Summary

Chlamydia is the most common bacterial STI worldwide. It is caused by Chlamydia trachomatis, an obligate intracellular bacterium. The hallmark of the disease is its "silent" nature: the vast majority of infections are asymptomatic, allowing unchecked transmission and causing insidious damage to the female reproductive tract (scarring, infertility). It presents a unique spectrum of disease depending on the serovar:

• D-K: Urethritis/Cervicitis (The common STI).
• L1-L3: Lymphogranuloma Venereum (LGV) - Invasive lymphatic disease.
• A-C: Trachoma (Eye disease - leading cause of preventable blindness).

Incubation Period

The silent delay.

• Symptoms: 1 to 3 weeks after exposure (if they appear).
• Test Positivity: 2 weeks.
• Infectivity: Immediate. You can pass it on before you test positive.

Key Facts

• Prevalence: Huge reservoir in young adults (<25 years). Screening programs target this group.
• Asymptomatic Rate:
  • Women: 70-80% have NO symptoms.
  • Men: 50% have NO symptoms.
• Microbiology: Cannot be cultured on standard agar. Requires tissue culture or DNA amplification (NAAT).

The Economic Burden

Why governments care.

• Cost: Treating simple Chlamydia costs ~$20.
• Sequelae: Treating IVF for infertility caused by Chlamydia costs ~$15,000 per cycle.
• Logic: Screening programs pay for themselves by preventing one case of PID for every ~100 cases detected.

Clinical Pearls

"The Tubal Factor": A single episode of Chlamydia increases the risk of tubal factor infertility. Repeated episodes multiply this risk exponentially. Treat early to save fertility.

Quick Reference: The 3 "C"s

"Contact Tracing is Treatment": Treating the patient but not the partner is a waste of time. Reinfection rates are high. Always treat partners from the last 6 months.

A Tale of Two Bodies

Chlamydia is unique. It lives inside cells.

1. Elementary Body (EB):
   • The Infectious form.
   • Spore-like, tough, survives outside the cell.
   • Metabolically inactive.
   • "The Seed".
2. Reticulate Body (RB):
   • The Replicative form.
   • Fragile, lives inside the host cell (inclusion).
   • Metabolically active (steals ATP).
   • "The Plant".

The Cycle (48-72 Hours)

1. EB attaches to host cell and enters (Endocytosis).
2. EB transforms into RB inside the vacuole.
3. RB undergoes binary fission (multiplies).
4. RBs transform back into EBs.
5. Cell bursts (Lysis), releasing thousands of new EBs to infect neighbors.

Why doesn't Penicillin work?

The wall problem.

• Peptidoglycan: Chlamydia has almost none. Most beta-lactams (Penicillins) attack the cell wall.
• Intracellular: Drugs must penetrate the human cell membrane and the Chlamydia vacuole.
• Winners: Tetracyclines (Doxy) and Macrolides (Azithro) work on protein synthesis inside the ribosome.

Urethritis (NGU)

• Discharge: Usually clear or mucopurulent (less purulent than Gonorrhea).
• Dysuria: "Burning" sensation.
• Meatal Itch.

The Testicular Exam

Is it Torsion?

• Symptom: Unilateral pain.
• Torsion: High riding testis. Absent cremasteric reflex. Surgical Emergency.
• Epididymitis: Swollen, tender epididymis (posterior to testis). Relieved by lifting (Prehn's sign - unreliable).
• Action: In young men, treat for Chlamydia/Gonorrhea. In >35, think E. coli.

Complications

• Epididymo-orchitis: Unilateral testicular pain and swelling. Common cause of acute scrotum in men <35.
• Prostatitis: Chronic pelvic pain.

Male Infertility: Fact or Fiction?

Less clear than in women.

• Theory: Chronic inflammation scares the tubules. Anti-sperm antibodies may form.
• Evidence: Weak. Unlike women (where tubes block), men probably remain fertile.
• Real Risk: Transmitting it to the female partner, who then becomes infertile.

Cervicitis & Urethritis

• Discharge: Vaginal discharge (mucopurulent).
• PCB: Post-coital bleeding (friable cervix).
• Dysuria: Often misdiagnosed as "UTI" if culture is negative ("Sterile Pyuria").

Cervical Ectropion (Erosion)

The red cervix.

• Normal: In young women (and on the Pill), the inner glandular cells roll out onto the visible cervix.
• Chlamydia: Infects these columnar cells easily.
• Sign: The ectropion becomes "angry", edematous, and bleeds on contact (PCB).

"It's just Thrush, right?"

The most common misdiagnosis.

• Thrush (Candida): Itch dominant. Curdy white discharge. No smell.
• Chlamydia: Pain/Dysuria dominant. Mucus discharge.
• Rule: If "Thrush treatment" fails, or if it recurs, Swab for Chlamydia.

The Pelvic Exam

What are you looking for?

• Speculum: "Mucopus" at the os (yellow mucus). Friable ectropion (bleeds when touched).
• Bimanual:
  • Cervical Excitation: Pain on wiggling the cervix.
  • Adnexal Tenderness: Pain in the ovaries/tubes (suggests PID).

Pelvic Inflammatory Disease (PID)

The silent destroyer.

• Symptoms: Deep pelvic pain, dyspareunia (pain on deep sex).
• Signs: Cervical Motion Tenderness ("Chandelier Sign").
• Sequelae:
  1. Tubal Infertility: Scarring blocks the egg.
  2. Ectopic Pregnancy: The egg gets stuck in the tube.
  3. Chronic Pelvic Pain: Adhesions.

Contraception: The Coil Risk

Can I get an IUD?

• Old Myth: "Never put a coil in someone with Chlamydia".
• New Rule: If they have Chlamydia, treat it. You can insert the coil on the same day as treatment start if asymptomatic.
• High Risk: If they have active PID (Pain/Fever), delay insertion until cured.

The Math of Infertility

The cost of delay.

• 1 Episode of PID: 12% risk of infertility.
• 2 Episodes: 23% risk.
• 3 Episodes: 54% risk.
• Ectopic Risk: Increased 7-10 fold after Chlamydia.
• Micro-cilia: Chlamydia destroys the tiny hairs in the tube that move the egg.

Differential Diagnosis: The Discharge

Mechanism: Ascending Infection

The climb.

1. Cervicitis: Bacteria colonize the cervix (The "foyer").
2. Endometritis: They ascend into the uterus (often silent).
3. Salpingitis: They enter the tubes. The body fights back with inflammation (Pus).
4. Scarring: The healing process creates fibrous bands (Adhesions) inside the delicate tube.

Fitz-Hugh-Curtis Syndrome

• Definition: Peri-hepatitis. Infection spreads up the paracolic gutter to the liver capsule.
• Laparocopy: "Violin String" adhesions between the liver and abdominal wall.
• Symptom: RUQ pain (mimics Cholecystitis).

The "Tropical" Variant

• Serovars: L1, L2, L3.
• Epidemiology: Historically tropical. Now emerging in MSM populations (Rectal LGV) in the West.
• Pathology: Invades Lymph Nodes, not just epithelium.

Pharyngeal Chlamydia

The throat reservoir.

• Prevalence: 1-2% of general population, up to 10% in MSM.
• Symptoms: Usually None. Rarely sore throat.
• Significance: It acts as a reservoir for transmission to genitals via oral sex.
• Treatment: Doxycycline works well (unlike Gonorrhea where the throat is hard to cure).

Anatomy: The Lymph Nodes

Where does it go?

• Penis/Vulva: Drain to the Inguinal nodes (Groin). This causes the Bubo.
• Rectum: Drains to the Deep Ililac nodes (Internal/Pelvic). This causes deep pelvic pain.
• Rule: If a patient has rectal LGV, they might not have a visible lump in the groin!

Proctitis in MSM

Pain in the bum is not normal.

• Cause: Receptive anal sex.
• Symptoms: Rectal pain, tenesmus (feeling need to poop), bloody discharge/mucus.
• Differential: Herpes (HSV), Gonorrhea, LGV.
• Rule: ANY rectal symptom in MSM requires an LGV Test (Rectal swab for Chlamydia DNA + Genotyping).

Stages

1. Primary: Small, painless genital ulcer (often missed).
2. Secondary: Inguinal Lymphadenopathy (Buboes).
   • Groove Sign: Enlarged nodes above and below the inguinal ligament.
   • Proctocolitis: Rectal pain, bleeding, discharge (mimics IBD/Crohn's).
3. Tertiary: Genito-anorectal syndrome. Strictures, fibrosis, elephantiasis.

The "Other" Chlamydia: Trachoma

The leading cause of infectious blindness.

• Serovars: A, B, Ba, C.
• Transmission: Flies, fingers, fomites (dirty towels). Not sexual.
• Pathology: Chronic conjunctivitis -> Scarring -> Entropion (Eyelids turn in) -> Eyelashes scatch the cornea (Trichiasis) -> Blindness.
• Prevention: The SAFE Strategy (Surgery, Antibiotics, Facial cleanliness, Environmental improvement).

Adult Inclusion Conjunctivitis

Autoinoculation.

• Cause: Touching genitals then touching the eye.
• Sign: Chronic follicular conjunctivitis caused by Serovars D-K (not Trachoma).
• Rx: Needs systemic Doxycycline (Drops don't work!).

Mechanism: Molecular Mimicry

Why the joints?

• HLA-B27: Patients with this gene are primed to overreact.
• The Trigger: Chlamydia antigens (LPS) travel to the synovium (joint lining).
• The Attack: T-cells attack the joint, thinking it is the bacteria.
• Result: Sterile arthritis (Culture of joint fluid is negative).

SARA (Sexually Acquired Reactive Arthritis)

Formerly Reiter's Syndrome.

• Triad:
  1. Urethritis: "Can't Pee".
  2. Conjunctivitis: "Can't See".
  3. Arthritis: "Can't Climb a Tree" (Large joints - Knee/Ankle).
• Mechanism: Autoimmune reaction to the bacteria (HLA-B27 associated).
• Skin: Keratoderma Blennorrhagica (Pustular rash on palms/soles). Circinate Balanitis (Rash on penis).

The "Staccato" Cough

The Neonatal Diagnosis.

• Timing: 1-3 months of age.
• Sound: Short, sharp, repetitive coughs (like a machine gun). Inspiration is brief.
• Sign: Afebrile (No fever).
• CXR: Hyperinflation + Diffuse interstitial infiltrates.
• Labs: Eosinophilia in the blood.

Neonatal Chlamydia

Vertical transmission during birth.

1. Ophthalmia Neonatorum: "Sticky eye". Purulent conjunctivitis 5-14 days after birth.
2. Pneumonia: Afebrile pneumonia. "Staccato Cough". Eosinophilia.

Mythbuster: The Smear Test

A common misunderstanding.

• Myth: "I had my smear test (Cervical Screening) last month, so I'm clean."
• Fact: Cervical Screening looks for HPV and cancer cells. It does NOT look for Chlamydia or Gonorrhea.
• Action: You must ask for an "STI Check" separately.

The Condom Fact Sheet

99% Effective... in theory.

• Typical Use Efficacy: 85%.
• Mistakes: Not leaving a reservoir tip. Putting it on inside out then flipping it (pre-cum transfer). Removing it "just for a second".
• Oral Sex: Chlamydia transmits easily via oral sex (Pharynx <-> Genitals). Flavoured condoms exist for a reason!

The Vaccine Quest

Why don't we have one?

• Problem: Natural immunity is poor. You can get Chlamydia 10 times.
• Challenge: The bug hides inside cells, evading antibodies. T-cell vaccines are hard to make.
• Status: Phase 1 trials are underway, but nothing close to market.

1. Condoms: Highly effective.
2. Screening:
   • UK: National Chlamydia Screening Programme (NCSP) for all active under-25s.
   • Target: Screen annually or on partner change.
3. Partner Notification (PN):
   • Explain the "Look Back" period (Usually 6 months).

The Rise of "Postal" Testing

Pee in the post.

• Method: User orders kit online. Swabs/pees at home. Mails it back.

• Pros: Removes stigma/embarrassment. High uptake.

• Cons: User error (sampling the wrong bit). Loss to follow-up (blocking the number if positive).

  The "Hard Conversation": Partner Notification

Script for patients.

"The clinic found an infection called Chlamydia. It's very common and easy to cure with tablets, but you might have it without knowing. You need to get a check-up this week. I've been treated, so once you're treated, we're good."

• Provide "Slips" or anonymous SMS notification.