Mycoplasma hominis – a cause of PID and BV

Mycoplasma hominis is a pathogenic species in the Mycoplasma genus, being one of the smallest free-living organisms known. ‘Free-living’ means they can replicate by themselves.

M. hominis do not have a cell wall, and therefore can not be Gram stained. Gram staining identifies bacteria by their cell wall absorbing a purple dye known as gentian crystal or gentian violet.

M. hominis can penetrate human cells and has a penchant for the human urogenital tract. M. hominis is implicated in vaginal infections but can cause infections in newborns and extragenital infections, particularly in those who are immunosuppressed.

Antibiotics often fail to remove this bacteria due to a high level of natural resistance. M. hominis is associated with pelvic inflammatory disease, bacterial vaginosis, and male infertility. It is considered a sexually transmitted infection.

We’ve known about M. hominis since 1937, when it was first isolated from the vagina. Another mycoplasma, M. genitalium, is not culturable, instead requiring DNA/RNA testing via polymerase chain reaction (PCR) assay.

M. hominis can be found in 20-50 per cent of sexually active biological females. In mouse studies, sex hormones play an enormous role in the colonisation, multiplication and persistence of mycoplasma and ureaplasmas. It’s unclear if this translates to humans.

Mycoplasmal species are not believed to stimulate inflammatory vaginitis, but M. hominis numbers increase significantly when the vagina is already dysbiotic, in bacterial vaginosis. Mycoplasmas are not thought to be the sole cause of BV, but it is unclear what role they do play.

M. hominis and Trichomonas vaginalis appear to have an affinity for one another.

Testing for M. hominis

M. hominis can be cultured or detected using PCR.

Treatment for M. hominis

In drug therapy, the tetracycline group of antibiotics was found to be effective at eliminating M. hominis, particularly when given to sexual partners who are also likely to be/are known to be infected. The treatment dose and length may make an important difference to successful elimination.

Mycoplasmas have a high degree of natural and acquired antibiotic resistance, so doing the most effective treatment first is important to avoid the development of resistance.

In herbal medicine, vaginal administration of antimicrobials while supporting the immune system is a useful strategy.

Other Mycoplasma bacteria

• M. gallisepticum
• M. genitalium
• M. hyopneumoniae
• M. mobile
• M. mycoides
• M. penetrans
• M. pneumoniae
• M. pulmonis
• Mesoplasma florum
• Ureaplasma urealyticum/parvum
• Phytoplasma asteris

References

Taylor-Robinson D. Mollicutes in vaginal microbiology: Mycoplasma hominis, Ureaplasma urealyticum, Ureaplasma parvum and Mycoplasma genitalium. Res Microbiol. 2017;168(9-10):875-881. doi:10.1016/j.resmic.2017.02.009

Dessì D, Margarita V, Cocco AR, Marongiu A, Fiori PL, Rappelli P. Trichomonas vaginalis and Mycoplasma hominis: new tales of two old friends. Parasitology. 2019;146(9):1150-1155. doi:10.1017/S0031182018002135

Ozturk S, Yildiz S, Dursun P, Yener Ilce B, Kaymaz O. Mycoplasma hominis profile in women: Culture, kit, molecular diagnosis, antimicrobial resistance, and treatment. Microb Pathog. 2019;135:103635. doi:10.1016/j.micpath.2019.103635