What would you suspect might be the cause of his arthropathy?

He has a gonococcal arthritis. This means he has disseminated gonococcal infection (DGI), which occurs in about 0.5-3% of patients with untreated gonorrhoea.

What other tests should you do?

• Blood tests
• FBC
• CRP/ESR
• Blood cultures, but only 10-30% of cultures will be positive
• Knee aspirate
• Fluid for gram stain
• Microbiology, but only 20-30% of cultures will be positive.

Given the low rate of positives from cultures what other diagnostic test may help?

Urine for a nuclear acid amplification technique (NAAT), such as polymerase chain reaction (PCR).

What information will you not get from a NAAT? Antibiotic sensitivities.

What would be your initial empirical antibiotic therapy? Intravenous third generation cephalosporin.

What co-infection may he have?
Chlamydia trachomatis

What serious complications may be associated with DGI? He is at risk of osteomyelitis, meningitis, endocarditis, ARDS, and septic shock. These are all becoming increasingly rare.