Chlamydia vs Gonorrhea
How to tell Chlamydia and Gonorrhea apart when a board question makes them look alike.
Chlamydia is often quieter and intracellular with reactive-arthritis risk; gonorrhea is more purulent, diplococcal, and can disseminate to joints/skin.
Side by side
Often milder urethritis/cervicitis, intracellular organism, and risk of silent pelvic inflammatory disease.
More purulent discharge, gram-negative intracellular diplococci, and disseminated tenosynovitis-dermatitis-arthritis risk.
Obligate intracellular infection of columnar epithelial cells.
Neisseria infection uses pili and surface variation to invade mucosa.
Nucleic acid testing identifies chlamydial infection; reactive arthritis and Fitz-Hugh-Curtis are high-yield sequelae.
Gram-negative intracellular diplococci support gonorrhea in symptomatic urethritis.
The trap
Coinfection is common, but diagnosis should still use organism clues and nucleic acid testing.
Watch it explained
Test it nowThe repair move
Use organism clue when given; otherwise use nucleic acid testing because symptoms overlap heavily.
Try a free question
CoreA man has dysuria and thick purulent urethral discharge. Gram stain shows gram-negative intracellular diplococci. Which organism is most likely?
Show answer and explanation
Answer: B. Neisseria gonorrhoeae. Gram-negative intracellular diplococci in symptomatic urethritis point to gonorrhea.
Why the other choices are tempting
- A. Chlamydia is obligate intracellular and diagnosed by nucleic acid testing; it is not a gram-negative diplococcus on smear.
- C. Treponema causes syphilis and is a spirochete.
- D. Haemophilus ducreyi causes painful chancroid ulcers.
- E. Mycoplasma lacks a cell wall and is not seen as diplococci.
Flashcards
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What is the fastest separator for Chlamydia vs Gonorrhea?
Chlamydia is often quieter and intracellular with reactive-arthritis risk; gonorrhea is more purulent, diplococcal, and can disseminate to joints/skin.
What clue should make you choose Chlamydia?
Often milder urethritis/cervicitis, intracellular organism, and risk of silent pelvic inflammatory disease.
Quick answers
What is the fastest way to tell Chlamydia from Gonorrhea?
Chlamydia is often quieter and intracellular with reactive-arthritis risk; gonorrhea is more purulent, diplococcal, and can disseminate to joints/skin.
What is the key clue for Chlamydia?
Often milder urethritis/cervicitis, intracellular organism, and risk of silent pelvic inflammatory disease.
What is the key clue for Gonorrhea?
More purulent discharge, gram-negative intracellular diplococci, and disseminated tenosynovitis-dermatitis-arthritis risk.
What is the common trap with Chlamydia vs Gonorrhea?
Coinfection is common, but diagnosis should still use organism clues and nucleic acid testing.