On chocolate agar, colonies are small raised, glistening, and gray-white. The bacterial cells are gram-negative and...

On chocolate agar, colonies are small raised, glistening, and gray-white. The bacterial cells are gram-negative and spherical, tending to occur in pairs with adjacent sides flattened. In gram stain preparations made from smears of purulent material, the cells tend to be located intracellularly. Biochemical results are oxidase positive, catalase positive, glucose positive, maltose positive, sucrose negative, lactose negative and beta lactamase positive.

Expert Solution

The organism is identified as Neisseria meningitidis. It is normally seen as a commensal organism in the naasopharynx of individuals. The organism is responsible for meningititis which is very common in early childhood period whose second peak condition occur during the age of 15 - 24 years. These organisms are distinguished from N. gonorrhoeae by their adjacent flattened sides or lens or half moon shaped structure. Another distinguishing feature of N.meningitidis is their capsulated nature.

Colony morphology in blood and chocolate agar

-small( 1mm)

-round, convex

- gray

-non-hemolytic

-transclucent (at 24hrs of incubation), after 48 hours of incubation it will become larger having opaque with a raised center.

The organism is mainly transmitted through droplet inhalation and the associated clinical manifestations include rashes, septicemia, Pyogenic meningitis, Waterhouse- Friderichsen syndrome which is normally characterized by the appearance of large sized purpuric rashes, multiorgan failure, adrenal haemorrhage etc.

The samples normally taken for laboratory diagnosis include cerebrospinal fluid, blood or nasopharyngeal swab.

*Serological test carried out to detect the capsular antigens is ELISA.

*Molecular diagnosis include PCR and the genes targetted by this include ctrA ie. Capsule transport gene and sodC (Cu-Zn superoxide dumutase gene).

Prevention

*Chemoprophylaxis include ceftriaxone, rifampicin, Ciprofloxacin.

*Vaccination include meningococcal polysaccharide vaccines formulated in either bivalent or quadrivalent forms.

gladiator answered 1 year ago

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