Neisseria species


Gram-Negative Cocci & Coccobacilli   
>Aggregatibacter aphrophilus (formally known as Haemophilus aphrophilus)
>Bordetella pertussis (Causative agent of pertussis or whooping cough. )
>Brucella species:
     1] Brucella abortus
     2] Brucella canis
     3] Brucella melitensis
     4] Brucella suis
>Eikenella corrodens
>Haemophilus species:
     1] Haemophilus influenzae
     2] Haemophilus ducreyi
     3] Haemophilus avium
>Moraxella catarrhalis (formerly known as Branhamella catarrhalis)
>Neisseria species:  (frequently colonize mucosal surfaces.)Led
     1] Neisseria gonorrhoeae
     2] Neisseria meningitidis
>Pasteurella multocida


  • Large genus of commensal bacteria that colonize the mucosal surfaces of many animals.
  • Of the 11 species that colonize humans, only two are pathogens. N. meningitidis and N. gonorrhoeae often cause symptomatic infections, a commensal-like behavior.
  • Most gonoccocal infections are asymptomatic and self-resolving, and epidemic strains of the meningococcus may be carried in >95% of a population where systemic disease occurs at <1% prevalence.
  • Neisseria species are Gram-negative bacteria included among the proteobacteria, a large group of Gram-negative forms.  All the medically significant species of Neisseria are positive for both catalase and oxidase.
  • Neisseria diplococci resemble coffee beans when viewed microscopically.
    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.
  • The genus includes:
    • N. gonorrhoeae (also called the gonococcus), which causes gonorrhea.
    • N. meningitidis (also called the meningococcus), one of the most common causes of bacterial meningitis and the causative agent of meningococcal septicemia.

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Important considerations:  The choice of an agent should be based on local antimicrobial sensitivities, site of infection, cost, and comorbid conditions.   Generally, the most common agents/regimens are listed first. Listed dosages may need to be adjusted for renal dysfunction. 

Neisseria gonorrhoeae:

  1. Ceftriaxone 250 mg IM x 1  +  Doxycycline 100mg orally twice daily x 7 days (for possible C. trachomatis)
  2. Azithromycin 2 grams po x 1.

Neisseria meningitidis:

  1. Ceftriaxone 2 grams IV q12h 
  2. Cefotaxime 2 grams IV q4-6h.
  3. Penicillin G  3 to 4 million units q4h IV
  4. Chloramphenicol 100 mg/kg/day in divided doses every 6 hours (Maximum daily dose is 4 grams e.g. 1 gram q6h)
Neisseria species