Can You Get Mycoplasma Genitalium From Kissing?

Mycoplasma genitalium is a sexually transmitted bacterium known for causing urogenital infections and its increasing resistance to antibiotics. While it is primarily spread through sexual contact, questions remain about whether non-genital transmission, such as kissing, could be a possible route of infection.

Understanding oral transmission risks is important for public health and personal risk assessment.

Primary Sexual Routes

Mycoplasma genitalium spreads through direct mucosal contact during sexual activity, with the urogenital tract as the primary infection site. Studies confirm that vaginal and anal intercourse are the most efficient transmission routes, facilitating bacterial exchange and colonization. The bacterium’s lack of a cell wall allows it to tightly adhere to epithelial cells, evade immune detection, and establish persistent infections.

Epidemiological data show that individuals with multiple sexual partners, inconsistent condom use, or a history of other sexually transmitted infections (STIs) face higher infection risks. A systematic review in Clinical Infectious Diseases found prevalence rates between 1% and 4% in the general population, rising to 38% in STI clinic attendees, highlighting the role of high-risk sexual behaviors. Unlike Neisseria gonorrhoeae or Chlamydia trachomatis, which often cause noticeable symptoms, Mycoplasma genitalium can persist asymptomatically, increasing the chance of unintentional transmission.

The bacterium affects both men and women differently. In men, it is a leading cause of non-gonococcal urethritis (NGU), responsible for up to 30% of cases. In women, it is linked to cervicitis, pelvic inflammatory disease (PID), and reproductive complications, including infertility. Its ability to establish long-term infections often necessitates targeted antibiotic therapy.

Possible Oral Transmission

The potential for Mycoplasma genitalium to spread through oral contact remains under investigation. Unlike Neisseria gonorrhoeae or Treponema pallidum, it is not traditionally associated with saliva or deep kissing. However, some studies have detected it in the oropharynx, raising questions about whether mouth-to-mouth contact could enable transmission.

A study in Sexually Transmitted Infections found that while oropharyngeal colonization was rare, it did occur, particularly among individuals who engaged in oral sex. This suggests the bacterium can survive in the oral cavity under certain conditions, but whether it persists long enough for transmission via kissing is unclear. Unlike the urogenital and rectal mucosa, which provide optimal environments for bacterial adherence and replication, the oropharyngeal environment may not support sustained colonization.

Salivary enzymes, immune factors, and the oral microbiome likely limit Mycoplasma genitalium’s survival in the mouth. Research on Chlamydia trachomatis indicates that while oropharyngeal infections can occur, they tend to be transient and less efficient for transmission than genital infections. Given Mycoplasma genitalium’s small genome and lack of a cell wall, its ability to establish a lasting presence in the oral cavity remains uncertain.

Oral Colonization Factors

Mycoplasma genitalium’s ability to persist in the mouth depends on bacterial characteristics and the oral environment. Its lack of a cell wall makes it highly dependent on host cells, limiting its ability to withstand fluctuations in pH, temperature, and enzymatic activity. The bacterium adheres primarily to epithelial surfaces in the urogenital tract, where conditions are more stable, raising doubts about its ability to colonize the oropharynx.

Adhesion proteins, such as P140 and P110, facilitate attachment to mucosal surfaces, supporting infection in the genital tract. However, the epithelial composition of the oropharynx differs from that of the urethra or cervix, potentially affecting colonization. Research on Mycoplasma pneumoniae suggests that while mycoplasmas can persist in the respiratory tract, colonization efficiency varies based on host factors and microbial competition. The oral cavity’s dense microbiome may further hinder Mycoplasma genitalium’s ability to survive outside the urogenital tract.

Saliva presents additional challenges. It contains antimicrobial peptides, lysozymes, and mucins that regulate microbial populations and prevent colonization by opportunistic pathogens. The constant flow of saliva and mechanical actions like swallowing reduce the likelihood of long-term bacterial survival. While Neisseria gonorrhoeae has adapted to evade salivary defenses, Mycoplasma genitalium’s survival strategies in this environment are not well understood. Its preference for intracellular persistence in urogenital tissues suggests it may not be well-equipped for prolonged survival in the oral cavity.

Testing For Non-Genital Sites

Detecting Mycoplasma genitalium at extragenital sites is challenging due to low bacterial loads and limitations in diagnostic methods. Unlike Neisseria gonorrhoeae or Chlamydia trachomatis, which are routinely tested at multiple anatomical locations, Mycoplasma genitalium screening outside the urogenital tract is not standardized. Its presence in non-genital sites, such as the oropharynx, is not well-established as a major transmission route, making routine testing uncommon.

Polymerase chain reaction (PCR) testing is the most sensitive method for detecting Mycoplasma genitalium, capable of identifying its genetic material even in low quantities. While urine and genital swabs are standard for diagnosis, some studies have explored throat swabs for extragenital detection. However, lower bacterial concentrations in the oropharynx increase the risk of false negatives, complicating test interpretation. This uncertainty is particularly relevant in research investigating whether oral colonization is transient or persistent.

Clinical Presentations Involving The Mouth

While Mycoplasma genitalium is primarily associated with urogenital infections, its presence in the oropharynx raises questions about potential symptoms. Unlike Neisseria gonorrhoeae or Treponema pallidum, there is little evidence linking it to distinct oral manifestations. However, case reports suggest it may contribute to mild, nonspecific symptoms such as throat discomfort or irritation, though these are often indistinguishable from symptoms caused by common respiratory pathogens.

A study in Sexually Transmitted Diseases found that individuals with concurrent genital and oropharyngeal Mycoplasma genitalium colonization did not report significant throat-related symptoms. This suggests that even when present in the mouth, the bacterium may not cause noticeable effects. In contrast, Mycoplasma pneumoniae has been associated with more pronounced respiratory infections, indicating that Mycoplasma genitalium may behave differently in the oropharyngeal environment. Given its tendency to persist asymptomatically in the genital tract, a similar pattern may occur in the oral cavity, where colonization does not necessarily lead to overt disease.