Lynda Sowemimo
Pathogenic Neisseriae
Microbiology Special Project
Northwestern College

Introduction
Neisseria is a large genus of bacteria that colonize the mucosal surfaces of many animals. This genus (family Neisseriaceae) of parasitic bacteria grow in pairs and occasionally tetrads, and thrive best at 98.6°F (37°C) in the animal body or serum media. Of the 11 species that colonize humans, only two are pathogens, Neisseria meningitidis and N. gonorrhoeae. In N. meningitides and N. gonorrhoeae, DNA transformation requires the presence of short DNA sequences (9-10 monomers residing in coding regions) of the donor DNA. These sequences are called DNA uptake sequences.
Biochemical identification/ Genetic transformation
Neisseria meningitidis (also called the meningococcus), one of the most common causes of bacterial meningitis and the causative agent of meningococcal septicaemia. Neisseria gonorrhoeae (also called the gonococcus), which causes gonorrhea. Neisseria meningitidis has a polysaccharide capsule that surrounds the outer membrane of the bacterium and protects against soluble immune effector mechanisms within the serum. It is considered to be an essential virulence factor for the bacteria. N. gonorrhea possesses no such capsule.
Neisseria meningitidis
Often referred to as meningococcus, Neisseria meningitidis is a gram negative bacterium that can cause meningitis and other forms of meningococcal disease such as meningococcemia, a life-threatening sepsis. Neisseria meningitidis is a Gram-negative bacterium since it has an outer and inner membranes with a thin layer of peptidoglycan in between. It tests positive for the enzyme cytochrome c oxidase. The bacterium is referred to as a coccus because it is round, and more specifically, diplococcus because of its tendency to form pairs.

Signs and symptoms
Meningococcus can cause meningitis and other forms of meningococcal disease. It initially produces general symptoms like fatigue, fever, and headache and can rapidly progress to neck stiffness, coma and death in 10% of cases. Symptoms of meningococcal meningitis are easily confused with those caused by other bacteria, such as Hemophilus influenzae and Streptococcus pneumoniae.
Septicaemia
Septicaemia caused by Neisseria meningitidis has received much less public attention than meningococcal meningitis even though septicaemia has been linked to infant deaths. Meningococcal septicaemia typically causes a purpuric rash, that does not lose its color when pressed with a glass ("non-blanching") and does not cause the classical symptoms of meningitis. This means the condition may be ignored by those not aware of the significance of the rash. Septicaemia carries an approximate 50% mortality rate over a few hours from initial onset.
Neisseria gonorrhoeae
Neisseria gonorrhoeae, also known as gonococci (plural), or gonococcus (singular). Neisseria gonorrhoeae is a species of Gram-negative coffee bean-shaped diplococci bacteria. Neisseria are fastidious Gram-negative cocci that require nutrient supplementation to grow in laboratory cultures, they grow on chocolate agar with carbon dioxide. Neisseria gonorrhoeae is Responsible for the sexually transmitted infection gonorrhea.
Transmission
Neisseria gonorrhoeaeis transmitted from person to person during sexual relations. Traditionally, the bacteria was thought to move attached to spermatozoon, but this hypothesis did not explain female to male transmission of the disease. A recent study suggests that rather than “surf” on wiggling sperm, Neisseria gonorrhoeaebacteria uses hair like structures called pili to anchor onto proteins in the sperm and move through coital liquid. It can also be transmitted to the unborn infant in utero and afterward become apparent as a neonatal infection.
Signs and symptoms
Symptoms of infection with Neisseria gonorrhoeaediffer, depending on the site of infection. Note also that 10% of infected males and 80% of infected females are asymptomatic. Men who have had a gonorrhea infection have a significantly increased risk of having prostate cancer. Infection of the genitals can result in a purulent (or pus-like) discharge from the genitals, which may be foul-smelling. Symptoms may include inflammation, redness, swelling, and dysuria. Neisseria gonorrhoeaecan also cause conjunctivitis, pharyngitis, proctitis or urethritis, prostatitis, and orchitis. Conjunctivitis is common in neonates (newborns), and silver nitrate or antibiotics are often applied to their eyes as a preventive measure against gonorrhea. Neonatal gonorrheal conjunctivitis is contracted when the infant is exposed to Neisseria gonorrhoeaein the birth canal and can lead to corneal scarring or perforation, resulting in blindness in the neonate.
Conclusion/Prevention
Neisseria meningitidis
All recent contacts of the infected patient over the 7 days before onset should receive medication to prevent them from contracting the infection. This especially includes young children and their child caregivers or nursery-school contacts, as well as anyone who had direct exposure to the patient through kissing, sharing utensils, or medical interventions such as mouth-to-mouth resuscitation.
Neisseria gonorrhoeae
Patients should also be tested for other sexually transmitted infections (there is a fivefold increase of HIV transmission), especially Chlamydia infections, since co-infection is frequent (up to 50% of cases). Antibacterial coverage is often included for Chlamydia because of this. Transmission can be reduced by the usage of latex barriers, such as condoms or dental dams, during intercourse, oral and anal sex, and by limiting sexual partners

References:
CDC. “Meningococcal Disease.” DBMD – Meningococcal Disease – General Information: CDC website; 7/15/05
CSTS. “Meningococcal meningitis.” Fact Sheet on Meningococcal meningitis: Rev. May 2003. Child Survival Technical Support; 7/17/05
Seib KL, Rappuoli, R (2010). "Difficulty in Developing a Neisserial Vaccine". Neisseria: Molecular Mechanisms of Pathogenesis. Caister Academic Press