important?
- 13 serogroups
- determined by polysaccharide capsule
- most important A, B, C, W-135
Which serogroups are in the polyvalent vaccine?
A, C, Y, W-135
Why are vaccines against group B mengingococcus complicated?
- B has a polysacchardie capsule similar in struct to human sialic acid
besides meningitis, what other infections is neisseria meningitidis associated with?
- meningococcemia
- respiratory tract infection
- pneumonia
- otitis media
- conjuncitivitis
- septic arthritis
- pericarditis
What is treatment for n. meningitidis?
- cephalosporins [ceftriaxone] most common
- pencillin [one of few gram neg that does not produce beta lactamase]
What is empiric treatment of bacterial meningitis [when no organism on gram stain]?
- ceftriaxone [against meningococcus, haemophilus, and pneumococcus]
- vancomycin [because of beta-lactam resistant pneumococcal strains]
- sometimes steroids [to minimize inflammatory response]
- sometimes ampicillin [against listeria]
What is shape of listeria monocytogenes?
- gram positive rod
- tumbling end of end motility
Who is most susceptible to listeria?
- infants and elderly [bimodal distribution]
- immunocompromised
- pregnant women
What drugs do and do not have activity against l. monocytogenes?
- cephalosporins do not have reliable activity
- ampicillin does have activity
When is mengitis chemoprophylaxis used?
- for close contacts of index case
- can prevent invasive disease if given within 14 days of exposure
How do you differentiate N. gonorrheoeae and N. meningitidis?
- N gonorrhoeae does not have true polysaccharide capsule
- N. gonorrhoeae only utilizes glucose
- N. meningitidis utilizes glucose or maltose
What are the virulence factors for N. gonorrhoeae?
- similar to N. meningitidis
- pili assist binding human mucosal surfaces
Which patients are most at risk for N. gonorrhoeae?
- 15-25 year old men and women highest rate
- high risk in patients with terminal complement deficiencies
What are symptoms of gonorrhea?
about 10% asymptomatic
- infection of genitals
- foul smelling purulent discharge
- inflammation, redness, dysuria
What are the diseases associated with N. gonorrhoeae?
- ophtalmia neonatorum: transmitted from mother to child in delivery
- pelvic inflammatory disease
- pharyngitis
- perihepatitis [fitz-hugh-curtis syndrome]
What are symptoms of pelvic inflmmatory disease?
- chronic infection causes damage to fallopian tubes, sterility, ectopic pregnancy
