WBR0208

Author	PageAuthor::Mugilan Poongkunran
Exam Type	ExamType::USMLE Step 3
Main Category	MainCategory::Primary Care Office
Sub Category	SubCategory::Musculoskeletal/Rheumatology, SubCategory::Infectious Disease, SubCategory::Infectious Disease, SubCategory::Musculoskeletal/Rheumatology
Prompt	[[Prompt::A 27-year-old male presents to his primary care physician's office for joint pain over the past several days. The patient denies feeling similar pain in the past. He has tried over the counter ibuprofen but it has not relieved his pain. His past medical history is otherwise unremarkable. He smokes one pack per day and has about 20 drinks per week. He uses marijuana occasionally but denies any injectable drug use. He is sexually active and uses condoms. He denies recent travel outside the country and has no allergies. Physical examinations show mild hyperemia and swelling in the right knee and right ankle. Range of movement is restricted because of pain. No rash is present. Arthrocentesis reveals a turbid fluid with WBC count of 20,000/mm3. What is the best next step to confirm the diagnosis?]]
Answer A	AnswerA::Joint fluid culture
Answer A Explanation	AnswerAExp::'''Incorrect''' : Joint fluid culture alone is positive only in 50% of individuals with gonococcal arthritis.
Answer B	AnswerB::Culture from joint fluid, urethra and oral cavity
Answer B Explanation	AnswerBExp::'''Correct''' : Culture of joint fluid and other mucosal surfaces is diagnostic in 80% of individuals.
Answer C	AnswerC::Blood culture
Answer C Explanation	AnswerCExp::'''Incorrect''' : Patients with the tenosynovitis, dermatitis, polyarthralgia form of DGI are more likely to have positive blood cultures than those presenting with purulent arthritis.
Answer D	AnswerD::RA factor
Answer D Explanation	[[AnswerDExp::Incorrect : Patients with the constellation of reactive arthritis, tenosynovitis, and urethritis (formerly Reiter syndrome), unlike those with typical DGI, also have one or more of the following: conjunctivitis; circinate balanitis; or keratoderma blenorrhagicum.]]
Answer E	AnswerE::Chemistry study of joint fluid culture
Answer E Explanation	[[AnswerEExp::Incorrect : Chemistry studies of the joint fluid, such as the concentrations of glucose, lactate dehydrogenase, or protein have only limited value; a reduction in glucose concentration and elevation of LDH are consistent with a bacterial infection, but are not diagnostic or particularly sensitive.]]
Right Answer	RightAnswer::B
Explanation	[[Explanation::Disseminated gonococcal infection (DGI) results from bacteremic spread of the sexually transmitted pathogen, neisseria gonorrhoeae, which can lead to a variety of clinical symptoms, including tenosynovitis, dermatitis, and multiple skin lesions. Gonoccocal infection should be suspected in sexually active individuals with mono or oligoarthritis. Culture of joint fluid and other mucosal surfaces is diagnostic in 80% of individuals. The mean synovial fluid leukocyte count in gonococcal arthritis is typically around 50,000 cells/mm3; in some cases, however, cell counts below 10,000 cells/mm3 may be observed. Educational Objective: Disseminated gonoccocal infection should be suspected in sexually active individuals with mono or oligoarthritis. References: Master the Boards Step 3 2013 page 379 Educational Objective: References: ]]
Approved	Approved::Yes
Keyword	WBRKeyword::Gonorrhea, WBRKeyword::Neisseria, WBRKeyword::Arthritis, WBRKeyword::Joint, WBRKeyword::Pain, WBRKeyword::Joint pain, WBRKeyword::STD, WBRKeyword::STI, WBRKeyword::Sexually transmitted infections
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