What infections cause watery semen and what antibiotics (abx) treat them?

Infections That Cause Watery Semen and Their Antibiotic Treatments

The primary infections causing watery semen are Chlamydia trachomatis, Neisseria gonorrhoeae, Mycoplasma genitalium, and Mycoplasma hominis, which should be treated with doxycycline 100 mg twice daily for 7-14 days or azithromycin 1g as a single dose. These infections can significantly impact semen quality and fertility, but appropriate antibiotic therapy can improve semen parameters and restore fertility.

Common Infectious Causes of Watery Semen

Sexually Transmitted Infections (STIs)

1. Chlamydia trachomatis

   • Most common bacterial STI affecting semen quality 1
   • Often asymptomatic but can cause epididymitis and urethritis
   • Can lead to reduced sperm count and motility

2. Neisseria gonorrhoeae

   • Causes urethritis and epididymitis that can affect semen quality 1
   • May present with urethral discharge but can be asymptomatic
   • Often co-exists with chlamydial infection

3. Mycoplasma species

   • Mycoplasma genitalium: Associated with watery semen and reduced fertility 2, 3
   • Mycoplasma hominis: Significantly affects semen parameters even in asymptomatic men 4
   • These infections can increase reactive oxygen species (ROS) in semen, damaging sperm

Diagnostic Approach

Testing Methods

• First-void urine for nucleic acid amplification test (NAAT) to detect Chlamydia and Gonorrhea 1, 5
• Urethral swab/smear for microscopic examination and culture 1
• Semen analysis to evaluate parameters (count, motility, morphology) 3, 4
• Specific PCR testing for Mycoplasma species 3

Antibiotic Treatment Regimens

First-Line Treatments

1. For Chlamydia trachomatis:

   • Azithromycin 1g orally in a single dose 1, 6
   • Doxycycline 100mg orally twice daily for 7 days 1, 7

2. For Neisseria gonorrhoeae:

   • Ceftriaxone 250-1000mg IM single dose PLUS
   • Azithromycin 1g orally in a single dose OR
   • Doxycycline 100mg orally twice daily for 7 days 1, 5

3. For Mycoplasma genitalium:

   • Azithromycin 1g orally in a single dose (first-line) 2
   • Moxifloxacin 400mg daily for 7-14 days (second-line if azithromycin fails) 2, 8

4. For Mycoplasma hominis:

   • Doxycycline 100mg orally twice daily for 7-14 days 4

Alternative Regimens

• Ofloxacin 300mg orally twice daily for 7 days 1
• Erythromycin base 500mg orally four times daily for 7 days (for patients who cannot take doxycycline or azithromycin) 1
• Erythromycin ethylsuccinate 800mg orally four times daily for 7 days 1

Treatment Efficacy and Outcomes

Impact on Semen Parameters

• Studies show significant improvement in semen parameters after antibiotic treatment:
  • Increased sperm count and motility 3, 4
  • Improved morphology 3
  • Decreased leukocytes in seminal fluid 3, 4
  • Reduced reactive oxygen species (ROS) levels 3, 4
  • Increased total antioxidant capacity (TAC) 3, 4

Fertility Outcomes

• Treatment of asymptomatic Mycoplasma hominis resulted in pregnancies in 58.3% of partners within 4 months after treatment 4
• Treatment of Mycoplasma genitalium infections led to pregnancies in 43.8% of partners within 4 months 3

Important Considerations

Treatment Challenges

• Azithromycin has declining efficacy for Mycoplasma genitalium (only 35% cure rate in some studies) due to emerging resistance 2
• Moxifloxacin remains highly effective (92% cure rate) for resistant Mycoplasma genitalium 2

Partner Treatment

• All sexual partners from the past 60 days should be evaluated and treated 1
• Both patient and partners should abstain from sexual intercourse until treatment is completed and all are symptom-free 1

Antibiotic Impact on Fertility

• Some antibiotics themselves may negatively affect male fertility 9
• Penicillins and quinolones may have minimal effects on male fertility compared to other classes 9
• Nitrofurans and sulfasalazine have well-documented negative effects on semen parameters 9

By addressing these infections promptly with appropriate antibiotic therapy, semen quality can be improved and fertility potentially restored in affected men.