Neisseria gonorrhoeae is one of those Step bugs that shows up everywhere—OB/GYN stems, urethritis questions, septic arthritis, and “why is this newborn’s eye doing that?” If you can picture it instantly, you’ll answer faster and miss fewer easy points.
The 5-second visual hack (sticky mental image)
Mnemonic: “GONO = GO, NO capsule, NO maltose”
Picture two kidney beans (diplococci) wearing pink Gram-negative jackets, hiding inside a neutrophil, holding a sign that says:
- “GO!” (gonorrhea spreads easily)
- “NO capsule”
- “NO maltose” (glucose only)
That single image maps to the classic USMLE identifiers.
One-liner (what to say to yourself on a question)
“Neisseria gonorrhoeae is a Gram-negative, oxidase-positive intracellular diplococcus that ferments glucose (not maltose), has no capsule, and causes urethritis/cervicitis, PID, septic arthritis, and neonatal conjunctivitis.”
Identification: what the lab and the stem are really telling you
Core ID features (memorize these as a bundle)
- Gram-negative diplococci (often described as “coffee bean-shaped”)
- Oxidase positive
- Intracellular in neutrophils on smear from urethral discharge (classic)
- Ferments glucose only (key distinction from N. meningitidis)
- No capsule (again: contrast with meningococcus)
Quick comparison table (high-yield)
| Feature | N. gonorrhoeae | N. meningitidis |
|---|---|---|
| Morphology | Gram− diplococci | Gram− diplococci |
| Oxidase | + | + |
| Location on smear | Inside neutrophils (often emphasized) | Can be intra/extra |
| Sugars fermented | Glucose only | Glucose + maltose |
| Capsule | Absent | Present |
| Big diseases | Urethritis, cervicitis, PID, septic arthritis, neonatal conjunctivitis | Meningitis, meningococcemia, Waterhouse-Friderichsen |
Virulence & pathogenesis: the “why” behind the presentations
High-yield virulence factors
- Pili with antigenic variation
- Promotes adherence to mucosa
- Immune evasion → repeat infections are common
- IgA protease
- Helps colonize mucosal surfaces
- LOS (lipooligosaccharide) (not classic LPS O-antigen)
- Drives inflammation and tissue damage
Clinical “must-recognize” presentations (Step 1 + Step 2)
Urogenital
- Urethritis (often purulent discharge, dysuria)
- Cervicitis (may be asymptomatic; can cause discharge/bleeding)
- PID (pelvic inflammatory disease)
- Think: ascending infection → fever, pelvic pain, cervical motion tenderness
- Major complication: infertility, ectopic pregnancy
Disseminated gonococcal infection (DGI)
Classic board pattern:
- Migratory polyarthritis
- Tenosynovitis
- Dermatitis (small pustular/vesicular lesions)
Also very testable:
- Septic arthritis (often monoarticular—knee is a favorite)
Neonates
- Neonatal conjunctivitis (ophthalmia neonatorum)
- Typically 2–5 days after birth for gonorrhea
- Can be severe/purulent and threatens vision
- Prevention: erythromycin eye ointment prophylaxis (routine in many settings)
Diagnostics: what to order and what it means
Best test in practice questions
- NAAT (nucleic acid amplification test) on urine or swab
- Sensitive and specific; commonly paired with chlamydia testing
Classic microbiology (still fair game)
- Thayer-Martin (VPN) medium: Vancomycin, Polymyxin (or colistin), Nystatin
- Selects for Neisseria by inhibiting contaminants
- No capsule, glucose fermentation only → points to gonorrhoeae
Treatment: the USMLE-safe approach
Uncomplicated gonorrhea (common exam answer)
- Ceftriaxone
- Plus treat empirically for Chlamydia unless it’s been excluded:
- Doxycycline (often first-line), or azithromycin depending on scenario/guidelines
Step 2 “public health” add-ons
- Treat sexual partners
- Test for other STIs (HIV, syphilis, etc.)
- Counsel on reinfection risk (antigenic variation + common coinfections)
Rapid-fire high-yield bullets (what they love to test)
- Gram− diplococci inside neutrophils → think N. gonorrhoeae
- Glucose only (vs meningococcus = glucose + maltose)
- No capsule (vs meningococcus has capsule)
- Antigenic variation of pili → no lasting immunity → recurrent infections
- DGI triad: dermatitis + tenosynovitis + migratory polyarthritis
- Neonatal conjunctivitis at 2–5 days, prevented with erythromycin ointment
- Thayer-Martin (VPN) selective medium