Neisseria meningitidis

Updated : December 4, 2023

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  • Neisseria meningitidis is a bacterium that causes meningococcal disease, a severe and potentially deadly illness that can affect the brain and spinal cord. The incidence of the meningococcal disease varies by geographic region and over time. 
  • According to the World Health Organization (WHO), Meningococcal illness is sporadic and can occur anywhere worldwide, with an estimated 1.2 million cases occurring annually. Sub-Saharan Africa, also referred to as the “meningitis belt,” has the highest prevalence of the illness, with outbreaks happening there every 5–10 years. The disease is caused primarily by serogroups A, C, W, X, and Y. 
  • In other regions, the incidence of meningococcal disease is lower, but sporadic outbreaks still occur. The disease is more common in infants, young children, and adolescents, with a second peak occurring in young adults. 
  • Neisseria meningitidis is a gram-negative bacterium that causes meningococcal disease, a severe infection that can lead to meningitis and sepsis. 
  • Structure:  The bacterium is approximately 0.5 to 1.0 micrometers in diameter and is surrounded by an outer membrane, periplasmic space, and inner membrane. The outer membrane comprises lipopolysaccharides, which contribute to the bacterium’s virulence. N. meningitidis also possesses pili, which are used for adhesion and genetic exchange. 
  • Classification:  N. meningitidis is classified as a member of the Neisseriaceae family, which includes other pathogenic species such as Neisseria gonorrhoeae. It is further classified based on its capsular polysaccharides, which are used to identify different serogroups. There are 13 serogroups of N. meningitidis, with A, B, C, W, X, and Y being the most common causes of meningococcal disease.  

There are 13 different serogroups of Neisseria meningitidis, but only 5 of them (A, B, C, W, and Y) cause most of the invasive meningococcal disease cases worldwide. These serogroups are classified based on the differences in the structure of their polysaccharide capsule. 

Here’s a breakdown of the antigenic types of Neisseria meningitidis

  • Serogroup A: This serogroup is responsible for most African meningococcal meningitis epidemics. It is characterized by a polysaccharide capsule made up of N-acetylmannosamine.
  • Serogroup B: This serogroup is responsible for most meningococcal disease cases in Europe and the Americas. It is characterized by a polysaccharide capsule made up of sialic acid.
  • Serogroup C: This serogroup is responsible for epidemics of meningococcal disease worldwide. It is characterized by a polysaccharide capsule made up of N-acetylneuraminic acid.
  • Serogroup W: This serogroup is responsible for recent meningococcal disease outbreaks in Africa and South America. It is characterized by a polysaccharide capsule made up of N-acetylneuraminic acid.

Serogroup Y is responsible for sporadic cases and meningococcal disease outbreaks worldwide. It is characterized by a polysaccharide capsule made up of N-acetylneuraminic acid.

 

  • Neisseria meningitidis is a bacterium that can cause meningococcal meningitis, a severe and potentially deadly infection of the linings that encircle the spinal cord and brain. The pathogenesis of N. meningitidis involves a complex interplay between the bacterium and the host immune system. 
  • The bacterium can colonize the upper respiratory tract of humans, which is carried asymptomatically in a large proportion of the population. However, in some individuals, the bacterium can invade the bloodstream and cross the blood-brain barrier, causing meningitis. 
  • N. meningitidis can evade the host immune system through several mechanisms, including producing a capsule inhibiting white blood cells’ phagocytosis. The bacterium can also secrete proteins that interfere with the host immune response, including complement-mediated lysis and antibody-mediated opsonization.
  • In addition, N. meningitidis can induce a robust inflammatory response in the host, contributing to the pathology of meningococcal meningitis. This inflammatory response is thought to be mediated by lipooligosaccharides (LOS) and other surface antigens, which activate immune cells and cytokine production. 
  • Neisseria meningitidis is a bacterium that can cause meningococcal meningitis and meningococcal septicemia. The host defenses against this bacterium involve both innate and adaptive immune responses. 
  • Innate immune responses include the activation of complement, a group of proteins that can directly kill bacteria or mark them for destruction by other immune cells. In addition, macrophages and neutrophils, phagocytic cells, can engulf and destroy the bacteria. 
  • Adaptive immune responses involve activating T cells and B cells, which produce specific antibodies that can recognize and neutralize the bacteria. 
  • Several virulence factors allow N. meningitidis to evade the host immune response. These include the capsule, which helps the bacterium evade complement-mediated killing, and the outer membrane proteins, which can bind to and interfere with the function of immune cells. 

Neisseria meningitidis can cause sepsis and meningitis, an infection of the membranes enclosing the brain and spinal cord. A potentially life-threatening infection of the bloodstream. The clinical manifestations of Neisseria meningitidis can vary depending on the severity of the infection, but common symptoms include: 

  • Fever
  • Headache
  • Stiff neck
  • Nausea and vomiting
  • Photophobia (sensitivity to light)
  • Altered mental status (confusion, lethargy, or coma)
  • Petechial rash (a rash of small red or purple spots that does not blanch when pressed)

Not all individuals infected with Neisseria meningitidis will exhibit all these symptoms; some may only have a mild form of the disease. However, early recognition and prompt treatment are critical in preventing severe complications. 

 

The diagnosis of  Neisseria meningitidis infection is usually made through laboratory tests such as blood cultures, cerebrospinal fluid (CSF) analysis, and polymerase chain reaction (PCR) testing. 

  • Gram stain: a simple and rapid test that involves staining a sample of body fluid or tissue with crystal violet, iodine, and safranin. Neisseria meningitidis bacteria appear purple, bean-shaped cocci (round cells) under a microscope.
  • Blood cultures involve taking a blood sample from the patient and growing it in a laboratory to see if the bacteria are present.
  • CSF analysis involves taking a sample of the fluid surrounding the brain and spinal cord through a lumbar puncture and analyzing it for the presence of bacteria.
  • PCR testing involves amplifying a small amount of DNA from the bacteria to detect its presence.

 

Control of  Neisseria meningitidis is essential to prevent disease spread and reduce the risk of outbreaks. 

There are several ways to control Neisseria meningitidis

  • Vaccination: Vaccines are available to protect against several strains of Neisseria meningitidis. The most commonly used vaccines are quadrivalent meningococcal conjugate (MenACWY) and serogroup B meningococcal (MenB). Vaccination is recommended for people at increased risk of meningococcal diseases, such as children, adolescents, college students, and travelers to areas with high rates of meningococcal disease.
  • Antibiotics: Antibiotics are used to treat people with meningococcal disease and to prevent the spread of the bacteria to others who may have been exposed. Close associates of a meningococcal illness patient, such as household members, healthcare workers, and daycare attendees, may be prescribed antibiotics to prevent the spread of the disease.
  • Surveillance: Surveillance of meningococcal disease is essential to monitor the incidence and trends and detect outbreaks. Surveillance helps public health officials identify populations at risk of meningococcal disease and develop targeted prevention and control strategies.
  • Education: Education about meningococcal disease and its prevention is essential to raise awareness and promote vaccination and other control measures. Education efforts should target high-risk populations, such as adolescents and college students. They should emphasize the importance of vaccination, early recognition of symptoms, and seeking prompt medical attention if the meningococcal disease is suspected.
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Neisseria meningitidis

Updated : December 4, 2023

Mail Whatsapp PDF Image



  • Neisseria meningitidis is a bacterium that causes meningococcal disease, a severe and potentially deadly illness that can affect the brain and spinal cord. The incidence of the meningococcal disease varies by geographic region and over time. 
  • According to the World Health Organization (WHO), Meningococcal illness is sporadic and can occur anywhere worldwide, with an estimated 1.2 million cases occurring annually. Sub-Saharan Africa, also referred to as the “meningitis belt,” has the highest prevalence of the illness, with outbreaks happening there every 5–10 years. The disease is caused primarily by serogroups A, C, W, X, and Y. 
  • In other regions, the incidence of meningococcal disease is lower, but sporadic outbreaks still occur. The disease is more common in infants, young children, and adolescents, with a second peak occurring in young adults. 
  • Neisseria meningitidis is a gram-negative bacterium that causes meningococcal disease, a severe infection that can lead to meningitis and sepsis. 
  • Structure:  The bacterium is approximately 0.5 to 1.0 micrometers in diameter and is surrounded by an outer membrane, periplasmic space, and inner membrane. The outer membrane comprises lipopolysaccharides, which contribute to the bacterium’s virulence. N. meningitidis also possesses pili, which are used for adhesion and genetic exchange. 
  • Classification:  N. meningitidis is classified as a member of the Neisseriaceae family, which includes other pathogenic species such as Neisseria gonorrhoeae. It is further classified based on its capsular polysaccharides, which are used to identify different serogroups. There are 13 serogroups of N. meningitidis, with A, B, C, W, X, and Y being the most common causes of meningococcal disease.  

There are 13 different serogroups of Neisseria meningitidis, but only 5 of them (A, B, C, W, and Y) cause most of the invasive meningococcal disease cases worldwide. These serogroups are classified based on the differences in the structure of their polysaccharide capsule. 

Here’s a breakdown of the antigenic types of Neisseria meningitidis

  • Serogroup A: This serogroup is responsible for most African meningococcal meningitis epidemics. It is characterized by a polysaccharide capsule made up of N-acetylmannosamine.
  • Serogroup B: This serogroup is responsible for most meningococcal disease cases in Europe and the Americas. It is characterized by a polysaccharide capsule made up of sialic acid.
  • Serogroup C: This serogroup is responsible for epidemics of meningococcal disease worldwide. It is characterized by a polysaccharide capsule made up of N-acetylneuraminic acid.
  • Serogroup W: This serogroup is responsible for recent meningococcal disease outbreaks in Africa and South America. It is characterized by a polysaccharide capsule made up of N-acetylneuraminic acid.

Serogroup Y is responsible for sporadic cases and meningococcal disease outbreaks worldwide. It is characterized by a polysaccharide capsule made up of N-acetylneuraminic acid.

 

  • Neisseria meningitidis is a bacterium that can cause meningococcal meningitis, a severe and potentially deadly infection of the linings that encircle the spinal cord and brain. The pathogenesis of N. meningitidis involves a complex interplay between the bacterium and the host immune system. 
  • The bacterium can colonize the upper respiratory tract of humans, which is carried asymptomatically in a large proportion of the population. However, in some individuals, the bacterium can invade the bloodstream and cross the blood-brain barrier, causing meningitis. 
  • N. meningitidis can evade the host immune system through several mechanisms, including producing a capsule inhibiting white blood cells’ phagocytosis. The bacterium can also secrete proteins that interfere with the host immune response, including complement-mediated lysis and antibody-mediated opsonization.
  • In addition, N. meningitidis can induce a robust inflammatory response in the host, contributing to the pathology of meningococcal meningitis. This inflammatory response is thought to be mediated by lipooligosaccharides (LOS) and other surface antigens, which activate immune cells and cytokine production. 
  • Neisseria meningitidis is a bacterium that can cause meningococcal meningitis and meningococcal septicemia. The host defenses against this bacterium involve both innate and adaptive immune responses. 
  • Innate immune responses include the activation of complement, a group of proteins that can directly kill bacteria or mark them for destruction by other immune cells. In addition, macrophages and neutrophils, phagocytic cells, can engulf and destroy the bacteria. 
  • Adaptive immune responses involve activating T cells and B cells, which produce specific antibodies that can recognize and neutralize the bacteria. 
  • Several virulence factors allow N. meningitidis to evade the host immune response. These include the capsule, which helps the bacterium evade complement-mediated killing, and the outer membrane proteins, which can bind to and interfere with the function of immune cells. 

Neisseria meningitidis can cause sepsis and meningitis, an infection of the membranes enclosing the brain and spinal cord. A potentially life-threatening infection of the bloodstream. The clinical manifestations of Neisseria meningitidis can vary depending on the severity of the infection, but common symptoms include: 

  • Fever
  • Headache
  • Stiff neck
  • Nausea and vomiting
  • Photophobia (sensitivity to light)
  • Altered mental status (confusion, lethargy, or coma)
  • Petechial rash (a rash of small red or purple spots that does not blanch when pressed)

Not all individuals infected with Neisseria meningitidis will exhibit all these symptoms; some may only have a mild form of the disease. However, early recognition and prompt treatment are critical in preventing severe complications. 

 

The diagnosis of  Neisseria meningitidis infection is usually made through laboratory tests such as blood cultures, cerebrospinal fluid (CSF) analysis, and polymerase chain reaction (PCR) testing. 

  • Gram stain: a simple and rapid test that involves staining a sample of body fluid or tissue with crystal violet, iodine, and safranin. Neisseria meningitidis bacteria appear purple, bean-shaped cocci (round cells) under a microscope.
  • Blood cultures involve taking a blood sample from the patient and growing it in a laboratory to see if the bacteria are present.
  • CSF analysis involves taking a sample of the fluid surrounding the brain and spinal cord through a lumbar puncture and analyzing it for the presence of bacteria.
  • PCR testing involves amplifying a small amount of DNA from the bacteria to detect its presence.

 

Control of  Neisseria meningitidis is essential to prevent disease spread and reduce the risk of outbreaks. 

There are several ways to control Neisseria meningitidis

  • Vaccination: Vaccines are available to protect against several strains of Neisseria meningitidis. The most commonly used vaccines are quadrivalent meningococcal conjugate (MenACWY) and serogroup B meningococcal (MenB). Vaccination is recommended for people at increased risk of meningococcal diseases, such as children, adolescents, college students, and travelers to areas with high rates of meningococcal disease.
  • Antibiotics: Antibiotics are used to treat people with meningococcal disease and to prevent the spread of the bacteria to others who may have been exposed. Close associates of a meningococcal illness patient, such as household members, healthcare workers, and daycare attendees, may be prescribed antibiotics to prevent the spread of the disease.
  • Surveillance: Surveillance of meningococcal disease is essential to monitor the incidence and trends and detect outbreaks. Surveillance helps public health officials identify populations at risk of meningococcal disease and develop targeted prevention and control strategies.
  • Education: Education about meningococcal disease and its prevention is essential to raise awareness and promote vaccination and other control measures. Education efforts should target high-risk populations, such as adolescents and college students. They should emphasize the importance of vaccination, early recognition of symptoms, and seeking prompt medical attention if the meningococcal disease is suspected.

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