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usmle-12851
A 53-year-old female patient comes to the physician’s office for her annual check-up visit. She has no complaints and her past medical history is notable for diabetes and hypertension. During this visit, the patient undergoes screening procedures per guidelines including a mammogram. On the screening mammogram a spiculated, irregular mass is found on the left breast. Further diagnostic mammography and biopsy reveal ductal adenocarcinoma of the breast in the upper outer quadrant of the left breast. Which of the following is the most important factor in determining this patient’s prognosis?
usmle-12852
A 30-year-old man is admitted to the hospital with a presumed pneumonia and started on antibiotics. Two days later, the patient shows no improvement. Blood cultures reveal yeast with pseudophyphae. Which of the following cell types is most likely deficient or dysfunctional in this patient?
usmle-12853
A 27-year-old man presents for followup 3 months after starting an antiretroviral regimen consisting of efavirenz, tenofovir, and emtricitabine. Labs drawn just prior to presentation reveal an undetectable viral load and a T-lymphocyte count of 317/mm^3. By comparison, his viral load was 6100/mL and his T-lymphocyte count was 146/mm^3 at the time of treatment initiation. He reports that he is tolerating the medications well and is not experiencing any major side effects. Which of the following treatment regimens should be recommended for this patient given the fully suppressed viral load?
usmle-12854
A 67-year-old woman presents to the infectious disease clinic after her PPD was found to be positive. A subsequent chest radiography shows a cavity in the apex of the right upper lobe, along with significant hilar adenopathy. The patient is diagnosed with tuberculosis and is started on the standard four-drug treatment regimen. Four weeks later, she returns for her first follow-up appointment in panic because her eyes have taken on an orange/red hue. Which of the following describes the mechanism of action of the drug most likely responsible for this side effect?
usmle-12855
A 42-year-old woman comes to her primary care physician with 2 days of fever and malaise. She also says that she has a painful red lesion on her left hand that she noticed after shucking oysters at a recent family reunion. Physical exam reveals a well-demarcated swollen, tender, warm, red lesion on her left hand. Pressing the lesion causes a small amount of purulent drainage. The material is cultured and the causative organism is identified. Which of the following characteristics describes the organism that is most associated with this patient's mechanism of infection?
usmle-12856
A 33-year-old immigrant from Bangladesh is evaluated by a primary care physician as a new patient. He immigrated from Bangladesh to the United States 1 month ago and lives with his extended family. He worked in a clothing factory in Bangladesh and has not been seen by a doctor in over 10 years. He reports that he has had a chronic cough for the past year that he attributes to smoking. He says that he feels well and has no complaints. He denies any past medical history and takes no medications. He smokes 2 packs of cigarettes per day. His temperature is 98.6°F (37°C), blood pressure is 120/75 mmHg, pulse is 105/min, and respirations are 20/min. On examination, he appears mildly cachectic with cervical lymphadenopathy. A purified protein derivative test leads to 12 mm of induration. A chest radiograph demonstrates an apical cavitary lesion. The patient is started on the standard medication regimen for his condition, including a medication that inhibits mycobacterial cell wall carbohydrate polymerization. Resistance to this medication is most likely to stem from which of the following processes?
usmle-12857
A 15-year-old boy is brought to the emergency department by ambulance after his mother found him having muscle spasms and stiffness in his room. His mother stated he scraped his foot on a rusty razor on the bathroom floor 2 days prior. On presentation, his temperature is 102.0°F (38.9°C), blood pressure is 108/73 mmHg, pulse is 122/min, and respirations are 18/min. On physical exam, he is found to have severe muscle spasms and rigid abdominal muscles. In addition, he has a dirty appearing wound on his right foot. The patient's mother does not recall any further vaccinations since age 12. Finally, he is found to have difficulty opening his mouth so he is intubated. Which of the following treatment(s) should be provided to this patient?
usmle-12858
A 75-year-old man presents to his physician after his daughter was concerned that his toe nails have become discolored. On physical examination, the nail plate of the great toe on both of his feet are yellow-brown, thickened, and appear both fragile and cracked (Figure A). A fungal culture is obtained and confirms a dermatophyte infection. The patient is prescribed a topical medication that inhibits the fungal enzyme squalene epoxidase. Which of the following is a potential adverse effect of this medication?
usmle-12859
A 7-year-old boy is brought to his pediatrician by his parents because of a new rash. The family immigrated from Laos one year ago and recently obtained health insurance. A week ago, the boy stated that he was “not feeling well” and asked to stay home from school. At the time, he starting having cough, nasal congestion, and irritated eyes – symptoms that persisted and intensified. His parents recall that at the time they noticed small whitish-blue papules over the red buccal mucosa opposite his molars. Five days ago, his parents noticed a red rash around his face that quickly spread downward to cover most of his arms, trunk, and then legs. His temperature is 102.5°F (39.2°C), blood pressure is 110/85 mmHg, pulse is 102/min, and respirations 25/min. On physical exam, he has intermittent cough, cervical lymphadenopathy, and nonpurulent conjunctivitis accompanied by a confluent, dark red rash over his body. This patient is at risk for which of the following complications later in life?
usmle-12860
A 68-year-old woman presents to the emergency room with productive cough and fever. She has a chronic cough that has been getting progressively worse over the last 2 weeks. Last night she developed a fever and vomited. She smoked one pack of cigarettes per day for 40 years and recently quit. Her past medical history includes COPD and her medications include ipratropium and fluticasone. On physical exam her temperature is 102.2°F (39°C), blood pressure is 131/78 mmHg, pulse is 110/min, respirations are 22/min, and oxygen saturation is 95% on room air. She has decreased breath sounds bilaterally with diffuse crackles. You obtain a sputum sample and identify an organism that grows selectively on medium containing factors V and X. Which of the following organisms is the most likely cause of this patient's symptoms?
usmle-12861
A 26-year-old female presents to the emergency department with high fever, productive cough, and hemoptysis. She says that she has also been getting red tender bumps under the skin as well as joint pain. She believes that her symptoms started a few days after a small earthquake hit near her hometown and was otherwise healthy prior to these symptoms. No pathogenic bacteria are detected on sputum culture or by Gram stain. Based on clinical suspicion a lung biopsy is performed and the results are shown in the image provided. The most likely pathogen causing this disease lives in which of the following locations?
usmle-12862
A 1-week-old infant presents to the ED with seizures that are very difficult to control despite loading with fosphenytoin. The parents note that the child was born at home and has been like this since birth. They note that it has been a difficult week trying to get any response from the infant. Upon examination the infant has poor muscle tone, severe difficulties with sucking and swallowing, corneal opacities, and hepatomegaly. Based on clinical suspicion, a genetic test is performed that reveals the diagnosis. The geneticist counsels that the infant has a rare disorder that causes the accumulation of very long chain fatty acids, adversely affecting myelination and leading to neurological symptoms. Most patients with this disorder die within 1 year. The most likely condition in this patient primarily affects which subcellular compartment?
usmle-12863
A 39-year-old male presents to the emergency department with fever, jaundice, and abdominal pain. The patient is a known intravenous drug-user. Serologic testing reveals an ALT of 1040 units/L, AST of 810 units/L, and titer evidence of infection with an enveloped, negative sense, single-stranded, closed circular RNA virus. Which of the following infections must also be present in this patient for him to develop his current disease?
usmle-12864
A 24-year-old woman presents to the ED with symptoms of pelvic inflammatory disease despite being previously treated with azithromycin for chlamydial infection. Based on your clinical understanding about the epidemiology of PID, you decide to obtain a gram stain which shows a gram-negative diplococci. What is the next step in order to confirm the identity of the organism described?
usmle-12865
A 30-year-old man presents to clinic. He was born in southeast Asia and immigrated to the US three years ago. He has a history of chronic hepatitis C which he contracted from intravenous drug use. He reports that he has continued to take ribavirin, but unfortunately has started using heroin again. The patient was seen in the clinic last week and had blood work done. His results are as follows: HBsAg - negative; HBsAb - negative; HBcAb - negative. In addition to encouraging the patient to seek treatment for his heroin addiction, what else should be done at this health visit for general health maintenance?
usmle-12866
A 53-year-old man presents to an urgent care center with severe fever that began during the day along with muscle and joint pains. He states that he felt fine the day before but then developed a fever to 103°F (39.4°C) and had to leave work after which he developed a headache and body pains. The patient states that he was recently in South Asia for a business trip and was otherwise feeling well since returning 2 weeks ago. On exam, the patient’s temperature is 103.3°F (39.6°C), blood pressure is 110/84 mmHg, pulse is 94/min, and respirations are 14/min. On physical exam, the patient appears flushed and has a rash that blanches when touched. On laboratory workup, the pathogen was identified as an enveloped virus with an icosahedral capsid and had positive-sense, single-stranded linear RNA. Which of the following is the most likely cause of this patient's presentation?
usmle-12867
A 25-year-old man visits a local clinic while volunteering abroad to rebuild homes after a natural disaster. He reports that he has been experiencing an intermittent rash on his feet for several weeks that is associated with occasional itching and burning. He states that he has been working in wet conditions in work boots and often does not get a chance to remove them until just before going to bed. On physical exam, there is diffuse erythema and maceration of the webspaces between his toes. He starts taking a medication. Two days later, he experiences severe nausea and vomiting after drinking alcohol. Which of the following is the mechanism of action of the drug most likely prescribed in this case?
usmle-12868
A 25-year-old male is hospitalized for acute agitation, photophobia, and dysphagia. His parents report that he has been experiencing flu-like symptoms for one week prior to hospital admission. Five weeks ago, the patient was in Mexico, where he went on several spelunking expeditions with friends. The patient ultimately becomes comatose and dies. Autopsy of brain tissue suggests a viral infection. The likely causal virus spreads to the central nervous system (CNS) in the following manner:
usmle-12869
The brain of a 75-year-old man is reviewed at autopsy (Figure A). His clinical course was marked by increasingly bizarre behavior, along with aphasia and echolalia. Given this history and gross pathology, what is the post-mortem histologic examination of the brain expected to show?
usmle-12870
A 56-year-old patient reports a history of recurrent dental caries. The bacteria causing this patient's dental problems most likely exhibits which of the following properties?
usmle-12871
A 30-year-old man presents to the physician after he discovered a raised, red, string-shaped lesion beneath the skin on his right foot. The lesion seems to move from one location to another over the dorsum of his foot from day to day. He says that the the lesion is extremely itchy and has not responded to over the counter topical treatment. He and his wife recently returned from a honeymoon in southern Thailand, where they frequented the tropical beaches. The physician diagnoses him with a parasitic infection and prescribes albendazole for the patient. With which of the following organisms is the patient most likely infected?
usmle-12872
A 20-year-old female arrives at the urgent care clinic at her university’s health plan asking for an HIV test. She is an undergraduate at the university and just started having sexual intercourse with her new boyfriend. They use protection only occasionally so she wants to get tested to make sure everything is okay. She has never been tested for STDs before. She reports no symptoms and has not seen a physician regularly for any medical conditions in the past. Her family history is uncertain because she was adopted. Her HIV immunoassay and HIV-1/HIV-2 differentiation immunoassay both come back positive. She asks on the phone, “Doctor, tell it to me straight. Do I have AIDS?” Which of the following is the most accurate response?
usmle-12873
A 42-year-old woman with a history of depression and headaches presents to the emergency room with severe, pulsating pain around the crown of her head beginning 12 hours ago. She last took ibuprofen 2 hours ago but did not feel any improvement in the pain. She has been nauseous and unable to get out of bed and is currently laying in the dark with the lights off. Her depression has improved, and she has stopped taking her sertraline 2 months ago. Other than ibuprofen as needed, she is not currently taking any additional medications. Which of the following would be the best treatment for her acute symptoms?
usmle-12874
A 55-year-old male presents with a low grade fever, chills, left-sided pleuritic pain, and cough two weeks after returning from a camping trip in Tucson, Arizona. He was prescribed antibiotics for possible pneumonia. Symptoms persisted for several weeks at which point a chest radiograph was ordered and showed several opacities in his upper left lobe. A biopsy was taken of one of the opacities (Figure A). Which of the following illnesses does this patient have?
usmle-12875
A 65-year-old woman presents to your office after three days of fever and productive cough. She is taking Tylenol for her fever and her last dose was yesterday morning. She reports reddish brown sputum. She has a history of hypertension and hypercholesterolemia for which she takes lisinopril and a statin. She has never smoked and drinks 1-2 glasses of wine a week. She recently returned from Italy and denies having any sick contacts. On physical exam, her temperature is 102.2°F (39°C), blood pressure is 130/78 mmHg, pulse is 90/min, respirations are 21/min, and pulse oximetry is 95% on room air. She has decreased breath sounds in the left lower lobe. Chest x-ray is shown. The causative organism would most likely show which of the following?
usmle-12876
A 76-year-old woman presents to her primary care physician with an intense, throbbing, right-sided headache. She has a history of migraine headaches and tried her usual medications this afternoon with no alleviation of symptoms. She states that this headache feels different because she also has pain in her jaw that is worse with chewing. The pain came on gradually and is getting worse. In addition, over the past few months, she has had some difficulty getting up out of chairs and raising both her arms over her head to put on her clothes. She has had no recent falls or injuries. On exam, the patient's temperature is 98.3°F (36.8°C), blood pressure is 115/70 mmHg, pulse is 93/min, and respirations are 15/min. The patient has tenderness over her right temple. She has no focal neurological deficits, and no abnormalities on fundoscopic exam. Her physical exam is otherwise within normal limits. Given the patient's most likely diagnosis, which of the following methods of treatment should be used in order to prevent any further complications?
usmle-12877
A 31-year-old woman presents to her primary care physician because she has been experiencing diarrhea over the last several days. She returned from a cruise ship vacation 3 days ago and has recently been to many countries in Central and South America. After returning, she developed bloody diarrhea, nausea, and right-upper quadrant abdominal pain. Stool examination shows blood and neutrophils and imaging reveals abscesses in the liver. Which of the following findings would most likely be seen in this patient?
usmle-12878
A 29-year-old woman presents to her primary care provider complaining of lower back pain. She reports a 3 day history of extreme right lower back pain. She also reports mild dysuria. Her past medical history is notable for recurrent urinary tract infections leading to 3 emergency room visits over the past year. Her family history is notable for renal cell carcinoma in her paternal grandfather and diabetes in her father. Her temperature is 99.5°F (37.5°C), blood pressure is 125/75 mmHg, pulse is 82/min, and respirations are 18/min. On exam, she has mild right costovertebral angle tenderness. Radiography demonstrates a vague radiopaque structure in the right lower abdomen. Results of a urinalysis are shown below: Appearance: Hazy, yellow Protein: Negative Specific gravity: 1.029 WBC: 2+ Casts: None Bacteria: None pH: 8.9 Blood: Negative Bilirubin: Negative Urobilinogen: < 2.0 A urine culture is pending. Which of the following pathogens is most likely responsible for this patient’s condition?
usmle-12879
A 36-year-old man working as a hospital technician presents with a four day history of a leg laceration after tripping on the sidewalk in the city. On presentation, a pustule on the lower leg is observed as seen in Figure A. He complains of pain on ambulation and palpation. A culture grows gram-positive cocci. After a failed trial of nafcillin, he is started on another antibiotic. Ten minutes after an infusion of the new antibiotic, he develops flushing and an erythematous rash on his face and trunk. What is the mechanism of resistance to the antibiotic most likely administered in this case?
usmle-12880
A 16-year-old boy presents to his pediatrician because he has noticed white plaques forming on his tongue over the last 5 days. He recently returned from a boy scout trip where he traveled across the country and hiked through the woods. His past medical history is significant for asthma for which he uses an inhaler as needed. He says that during the trip he felt short of breath several times and had to use the inhaler. He also says that several of his friends appeared to get sick on the same trip and were coughing a lot. He has not experienced any other symptoms since returning from the trip. On presentation, he is found to have white plaques on the tongue that can be scraped off. Which of the following is a characteristic of the most likely cause of this patient's disease?
usmle-12881
A 31-year-old female with a bacterial infection is prescribed a drug that binds the dipeptide D-Ala-D-Ala. Which of the following drugs was this patient prescribed?
usmle-12882
A 21-year-old university student is found unconscious on the floor of his dorm room by his friends. He is rushed to the emergency room, and his temperature is 103°F (39.5°C) and blood pressure is 84/64 mmHg. On physical examination, he is observed to have purple-rose spots on his neck, abdomen, and lower legs as shown in Figure A. Laboratory data reveals metabolic acidosis. Infection with what organism is most likely responsible for this patient’s condition?
usmle-12883
A 47-year-old man with a history of HIV1 infection presents to his HIV clinic to discuss his antiretroviral medications. He is interested in including maraviroc in his maintenance regimen after seeing advertisements about the medication. On exam, his temperature is 98.8°F (37.1°C), blood pressure is 116/74 mmHg, pulse is 64/min, and respirations are 12/min. His viral load is undetectable on his current regimen, and his blood count, electrolytes, and liver function tests have all been within normal limits. In order to consider maraviroc for therapy, a tropism assay needs to be performed. Which of the following receptors is affected by the use of maraviroc?
usmle-12884
A 23-year-old woman is seen by her primary care physician for fatigue. She says that she has always felt a little short of breath compared to her friends; however, she did not think that it was abnormal until she started trying a new exercise regimen. On physical exam, she is found to have mild conjunctival pallor and a peripheral blood smear is obtained showing echinocytes but no intracellular accumulations. Upon further questioning, she recalls that several relatives have had similar issues with fatigue and pallor in the past. Which of the following is true about the rate limiting enzyme of the biochemical pathway that is affected by this patient's most likely condition?
usmle-12885
A 15-year-old Caucasian male is brought to his pediatrician by his parents, who note the development of a tremor in their child. Urine and serum analysis reveal elevated levels of copper. Which of the following clinical manifestations would the physician most expect to see in this patient?
usmle-12886
A 45-year-old man presents to his primary care provider for two weeks of low-grade fever and sore throat. Upon further questioning, the patient is found to have unprotected sex with both men and women with 3-5 partners per month. On workup, he is found to have an HIV viral load of 15,000 copies/mL with a CD4+ of 170 cells/mm^3. He is started on medical therapy. What should be included in his medication regimen?
usmle-12887
A 24-year-old male is brought into the emergency department complaining of chills, headaches, and malaise for several days. He also states that he experiences shortness of breath when climbing two flights of stairs in his home. He admits to occasionally using intravenous drugs during the previous year. On exam, his vital signs are temperature 39.2° C, heart rate 108/min, blood pressure 124/82 mm Hg, respiratory rate 20/min, and oxygen saturation 98% on room air. A holosystolic murmur is heard near the lower left sternal border. An echocardiogram confirms vegetations on the tricuspid valve. What is the most likely causative organism of this patient's condition?
usmle-12888
A 26-year-old female who is 12 weeks pregnant presents to her primary care physician because she is concerned about her acne. While she has struggled with acne for most of her adult life, the acne has become more severe in the past few months. She has used benzoyl peroxide, salicylic acid, and topical antibiotics in the past but these treatments have had little effect. The patient would like to try minocycline, which worked for a friend of hers. The physician responds that this drug cannot be given to pregnant women, and offers to start the patient on the drug after she delivers the baby. Minocycline may to toxic to the fetus through which mechanism?
usmle-12889
A 9-year-old boy is brought to the clinic by his parents for an annual wellness examination. He is a relatively healthy boy who was born at term via vaginal delivery. He is meeting his developmental milestones and growth curves and is up-to-date on his immunizations. The father complains that he is picky with his food and would rather eat pizza. The patient denies any trouble at school, fevers, pain, or other concerns. A physical examination demonstrates a healthy boy with a grade 3 midsystolic ejection murmur at the second intercostal space that does not disappear when he sits up. What is the most likely explanation for this patient’s findings?
usmle-12890
A 36-year-old woman with no significant medical history presents with a four-week history of epigastric pain. The pain tends to occur two hours after meals. She has lost 4 pounds over the last four weeks. She is allergic to azithromycin and clarithromycin. A urea breath test detects radiolabeled carbon dioxide in exhaled breath. Two days after starting definitive treatment, she returns to the hospital with flushing, headaches, nausea and vomiting after having a few beers that night. What is the mechanism of the drug involved in the adverse reaction?
usmle-12891
A 68-year-old male is brought to his primary care physician by his wife who is concerned that the patient seems more confused and irritable than usual. Three months ago, she started noticing that he appeared confused while doing simple tasks and seemed to be off balance. He has fallen several times over that time period. She has also noticed that if he is startled by one of their grandchildren, his arm starts to twitch uncontrollably. His past medical history is notable for transient ischemic attacks, hypertension, and hyperlipidemia. He takes aspirin, enalapril, hydrochlorothiazide, and rosuvastatin. He has a 30 pack-year smoking history. His family history is notable for Alzheimer’s disease in his mother and maternal uncle. His temperature is 98.6°F (37°C), blood pressure is 130/70 mmHg, pulse is 95/min, and respirations are 16/min. Physical examination reveals dysmetria and an ataxic gait. This patient’s condition is most strongly associated with which of the following findings on brain autopsy?
usmle-12892
A 7-year-old girl presents for a follow-up visit after recent discharge from the hospital. She was admitted about 4 months ago for symptoms of seizures, altered mental status, and fever. She was diagnosed during that admission with herpes encephalitis and recovered well after being treated with acyclovir. However, at this visit, her parents complain of some “strange behaviors” that have developed over the past several weeks. For example, she seems to be snacking uncontrollably and eats significantly more than she did before. Her teacher has also sent home notes stating that she has been chewing on art supplies such as crayons and glue and that she has been sent to the principal twice for rubbing her genitals inappropriately during class. The pediatric neurologist decides to get a follow-up MRI. Which of the following parts of the brain is most likely to have abnormal findings?