16.2 Candidiasis, Trichomoniasis, Chlamydia & Gonorrhea

Vulvovaginal Candidiasis: Clinical Classification & Treatment

Vulvovaginal Candidiasis (VVC) results from symptomatic fungal overgrowth within the vaginal vault. Over 75% of women experience at least one lifetime episode, and 40% to 45% experience two or more.

Classification: Uncomplicated vs. Complicated

• Uncomplicated VVC (90%): Sporadic, infrequent episodes (<4 per year); mild-to-moderate symptoms; suspected Candida albicans; immunocompetent non-pregnant host.
  • Treatment: Single-dose Fluconazole 150 mg PO; OR short-course topical azoles (Clotrimazole, Miconazole, or Terconazole cream/suppositories for 1 to 7 days).
• Complicated VVC: Recurrent VVC (RVVC), severe edema/fissuring, non-albicans species (Candida glabrata), or occurring in compromised hosts (uncontrolled diabetes, immunosuppression, pregnancy).
  • Recurrent VVC (RVVC): Defined as ≥4 microbiologically confirmed episodes within 12 months.
  • RVVC Regimen: Induction therapy with Fluconazole 150 mg PO every 72 hours for 3 doses (Days 1, 4, and 7), followed by maintenance suppressive therapy with Fluconazole 150 mg PO once weekly for 6 months.
  • Non-Albicans Infection (Candida glabrata): Frequently resistant to azoles. First-line therapy is topical Boric Acid 600 mg in a gelatin capsule inserted intravaginally daily at bedtime for 14 to 21 days. Warning: Boric acid is fatal if ingested orally and is strictly contraindicated during pregnancy!

[!CAUTION] Pregnancy Warning on Oral Fluconazole: Oral fluconazole is CONTRAINDICATED in pregnancy due to epidemiological and pharmacokinetic data demonstrating an increased risk of spontaneous abortion, as well as congenital craniofacial and cardiac malformations associated with first-trimester exposure. During pregnancy, ONLY topical azole therapies (e.g., Clotrimazole 1% or 2% vaginal cream, or Miconazole vaginal cream for 7 consecutive days) may be prescribed!

Trichomoniasis: Parasitology, Diagnosis & CDC Updates

Trichomonas vaginalis is an obligate, flagellated parasitic protozoan that infects the squamous epithelium of the lower urogenital tract. It is exclusively transmitted through sexual intercourse.

• Clinical Presentation: Copious, malodorous, frothy yellow-green discharge with severe vulvar pruritus, dyspareunia, and postcoital bleeding. Classic physical exam finding: Colpitis macularis ("strawberry cervix"), characterized by prominent micro-petechiae across the ectocervix, visible in up to 45% of cases on colposcopy.
• Diagnostic Modalities:
  • Saline Wet Mount: Direct visualization of live, motile, oval-to-pear-shaped trichomonads displaying rapid, jerky, undulating flagellar movement alongside abundant polymorphic leukocytes. Wet mount sensitivity is poor (50% to 60%) because trichomonads rapidly lose motility once removed from the body.
  • Nucleic Acid Amplification Testing (NAAT): The gold-standard diagnostic modality (sensitivity and specificity >95% to 100%). FDA-cleared NAATs (Aptima, BD MAX) using vaginal, endocervical, or urine specimens are recommended for all symptomatic women and high-risk screening.
• CDC Treatment Guidelines (Updated):
  • Preferred Regimen for Women: Metronidazole 500 mg PO BID for 7 days. Randomized controlled trials demonstrated that the 7-day multidose regimen achieves a 50% lower treatment failure rate compared to the historical single 2 g dose.
  • Alternative Regimen: Tinidazole 2 g PO in a single dose.
  • Pregnancy: Metronidazole 500 mg PO BID for 7 days is safe and recommended in all trimesters of pregnancy.
  • Mandatory Partner Management: Both sexual partners must be treated simultaneously. Patients must strictly abstain from sexual intercourse until both partners have completed therapy and symptoms have completely resolved. Expedited Partner Therapy (EPT) should be provided where permitted by state law.
  • Rescreening Requirement: Mandatory repeat screening with NAAT 3 months post-treatment due to high reinfection rates (up to 17%).

Sexually Transmitted Bacterial Infections: Chlamydia & Gonorrhea

Chlamydia trachomatis

Chlamydia trachomatis is an obligate intracellular bacterium and the most commonly reported bacterial STI in the United States. Up to 70% to 80% of women are entirely asymptomatic, serving as an unrecognized reservoir for ascending infection.

• Clinical Features: Endocervical mucopurulent discharge, cervical friability (contact bleeding during Pap or swab collection), postcoital bleeding, dysuria, and pyuria.
• Screening Imperatives: Annual universal screening for all sexually active women aged <25 years, and women aged ≥25 years with new/multiple partners or inconsistent barrier use. Universal first-trimester prenatal screening with repeat third-trimester screening for high-risk individuals.
• Diagnostic Gold Standard: NAAT on first-catch urine, self-collected or clinician-collected vaginal swab (highest sensitivity), or endocervical swab.
• CDC Treatment Guidelines (Updated):
  • First-Line Regimen (Non-Pregnant): Doxycycline 100 mg PO BID for 7 days. Clinical trials demonstrated doxycycline's clear superiority over single-dose azithromycin, particularly for concurrent rectal chlamydial infection (microbial cure 97% vs. 74%).
  • First-Line Regimen in Pregnancy: Azithromycin 1 g PO in a single dose. (Doxycycline is strictly contraindicated during pregnancy due to fetal hepatotoxicity, permanent tooth discoloration, and inhibition of long-bone growth).
  • Alternative in Pregnancy: Amoxicillin 500 mg PO TID for 7 days.
• Follow-Up & Test-of-Cure (TOC):
  • In non-pregnant individuals treated with first-line doxycycline, a test-of-cure is not recommended unless therapeutic compliance is questioned or symptoms persist. Rescreening with NAAT is mandatory at 3 months to detect reinfection.
  • In pregnant individuals, a Test-of-Cure (TOC) via NAAT is MANDATORY 4 weeks after treatment completion, followed by repeat screening in the third trimester.

Neisseria gonorrhoeae

Neisseria gonorrhoeae is a fastidious, Gram-negative intracellular diplococcus that infects mucosal columnar and transitional epithelium. Co-infection with C. trachomatis occurs in up to 30% to 40% of cases.

• Clinical Presentation: Copious, thick, green-yellow purulent endocervical discharge, severe dysuria, intermenstrual bleeding, labial pain, and Bartholin's or Skene's gland abscesses.
• CDC Treatment Guidelines (Weight-Based Monotherapy):
  • Weight <150 kg (330 lbs): Ceftriaxone 500 mg IM in a single dose.
  • Weight ≥150 kg (330 lbs): Ceftriaxone 1 g (1,000 mg) IM in a single dose.
  • Rule on Co-Infection: If chlamydial infection has NOT been excluded by NAAT, clinicians must add Doxycycline 100 mg PO BID for 7 days (or Azithromycin 1 g PO in pregnancy).
  • Severe Cephalosporin Allergy: Gentamicin 240 mg IM single dose PLUS Azithromycin 2 g PO single dose.
  • Follow-Up: Retest with NAAT at 3 months. A test-of-cure at 7 to 14 days is required only for pharyngeal gonorrhea treated with an alternative regimen.