Neisseria

Tiny germs live in many animals.

Some of these germs look like coffee beans. They grow in small pairs. They like to stay warm inside a body.

Most of these germs do not hurt us. But two kinds can make people sick. One kind can cause a bad sickness in the brain. The other kind causes a sickness called gonorrhea.

These germs are very smart. They can change their skin to hide. This helps them stay safe from our bodies.

They can also move around. Some germs even help make plaque on dog teeth.

It is fun to learn about these tiny things.

Neisseria is a large group of tiny germs called bacteria.

Under a microscope, these bacteria look like coffee beans. They often grow in pairs. Some grow in groups of four. They like to stay warm. They grow best at 98.6 °F inside an animal's body.

Many Neisseria species live in animals without causing harm. We call these harmless germs commensal. But two types can make people sick. One is N. meningitidis. It can cause sickness in the brain. The other is N. gonorrhoeae. It causes a disease called gonorrhea.

These germs are very good at hiding. They use a way called antigenic variation. This means they change their surface parts. This helps them hide from the body's immune system. They also have tiny hair-like parts called pili. These pili help them stick to cells and move around.

Some Neisseria can even help make plaque on dog teeth. Scientists study these germs to make vaccines. A vaccine is a way to teach the body to fight germs. Scientists have made vaccines for some types of N. meningitidis.

Researchers use DNA to study how these germs work. They look at the genome, which is the set of instructions for the germ.

Neisseria is a large group of bacteria that live on the mucous membranes of many animals.

Most of these bacteria are commensal, which means they live there without causing harm. There are 11 species that live in humans, but only two are pathogens. Pathogens are germs that cause disease. These two are N. meningitidis and N. gonorrhoeae. Under a microscope, these bacteria look like tiny coffee beans. They usually grow in pairs or sometimes in groups of four. They thrive best at 98.6 °F, which is the temperature inside an animal's body.

These bacteria use clever ways to stay alive inside a host. One way is called antigenic variation. This is when the bacteria change their surface parts to hide from the immune system. They also use tiny hair-like structures called type IV pili. These pili help the bacteria stick to cells and move around using a twitching motion. Some species even use these pili to form microcolonies. N. meningitidis also has a polysaccharide capsule. This is a protective outer layer that shields the bacteria from the body's defenses. N. gonorrhoeae does not have this capsule, but it uses a different layer called lipooligosaccharide, or LOS. This LOS helps the bacteria stick to tissues and protects them from certain defenses.

A scientist named Albert Neisser discovered the first example of this group. He was a German bacteriologist who found N. gonorrhoeae in 1879. Neisser also helped find the germ that causes leprosy. He was able to do this because he helped create new ways to stain bacteria so they could be seen. Today, scientists still study these germs at the International Pathogenic Neisseria Conference. This meeting happens every two years. It started in 1978 and moves between North America and Europe. In 2006, the group met in Cairns, Australia, for the first time.

Scientists have learned a lot by looking at the genomes of these bacteria. A genome is the complete set of instructions for a living thing. At least 10 Neisseria species have had their genomes completely sequenced. N. meningitidis is very well studied, with more than 70 strains sequenced. N. gonorrhoeae has at least 10 sequenced strains. These two species are quite similar. For example, they share 68% of their genes. N. meningitidis can have between 2,440 and 2,854 proteins. N. gonorrhoeae has between 2,603 and 2,871 proteins. N. weaveri has a much smaller genome with only 2,060 proteins.

Understanding Neisseria helps us deal with health problems around the world. Vaccines are very important for controlling diseases caused by N. meningitidis. We have vaccines that can prevent several groups, such as serogroup A, B, C, Y, and W-135. However, making a vaccine for gonorrhea is much harder. Some strains of N. gonorrhoeae are now called "superbugs" because they have resistance to certain medicines. These bacteria can also use a process called genetic transformation. This is when a bacterium takes up DNA from a neighbor to fix its own instructions. This helps them stay healthy and adapt to new environments.

Neisseria is a large genus of bacteria that colonize the mucous membranes of many animals. These organisms belong to a group called the Pseudomonadota, which are Gram-negative bacteria. When viewed through a microscope, Neisseria cells resemble small coffee beans. They typically grow in pairs, known as diplococci, but can occasionally appear in groups of four. Most species within this genus are commensal, meaning they live on a host without causing harm. However, out of the 11 species that colonize humans, two are significant pathogens: N. meningitidis and N. gonorrhoeae.

These bacteria use several sophisticated mechanisms to survive within a host. One method is antigenic variation, where the bacteria alter their surface molecules to avoid being recognized by the immune system. They also utilize type IV pili, which are hair-like structures on their surface. These pili allow for attachment to various tissues and enable twitching motility. The pili also assist in microcolony formation and natural competence. Natural competence allows the bacteria to take up DNA from their environment, which helps them adapt and grow.

Pathogenic Neisseria have developed specific tools to evade the host's immune response. N. meningitidis possesses a polysaccharide capsule that surrounds its outer membrane. This capsule acts as a shield against soluble immune effector mechanisms in the blood serum. In contrast, N. gonorrhoeae lacks this capsule but uses lipooligosaccharide, or LOS, for protection. LOS functions as an endotoxin and helps the bacteria adhere to the urethral epithelium. Specific enzymes can modify LOS to prevent the immune system from attacking the bacteria. For example, the enzyme Lst can perform LOS sialylation to prevent phagocytosis by neutrophils.

Scientists can identify different species by observing their biochemical reactions. All medically significant Neisseria species test positive for both catalase and oxidase. They can also be distinguished by the specific sugars they use to produce acid. For instance, N. gonorrhoeae produces acid from glucose alone. However, N. meningitidis is able to produce acid from both glucose and maltose. These chemical signatures allow researchers to tell the different species apart in a laboratory setting.

The history of this genus began with the German bacteriologist Albert Neisser. In 1879, Neisser discovered N. gonorrhoeae, the pathogen responsible for gonorrhea. He also co-discovered the bacterium that causes leprosy, Mycobacterium leprae. His ability to identify these organisms was aided by new staining techniques he helped develop. Today, researchers continue to study these bacteria through the International Pathogenic Neisseria Conference. This forum has met every two years since 1978 to discuss immunology and vaccinology. While it usually rotates between North America and Europe, it visited Cairns, Australia, in 2006.

Modern science has provided deep insights through genome sequencing. At least 10 Neisseria species have had their entire genomes sequenced. N. meningitidis is the most studied, with over 70 sequenced strains. N. gonorrhoeae has at least 10 sequenced strains. These two species share approximately 68% of their genes. The number of proteins encoded varies by species. N. meningitidis encodes between 2,440 and 2,854 proteins, while N. gonorrhoeae encodes between 2,603 and 2,871 proteins. N. weaveri holds the record for the smallest known genome in the genus with only 2,060 encoded proteins.

Understanding these bacteria is vital for global public health and vaccine development. Vaccines are effective at preventing several serogroups of N. meningitidis, including A, B, C, Y, and W-135. However, creating a vaccine for N. gonorrhoeae remains a major challenge due to the bacteria's variability. Furthermore, N. gonorrhoeae has become a "superbug" due to its resistance to antibiotics like ceftriaxone. The bacteria use genetic transformation to combat this. They take up DNA from neighbors using DNA uptake sequences, or DUSs. This process helps them repair damaged DNA and maintain their genetic integrity.