Pbl 3 –pod 1 : the morphology and structure of Neisseria meningitidis, the transmission and...

PBL 3 –POD 1Asem shadid

Objective :

describe the morphology and structure of Neisseriameningitidis

describe the transmission and clinical features of meningitides

describe the process of development of meningitides

what is the diagnostic test required for Neisseriameningitidis

list the other causes of meningitis and its cfc finding

describe the morphology and structure of

Neisseria meningitides :

• Meningitis is an acute inflammation of the protective membranes covering the brain and spinal cord, known collectively as the meninges.

• The meninges are the membranes that envelop the central nervous system.

• the meninges consist of three layers:the dura mater, the arachnoid mater, and the pia mater.

• The primary function of the meninges is to protect the central nervous system.

• Meningitis can be life-threatening

• The inflammation may be caused by infection with viruses, bacteria, or other microorganisms, and less commonly by certain drugs.

Capsulated Gram negative cocci in pairs (diplococci)

0.5 – 1 µm in size

Kidney shaped, flat sides adjacent

Intracellular, usually

Non motile

Non spore forming.

Morphology

• Neisseria meningitidis, often referred to as meningococcus, is a bacterium that can cause meningitis .

• N. meningitidis is a major cause of illness and death during childhood in industrialized countries and has been responsible for epidemics - االوبئة - in Africa and in Asia.

• The bacteria are round and are often joined in pairs.

• They are Gram-negative since they have outer and inner membranes with a thin layer of peptidoglycan in between.

• Pili – helps in meningeal invasion

• A pilus is a hair like found on the surface of many bacteria..

describe the transmission and clinical features of

meningitides :-

• Transmission

• Meningococcus is spread through the exchange of saliva and other respiratory secretions during activities like coughing, sneezing, kissing, and chewing on toys.

• Direct contact and air borne droplets

• Close contact with infectious person

• Incubation period – 1 to 7 days

• Incubation period is the time elapsed between exposure to a pathogenic organism and when symptoms and signs are first apparent.

• Although dangerous disease, not easily spread.

• 15% adults carry disease causing strains in nose and throat.

Clinical features

Meningitis and meningococcal septicaemia may not always be easy to detect, in early stages the symptoms can be similar to flu.

They may develop over one or two days, but sometimes develop in a matter of hours.

It is important to remember that symptoms do not appear in any particular order and some may not appear at all.

describe the process of development of

meningitides

Nasopharyngeal Colonization

Local Invasion

Bacteremia

1

2

3

Meningeal Invasion Bacterial Replication

Release of bacterial components

4 5

6

what is the diagnostic test required for Neisseria

meningitidis

• Severe stiffness of the hamstrings causes an inability to straighten the leg when the hip is flexed to 90 degrees.

• Severe neck stiffness causes a patient's hips and knees to flex when the neck is flexed.

Signs

list the other causes of meningitis and its cfc

finding

Bacterial meningitis

• Acute bacterial meningitis usually occurs when bacteria enter the bloodstream and migrate to the brain and spinal cord.

• A number of strains of bacteria can cause acute bacterial meningitis. The most common include:

• Streptococcus pneumoniae (pneumococcus). This bacterium is the most common cause of bacterial meningitis in infants, young children and adults in the United States. There is a vaccine to help reduce the occurrence of this infection.

• Neisseria meningitidis (meningococcus). This bacterium is another leading cause of bacterial meningitis. Meningococcal meningitis commonly occurs when bacteria from an upper respiratory infection enter your bloodstream. This infection is highly contagious .

• Haemophilus influenzae (haemophilus). have greatly reduced the number of cases of this type of meningitis.

• Listeria monocytogenes (listeria).

Thank youAsem shadid