Show Notes
3.25 Proteus Species Microbiology review for the USMLE Step 1 exam Proteus species are gram-negative rods that cause hospital acquired urinary tract infections They have swarming motility and can move quickly in a coordinated fashion across surfaces due to their numerous flagella They can self-elongate and secrete a sticky polysaccharide when in contact with solid surfaces, allowing for attachment and easy motility Proteus mirabilis and Proteus vulgaris are the two main species that cause infections in humans Proteus mirabilis tends to cause hospital acquired UTIs and can cling to medical devices such as catheters, where it can infect the epithelium of the urinary tract and ascend up to the kidneys Proteus mirabilis expresses urease, converting urea to ammonia, which can cause the formation of struvite kidney stones Proteus vulgaris is less common than Proteus mirabilis and tends to be more difficult to treat due to drug-resistance plasmids Treatment for Proteus mirabilis infection depends on the type of infection, and for uncomplicated UTIs, patients can be given bactrim, while fluoroquinolones are given for pyelonephritis.
More from Step 1 Basics (USMLE)
4.11 Antibody Review Rheumatology review for the USMLE Step 1 Exam. ANA Principles ANA (Anti-Nuclear Antibody): Non-specific antibody. Reacts against nuclear antigens, including proteins, DNA, RNA, and nucleic acid-protein complexes. Includes a group of antibodies such as anti-dsDNA, anti-histone, SSA/Ro, SSB/La, Scl-70, anti-aminoacyl-tRNA synthetase (Jo-1). Found in 20-30% of the general public without connective tissue disorder symptoms.
4.10 Gout and Pseudogout Rheumotology review for the USMLE Step 1 Exam. Gout Caused by uric acid crystal deposition due to purine metabolism. Triggers inflammation when crystals precipitate in cooler joint fluid. Presents with severe, red, and swollen monoarticular joints, often in the big toe. Diagnosis through synovial fluid analysis. Acute treatment: colchicine, NSAIDs, and glucocorticoids. Preventive treatment: allopurinol, febuxostat, probenecid, and lifestyle changes. Pseudogout Resulting from calcium pyrophosphate crystal deposition, often due to ATP breakdown. Manifests with painful, swollen joints, typically affecting multiple upper extremity joints, especially the knee. Diagnosis through synovial fluid analysis. Acute treatment resembles gout management. No direct preventive treatment to lower calcium pyrophosphate levels. Thanks for listening!
4.09 Rheumatologic Emergencies Rheumatology review for USMLE Step 1 Exam Giant Cell Arteritis (GCA) A large vessel vasculitis, mainly in older individuals. Symptoms: headache, jaw claudication, vision loss. Ischemia from granulomas in large vessels causes vision loss. Immediate high-dose corticosteroids are crucial. Scleroderma Renal Crisis A complication of scleroderma. Symptoms: finger edema, skin tightening, sudden hypertension, rising creatinine. Renal artery fibrosis leads to high blood pressure. Treat with IV ACE inhibitor, not steroids. Acute Transverse Myelitis in SLE Inflammation of the spinal cord in lupus. Symptoms: bilateral numbness, tingling, weakness. Treat with corticosteroids. Catastrophic Antiphospholipid Syndrome (CAPS) A rare, life-threatening form of APS. Symptoms: unexplained miscarriages, unexplained clots, multiorgan failure. Treat with anticoagulation followed by immune suppression
1.06 Systolic Heart Murmurs Cardiovascular system review for the USMLE STEP 1 Exam Heart murmurs are caused by turbulent blood flow in the heart
5.13 OCD and Related Disorders Psych review for the USMLE Step 1 Exam Obsessive Compulsive Disorder (OCD): Unwanted thoughts (obsessions) and repetitive behaviors (compulsions). Treat with CBT + SSRIs/SNRIs. Tic Disorders: Tourette Syndrome involves multiple motor and at least one vocal tic. Treat with Habit Reversal Therapy. Body Dysmorphic Disorder: Preoccupation with minor flaws, treat with SSRIs and CBT. Trichotillomania: Hair pulling disorder, treat with Habit Reversal Training and sometimes SSRIs. PANDAS: Pediatric disorder after strep infection, sudden OCD-like symptoms. Treat with antibiotics, CBT, and SSRIs.