The term “mycoplasma” is used to refer to any microorganism that belongs to the class Mollicutes. Among them, genital mycoplasmas are primarily sexually transmitted (albeit they may also be transmitted to infants in utero or during birth). They have the smallest genomes among known free-living microorganisms, and they may give rise to various clinical syndromes.
Successful treatment depends on considering the possibility of genital mycoplasmas as etiologic agents early in the course of the disease, followed by suitable diagnostic approaches for the detection of these agents, and adequate antimicrobial coverage. But since the causal relationship with genital disease may be unproved in many instances, official indications in obstetrics and gynecology, and also urology, for specific therapy of genital mycoplasmas are scarce.
Main Treatment Guidelines
Medical treatment for genital mycoplasmas should be tailored to the individual patient, taking into consideration the type of infection (i.e. whether it is localized or systemic), as well as the presence of immunodeficiency or certain other underlying conditions. As already mentioned, a pivotal step in pathogen-specific disease management is securing appropriate material for diagnostic procedures and its proper handling to preserve the viability of this group of microorganisms.
Even though immunosuppressed individuals (for example, those that exhibit specific antibody deficiencies) may not be commonly encountered by most medical professionals, they may have an excessively high risk of developing serious sequelae to infection with genital mycoplasmas. Hence these organisms should always be considered in the differential diagnosis.
Management of these infections is exceptional only with respect to the selection of specific antibiotics to cover Ureaplasma urealyticum, Mycoplasma hominins and Mycoplasma genitalium (and other potential pathogenic species). It must be emphasized that these organisms often act as opportunistic agents, and thus they may be present with other pathogenic species at the same time. Therefore, any treatment decisions must take this possibility into account.
Drugs of Choice
Because genital mycoplasmas lack a cell wall, they are resistant to antimicrobial agents that are active against this structure. Therefore penicillins, cephalosporins and vancomycin are ineffective in the treatment of conditions caused by these microorganisms.
On the other hand, antimicrobial agents that halt protein synthesis are active against most mycoplasmas. Traditionally tetracyclines have been consistently effective against both Ureaplasma urealyticum and Mycoplasma hominis, but there is an increase in the occurrence of resistance to this group of drugs among clinical isolates.
Mycoplasma hominis is sensitive to lincomycin, but resistant to erythromycin; the opposite is true for Ureaplasma urealyticum. Furthermore, Mycoplasma hominis is highly sensitive to clindamycin, whereas Ureaplasma urealyticum is moderately sensitive to the same drug. The aminoglycosides also show some activity against genital mycoplasmas.
Fluoroquinolones have become useful alternatives for treating certain infections caused by the triad of most important genital mycoplasmas (i.e. Ureaplasma urealyticum, Mycoplasma hominis and Mycoplasma genitalium). It is noteworthy that the antimicrobial activity of fluoroquinolones is not affected by either macrolide or tetracycline resistance.
But although genital mycoplasmas generally respond well to ciprofloxacin and levofloxacin, this is not true for Mycoplasma genitalium. In addition, the rate of treatment failure when using doxycycline is high, and macrolide resistance is on a steep rise. This is the reason why moxifloxacin is currently endorsed as the drug of choice in the therapy of azithromycin-resistant Mycoplasma genitalium.
In conclusion, the deficiency of diagnostic tests contributed to the general unfamiliarity of both clinical microbiologists and physicians with genital mycoplasmas. As their role in genital, neonatal and perinatal pathology will undoubtedly be elucidated by increased research endeavors, the need for their accurate identification and directed treatment will become ever more important.
Reviewed by Liji Thomas, MD.
- Waites KB. Mycoplasma. In: Schlossberg D, editor. Clinical Infectious Disease. Cambridge University Press, 2008; pp. 1145-1156.
- Martin DH. Genital Mycoplasmas: Mycoplasma genitalium, Mycoplasma hominis and Ureaplasma Species. In: Bennett JE, Dolin R, Blaser MJ, editors. Mandell, Douglas, and Bennett's Principles and Practice of Infectious Diseases. Elsevier Health Sciences, 2015; pp. 2190-2193.