Updated: 11/3/2018

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)
    • doxycycline
      • add ceftriaxone for possible concomitant N. gonorrhoeae infection
    • 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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Questions (4)
Lab Values
Blood, Plasma, Serum Reference Range
ALT 8-20 U/L
Amylase, serum 25-125 U/L
AST 8-20 U/L
Bilirubin, serum (adult) Total // Direct 0.1-1.0 mg/dL // 0.0-0.3 mg/dL
Calcium, serum (Ca2+) 8.4-10.2 mg/dL
Cholesterol, serum Rec: < 200 mg/dL
Cortisol, serum 0800 h: 5-23 μg/dL //1600 h:
3-15 μg/dL
2000 h: ≤ 50% of 0800 h
Creatine kinase, serum Male: 25-90 U/L
Female: 10-70 U/L
Creatinine, serum 0.6-1.2 mg/dL
Electrolytes, serum  
Sodium (Na+) 136-145 mEq/L
Chloride (Cl-) 95-105 mEq/L
Potassium (K+) 3.5-5.0 mEq/L
Bicarbonate (HCO3-) 22-28 mEq/L
Magnesium (Mg2+) 1.5-2.0 mEq/L
Estriol, total, serum (in pregnancy)  
24-28 wks // 32-36 wks 30-170 ng/mL // 60-280 ng/mL
28-32 wk // 36-40 wks 40-220 ng/mL // 80-350 ng/mL
Ferritin, serum Male: 15-200 ng/mL
Female: 12-150 ng/mL
Follicle-stimulating hormone, serum/plasma Male: 4-25 mIU/mL
Female: premenopause: 4-30 mIU/mL
midcycle peak: 10-90 mIU/mL
postmenopause: 40-250
pH 7.35-7.45
PCO2 33-45 mmHg
PO2 75-105 mmHg
Glucose, serum Fasting: 70-110 mg/dL
2-h postprandial:<120 mg/dL
Growth hormone - arginine stimulation Fasting: <5 ng/mL
Provocative stimuli: > 7ng/mL
Immunoglobulins, serum  
IgA 76-390 mg/dL
IgE 0-380 IU/mL
IgG 650-1500 mg/dL
IgM 40-345 mg/dL
Iron 50-170 μg/dL
Lactate dehydrogenase, serum 45-90 U/L
Luteinizing hormone, serum/plasma Male: 6-23 mIU/mL
Female: follicular phase: 5-30 mIU/mL
midcycle: 75-150 mIU/mL
postmenopause 30-200 mIU/mL
Osmolality, serum 275-295 mOsmol/kd H2O
Parathyroid hormone, serume, N-terminal 230-630 pg/mL
Phosphatase (alkaline), serum (p-NPP at 30° C) 20-70 U/L
Phosphorus (inorganic), serum 3.0-4.5 mg/dL
Prolactin, serum (hPRL) < 20 ng/mL
Proteins, serum  
Total (recumbent) 6.0-7.8 g/dL
Albumin 3.5-5.5 g/dL
Globulin 2.3-3.5 g/dL
Thyroid-stimulating hormone, serum or plasma .5-5.0 μU/mL
Thyroidal iodine (123I) uptake 8%-30% of administered dose/24h
Thyroxine (T4), serum 5-12 μg/dL
Triglycerides, serum 35-160 mg/dL
Triiodothyronine (T3), serum (RIA) 115-190 ng/dL
Triiodothyronine (T3) resin uptake 25%-35%
Urea nitrogen, serum 7-18 mg/dL
Uric acid, serum 3.0-8.2 mg/dL
Hematologic Reference Range
Bleeding time 2-7 minutes
Erythrocyte count Male: 4.3-5.9 million/mm3
Female: 3.5-5.5 million mm3
Erythrocyte sedimentation rate (Westergren) Male: 0-15 mm/h
Female: 0-20 mm/h
Hematocrit Male: 41%-53%
Female: 36%-46%
Hemoglobin A1c ≤ 6 %
Hemoglobin, blood Male: 13.5-17.5 g/dL
Female: 12.0-16.0 g/dL
Hemoglobin, plasma 1-4 mg/dL
Leukocyte count and differential  
Leukocyte count 4,500-11,000/mm3
Segmented neutrophils 54%-62%
Bands 3%-5%
Eosinophils 1%-3%
Basophils 0%-0.75%
Lymphocytes 25%-33%
Monocytes 3%-7%
Mean corpuscular hemoglobin 25.4-34.6 pg/cell
Mean corpuscular hemoglobin concentration 31%-36% Hb/cell
Mean corpuscular volume 80-100 μm3
Partial thromboplastin time (activated) 25-40 seconds
Platelet count 150,000-400,000/mm3
Prothrombin time 11-15 seconds
Reticulocyte count 0.5%-1.5% of red cells
Thrombin time < 2 seconds deviation from control
Volume  
Plasma Male: 25-43 mL/kg
Female: 28-45 mL/kg
Red cell Male: 20-36 mL/kg
Female: 19-31 mL/kg
Cerebrospinal Fluid Reference Range
Cell count 0-5/mm3
Chloride 118-132 mEq/L
Gamma globulin 3%-12% total proteins
Glucose 40-70 mg/dL
Pressure 70-180 mm H2O
Proteins, total < 40 mg/dL
Sweat Reference Range
Chloride 0-35 mmol/L
Urine  
Calcium 100-300 mg/24 h
Chloride Varies with intake
Creatinine clearance Male: 97-137 mL/min
Female: 88-128 mL/min
Estriol, total (in pregnancy)  
30 wks 6-18 mg/24 h
35 wks 9-28 mg/24 h
40 wks 13-42 mg/24 h
17-Hydroxycorticosteroids Male: 3.0-10.0 mg/24 h
Female: 2.0-8.0 mg/24 h
17-Ketosteroids, total Male: 8-20 mg/24 h
Female: 6-15 mg/24 h
Osmolality 50-1400 mOsmol/kg H2O
Oxalate 8-40 μg/mL
Potassium Varies with diet
Proteins, total < 150 mg/24 h
Sodium Varies with diet
Uric acid Varies with diet
Body Mass Index (BMI) Adult: 19-25 kg/m2
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(M1.MC.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? Review Topic

QID: 101476
FIGURES:
1

Bordet-Gengou agar

9%

(24/264)

2

Löwenstein-Jensen agar

13%

(34/264)

3

Charcoal yeast extract agar with cysteine and iron

14%

(36/264)

4

Eaton's agar

14%

(36/264)

5

Yolk sac of a chick embryo

50%

(131/264)

M1

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