What is Mycoplasma genitalium?

Mycoplasma Genitalium: An Emerging Sexually Transmitted Pathogen

Mycoplasma genitalium is a sexually transmitted bacterium that causes nongonococcal urethritis in men and cervicitis and pelvic inflammatory disease in women, with increasing concern due to rising antimicrobial resistance. 1, 2

Organism Characteristics

• M. genitalium belongs to the class Mollicutes and is the smallest prokaryote capable of independent replication 2
• First isolated in 1981 from urethral swabs of men with urethritis 2
• Fastidious organism that is difficult to culture, requiring specialized molecular diagnostic methods

Clinical Significance

In Men:

• Important cause of nongonococcal urethritis (NGU) 1, 2
• Responsible for 15-25% of nonchlamydial NGU cases 1
• Often presents with urethral discharge and dysuria
• Can cause epididymitis

In Women:

• Associated with cervicitis 1
• Causes pelvic inflammatory disease (PID) 1, 2
• Can lead to tubo-ovarian abscess and salpingitis 1
• Associated with infertility 3, 4
• Increases susceptibility to HIV infection 4

Prevalence:

• 0.5-10% in the general population 4
• 20-40% in women with sexually transmitted infections 4
• Higher prevalence in patients attending sexual health clinics 2

Pathogenesis

M. genitalium employs several mechanisms to establish infection:

• Adhesion to host cells using a specialized tip organelle 3
• Gliding motility that facilitates spread 3
• Intracellular invasion capability 3
• Antigenic variation to evade host immune response 3
• Can establish chronic infections through intracellular localization 3

Diagnosis

• Nucleic acid amplification tests (NAATs) are the preferred diagnostic method 1, 2
• No FDA-cleared assay is currently available, but multiple laboratories have validated molecular assays 1
• Culture is difficult and not routinely performed 2
• Testing should include detection of macrolide resistance-mediating mutations 2
• Testing is recommended for:
  • Men with persistent or recurrent urethritis
  • Women with cervicitis or PID
  • Not recommended for asymptomatic screening 2

Treatment Challenges

Antimicrobial Resistance:

• Rising resistance to macrolides (azithromycin) is a major concern 2, 5, 6
• Resistance is associated with mutations in the 23S rRNA gene 6
• Azithromycin treatment failure rates are increasing globally 6
• Fluoroquinolone resistance is also emerging 6
• Cases of multidrug-resistant infections have been reported 6

Treatment Options:

• Azithromycin has been the preferred treatment, but efficacy is declining 6
• Extended azithromycin regimen (1.5g) may be more effective than single 1g dose 6
• Moxifloxacin is effective against macrolide-resistant strains 6
• Doxycycline has poor efficacy against M. genitalium 6
• Pristinamycin and solithromycin may be options for multidrug-resistant infections 6

Clinical Management

• Testing for antimicrobial resistance is recommended when M. genitalium is detected 3
• Treatment should be guided by resistance testing when available 2
• Partner notification and treatment is important to prevent reinfection 2
• Follow-up testing to confirm cure may be necessary in persistent cases

Public Health Implications

• Surveillance is essential to monitor changing epidemiology and resistance patterns 2
• Limited availability of diagnostics has led to syndromic management, contributing to antimicrobial resistance 2
• There is significant concern regarding the emergence of untreatable strains 2

Conclusion

M. genitalium is an important sexually transmitted pathogen with significant implications for reproductive health. The rising antimicrobial resistance poses a serious challenge to effective treatment. Improved diagnostic capabilities and resistance testing are essential for appropriate management of this infection.