A diagnosis of a sexually transmitted infection (STI) like Mycoplasma genitalium (MG) often leads to difficult conversations about relationship trust and the source of the infection. It is a common, yet often overlooked, bacterial infection. Understanding the biology and transmission of MG is the first step in addressing the emotional implications of the diagnosis. Factual information can help individuals navigate the situation with clarity rather than immediate suspicion.
Understanding Mycoplasma Genitalium
Mycoplasma genitalium (Mgen) is a bacterium that causes a sexually transmitted infection. It is distinct from other common STIs like Chlamydia or Gonorrhea because it lacks a cell wall, which affects antibiotic treatment. Mgen is considered an emerging pathogen due to increasing awareness of its prevalence and the issue of antibiotic resistance.
Prevalence estimates suggest MG affects roughly 1% to 2% of the general young adult population, with higher rates in sexual health clinics. A major factor contributing to its spread is its frequently asymptomatic nature. Over 90% of men and more than half of women may not show any symptoms, allowing the infection to persist and be unknowingly transmitted.
Transmission, Asymptomatic Carriage, and Timeline
MG is primarily transmitted through sexual contact, specifically vaginal and anal intercourse without barrier protection. Transmission through oral sex is also possible, though the exact risk is still being determined. The bacterium infects the urethra in men and the cervix and urethra in women, potentially leading to conditions like urethritis or cervicitis.
A defining characteristic of MG is its capacity for long-term asymptomatic carriage. This means a recent positive test does not necessarily indicate a recent infection. The infection can remain in a person’s system for months or even years without symptoms. Untreated infections in women have been reported to persist for up to two to three years.
Because MG often causes no symptoms and can last for extended periods, determining the precise timeline of acquisition is nearly impossible. Even when symptoms appear, they typically develop one to three weeks after exposure, but this timeframe varies widely. This prolonged, silent presence means a person diagnosed today could have been infected long before their current relationship began.
Addressing the Infidelity Implication
The facts about MG’s transmission and persistence directly counter the assumption that a positive diagnosis automatically implies infidelity in a current partnership. The long duration of asymptomatic carriage means the infection could have been acquired from a previous partner, potentially years before the current relationship started. Either partner could have been carrying the bacterium silently and unknowingly for an extended period.
The infection may have been introduced by the diagnosed partner before the relationship began and remained dormant, or it could have been acquired from a previous partner of the currently undiagnosed individual. An MG diagnosis is a medical finding, not forensic evidence of a specific event or timeline within the relationship. Focusing on the pathogen’s capacity to persist silently shifts the conversation away from blame.
The most constructive response is to communicate openly and focus on treatment for both partners. Assigning fault based solely on a positive test result ignores the established scientific reality of this infection’s natural history. The priority should be preventing potential long-term complications, such as pelvic inflammatory disease in women, and ensuring successful eradication.
Testing and Treatment Protocols
Diagnosis of Mycoplasma genitalium relies on specialized laboratory methods, specifically Nucleic Acid Amplification Tests (NAATs), since the bacterium is difficult to culture. These tests typically use urine samples or swabs from the vagina, cervix, or urethra to detect the organism’s genetic material. MG testing is often not included in standard STI screening panels, contributing to its status as an overlooked infection.
Treatment for MG is complicated by the bacterium’s growing resistance to common antibiotics. Single-dose Azithromycin, once a standard treatment, is now often avoided because it can induce macrolide resistance, which is now prevalent. Current recommended protocols often involve a two-stage approach: starting with Doxycycline to reduce the bacterial load, followed by a second, more potent antibiotic like Azithromycin or Moxifloxacin.
Due to high rates of antibiotic resistance, follow-up testing, known as a Test of Cure, is recommended to confirm successful eradication. Simultaneous treatment of all sexual partners is necessary to prevent re-infection and break the cycle of transmission. Resistance testing, if available, can help guide the choice of the second antibiotic, as treatment failure is common when resistance is not considered.