Neisseria gonorrhoeae is the bacterium that causes gonorrhea, one of the most common sexually transmitted infections worldwide. In the United States alone, there were over 543,000 reported cases in 2024. The bacterium infects the mucous membranes of the reproductive tract, throat, rectum, and eyes, and it has become increasingly difficult to treat as it develops resistance to nearly every antibiotic ever used against it.
How the Bacterium Works
Under a microscope, Neisseria gonorrhoeae appears as pairs of kidney-bean-shaped cells. It’s a Gram-negative bacterium, meaning it has a thin cell wall surrounded by an outer membrane, which influences how it responds to antibiotics and how the immune system recognizes it.
What makes this bacterium effective at causing infection is its surface structures. Hair-like projections called pili allow it to latch onto the cells lining your mucous membranes. Strains that have these pili can attach to human epithelial cells and resist being destroyed by immune cells. Strains without pili can’t attach and are quickly cleared by the body’s defenses. Once attached, the bacterium can slip inside your cells, which helps it hide from the immune system and establish infection.
Symptoms and Incubation Period
One of the biggest challenges with gonorrhea is that most people who have it don’t know it. Roughly 90% of women with urogenital gonorrhea have no symptoms at all. In men, asymptomatic rates range from about 56% to 87%, depending on the study and the site of infection.
When symptoms do appear, the timeline differs. In men, urethral infection typically shows up within 2 to 14 days after exposure, usually as painful urination and discharge. Cervical infection in women generally takes longer than 10 days to produce symptoms, which can include unusual vaginal discharge, bleeding between periods, or pelvic discomfort. Rectal and throat infections are often silent regardless of sex.
Because so many infections are asymptomatic, people can unknowingly transmit the bacterium to partners for weeks or months. This is a major reason public health guidelines recommend routine screening for sexually active people at higher risk.
How Gonorrhea Is Diagnosed
The preferred diagnostic method is a nucleic acid amplification test, commonly called a NAAT. This test detects the bacterium’s genetic material from a urine sample or a swab of the infected site. NAATs are highly accurate: in comparative studies, they achieved 98.7% sensitivity and 100% specificity, meaning they catch nearly every true infection and produce virtually no false positives.
Traditional bacterial culture, where a lab grows the organism from a swab, is less sensitive at about 86% but remains important. Culture is the only method that allows doctors to test which antibiotics the bacteria are still susceptible to, which matters increasingly as resistance spreads.
Treatment and Antibiotic Resistance
Uncomplicated gonorrhea is currently treated with a single injection of a cephalosporin antibiotic. Previous guidelines recommended giving a second antibiotic alongside it as a safeguard against resistance, but that dual-therapy approach has been dropped in the U.S. due to concerns about disrupting the body’s normal bacterial balance without enough added benefit.
The bigger story is how rapidly this bacterium outpaces treatment options. Neisseria gonorrhoeae has developed resistance to penicillins, sulfonamides, tetracyclines, fluoroquinolones, and macrolides. In many countries, ciprofloxacin resistance is now extremely high. Resistance to azithromycin is climbing, and resistance or reduced susceptibility to the current last-line cephalosporin treatments continues to emerge. The WHO’s global surveillance program has found high levels of resistance to the current frontline drug, driven largely by the spread of particularly resistant strains.
This pattern makes Neisseria gonorrhoeae one of the most concerning multidrug-resistant organisms tracked by public health agencies. If resistance to the remaining cephalosporins becomes widespread, there are very few backup options available.
Complications of Untreated Infection
Left untreated, gonorrhea can cause serious damage at the site of infection and beyond. In women, it can lead to pelvic inflammatory disease, which scars the fallopian tubes and increases the risk of infertility and ectopic pregnancy. In men, it can cause epididymitis, a painful inflammation of the tube behind the testicle that can also affect fertility.
In roughly 0.5% to 3% of untreated cases, the bacterium enters the bloodstream and spreads throughout the body, a condition called disseminated gonococcal infection. This can cause joint pain and swelling (septic arthritis), inflammation of the tendons, and characteristic skin lesions. In rare cases, it leads to infection of the heart valves or the membranes surrounding the brain.
Who Gets Infected
Gonorrhea rates in the U.S. stood at about 160 cases per 100,000 people in 2024, with men diagnosed at higher rates (203 per 100,000) than women (116 per 100,000). The overall trend has been encouraging in the short term: cases declined for the third consecutive year, dropping 10% from 2023 to 2024.
Higher rates among men partly reflect the biology of detection (symptomatic urethritis prompts testing) and the concentration of cases among men who have sex with men, a group disproportionately affected. But because women are far more likely to be asymptomatic, reported case counts almost certainly underrepresent the true burden of infection in women.
Vaccine Prospects
There is no gonorrhea-specific vaccine, but an unexpected finding has generated interest. A vaccine originally designed to prevent meningococcal B disease shares enough protein targets with Neisseria gonorrhoeae to offer partial cross-protection. A systematic review and meta-analysis published in the Journal of Infectious Diseases found that receiving at least one dose of this vaccine was about 32% effective at preventing gonorrhea. Two doses provided 33% to 40% effectiveness.
That level of protection wouldn’t eliminate gonorrhea, but at a population level it could meaningfully reduce transmission. There are caveats: one randomized controlled trial found no efficacy, and observational studies suggest the protective effect may fade after about three years, dropping from roughly 35% to 23%. Still, for an infection with no other vaccine candidate and shrinking treatment options, even partial protection is significant.