WBR0152
| Author | [[PageAuthor::William J Gibson (Reviewed by Yazan Daaboul, M.D.)]] |
|---|---|
| Exam Type | ExamType::USMLE Step 1 |
| Main Category | MainCategory::Microbiology |
| Sub Category | SubCategory::Musculoskeletal/Rheumatology |
| Prompt | [[Prompt::A 54-year-old homeless man presents to the emergency department with back pain, fever, and dry cough. He reports that these symptoms have approximately been present for the past 2 months. The patient was evaluated for similar symptoms 1 month earlier but a definite diagnosis was not made at the time. He reports he has been smoking 1 pack of cigarettes daily for the past 30 years and drinks 7-8 beers each day. The patient denies intravenous drug use. Upon review of systems, the patient complains of a 6-month history of anorexia, weight loss, and night sweats. Work-up in the ED is remarkable for a hilar opacity in the lung and presence of a mass with lytic destruction of the anterior portion of the T6-T9 vertebral bodies on imaging. CT-guided fine needle aspiration (FNA) of the vertebral mass confirms the diagnosis. Which of the following organisms is most likely responsible for this patient's symptoms?]] |
| Answer A | AnswerA::''Pseudomonas aeruginosa'' |
| Answer A Explanation | [[AnswerAExp::Psuedomonas aeruginosa may cause osteomyelitis and should be suspected among intravenous drug users. However, the hilar opacity implicates tuberculosis infection more strongly. The presentation of this patient is more consistent with Pott's disease.]] |
| Answer B | AnswerB::''Salmonella typhi'' |
| Answer B Explanation | [[AnswerBExp::Salmonella is a common cause of osteomyelitis among indiviuals with sickle cell anemia.]] |
| Answer C | AnswerC::''Mycobacterium tuberculosis'' |
| Answer C Explanation | AnswerCExp::Pott's disease is a presentation of extrapulmonary tuberculosis that involves the spinal vertebrae. The hilar and spinal lesions in this patient strongly suggest tuberculosis infection. |
| Answer D | AnswerD::''Staphylococcus aureus'' |
| Answer D Explanation | [[AnswerDExp::While Staphylococcus aureus is the most common cause of osteomyelitis overall, it is not responsible for Pott’s disease.]] |
| Answer E | AnswerE::''Neisseria gonorrhea'' |
| Answer E Explanation | AnswerEExp::''N. gonnorrhea'' does not commonly causes osteomyelitis. When it does, it is a subacute illness with minimal systemic symptoms. |
| Right Answer | RightAnswer::C |
| Explanation | [[Explanation::Pott’s disease (spinal tuberculosis) is an infection of the spinal vertebrae caused by extrapulmonary Mycobacterium tuberculosis. It is a destructive form of tuberculosis (TB). Approximately 20-30% of patients with TB have extrapulmonary involvement. Pott's disease accounts for approximately 50% of skeletal tuberculosis. The spine is usually involved by hematogenous spread (aterial or venous) into the well-vascularized vertebral bodies from a primary pulmonary or genitourinary lesion. Pott's disease is a slowly growing disease that might persist for several months before appropriate diagnosis and management are performed. Common symptoms of Pott's disease are local chronic back pain, stiffness, back muscle spasms, spinal deformities, presence of cold abscesses, and constitutional symptoms. The anterior spine is often affected in Pott's disease, resulting in a kyphotic deformity with "gibbus formation" (sharp kyphotic angulation). Pott's disease may be complicated by neurological involvement or spinal epidural abscess.
Homelessness and the presence of a lung lesion should raise the suspicion for TB. In addition to homelessness, other risk factors for TB include poverty, overcrowding, malnutrition, alcoholism, drug abuse, HIV, diabetes mellitus, immunosuppressive drugs, peritoneal dialysis, and imprisonment. The patient has positive radiographic findings for a spinal lesion, consistent with tuberculosis infection. The treatment for Pott's disease is the standard treatment for other tuberculosis infection: RIPE: Rifampin, isoniazid, pyrazinamade, and ethambutol. If antibiotics fail, surgical intervention may be required, especially among patients with complicated disease and severe symptoms. |
| Approved | Approved::Yes |
| Keyword | WBRKeyword::Tuberculosis, WBRKeyword::Mycobacterium tuberculosis, WBRKeyword::Microbiology, WBRKeyword::Bacteria, WBRKeyword::Pott's disease, WBRKeyword::Extrapulmonary, WBRKeyword::TB, WBRKeyword::Spinal TB, WBRKeyword::Back pain |
| Linked Question | Linked:: |
| Order in Linked Questions | LinkedOrder:: |