Neiss

• Neisseria


  Aerobic, non-motile, non-spore forming gram negative diplococci with adjacent ends flattened that resemble tiny "coffee beans" or "kidney beans," except: N. weaver, N. elongata, & N. bacilliformis which are rod-shaped
• Neisseria genus

  • Aerobic
  • Non-motile
  • Non-spore forming

  
• Gram Negative


  Does not retain Crystal violet, but retains safranin
• Diplococci


  • Spherical, in pairs
  • Distinguishing characteristics: presence of adjacent ends that are flattened

  
• Neisseria species that are rod-shaped

  • N. weaver
  • N. elongata
  • N. bacilliformis
• Neisseria species that are catalase (-) and cytochrome oxidase (-)

  • N. elongata spp nitroreducens
  • N. bacilliformis
• Catalase


  An enzyme that converts hydrogen peroxide to water and oxygen resulting in effervescence (bubble formation)
• Neisseria

  • Capnophilic (3 – 10% CO2)
  • Humidophiles
• Optimal Temperature

  Between 35*C and 37* C (32C-36C)
• Natural Habitat

  Mucus Membranes of the RT and urogenital tracts

  
• Primary pathogens

  • N. gonorrhoea
  • N. meningitidis

  
• Capnophilic


  Requires increased concentration of carbon dioxide that is 3 – 10%
• Achieving capnophilic environment

  1. Routinely, candle jar

  2. Commercial systems (CO2 Bio-bag Type C, CO2 GEN Compact, CO2 incubator)
• Humidophiles


  Requires increased moisture
• Achieving humid environment


  1. In the candle jar

  2. CO2 incubator with a pan of water
• Neisseria gonorrhea and Neisseria meningitidis


  • Highly fastidious: Required iron for growth
  • Require enriched media for growth

  
• Enriched media for N. gonorrhea

  CAP supplemented with cysteine, X (hemin) and V (NAD or Coenzyme I) factors

  
• Enriched media for N. meningitidis

  SBA as the minimal growth standard

  
• Both N. gonorrhea and N. meningitidis are highly sensitive to temperature changes and must be protected from cold! They must be inoculated immediately on their respective primary isolation media.

  
• Virulence Factors


  Components present on the surface of bacterial cells or components that are secreted by bacterial cells that contribute to their ability to cause disease and contributes to the degree of their pathogenicity
• Receptors for human transferrin

  Competes human hosts for iron
• Polysaccharide Capsule (N. meningitidis only)


  Resist Phagocytosis
• Pili


  • For attachment to host's mucus membranes
  • For conjugation and transfer of genetic materials such as genes that code for antimicrobial resistance
• Cell membrane proteins

  • Por (Protein I) - Channel for passage of nutrients and waste products
  • Opa (protein II) - facilitate adherence of organisms to phagocytic and epithelial cells
  • Reduction modified protein (Protein III) - blocks host IgG
• PorB (Protein I)


  Expressed only by N. gonorrhea - protective against host's inflammatory response and complement mediated killing

  
• IgA Protease


  Cleaves IgA antibodies in mucus membranes
• LOS (Lipooligosaccharide)


  Contains the endotoxin portion of the organism
• IgA protease


  Enzyme secreted by pathogenic Neisseria that can cleave IgA antibodies present on mucosal surfaces, leading to destruction of IgA and allowing the pathogenic bacteria to colonize and establish infections in mucosal surfaces

  
• LOS (Lipooligosaccharide)


  Contains the endotoxin portion of the pathogenic Neisseria organism
• The LOS of pathogenic Neisseria is similar to the LPS of other Gram-negative bacteria, and the Lipid A portion contains the endotoxin

  
• The LOS is anchored in the outer layer, while the Lipid A is found beneath the outer membrane
• When bacterial cells, particularly Gram-negative bacteria, lyse, the Lipid A becomes liberated and the endotoxin would be present in the circulation
• In cases of rapid growth of pathogenic Neisseria inside the host, their growth releases outer membrane fragments called blebs which contain the LOS, including the Lipid A portion with the endotoxin

  
• Endotoxins


  Substances present in the Lipid A portion of the LOS that can stimulate macrophages to produce increased amounts of pro-inflammatory cytokines

  
• When endotoxins are released either through lysis or blebs

  In large amounts, they can stimulate macrophages to produce increased amounts of pro-inflammatory cytokines such as tumor necrosis factor, interleukin I, chemokines, and other inflammatory mediators

  
• Endotoxemia


  Refers to the increased presence of endotoxins in the blood, which can stimulate macrophages to produce an increased amount of pro-inflammatory cytokines

  
• Normally, in the presence of inflammation, these pro-inflammatory cytokines are beneficial as they promote inflammation and help in the activation of the immune response and localization and elimination of the cause of tissue injury or infection
• However, when there is excessive amounts of pro-inflammatory cytokines produced by macrophages as a result of endotoxin stimulation, the excessive amounts of inflammatory mediator could cause a heightened inflammation, which becomes harmful to the host

  
• Effects of Endotoxin

  • Prolonged inflammation and fever
  • Prolonged vasodilation (vascular permeability)
  • Hypotension
  • Tachycardia
  • Septic shock
  • Intravascular coagulation

  
• Inflammation is a "double-edged" sword - it is beneficial when it achieves its primary purpose in the immune response, but when it becomes heightened due to endotoxin stimulation, the excessive inflammatory response can be damaging to the host