(incomplete) Neisseria Flashcards
Name the two important Neisseria pathogens and what diseases they cause.
Neisseria meningitidis: causes meningococcal meningitis
Neisseria gonorrhoeae: causes gonorrhea
Common features of meningococcus and N. gonococcus
Gm- diplococci (the ONLY Gm- coccus that is pathogenic!!!!) - look like kidney beans
Require rich medium for isolation (Thayer-Martin selective medium [modified chocolate agar], 5-10% CO2)
Readily killed by drying, heat, disinfectants
No known animal reservoir
Secrete IgA1 protease
Have pili and outer membrane proteins -> colonization
Has LOS rather than LPS (no O antigens, still endotoxic)
Describe methods for diagnosis of meningococcus and N. gonococcus
Oxidase positive (very diagnostic)
N. gonorrhoeae: glucose +, maltose/lactose/sucrose -
(G = Gonorrhoeae = Glucose)
N. meningitidis: glucose/maltose +, lactose/sucrose -
(M = meningitidis = Maltose)
Non-pathogenic Neisseria lactamica: glucose/maltose/lactose +, sucrose -
(L = lactamica = Lactose)
General properties of meningococcus
Multiplies outside of cells, NOT once phagocytized
Causes extremely severe CNS or septicemia
Active endotoxin -> damaged small vessels
Lives in nasopharynx (short-term carrier state, then goes away; causes disease in some)
- ***Polysaccharide CAPSULE -> antiphagocytic properties
- -Smooth colonies
- -Helps classify it into serogroups
- -Serogroups A, B, C = most common
Pathogenicity of meningococcus
Transmission: person to person via airborne respiratory droplets
- -Carrier state from days to months
- -Increased transmission in crowded conditions
- -Mild form = pharyngitis, fever
Incubation period: days to a week
Pathogenesis of meningitis: moves from nasopharynx -> bloodstream
–Immediate treatment critical for survival
What is the meningitis belt, and why is it the meningitis belt?
The place with the largest burden of meningococcus in the world
From Senegal -> Ethiopia
Seasonal outbreaks of N. meningitidis A (only seen here)
–Dry season -> URIs -> damaged nasopharyngeal mucosa -> increased risk of meningococcal disease
Transmission facilitated by overcrowded housing, large population displacements -> large epidemics
Diagnosis of meningococcus (3)
URI followed by signs of meningitis
***Petechiae on skin!!!
Culture and latex agglutination for capsule antigen in CSF
Treatment of meningococcus: antibiotics, prophylactics, problems with treatment
**Cephalosporins (ceftriaxone)
Ciprofloxacins increasingly used
Also IV penicillin
Prophylactic rifampin, cipro for close contacts
Problem: rapid treatment -> toxic shock, but can’t be avoided
Prevention of and immunity to meningococcus: vaccines
Quadrivalent vaccine against A, C, Y, W-135
–Moderately successful, for epidemics and military/college campuses
MenAfriVac: new vaccine for meningitis belt; very cheap conjugate vaccine
Lumbar puncture and meningitis: why use it? What other things can cause meningitis?
a
General properties of gonococcus
Causes gonorrhea, PID --Less common: arthritis, conjunctivitis Gm- diplococcus Oxidase + Only ferments glucose ***NO CAPSULE
Pathogenicity of gonococcus
a
What is Waterhouse-Friderichsen syndrome? [not for quiz]
Uncommonly, meningococcemia -> adrenal failure, circulatory collapse, shock, rapid death
Generally, what is thought to cause outbreaks of meningitis in college campuses, and what normally prevents cases in carriers?
Immunity evoked within a week by carrier state
College dorm -> diverse groups brought together -> exposure to serotypes never encountered before
What age groups are most affected by meningococcus? (3)
Kids 65
