NEISSERIA

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NEISSERIA
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• The genus Neisseria contains two important
  pathogens
• 1. Neisseria meningitidis
• 2. Neisseria gonorrhoeae.
• N. meningitidis causes meningitis and
  meningococcemia.
• N. gonorrhoeae causes gonorrhea,neonatal
  conjunctivitis (ophthalmia neonatorum) and pelvic
  inflammatory disease (PID).

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• Properties
• Neisseriae are gram-negative diplococci ( Bean
  shaped).
• Oxidase-positive i.e., they possess the enzyme
  cytochrome c and produce oxidase.
• They are cultured on "chocolate" agar
• N.meningitidis is maltose fermenter
• N. gonorrhoeae is maltose non fermenter
• N.meningititidis produces no beta lactamases.
• Some of N. gonorrhoeae produce beta lactamases.

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• Meningococcus has at least 13 serogroups on the
  basis of capsular polysaccharides. Important ones
  are A,B,C,Y and W-135.
• The endotoxin of N. meningitidis is a
  lipopolysaccharide (LPS) but the endotoxin of N.
  gonorrhoeae is a lipooligosaccharide (LOS).
• N.meningitidis is encapsulated while N.gonorrhoea
  has no capsule

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PILLI
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• NEISSERIA MENINGITIDIS
• Pathogenesis
• Humans are the only natural hosts
• The organisms are transmitted by airborne
  droplets
• Colonize the nasopharynx and become transient
  flora of the upper respiratory tract.
• From the nasopharynx, the organism can enter the
  bloodstream and spread to meninges or cause
  meningococcemia.

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• N. meningitidis is the most common cause of
  meningitis in persons between the ages of 2 and
  18 years.
• Outbreaks of meningitis are most common in winter
  and early spring, and favored by close contact
  between individuals.
• It has three important virulence factors
• 1. Polysaccharride capsule. It is
  antiphagocytic in nature.

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• 2. Endotoxin. It induces septic shock by causing
  release of cytokines.
• 3. IgA protease. It cleaves the IgA antibodies
  present in respiratory mucosa

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• Clinical Findings
• 1. Meningitis
• 2. Meningococcemia
• 1.Meningitis. The symptoms are fever, headache,
  stiff neck, and an increased level of Neutrophils
  in spinal fluid.
• 2.Meningococcemia.
• It occurs due to multiplication of bacteria in
  the blood stream.

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• The severe form of it is life-threatening
  Waterhouse-Friderichsen syndrome.
• It is the septic shock induced by meningococcus
• Also called Fulminant meningococcemia.
• Feature include high fever, shock, widespread
  purpura, disseminated intravascular coagulation,
  thrombocytopenia, and adrenal insufficiency due
  to bilateral adrenal hemorrhages.

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• Laboratory Diagnosis
• A. Specimens include.
• 1. Blood for culture and smears
• 2. Spinal fluid for smear, culture, chemical
• analysis.
• B. Blood smears on gram staining show gram
• negative bean shaped diplococci.
• C. Culture. The organism grows best on
  chocolate agar incubated at 37C in a 5 CO2
  atmosphere. Colonies are transparent or opaque.

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• D. Oxidase test. Positive
• E. Manitol fermentation. The difference between
  N. meningitidis and N. gonorrhoeae is made on the
  basis of manitol fermentation. Meningococci
  ferment maltose, whereas gonococci do not

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1. Latex agglutination test, which detects capsular
   polysaccharide in the spinal fluid.

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• Prevention
• Chemoprophylaxis and immunization both used for
  prevention.
• Rifampin or ciprofloxacin used for prophylaxis in
  people who had close contact with the patient
• There are two forms of the meningococcal
  vaccine, each contains the capsular
  polysaccharide of groups A, C, Y, and W-135 as
  antigens (Tetravalent vaccine)
• 1. Unconjugated
• 2. Conjugated

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• Neisseria gonorrhoeae (Goonococcus).
• Non motile.
• Humans are only reservoir, not part of normal
  flora
• Causes disease only in humans.
• Killed by drying thats why transmitted sexually.

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• Pathogenecity
• The virulence factors are.
• Pili. Most important virulence factors.
• Piliated gonococci are usually virulent, whereas
  non piliated strains are avirulent.
• Two virulence factors in the cell wall
• a. Lipooligosaccharride (LOS) (a modified
  form of endotoxin). Endotoxin of gonococci is
  weaker than that of meningococci.
• b. Outer membrane proteins.(OMP).

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• OMP cause attachment of bacteria to epithelial
  cells of the urethra, rectum, cervix, pharynx, or
  conjunctiva, like pilli.
• IgA protease.
• The main host defenses against gonococci are
  antibodies (IgA and IgG), complement, and
  neutrophils.
• IgA protease degrades one of these antibodies.
• Certain strains of gonococci cause disseminated
  infections.
• These gonococci resist killing by bacteria due to
  protein Porin A (OMP).
• It inactivates the C3b component of complement.

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PILLI
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• Clinical Findings
• Transmitted sexually both in males and females.
• Cause pyogenic infections.
• Females are usually asymptomatic.
• N. gonorrhea causes following infections.
• 1. Genitourinary tract infections ( Gonorrhea)
• 2. Disseminated infection via spread through
  blood
• stream.
• 3. Rectal infections.

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• 4. Pharyngitis
• 5. Ophthalmia neonatorum
• 1. Genitourinary tract infections
• Gonorrhea in men has features of urethritis
  accompanied by dysuria and a purulent discharge.
  Epididymitis can occur.
• In women, infection is initially in the
  endocervix (cervicitis), causing a purulent
  vaginal discharge and intermenstrual bleeding.

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• The most frequent complication is ascending
  infection to the uterine tubes (salpingitis)
  which can lead to sterility or ectopic pregnancy
• 2. Disseminated gonococcal infection(DGI)
• Commonly manifest as arthritis, synovitis, or
  skin pustules.
• Disseminated infection is the most common cause
  of septic arthritis in sexually active adults.

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• 3.Rectal infections
• Prevalent in male homosexuals, are characterized
  by constipation, painful defecation, and purulent
  discharge.
• 4.Pharyngitis is contracted by oral-genital
  contact. The condition may mimic a mild viral or
  a streptococcal sore throat.

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• 5.Ophthalmia neonatorum is an infection of the
  conjunctiva acquired by a newborn during passage
  through the birth canal of an infected mother .
• If untreated, acute conjunctivitis may lead to
  blindness.

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• Lab diagnosis
• 1.In the male, the finding of numerous
  neutrophils containing gram negative diplococci
  in a smear of urethral exudate provides a
  diagnosis of gonococcal infection.
• 2.In the female a positive culture is also
  needed.
• 3.Culture
• N. gonorrhoeae grows best under aerobic
  conditions, and most strains require CO2 also.

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• Gonococci are very sensitive to heating or
  drying. Cultures must be plated rapidly.
• N. gonorrhoeae grows rapidly producing small,
  raised, grey or translucent colonies after
  overnight incubation.
• 4. Oxidase test. Positive.

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• Prevention
• The prevention of gonorrhea involves the use of
  safety measures and the immediate treatment of
  symptomatic patients and their contacts.