Neisserial infections
Neisserial infections are caused by bacteria from the genus Neisseria, which includes Neisseria meningitidis and Neisseria gonorrhoeae. These gram-negative cocci can infect various parts of the body, leading to serious health conditions. N. meningitidis is known for causing meningitis, an infection of the protective tissue surrounding the brain and spinal cord, often transmitted through respiratory droplets. Symptoms include high fever, stiff neck, and possibly a rash. In contrast, N. gonorrhoeae is responsible for gonorrhea, a sexually transmitted infection that primarily affects the genitourinary tract but can also infect the throat and rectum. Symptoms of gonorrhea may be less pronounced in women, often presenting as a pus-filled discharge. Diagnosis for both infections typically involves laboratory testing, and treatment varies, with antibiotics playing a central role. Preventive measures include vaccination for meningitis and safe sex practices for gonorrhea. Understanding these infections is crucial for awareness and prevention, especially in high-risk groups.
Neisserial infections
- ANATOMY OR SYSTEM AFFECTED: Brain, central nervous system, eyes, genitourinary tract, spinal cord, throat
- ALSO KNOWN AS: Bacterial meningitis, clap, gonococcus, gonorrhea, meningococcus, spinal meningitis
Definition
Neisseria is a gram-negative, bean-shaped cocci that grows in pairs, or diplococci. The bacterium infects the genitourinary tract, rectum, throat, conjunctiva, and the tissue covering the brain and spinal cord.
Causes
Most meningococci are grouped based on the composition of their polysaccharide capsule. Meningococci in groups A, B, C, W135, and Y cause meningitis. However, N. meningitidis commonly inhabits the human throat without causing disease. Disease begins when meningococci invade a person’s bloodstream. From the blood, the bacteria penetrate the tissue covering the brain and spinal cord and infect the cerebrospinal fluid. Excessive production of endotoxin can lead to tissue destruction, amputations, and death in 85 percent of untreated cases.
N. gonorrhoeae causes the sexually transmitted disease gonorrhea. The genitourinary tract, throat, and rectum are infected through sexual contact. The conjunctiva of a newborn can be infected during childbirth in cases in which the pregnant woman is infected.
Risk Factors
N. meningitidis is transmitted in droplets caused by coughing, so persons in close contact, such as dormitory residents or personnel in military barracks, are at risk for transmission. It is hypothesized that tobacco smokers are more susceptible. N. gonorrhoeae is transmitted through sexual contact; failing to use condoms is the greatest risk.
Symptoms
Meningococcal meningitis is characterized by a rapidly rising fever followed by coma. Common symptoms are a stiff neck disallowing the infected person from touching chin to chest and a spotty rash that does not “bleach” when pressed with a clear glass.
Men with gonorrhea have pain with urination and have a pus-filled discharge. These symptoms usually develop less than one week after sexual contact with an infected partner. If untreated, the gonococci can infect the prostate gland. Sterility results if the sperm ducts are blocked with scar tissue.
The symptoms of gonorrhea are less pronounced in women. Gonococci enter the vagina and then move into the cervix, uterus, and Fallopian tubes. The only symptom of infection is a pus-filled discharge. Sterility, a long-term consequence of gonorrhea in women, occurs when scar tissue is deposited and blocks the Fallopian tubes. Pelvic inflammatory disease caused by N. gonorrhoeae also can lead to loss of fertility.
Screening and Diagnosis
Definitive diagnosis of meningococcal meningitis is performed by identifying the bacterium in the cerebrospinal fluid, which is retrieved by a spinal tap. In the laboratory, clinical specimens are applied to a glass slide and stained using the Gram-staining procedure. Gram-negative, bean-shaped diplococci that are visible under the microscope indicate infection. Especially in females, the Gram’s stain can yield a false-negative result. Analysis to detect bacterial deoxyribonucleic acid (DNA) is performed in many labs too.
Treatment and Therapy
Rifampin is used to prevent the development of meningitis in asymptomatic persons exposed to infected persons. Erythromycin and chloramphenicol are used to treat meningitis in persons who are sensitive to penicillin and ampicillin. Triple antibiotic therapy with doxycycline, ciprofloxacin, and metronidazole is recommended for gonorrhea.
Prevention and Outcomes
Meningitis caused by four groups is preventable with a tetravalent glycoconjugate vaccine. Group B meningococcal infection is not vaccine preventable because the capsular polysaccharide shares the same structure with fetal brain tissue and is, therefore, nonimmunogenic. Suspicion of meningococcal meningitis will cause public health officials to recommend immediate initiation of antibiotic treatment for all close contacts of the infected person. Gonorrhea is preventable through the use of condoms or through abstinence.
Bibliography
Handsfield, H. H., et al. “ Neisseria gonorrhoeae.” In Mandell, Douglas, and Bennett’s Principles and Practice of Infectious Diseases, edited by Gerald L. Mandell, John F. Bennett, and Raphael Dolin. 7th ed. New York: Churchill Livingstone/Elsevier, 2010.
Schrier, Robert W., ed. Diseases of the Kidney and Urinary Tract. 8th ed. Philadelphia: Wolters Kluwer Health/Lippincott Williams & Wilkins, 2007.
Shmaefsky, Brian. Meningitis. Rev. ed. Philadelphia: Chelsea House, 2010.
Walsh, Lloyd. "Beyond the Usual Suspects: Reviewing Infections Caused by Typically-Commensal Neisseria Species." Journal of Infection, vol. 87, no. 6, Dec. 2023, pp. 479-489, doi.org/10.1016/j.jinf.2023.09.007. Accessed 4 Feb. 2025.