Understanding Key Sexually Transmitted Infections

📚 Study Guide: Key Sexually Transmitted Infections (STIs)

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Source Information: This study material has been compiled from a lecture audio transcript and copy-pasted text, providing a comprehensive overview of Syphilis, Chancroid, Granuloma Inguinale, and Lymphogranuloma Venereum.

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Introduction to Sexually Transmitted Infections (STIs)

This guide provides a structured overview of several critical sexually transmitted infections (STIs), focusing on their etiology, pathogenesis, clinical manifestations, diagnosis, prognosis, and treatment. Understanding these infections is crucial for effective patient management and public health.

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1. Syphilis

Syphilis is a complex systemic infection caused by Treponema pallidum. Its diagnosis and treatment depend heavily on the stage of the disease and the patient's history.

1.1. Patient Approach and Diagnosis 📊

Diagnosis of Syphilis relies on a combination of serological tests and clinical history. Key tests include:

• VDRL (Venereal Disease Research Laboratory): A non-treponemal test, often used for screening and monitoring treatment response.
• TPH (Treponema Pallidum Hemagglutination Assay): A treponemal test, specific for T. pallidum antibodies.
• FTA-Abs (Fluorescent Treponemal Antibody Absorption): Another specific treponemal test, often used to confirm positive TPH results.

Here's an interpretation guide for serological results:

| VDRL | TPH | FTA-Abs | History | Interpretation | Action | | :--- | :-- | :------ | :------ | :---------------------------------------------- | :------------------------------------------------------------------ | | (-) | (+) | (+) | None | Old case requiring treatment | ✅ Treatment | | (-) | (+) | (+) | Treated | Residual seroreactivity (IgM negative) | 🚫 No treatment needed | | (+) | (+) | (+) | None | New case requiring treatment | ✅ Treatment | | (+) | (+) | (+) | Treated | Residual/Inadequate treatment/Reinfection | 💡 Check IgM for further clarification | | (+) | (-) | (-) | None | Non-specific reactivity (e.g., collagenosis) | ⚠️ Investigate underlying conditions | | (-) | (-) | (+) | None | Suspicious result | 🔄 Retest |

1.2. Treatment 💊

Treatment varies based on the clinical stage:

• Early Syphilis, Early Latent Syphilis:
  • Main Treatment: 2.4 million units (MÜ) Benzathine Penicillin, administered over 2 weeks.
  • Alternative (2 weeks): Doxycycline 100mg (2x1), Tetracycline 500mg (4x1), Erythromycin 500mg (4x1), or Ceftriaxone 250mg IM (1x1 for 10 days).
• Late Latent Syphilis, Tertiary Syphilis:
  • Main Treatment: 2.4 MÜ Benzathine Penicillin, administered over 3 weeks.
  • Alternative (4 weeks): Doxycycline 100mg (2x1) or Tetracycline 500mg (4x1).
• Neurosyphilis, Congenital Syphilis:
  • Main Treatment: Crystalline Penicillin 2.4 MÜ IV every 4 hours for 10-14 days, or Procaine Penicillin 2.4 MÜ.
  • Alternative: Procaine Penicillin 2-4 MÜ IM for 10-14 days, or Erythromycin 500mg (4x1).
• Pregnancy:
  • Main Treatment: 2.4 MÜ Procaine Penicillin.

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2. Chancroid (Soft Chancre / Ulcus Molle)

2.1. Overview

• Etiology: Haemophilus ducreyi (Gram-negative, pleomorphic coccobacillus).
• Epidemiology: Prevalent in Africa, South Asia, India, South America, and Turkey.
• Gender Ratio: Males > Females (often > 1:1).

2.2. Pathogenesis

• Transmission: Primarily sexual contact; accidental exposure possible for healthcare personnel.
• Mechanism: Requires compromised skin/mucosa; does not penetrate intact skin.
• Virulence Factor: Lipopolysaccharide capsule in the cell wall drives inflammatory response.

2.3. Clinical Manifestations

• Incubation Period: 2-3 days.
• Lesion Progression: Erythematous papule → vesicle → fragile, painful, multiple ulcers.
• Ulcer Characteristics:
  • "Sign of double border" (distinct ulcer edges).
  • Yellow-gray, purulent, soft base.
  • Serrated upper edges, undermined margins ("soft" ulcer).
  • Erythematous halo around the ulcer.
  • Often multiple, with 'kissing lesions' (two ulcers in contact).
  • Base is dirty, covered with necrotic yellow purulent exudate.
• Lymphadenopathy: Unilateral inguinal lymphadenopathy and bubo formation in ~50% of cases.
• Systemic Symptoms: Fatigue, fever (relatively rare).
• Location:
  • Males: Frenulum, coronal sulcus.
  • Females: Labia, urethral meatus, posterior commissure, vagina, cervix.
  • Other: Anal involvement common (auto-inoculation); extragenital ulcers rare (inguinal, lower femoral, perioral, perimammary).

2.4. Prognosis

• Does not heal spontaneously without treatment.
• Complications: Scar formation (ulcer and bubo), phimosis, urethral fistula, lymphangitis dorsalis penis, secondary infections, increased susceptibility to other STIs.

2.5. Diagnosis

• Smear: From ulcer or bubo, stained with Giemsa or methylene blue, shows bacteria in "fish school" or "railroad tracks" pattern.
• Culture: Standard method, ~80% sensitivity; Nairobi medium commonly used.
• Multiplex PCR: Effective diagnostic tool.
• Biopsy: Reveals H. ducreyi within/outside macrophages; trizonal pattern (necrotic, granulation, inflammation areas).

2.6. Differential Diagnosis

• Syphilis, Genital Herpes, Granuloma Inguinale, Lymphogranuloma Venereum.
• Non-venereal: Traumatic ulcer, erythema multiforme, fixed drug eruption, Behçet's disease.

2.7. Treatment 💊

• Azithromycin 1g single dose.
• Ceftriaxone 250mg IM single dose.
• TMP-SMX 160/80mg (2x1 for 10 days).
• Ciprofloxacin 500mg PO (2x1 for 3 days).
• Erythromycin 500mg PO (4x1 for 7 days).
• Adjunctive: Ulcer debridement, bubo aspiration.

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3. Granuloma Inguinale (Donovaniasis)

3.1. Overview

• Etiology: Calymmatobacterium granulomatis (Gram-negative bacterium).
• Epidemiology: Asia, Africa, America; common in homosexual individuals and low socioeconomic communities.
• Gender Ratio: Males > Females (> 1:1).

3.2. Pathogenesis

• Transmission: Sexual contact.
• Mechanism: Does not penetrate intact skin.
• Characteristics: Element of intestinal flora, low virulence.
• Routes: Anal or contaminated vaginal intercourse.

3.3. Clinical Manifestations

• Incubation Period: Few days to several months.
• Lesion Progression: Erythematous papular lesion → ulcer.
• Ulcer Characteristics: Irregular, notched, raised, dirty red base, "cobblestone-like" granulomatous appearance.
• Lymphadenopathy: True lymphadenopathy is absent. May have pseudobuboes (subcutaneous granulomatous nodules) or ulcerative vegetating lesions.
• Systemic Symptoms: Extragenital ulcers and systemic infections are rare.

3.4. Prognosis

• Does not heal spontaneously; becomes chronic if untreated.
• Complications: Destructive scar formation (hypertrophic scars), lymphedema (elephantiasis, ulceration), phimosis, increased risk of squamous cell carcinoma (SCC).

3.5. Diagnosis

• Smear: From ulcer or pseudobubo, stained with Giemsa or Wright, reveals rod-like or "safety-pin-shaped" bodies (Donovan bodies) within histiocytes.
• Culture: Difficult to grow the causative agent.
• Biopsy: Helpful diagnostic aid.

3.6. Differential Diagnosis

• Chancroid, Syphilis, Herpes, Lymphogranuloma Venereum, genital malignancies.

3.7. Treatment 💊

• Doxycycline 100mg PO (2x1 for 21 days).
• Erythromycin 500mg PO (4x1 for 21 days).
• Other options (resistance concerns for Tetracycline): Tetracycline 500mg PO (4x1 for 21 days), Ampicillin, TMP-SMX, Chloramphenicol, Gentamicin.
• Adjunctive: Surgical revision for scars.

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4. Lymphogranuloma Venereum (LGV)

4.1. Overview

• Etiology: Chlamydia trachomatis serovars L1, L2, L3.
• Epidemiology: Asia, Africa, South America; risk groups include soldiers and sailors.
• Gender Ratio: Males > Females (> 1:1).

4.2. Pathogenesis

• Transmission: Sexual contact.
• Mechanism: Does not penetrate intact skin.
• Key Feature: Lymphatic destruction.

4.3. Clinical Manifestations

• Incubation Period: At least 2 weeks.
• Primary Lesion (25-50%): Erythematous papule → papulovesicle → papulopustule → small, flat, gray ulcer with serous discharge. Often non-specific, hidden, and may heal spontaneously.
• Lymphadenopathy: Unilateral inguinal lymphadenopathy forming "sign of the groove" and bubo formation is a hallmark.
• Location:
  • Males: Prepuce, glans, coronal sulcus, urethral meatus.
  • Females: Labia, vagina, cervix.
  • Rectal Involvement: Common in homosexual individuals, leading to genitoanorectal syndrome (bloody mucopurulent discharge).
  • Other: Ocular involvement (oculoglandular syndrome), sepsis, systemic infection (rare).

4.4. Prognosis

• Spontaneous healing is possible, but destructive scar formation is common.
• Complications: Hypertrophic scars, lymphedema (elephantiasis, ulceration), phimosis, fistulas, strictures, increased risk of SCC.

4.5. Diagnosis

• Culture: Difficult to grow the causative agent.
• Serology: Positive 2-4 weeks post-infection.
  • Complement Fixation Test: Most common; titer > 1/64 or 4x increase in initial titer is positive.
  • Frei ID skin test: No longer used.
• Biopsy:
  • Skin: Mixed granulomatous and neutrophilic inflammatory response.
  • Lymph Node: Irregular necrotic foci and neutrophilic infiltration ("stellate abscesses").

4.6. Differential Diagnosis

• Syphilis, Genital Herpes, Chancroid, Granuloma Inguinale.
• Non-venereal: Tuberculosis, Hodgkin lymphoma, other lymphomas.