The document discusses the genus Neisseria, which includes pathogenic species such as Neisseria gonorrhoeae and Neisseria meningitidis, characterized as gram-negative diplococci that require enriched media for growth. It outlines their microbiological properties, methods for laboratory identification, and clinical significance, particularly focusing on the diseases they cause, transmission routes, and prevention strategies. Treatment options for infections include antibiotics like penicillin, ceftriaxone, and prophylactic measures, with an emphasis on the importance of awareness and detection to control the spread of these infections.

1. Neisseria
N. gonorrhoeae & N. menigitidis

2. GRAM NEGATIVE COCCI
Genus-Neisseria
• (a) N. gonorrhoeae (Gonococcus)
• (b) N. meningitidis (Meningococcus)
Genus–Moraxella
• M. catarrhalis-Gm-ve diplococci, infections of
respiratory system, middle ear, eye, CNS and joints;
disease usually of immunocompromised hosts
Genus-Acinetobacter
Non motile coccobacilli, encapsulated and oxidase
negative; widely distributed in nature & part of
normal flora hence isolation does not alone signify
etiology. Can infect any organ, tissue.

3. Neisseria
• The genus Neisseria consists of Gram negative, aerobic,
catalase & oxidase positive, non-motile diplococci (arranged
in pairs).
• Pathogenic
• Non-Pathogenic (commensals).
Pathogenic species:
-N. meningitidis (pyogenic menigitis)
-N. gonorrhoeae (gonorrhoea)
Non-pathogenic species:
-N. flavescens
-N. sicca
N. subflava

4. Neisseria Meningitidis ( meningococcus)
First isolated by Weichselbaum in 1887, from
the spinal fluid of a patient.
Morphology:
• They are gram negative, spherical or oval
cocci,
• 0.6-0.8 μm in size,
• arranged in pairs with the adjacent sides
flattened.
• Non-motile.
• Generally intracellular when isolated from
lesions.
.

5. Culture media:
• They are fastidious organism.Do not grow on ordinary
media.
• Growth occurs on media enriched with blood or serum.
These substances promote growth by providing additional
nutrients. Blood agar, Chocolate agar and Mueller-Hinton
agar are commonly used media.
• Selective media: Thayer Martin medium with antibiotics
(Vancomycin, Colistin, Nystatin & Trimethoprim), Martin-
Lewis (ML) medium & New-York City(NYC) medium

6. Thayer-Martin agar (or Thayer-Martin medium)
• Mueller-Hinton agar with 5% chocolate sheep blood and antibiotics.
It is used for culturing and primarily isolating pathogenic Neisseria
bacteria, including Neisseria gonorrhoeae It usually contains the
following combination of antibiotics called VCN inhibitor:
• Vancomycin, which is able to kill most Gram-positive organisms,
although some Gram-positive organisms such as Lactobacillus and
Pediococcus are intrinsically resistant;
• Colistin, which is added to kill most Gram-negative organisms except
Neisseria, although some other Gram-negative organisms such as
Legionella are also resistant;
• Nystatin, which can kill most fungi.
• Trimithoprim, which inhibits Gram-negative organisms, especially
swarming proteus

7. Culture media (cont.)
Thayer Martin medium & Martin-Lewis (ML) medium are
Chocolate based media, while New-York City(NYC)
medium is a clear peptone-cornstarch agar based
medium.
All the three media contain antibiotics to inhibit bacteria,
yeasts & molds. These media can be used to grow
*N. gonorrhoeae.
They are strict aerobes & can’t grow anaerobically. The
optimum temperature & pH for growth are 35°C-36°C &
7.4-7.6 respectively. A moist environment with 5-10% CO2
is must for the growth to occur.
On solid media, the colonies are small (1mm in diameter),
round, convex, grey, translucent with entire edges. The
colonies are butyrous in consistency & easily emulsifiable.
In liquid media, it produces granular turbidity.

8. Biochemical Reactions
• N. meningitidis is catalase & oxidase positive.
• The prompt oxidase reaction helps to identify neisseria (both
meningococci & gonococci in mixed cultures).
• Glucose & maltose are fermented with acid production but
no gas (gonococci ferment glucose but not maltose). They do
not ferment lactose or sucrose. Indole & H2S are not produced
& nitrates are not reduced.

9. Oxidase Test
When freshly prepared oxidase
reagent (1% tetramethyl paraphenylene diamine
hydrochloride) is poured on the culture
plate, neisseria colonies become
deep purple.(Oxidase-positive bacteria possess cytochrome
oxidase or indophenol oxidase (an iron-containing hemoprotein).
The test may also be performed by
rubbing bacterial growth with a loop
on a filter paper strip moistened with
the oxidase reagent. A deep purple
colour is a positive reaction.

10. Resistance
• These are very delicate organisms, being
highly susceptible to heat, dessication &
to disinfectants.
• They are susceptible to Penicillin,
Ampicillin, Chloramphenicol, Macrolides
& Ciprofloxacin.
• Strains resistant to Penicillin have been
reported in several countries.

11. Pathogenesis
• Cerebrospinal meningitis & meningococcal
septicemia are two main types of meningococcal
disease.
• Meningococci are strict human parasites inhabiting
the nasopharynx.
• Infection is usually asymptomatic.
• In some, local inflammation leads to rhinitis &
pharyngitis.
• Dissemination occurs only in a small proportion.
• The cocci spread from the nasopharynx to the
meninges may be directly along the olfactory nerve,
through the cribriform plate to the subarachnoid
space, or more probably, through the bloodstream.
• In certain cases the site of entry of the
meningococcus may be conjunctiva.

12. Clinical significance-

13. Laboratory identification
• Under light microscope (Centrifuged) CSF smear
show gram negative diplococci in association with
polymorphs.
• Carriers can be detected by culturing swabs from
nasopharyngeal region. Can be cultured easily
from CSF or blood on plain chocolate agar (as they
are normally sterile). Thayer Martin medium is
required for samples obtained from a skin lesion
or a nasophryngeal swab to eliminate
contaminating organisms.
• Meningococcus is oxidase positive and ferments
both glucose & maltose.
• CSF cytology & biochemistry gives clue.

14. TREATMENT & PREVENTION
• Penicillin/Chloramphenicol/ Cephalosporins
• Prophylaxis: Rifampicin or Ciprofloxacin
• Vaccines: Monovalent or Polyvalent(A,C,W135 and Y)

17. Characteristics of Neisseria gonnohorea
• Gram-negative diplococci with adjacent
sides concave (pear or bean shaped).
• Infects mucus-secreting epithelial cells
• Frequently appear as intracellular gram-
negative diplococci within
polymorphonuclear neutrophils; some
cell may contain as many as hundred
cocci.
• Neisseria gonorrhoeae fastidious
showing optimal growth on enriched
chocolate agar.
Neisseria gonorrhoeae in Urethral Exudates

18. Characteristics of Neisseria gonnohorea
• Gonococci posses pilli on their surface.
• Pilli facilitates adhesion of the cocci to mucosal surface &
promotes virulence by inhibiting phagocytosis.
• Infects mucus-secreting epithelial cells.
• They agglutinate human RBCs.

19. Cultural Characteristics
• Gonococci are non motile. More difficult to grow.
• Are aerobic and facultative anaerobic.
• pH 7.2-7.6 at optimum temperature 35-36℃.
• Grow well on chocolate agar, Muller Hinton agar.
• Selective medium (Thayer Martin medium)

20. Biochemical Reactions
• Oxidase Positive
• Catalase Positive
• Ferments Glucose with acid but not Maltose .

21. 22
Transmission
•Efficiently transmitted by:
–Male to female via semen
–Female to male urethra
–Rectal intercourse
–Perinatal transmission (mother to infant)
•Gonorrhoea is associated with increased
transmission of and susceptibility to HIV
infection

22. 23
Complications in Men
• Primary site: Urethera
• Leads to Urethritis
• Swollen or tender testicles (epididymitis)
• Disseminated gonococcal infection (DGI)
Gonorrhea

23. IN MEN:
 Most infections among men are acute and symptomatic
with purulent discharge & dysuria (painful urination) after 2-
5 day incubation period
 Male host seeks treatment early preventing serious
sequelae, but not soon enough to prevent transmission to
other sex partners
 The two bacterial agents primarily responsible for urethritis
among men are N. gonorrhoeae and Chlamydia
trachomatis

24. 25
Gonorrhea Symptoms in Women
• Primary site: Vagina
• Usually asymptomatic often untreated until PID complications develop
• Inflammation of the endocervix
• Purulent vaginal discharge
• Painful urination
• Abnormal vaginal bleeding
• Pain and bleeding during sexual intercourse

25. 26
Complications in Women
•Pelvic inflammatory disease (PID)
• May also be asymptomatic, but difficult diagnosis accounts for many false
negatives
• Can cause scarring of fallopian tubes leading to infertility or ectopic pregnancy
•Disseminated gonococcal infection (DGI)
• Result of gonococcal bacteremia
• Often skin lesions
• Petechiae (small, purplish, hemorrhagic spots)
• Pustules on extremities
• Arthralgias (pain in joints)
• Septic arthritis
• Occasional complications: Hepatitis, Rarely endocarditis or meningitis
The acidic pH of vaginal secretions in female, due to the fermentation of glycogen by lactobacillus (normal
flora), renders vagina free of many pathogens.

26. 27
Gonorrhea in Infants
• A mother can pass gonorrhea to
her baby during childbirth
• Ophthalmia neonatorum
Gonorrhea

27. Laboratory Diagnosis
• Specimen:
• Discharge or Uretheral swab,
Endocervical swab
• Specimens should be processed
immediately using prewarmed culture
plate or transported in Stuart’s transport
medium.
Stuart’s transport media

28.  Gram’s staining: Small, gram-negative diplococci in presence of
polymorphonuclear leukocytes (PMN’s) seen microscopically in
purulent urethral discharge
 Susceptible to drying and cooling, so immediate culture of
specimen onto pre-warmed selective (e.g., modified Thayer-Martin,
Martin-Lewis agars) and non-selective media (chocolate blood agar)
with moist atmosphere containing 5% carbon dioxide
Laboratory Diagnosis

29. Lab Examination
• Ferment Glucose with acid only.
• Do not ferment maltose
• Oxidase positive
• Serology:
• ELISA

30.  Penicillin no longer drug of choice due to:
•Continuing rise in the MIC
Uncomplicated infections: ceftriaxone, cefixime or
fluoroquinolone
Combined with doxycycline or azithromycin for dual
infections with Chlamydia
Treatment of newborns with opthalmia neonatorum with
ceftriaxone
Treatment

32. Measures to limit epidemic include
Education/ Counselling
aggressive detection
follow-up screening of sexual partners
inappropriate self medication leads to
widespread of antimicrobial resistance
Prevention/ Control of Gonorrhea

34. MENINGOCOCCAL MENINGITIS: A RARE
BUT POTENTIALLY DEVASTATING.