Neisseria meningitidis

Tiny germs live in many people.

These germs are round. They often live in pairs.

They can spread when people cough or sneeze. They can also spread by kissing.

Some germs make people feel very sick. They can cause a bad headache. They can also cause a fever. These germs can move into the blood.

Doctors must act fast to help. They use medicine to fight the germs. This helps keep people safe. It is good to learn about these tiny germs.

Neisseria meningitidis is a tiny germ.

It is a diplococcus. This means it is round and grows in pairs.

These germs live only in humans. About 10% of adults carry them in their nose and throat.

These germs can spread through saliva. This happens when people cough, sneeze, or kiss. They can also spread by sharing water. Some germs can cause meningitis. This is a sickness that affects the brain and spine. Other germs can cause septicaemia. This is a very serious infection in the blood.

To make people sick, the germs must stick to cells. They use long, thin parts called pili to hold on. They also use proteins to enter the body. The germs can even swap DNA. This is a way they pick up new traits from other germs. This helps them hide from the body's defenses. Doctors must act fast to help sick people. They use medicine called antibiotics to fight the germs.

Scientists can see the germs growing in a lab to find them.

Neisseria meningitidis is a tiny living thing called a bacterium.

Scientists call it a Gram-negative diplococcus. This name tells us it has an inner and outer membrane. It also tells us it is round and grows in pairs.

These bacteria live only in humans. About 8% to 25% of adults carry them in their nose and throat. Most of the time, they do not cause any harm. However, they can sometimes cause very serious illnesses. These include meningitis and a blood infection called septicaemia.

To make a person sick, the bacteria must first stick to host cells. They use long, thin extensions called pili to hold on tight. They also use special proteins named Opa and Opc to help them attach.

Once they are attached, they can move into the body. The bacteria can even swap DNA with each other. This process is called genetic transformation. It allows them to pick up new traits from neighboring cells. This helps them stay strong and hide from the body's defenses.

Scientists have studied these bacteria for a long time. They have found different types, or serogroups, of the bacteria. There are 13 known types based on their outer coating. Six main types, named A, B, C, W135, X, and Y, cause most diseases. In the United States, type B is the most common cause of sickness. In Africa and Asia, type A is often the most common. Knowing these types helps scientists try to make vaccines.

There are many important facts about how these bacteria work. Each bacterium is very small, between 0.6 and 1.0 micrometers. The genome of the MC58 strain has 2,272,351 base pairs. This strain has 2,158 open reading frames, which are parts of the DNA. In 2013, a new strong strain appeared in Nigeria. It was a type C strain that had picked up new DNA. This made it much more dangerous to people.

Understanding these bacteria is like being a detective. Doctors look for signs like fever, headache, or a special rash.

A septicaemia rash does not lose its color when you press a glass against it. To be sure, doctors take a sample of fluid from the spine. They look for the round pairs under a microscope. They can also grow the bacteria on special plates in a lab. This helps them find the exact cause of the sickness.

Neisseria meningitidis, often called the meningococcus, is a Gram-negative bacterium.

This classification means it possesses both an inner and an outer membrane. The term "diplococcus" describes its physical shape as round cells that grow in pairs.

This pathogen is exclusively human, meaning it cannot survive in other animals. It lives in the nasopharynx, which is the part of the throat behind the nose. While 8% to 25% of adults carry these bacteria without getting sick, they can cause life-threatening diseases. These include meningitis, an infection of the membranes covering the brain, and septicaemia, a severe blood infection.

To cause disease, the bacteria must successfully invade a host. They use long, thin extensions called pili to attach to the epithelial cells in the throat.

Specialized surface proteins, known as Opa and Opc, also help the bacteria stick to host receptors. Once they enter the bloodstream, they must survive a very hostile environment. They use proteins like FetA and Hmbr to steal iron from human transferrin and lactoferrin. To avoid being killed by the immune system, they produce enzymes like catalase and superoxide dismutase. They also use a protein called fHbp to inhibit the complement pathway, which is a part of the body's natural defense system.

Scientists classify these bacteria into different subtypes based on their polysaccharide capsule. This capsule is a sugary coating that protects the bacteria from being eaten by immune cells.

There are 13 identified capsular types, but six main serogroups cause most global disease. These are known as A, B, C, W135, X, and Y. The distribution of these types changes depending on where you are in the world. For example, serogroup A is most prevalent in parts of Africa and Asia. In the United States, serogroup B is the most common cause of illness and death.

One of the most fascinating aspects of this bacterium is its ability to change its DNA. This process is called genetic transformation.

The bacteria can take up DNA from neighboring cells and integrate it into their own genome. They use specific sequences called DNA uptake sequences, or DUSs, to help identify this DNA. This allows them to repair damaged DNA caused by the body's oxidative stress. It also allows them to acquire new traits, such as a new capsule, to hide from the immune system. This high rate of genetic exchange makes it very difficult to create a single vaccine for all types.

Researchers have mapped the genomes of several strains to understand them better. The genome of the MC58 strain, which belongs to serogroup B, contains 2,272,351 base pairs.

This genome includes 2,158 open reading frames, which are the sections of DNA that provide instructions for proteins. Another strain, H44/76, has a genome size of 2.18 Mb. Both strains show a GC content of 51.5%, which refers to the percentage of nitrogenous bases in their DNA. These genetic studies help scientists track how the bacteria evolve and spread.

In 2013, a significant event occurred in Nigeria involving a hypervirulent strain. A common, non-pathogenic strain of serogroup C acquired new genetic material through gene transfer. It picked up an 8-kb prophage called the meningococcal disease-associated island, or MDAæ. It also acquired a full serogroup C capsule operon. This combination made the strain much more dangerous to humans. This event serves as a real-world example of how bacteria can rapidly become more harmful by swapping DNA.

Identifying the infection is a medical emergency because the disease moves very quickly. Symptoms often start with general issues like fever, headache, and fatigue.

However, it can rapidly progress to neck stiffness, coma, or death. Septicaemia can cause a specific type of rash called petechiae or purpura. A key sign of this rash is that it is "non-blanching," meaning it does not lose color when pressed with a glass slide. Doctors often perform a Gram stain on cerebrospinal fluid to look for the presence of Gram-negative diplococci. The gold standard for diagnosis is isolating the bacteria by growing it on a culture medium like chocolate agar.