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, candlejar
2. Commercial systems (CO2 Bio-bag Type C, CO2 GEN Compact, CO2 incubator)
Humidophiles
Requires increased moisture
Achieving humid environment
1. In the candlejar
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.
VirulenceFactors
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
PolysaccharideCapsule (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
Expressed only by N. gonorrhea - protective against host's inflammatory response and complement mediated killing
IgAProtease
Cleaves IgA antibodies in mucus membranes
LOS (Lipooligosaccharide)
Contains the endotoxin portion of the organism
IgAprotease
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