Neisseriales

Neisseriales is an order of Gram-negative bacteria within the class Betaproteobacteria. This order includes several genera, most notably the genus Neisseria, which contains species of significant medical importance, such as Neisseria gonorrhoeae and Neisseria meningitidis.

Characteristics

Neisseriales are characterized by their Gram-negative cell wall structure, which includes a thin peptidoglycan layer and an outer membrane containing lipopolysaccharides. Members of this order are typically aerobic, although some can grow in microaerophilic conditions. They are non-motile and often appear as diplococci under the microscope.

Genus Neisseria

The genus Neisseria is the most well-known within the order Neisseriales. It includes several species that are part of the normal flora of the human body, as well as pathogenic species.

Neisseria gonorrhoeae

Neisseria gonorrhoeae is the causative agent of gonorrhea, a sexually transmitted infection. It primarily infects the mucous membranes of the urogenital tract, but can also affect the throat and rectum. Diagnosis is typically made through nucleic acid amplification tests (NAATs) or culture.

Neisseria meningitidis

Neisseria meningitidis is a leading cause of bacterial meningitis and septicemia, particularly in children and young adults. It is transmitted through respiratory droplets and can colonize the nasopharynx asymptomatically. Vaccination is available and recommended in many countries to prevent meningococcal disease.

Other Genera

In addition to Neisseria, the order Neisseriales includes other genera such as Chromobacterium, which is known for producing the purple pigment violacein, and Eikenella, which is part of the normal flora of the human mouth and can be involved in human bite wound infections.

Clinical Significance

The clinical significance of Neisseriales primarily stems from the pathogenic species within the genus Neisseria. These bacteria have developed mechanisms to evade the host immune system, such as antigenic variation and the ability to acquire iron from host proteins. Treatment of infections caused by these bacteria often involves antibiotics, although resistance is an increasing concern.

Also see

• Gram-negative bacteria
• Betaproteobacteria
• Bacterial meningitis
• Sexually transmitted infections