What is the most likely diagnosis for a 26-year-old man with severe bilateral joint pain, recent history of unprotected receptive oral intercourse, and elevated inflammatory markers (Erythrocyte Sedimentation Rate (ESR) and C-Reactive Protein (CRP))?

Most Likely Diagnosis: Disseminated Gonococcal Infection (DGI)

The most likely diagnosis is disseminated gonococcal infection (DGI), given the classic triad of migratory polyarthritis, recent unprotected oral sexual contact, and pharyngitis with pustular exudates in a young sexually active man.

Clinical Reasoning

Key Diagnostic Features Supporting DGI

• Sexual exposure history: Recent unprotected receptive oral intercourse with a male partner approximately 1 week ago provides the critical epidemiologic link 1
• Pharyngeal involvement: Erythematous pharynx with pustular tonsillar exudates indicates primary gonococcal pharyngitis, which serves as the portal of entry for dissemination 1
• Polyarticular inflammatory arthritis: Bilateral involvement of multiple joints (PIPs, MCPs, wrists, ankles, MTPs) with warmth, erythema, and boggy swelling is characteristic of the arthritic phase of DGI 1
• Elevated inflammatory markers: ESR of 85 mm/h and CRP of 11 mg/dL indicate significant systemic inflammation consistent with bacterial infection 1
• Recent fevers: History of fever to 38.9°C supports systemic bacterial dissemination 1

Distinguishing DGI from Other Differential Diagnoses

Reactive arthritis is less likely because:

• DGI typically presents with true septic arthritis rather than sterile reactive arthritis 1
• The presence of pustular pharyngeal exudates suggests active gonococcal infection rather than post-infectious reactive process 1
• Reactive arthritis usually develops 1-4 weeks after the initial infection, whereas this patient's symptoms appeared within 1 week 1

Adult-onset Still's disease (AOSD) is unlikely because:

• AOSD typically presents with quotidian fevers (spiking daily), salmon-pink evanescent rash, and marked leukocytosis—none of which are present 1
• The patient's CBC is normal, whereas AOSD usually shows leukocytosis with neutrophilia 1
• The clear sexual exposure history and pharyngeal findings point toward infectious etiology 1

Acute rheumatic fever is excluded because:

• The patient lacks the characteristic migratory large joint arthritis (knees, ankles, elbows, wrists) without small joint involvement 2
• The soft ejection murmur is nonspecific and not diagnostic of carditis 2
• Rheumatic fever follows Group A Streptococcal pharyngitis by 2-3 weeks, not 1 week 2

Septic arthritis (non-gonococcal) is less likely because:

• Typical bacterial septic arthritis presents as monoarthritis, not symmetric polyarthritis 3
• The patient is currently afebrile on examination 3
• Multiple joint involvement in a young, otherwise healthy patient strongly suggests DGI rather than hematogenous spread of other bacteria 3

Diagnostic Approach

Immediate Testing Required

• Pharyngeal culture and nucleic acid amplification testing (NAAT) for Neisseria gonorrhoeae from the tonsillar exudates 1
• Blood cultures (ideally 2-3 sets) before initiating antibiotics, as bacteremia occurs in 20-30% of DGI cases 1
• Arthrocentesis of at least one affected joint with synovial fluid analysis including:
  • Cell count and differential (expect WBC >50,000/μL in septic arthritis) 1
  • Gram stain (positive in only 25% of DGI cases) 1
  • Culture on chocolate agar (positive in 25-50% of cases) 1
• Urethral and rectal NAAT for N. gonorrhoeae and Chlamydia trachomatis, as co-infection is common and urethral infection may be asymptomatic 1

Additional Supportive Testing

• HIV testing should be performed given the sexual exposure history and risk factors 1
• Syphilis serology (RPR or VDRL) as part of comprehensive STD screening 1
• Hepatitis B and C serology for complete STD evaluation 1

Critical Management Considerations

Treatment Should Not Be Delayed

Empiric antibiotic therapy must be initiated immediately after obtaining cultures, as delay increases risk of permanent joint damage 1. The CDC guidelines recommend empiric coverage for both N. gonorrhoeae and C. trachomatis because negative endocervical (or urethral) screening does not preclude upper tract or disseminated infection 1.

Common Pitfalls to Avoid

• Do not wait for culture results before initiating treatment, as gonococcal cultures have low sensitivity (25-50%) and require special media 1
• Do not rely on Gram stain alone to rule out gonococcal infection, as it is positive in only 25% of DGI cases 1
• Do not overlook partner notification, as the sexual contact requires evaluation and presumptive treatment 1
• Do not assume normal genital examination excludes gonococcal infection, as pharyngeal and rectal infections can disseminate without urethritis 1

Expected Clinical Course

DGI classically presents in two stages:

1. Bacteremic/dermatitis stage: Migratory polyarthralgias, tenosynovitis, and dermatitis (pustular or vesiculopustular lesions on extremities)—this patient may be transitioning from this stage 1
2. Septic arthritis stage: Purulent monoarthritis or oligoarthritis with less prominent skin findings—this patient demonstrates polyarticular involvement suggesting early septic arthritis phase 1

The absence of characteristic skin lesions does not exclude DGI, as they occur in only 50-70% of cases and may be transient 1.