The document discusses the Neisseriae bacteria, specifically Neisseria meningitidis and Neisseria gonorrhoeae. It describes their morphology, cultural characteristics, biochemical properties, virulence factors, pathogenesis, laboratory diagnosis, treatment and prevention. N. meningitidis causes meningitis while N. gonorrhoeae causes gonorrhea. Both are Gram-negative diplococci that require special culture conditions and produce oxidase and possess virulence factors like capsules, endotoxins, and IgA proteases. Laboratory diagnosis involves Gram staining, culture, oxidase and fermentation tests. Treatment involves penicillin and prevention involves vaccines and contact tracing.

2. TheNeisseriaeareGramnegativediplococci
Pathogensare:-N.Meningitidis
N.Gonorrhoeae

3. Neisseria Meningitidis
General characteristics
•Gram-negative,bean-shaped,diplococci
•Donotpossessflagellaorspores
•Capsulatedandpossesspili.
•Strictparasites,donotsurvivelongoutsideofthe
host
•Aerobic
•Oxidativemetabolism
•Producecatalaseandoxidase
•Pathogenic species require enriched complex
mediaandCO2

4. Morphology
• Gram-negative,bean-shaped,diplococci
• Donotpossessflagellaorspores.
• Capsulatedandpossesspili.
• 0.8x0.6µmindiameter.
Cultural characteristics
• Cangrowinbloodagar,Chocolateagar.
• Growthisimprovedbyadditionofbloodorserum.
• Growth is also improved by incubation in the
presenceof2- 8%CO2
• Growthtemperatureis36-39⁰CandpHrangesof6-8.
• Coloniesare1-2mmindiameter,convex,greyand transparent.No
hemolysisinbloodagar.

5. Biochemical properties
•Oxidase-positive; i.e., they possess the
enzyme cytochrome and produce
oxidase.
•N.Meningitidisismaltosefermenter.
•N.Meningitidis produces no beta
lactamases.

6. Ithasthreeimportantvirulencefactors:
1. Polysaccharride capsule. It is antiphagocytic
innature.
2. The endotoxin of N. Meningitidis is a
lipopolysaccharide (LPS). It induces septic
shockbycausingreleaseofcytokines.
3. IgA protease. It cleaves the IgA antibodies
presentin respiratorymucosa.

7. by airborne
Pathogenesis
• Humansaretheonlynaturalhosts
• The organisms are transmitted
droplets
• Colonizethenasopharynxandbecometransient floraofthe
upperrespiratorytract.
• From the nasopharynx, the organism can enter the
bloodstream and spread to meninges and grow in the
cerebrospinalfluid.

8. Diseases
• N.Meningitidisisthemostcommoncause of meningitisin
personsbetweentheagesof2and 18years.
• Outbreaks of meningitis are most common in winter and
early spring, and favored by close contact between
individuals.
1. Meningitis
2. Meningococcemia (multiplication of bacteria in the blood
stream)

9. Laboratory diagnosis
•Itis frequentlyisolatedfromsamplessuchas
blood,CSF
.
•Different methods for laboratory
diagnosis are:
Gramstaining
Culture
Oxidasetest
Fermentationtests
Latexagglutinationtest

10. Gram staining
The diagnosis is suggested by the finding of gram
negativebacteriabeanshaped capsular diplococci.

11. Culture
The organism is cultured on blood agar or chocolate agar
incubatedat37°C ina5%CO2 atmosphere. Coloniesare1-2 mmin
diameter, convex,greyandtransparent.Nohemolysis

12. Oxidase test: Determinesthepresenceofcytochrome oxidase.
ItisPositiveinN.Meningitidis.
Growthe isolate(s) to be tested for 18-24 hours on a blood
agar plate at 35-37°C with ~5% CO2. Dispense a few drops of
Kovac's oxidase reagent. Tilt the plate and observe colonies for a
color change to purple. Positive reactions will develop within 10
secondsintheformofa purplecolor.

13. fermentation: N. Meningitidis ferment
fermentation: N. Meningitidis ferment
Manitol
manitol.
Maltose
maltose.
Latex agglutination test, which detects capsular
polysaccharideinthespinalfluid.

14. Treatment and Prevention
• PenicillinGorsulphonamidesarethedrugsof choice.
or third generation
such as cefotaxime or
• Cholramphenicol
cephalosporin
ceftriaxone are recommended for patients
whoareallergictopenicillin.
• M
eningococcal vaccine, is available which
containsthecapsularpolysaccharide.

15. Neisseria Gonorrhoeae
•N. Gonorrhoeae causes gonorrhea, neonatal
conjunctivitis (ophthalmia neonatorum) and
pelvicinflammatorydisease(PID).
Morphology
• Ovalshaped
• Gramnegativediplococci
• Sizeis0.6to0.8µm.
• Occursinpair
• Nonmotile
• Capsulatedandhavepilli

16. Cultural characteristics
•Cangrowin enrichedmediasuchaschocolate
agar.
•Growthis also improved by incubation in the
presenceof5- 10%CO2
•Growth temperature is 37⁰C and no growth if
thetemperatureis lessthan25⁰Cormore than
38.5⁰C
•pHrangesof 7.2-7.6.

17. Biochemical properties
Thevirulencefactorsare.
1. Pili: Mostimportantvirulencefactors.
Piliatedgonococciareusuallyvirulent,whereas non
piliatedstrainsareavirulent.
2. Twovirulencefactorsinthecellwall
a) Lipooligosaccharride (LOS) (amodifiedform
of endotoxin).Endotoxinofgonococciisweakerthan
thatofmeningococci.
b) Outer membrane proteins(OMP) :OMPcause
attachmentofbacteriatoepithelialcellsofthe urethra,
rectum,cervix,pharynx,orconjunctiva,like pilli.

18. 3. IgAprotease
• The main host defenses against gonococci
are antibodies (IgA and IgG), complement,
and neutrophils.
•IgA protease degrades one of these
antibodies. Other biochemical properties
are;
• They ferment glucose
• They are oxidase positive

19. Pathogenesis
• Humans are only reservoir, not part of normal
flora.
• Causes disease only in humans.
• Transmitted sexually both in males and
females.
• N. gonorrhea causes following infections.
1. Gonorrhea
2. Neonatal conjunctivitis (ophthalmia
neonatorum)
3. Pelvic inflammatory disease (PID).

20. Laboratory diagnosis
• It is frequently isolated from samples such
as blood, urethral discharge in men,
cervical discharge in females.
• Different methods for laboratory diagnosis
are:
Gram staining
Culture
Oxidase test
Fermentation tests

21. Gram staining
The diagnosis is suggested by the finding of gram
negativebacteriabeanshapedcapsular diplococci.

22. Culture
The organism is cultured on Thayar - Martin Agar or
Mueller-Hintonagar(chocolateAgar) incubatedat37°Cina5%CO2
atmosphere.Colonies are1-2mmindiameter,greyandtransparent.N.
gonorrheagrowsrapidly producingsmall,Nohemolysis.

23. Oxidase Test
• Testonfilterpaperordirectlyonplate
• Oxidasereagent=Dimethylortetramethyl oxidasereagent
• Violet-purple color indicates a positive result.

24. Manitol fermentation: N.Gonorrheafermentmanitol.
Maltose fermentation: N. Gonorrhea do not ferment maltose.

25. Treatment and Prevention
Treatment
• Penicillin
• Tetracycline if beta-lactamase positive strain. Canalso use
cephalosporinsand flouroquinolones.
Prevention
• The prevention of gonorrhea involves the use of safety
measures and the immediate treatment of symptomatic
patientsandtheir contacts.