Updated: 10/28/2019

Chlamydia trachomatis

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Snapshot
  • A 5-year-old girl presents to the community clinic with a complaint of an intensely irritating foreign-body sensation in her left eye. On physical exam, she exhibits erratic twitching of her eyelid, inflammatory thickening of the upper tarsal conjunctiva, and evidence of conjunctival scarring. The girl and her family recently arrived in the United States from a refugee camp in Ethiopia, where they lived in crowded sleeping arrangements and had inadequate water access for personal hygiene.
Overview

Introduction
  • Classification
    • Chlamydia trachomatis
      • obligate intracellular bacteria
  • Pathogenesis
    • transmission
      • sexual intercourse
      • passage through birth canal
      • trachoma transmitted by hand-to-eye contact and flies
    • location of infection
      • genital tract
      • eyes
    • molecular biology
      • obligate intracellular organism 
        • cannot make their own ATP
        • requires live cells for growth in laboratory   
      • 2 forms
        • reticulate body
          • intracellular, metabolically active, replicating form
          • "Reticulate Replicates"
          • collections of reticulate bodies can be seen in the cytoplasm under light microscopy and are called "inclusion bodies"
        • elementary body
          • infectious, inactive, extracellular form
          • small, dense
          • "Elementary is Enfectious and Enters cell via Endocytosis"
      • infection of mucosal surfaces leads to granulomatous response and damage
      • cell wall lacks peptidoglycan 
        • beta-lactam antibiotics are thus ineffective
  • Diseases
    • trachoma
      • most common cause of preventable blindness
      • serotypes A, B, C
    • chlamydia 
      • the most common bacterial STD in the United States
      • serotypes D-K 
    • lymphogranuloma venereum 
      • serotypes L1-3 ("L for lymphogranuloma")
  • Associated conditions
    • co-infection with Neisseria gonorrhoeae
    • pelvic inflammatory disease (PID)
Presentation
  • Trachoma
    • itching and irritation of the eyes and eyelids
    • discharge from the eyes containing mucus or pus
    • eyelid inflammation
    • blepharospasm
    • conjunctival scarring
    • trichiasis (inward-growing eyelashes)
  • Chlamydia
    • in females
      • dysuria
      • yellow mucopurulent discharge from the urethra
      • vaginal discharge
      • abnormal vaginal bleeding
      • dyspareunia
      • fever (in pelvic inflammatory disesease)
      • asymptomatic in 80% of patients
    • in males
      • dysuria
      • yellow mucopurulent discharge from the urethra
      • unilateral pain and swelling of the scrotum
      • fever
      • asymptomatic in 50% of patients
    • in newborns
      • symptoms of conjunctivitis beginning at 1-2 weeks
        • eye discharge
        • eyelid swelling
      • symptoms of pneumonia beginning at 1-3 months
        • cough
        • fever
  • Lymphogranuloma venereum
    • painful, localized inguinal adenopathy (buboes)
    • genital ulceration
Studies
  • Laboratory diagnosis
    • polymerase chain reaction (PCR) 
    • nucleic acid amplification test (NAAT)
    • cytology for diagnosing infant conjunctivitis and trachoma
      • visualization of intracytoplasmic inclusions
  • Histology
    • cytoplasmic inclusions (reticulate bodies)
      • seen on Giemsa or fluorescent antibody-stained smear
  • Additional studies
    • pregnancy test for females with suspected chlamydial infection
      • doxycycline contraindicated in pregnancy
    • strongly consider testing sexual partners for Chlamydia 
Differential
  • Bacterial vaginosis
    • distinguishing factor
      • gray vaginal discharge with a fishy smell
  • Trichomonas vaginitis
    • distinguishing factor
      • frothy, yellow-green discharge
      • motile trichomonads on wet mount
  • Urinary tract infection
    • distinguishing factor
      • lack of cytoplasmic inclusions seen on Giemsa or fluorescent antibody-stained smear
Treatment
  • Medical 
    • azithromycin (one-time treatment)  
      • treatment of choice for pregnant patients
    • doxycycline
      • add ceftriaxone for possible concomitant N. gonorrhoeae infection
      • contraindicated in pregnant patients due to risk of teeth discoloration in the fetus
    • topical and oral erythromycin for neonatal chlamydial conjunctivitis 
Complications
  • Pelvic inflammatory disease (PID)
    • may include 
      • salpingitis
      • endometritis
      • hydrosalpinx
      • tubo-ovarian abscess
    • risk factor for ectopic pregnancy, infertility, chronic pelvic pain, and adhesions
 

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(M1.MC.13.17) A sample is taken of an ulcer in the inguinal region of a 29-year-old Malaysian male who has had unprotected sex in the past few months. Intracytoplasmic inclusions are seen in the Giemsa staining in Image A. On which of the following can the organism in the staining be grown? Tested Concept

QID: 101476
FIGURES:
1

Bordet-Gengou agar

9%

(27/306)

2

Löwenstein-Jensen agar

13%

(41/306)

3

Charcoal yeast extract agar with cysteine and iron

14%

(43/306)

4

Eaton's agar

13%

(40/306)

5

Yolk sac of a chick embryo

50%

(152/306)

M 1 E

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