The document discusses Neisseria, a genus of bacteria that includes the pathogenic N. gonorrhoeae which causes gonorrhea. N. gonorrhoeae is a gram-negative coccus found in pairs that requires an environment of 35-36°C and 5-10% CO2 to grow. It is identified through positive oxidase and catalase tests and acid production from glucose but not other sugars. Colonies are pinkish-brown and smooth. Gonorrhea spreads through sexual contact and initially adheres to mucosal surfaces through pili before invading tissues. Globally an estimated 16 million cases occurred annually in 1970 though rates have fluctuated since.

1. PG DEPARTMENT OF MICROBIOLOGY
VIVEKANANDHA ARTS AND SCIENCE COLLEGE FOR WOMEN
SANKAGIRI
NEISSERIA
MEDICAL BACTERIOLOGY
K.. DIVYAPRABHA
III - BSC MICROBIOLOG
VIVEKANANDHA ARTS AND SCIENCE COLLEGE FOR WOMEN
SANKAGIRI, SALEM
TAMILNADU

2. INDROCUTION
● Neisseria is named after Albert Ludwig Sigesmund Neisser, a
German physician who discovered Neisseria
● The Gram-negative bacteria genus Neisseria includes both
pathogenic and commensal species that are found primarily
in the upper respiratory tract of humans and animals.
● a genus (the type of the family Neisseriaceae) of parasitic
bacteria that grow in pairs and occasionally tetrads, thrive
best at 98.6°F (37°C) in the animal body or serum media, and
include the gonococcus (N. gonorrhoeae) and

3. Scientific classification
Domanic Bacteria
Phylum Pseudomonadota
Class Betaproteobacteria
Order Neisseriales
Family Neisseriaceae
Genus Neisseira Trevisan, 1885

4. ● Neisseria species are Gram-negative cocci, 0.6 to 1.0 μm in diameter.
● The organisms are usually seen in pairs with the adjacent sides flattened.
● Pili, hairlike filamentous appendages extend several micrometers from the
cell surface and have a role in adherence
MORPHOLOGY

5. Types
Neisseria Menigahinitis
Neisseria gonorrhoeae

6. Morphology of Neisseria gonorrhoeae:
● Under the microscope, it appears as a gram-negative coccus which is present in pairs
(diplococci) with the flattening of the adjacent sides.
● The diameter ranges from 0.6-1 μm.
● The diplococci have kidney/coffee bean shape.
● It is a non-spore forming bacteria and is able to move using twitching motility.
● Gonococci exhibit pili on their surface.
● Pili enhances the binding of the cocci to the mucosal surfaces and promotes virulence
by restricting phagocytosis.
● Human red blood cells are agglutinated by piliated gonococci, but not red cells from
other

7. Cultural and biochemical characteristics for identification of Neisseria
gonorrhoeae:
● Gonorrhoeae is a fragile organism with strict environmental and nutritional requirements.
● pH 7.0-7.4 and at a temperature of 35-36 °C, growth occurs best.
● It is an aerobe meaning it needs oxygen to grow, however it can grow in anaerobic conditions as well.
● The supply of 5-10 percent CO2 is needed.
● They grow rapidly on chocolate agar and Mueller-Hinton agar.
● The Thayer-Martin medium (chocolate agar containing antimicrobials such as vancomycin, colistin and
nystatin) is a common selective medium that inhibits most contamination, including nonpathogenic
Neisseria.
● Trimethoprim lactate may be introduced to the Thayer-Martin medium to suppress swarming Proteus
species that are sometimes present in cervicovaginal and rectal specimens.
● Neisseria gonorrhoeae shows positive oxidase test (having cytochrome c oxidase) and is catalase positive
as well, i.e. it can convert hydrogen peroxide to oxygen.
● The acid production takes place only from glucose and not from maltose, and also it does not ferment
lactose or sucrose.
● It tests negative for nitrate reduction test.
● In enzyme substrate test, it tests positive for hydroxyprolylaminopeptidase.

8. Colonial morphology of Neisseria gonorrhoeae:
● In a humid aerobic environment enriched with 5-10% CO2, colonies are thin, round, translucent, convex or
slightly umbonate, with finely granular surface and lobate margins after incubation for 24 hours.
● The colonies of Neisseria gonorrhoeae are pinkish brown.
● They are easily emulsifiable and soft.
● The colonies are larger (1.5-2.5 mm) after 48 hours, often with a crenated margin and an opaque elevated
center.
● The transparent, golden-brown pigmentation noticeable in 48 hr cultures after incubation results from cell
autolysis.
● With gonococcal colonies, substantial variance in size exists and the colony out-line is irregular in most
culture media, unlike the circular colonies of N. meningitidis.
● Growth is slower on the Thayer-Martin medium.
● Even if colonies are similar to those on the MNYC medium, they are typically smaller.
Types of gonococci:
● On the basis of colonial appearance, auto-agglutinability and virulence, Kellogg classified gonococci into
four types (T1-T4).
● T1 and T2 form small brown colonies and possess several numbers of fimbriae (pilated types P1 and P2).
They are virulent and auto-agglutinable.
● Types T3 and T4 are non-piliated (P-), are avirulent type and form smooth suspensions.
● The fresh isolates obtained from acute cases of gonorrhea normally form T1 and T2 colonies.
● They transition to T3 or T4 colonial morphology in serial subculture.
● The forms T1 and T2 are often referred to as P+ and P++, while T3 and T4 are known as P-.

9. Pathogenesis of Neisseria gonorrhoeae:
● Gonorrhea is a sexually transmitted disease.
● Gonorrhea is a condition that is essentially limited to humans’ mucus-secreting epithelial cells.
● The first stage in the infection is the adhesion of gonococci to the urethra or other mucosal surfaces.
● For the first attachment, the existence of pili is important.
● As the adhesion is quick and firm, the micturition after exposure offers no protection against infection.
● By the third day following infection, the cocci penetrate into the intercellular spaces and enter the
subepithelial connective tissue.
● Gonococci presumably penetrate between columnar epithelial cells.
● Stratified squamous epithelium is comparatively resistant to infection.
● The period of incubation is 2-8 days.
● Gonococci invade the genitourinary tract, eye, rectum, and throat mucous membranes, causing acute
suppuration that can lead to tissue invasion; which are followed chronic inflammation

10. Epidemiology of Neisseria gonorrhoeae:
● Gonorrhea exists in humans only and no other reservoir is yet known.
● Although a proportion of those infected, especially women, may remain asymptomatic, it is never discovered
as a normal commensal.
● Gonococcal disease has historically been a key factor in areas where there has been limited access to
healthcare services.
● This is reflected in the high rates of gonorrhea in the developing world, particularly in sub-Saharan Africa
and Asia, as well as in the rates currently rising in the former Eastern Bloc/Soviet Union.
● Typically, acute gonorrhea is quickly detected and treated, and was well managed until the 1960s in most of
the world.
● The occurrence of new cases worldwide was estimated at 16 million in1970, making it one of the most
common infectious diseases.
● In the 1980s, with the AIDS scare, there was a significant decrease in gonorrhea incidence, although this
has not been sustained.
● A higher frequency of gonorrhea was found in patients belonging to group B of the blood, the basis for this is
yet not understood.