DES 2016. Final ( Part 15 )

97) A 19-year-old football linebacker is admitted following a motor vehicle accident. He had an extensive cerebral bleed, which led to a deep coma. He also has fractures of the C4 vertebra, pelvis, and right femur. Following admission, he is intubated and central lines are placed. During the next few days, he develops acute renal failure due to rhabdomyolysis. While he is recovering from acute renal failure, he is found to have a serum calcium level of 12.1 mg/dL. Other investigations are: Serum albumin 3.0 g/dL, Serum creatinine 2.8 mg/dL, Serum phosphorus 3.8 mg/dL, Blood glucose 108 mg/dL, PTH 9 pg/mL, PTHrP undetectable, 1, 25-dihyroxy vitamin D 19 pg/mL (normal 20-60 kg/mL). What is the most likely cause of this patient's hypercalcemia?

98) A 28-year-old avid mountain climber and his friend are vacationing in Andes, South America. During their mountain climbing expedition, the pair somehow manages to get lost. It has been over 16 hours since their food supply ran out. Their glycogen stores are becoming depleted, and their bodies are beginning to utilize the process of gluconeogenesis. Which of the following intermediates is alanine being converted into during this process?

99) A 60-year-old Caucasian male presents to your office complaining of decreased hearing on the right side. He also feels that something is wrong with his head because his hat size had increased over the last two years. His past medical history is significant for hypertension and peptic ulcer disease. His current medications are hydrochlorothiazide and enalapril. He also takes ibuprofen for occasional headaches, and ranitidine for infrequent episodes of heartburn. Lab tests showed increased alkaline phosphatase levels. Which of the following is the most likely mechanism underlying this patient's condition?

100) A 60-year-old man presents to his primary care physician for routine medical care. He has no complaints, takes no medications, and has a family history of DM. Examination is unremarkable. A screening laboratory test reveals a fasting blood glucose level of 152 mg/dL. One week later the test is repeated and a value of 144 mg/dL is obtained. Which of the following is the most likely cause of these findings?

102) A 28-year-old woman presents to her gynecologist for her annual examination. She mentions that she and her husband have been trying to conceive for 9 months without success and that her menstrual cycles have become irregular. Her gynecologist suggests that she and her husband continue to try to conceive and that the woman return in 3 months for some laboratory studies if she still has not become pregnant. In the interim, a routine visit to the ophthalmologist reveals bitemporal hemianopsia. Which of the following is the most likely cause of this woman’s infertility?

103) A 50-year-old obese female is taking oral hypoglycemic agents. While being treated for an upper respiratory infection, she develops lethargy and is brought to the emergency room. Neurological examination is nonfocal; she does not have neck rigidity. Laboratory results are as follows: Na: 134 mEq/L, K: 4.0 mEq/L, HCO3: 25 mEq/L, Glucose: 900 mg/dL, BUN: 84 mg/dL, Creatinine: 3.0 mg/dL, HgA1c: 6.8%, BP: 120/80 mmHg lying down, 105/65 mmHg sitting. Which of the following is the most likely cause of this patient’s coma?

104) An obese 18-year-old woman is brought to the emergency department by her mother, who noted that she had been lethargic all day, and suffered a brief, seizure-like episode. One month earlier, the patient had been started on medication for type 2 DM. Lactic acid levels are normal. Which of the following medications most likely played a role in the patient’s current presentation?

105) A 52-year-old African-American woman with type 2 diabetes mellitus (DM) presents to her physician’s office and states that she has been feeling lousy in the morning. She notes that she reliably checks her blood glucose levels, and is frustrated at the fact that she often has a blood sugar level in the 120s at night, followed by a level in the 170s to 180s the following morning. The patient’s primary care physician increased her nightly dose of neutral protamine Hagedorn insulin 1 month ago, but her morning glucose levels have only become more elevated. She has recently begun to limit her carbohydrate intake at night, with no effect. This patient’s morning hyperglycemia might most likely be alleviated by which of the following?

106) A 26-year-old G1P0 woman at 12 weeks gestation presents to her obstetrician for her first visit. Her pregnancy thus far has been notable only for some mild nausea and vomiting that lasted throughout her first trimester. She reports feeling overly tired lately and very weak. Her past medical history is significant for pernicious anemia. On physical examination she is an anxious-appearing, thin woman. Her blood pressure is 130/85 mmHg, heart rate is 115/ min, and respiratory rate is 18/min. Fetal heart tones are present at 135/min. The uterine fundus is at 12 cm. The woman has a diffuse, non- tender goiter, a resting tremor, and poor global muscle strength. Which is the most likely mechanism underlying this woman’s condition?

107) A 60-year-old woman recently diagnosed with type 2 DM complains of daily headaches and double vision that have gradually worsened over the previous month. An MRI shows a large pituitary adenoma. Which of the following is most likely being secreted by this tumor?

108) A 45-year-old Asian male complains of a progressively worsening sore throat and difficulty swallowing for the past 24 hours. You notice that his voice is muffled and he is drooling. He also has a harsh shrill associated with respiration. His temperature is 39.3°C (103°F), blood pressure is 120/80 mmHg, pulse is 106/min, and respiratory rate is 22/min. On examination, a few cervical lymph nodes are palpable and there is tenderness to palpation over his larynx. Which of the following are the two most common organisms that cause this condition?

109) A 65-year-old female complains of difficulty eating over the last two days. She states that food drops out of her mouth. She has also been having some discharge in her left ear recently. She denies any sore throat, nasal discharge, chest pain, cough, or difficulty breathing. Her past medical history is significant for type 2 diabetes mellitus, hypertension, and hyperlipidemia. She has been poorly complaint with follow-up appointments. Her temperature is 38.8°C (101.7°F), pulse is 96/min, blood pressure is 140/90 mmHg, and respirations are 18/min. Examination of the left ear canal shows granulations. There is facial asymmetry, and the angle of the mouth on the left is deviated downward. Which of the following is the most likely causative organism for this patient's condition?

110) A 62-year-old male comes to your office for a routine follow-up appointment. He has smoked one pack of cigarettes per day for the past 30 years and adamantly refuses to quit. He also drinks six to ten beers each weekend. His past medical history is significant for type 2 diabetes mellitus and hypertension. His last hemoglobinA1c was 8.3%. He is overweight with a current BMI of 27.5 kg/m2. While examining him, you notice a whitish patch over the anterior floor of his mouth. The lesion appears to have a granular texture and is not removed by scraping with a tongue depressor. Which of the following is most likely cause of his oral lesion?

111) A 51 -year-old obese male presents to your office complaining of difficulty swallowing solids but not liquids. His medical history is significant for GERD. Six months ago he was diagnosed with Barrett's esophagus. He reports that three months after the diagnosis of Barrett's esophagus, his heartburn resolved. Barium swallow now reveals an area of symmetric, circumferential narrowing affecting the distal esophagus. Which of the following best explains this finding?

112) A 23-year-old man comes to the physician because of a two-month history of loose stools, decreased appetite, and weight loss. He has no history of medical problems. He takes no medications. His temperature is 36.7°C (98°F), blood pressure is 120/76 mmHg, pulse is 90/min, and respirations are 16/min. Laboratory studies show: Hemoglobin 11.2 g/dL, MCV 80 fl, Leukocyte count 9,500/cmm, Segmented Neutrophils 65%, Bands 3%, Eosinophils 1%, Basophils 0%, Lymphocytes 25%, Monocytes 6%, Platelets 550,000/cmm, ESR 50 mm/hr, Serum sodium 145 mEq/L, Serum potassium 4.0 mEq/L. Test of the stool for occult blood is positive. Which of the following is the most likely type of diarrhea in this patient?

113) A 66-year-old man presents with a four week history of increasing back pain and severe constipation. He has no weakness or sensory symptoms in his legs. He takes acetaminophen for back pain, metoprolol for high blood pressure, and an over-the-counter fiber supplement for constipation. A screening colonoscopy 5-year ago was unremarkable. Rectal examination shows no abnormalities. Examination of the stool for occult blood is negative. His blood pressure is 135/80 mmHg and heart rate is 80/min. Abdominal examination shows no abnormalities. Laboratory studies show: Hb 9.5 g/dl, WBC 7,000/cmm, Platelets 300,000/cmm, BUN 28 mg/dl, Serum Creatinine 1.9 mg/dl, ESR 80/hr. Which of the following is the best explanation for this patient's constipation?

114) A 12-year-old girl comes to the physician for chronic weight loss and fatigue. She has a history of bulky, floating, foul-smelling stools, flatulence and meteorism. She also has bone pain and easy bruising. Laboratory studies show anemia with serum iron: 25 mg/dl , ferritin: 25 mg/dl and serum total iron binding capacity 600 mg/dl (normal 300-360 mg/dL); PT is 16 sec. Physical examination shows loss of subcutaneous fat, pallor, hyperkeratosis and abdominal distention; bowel sounds are increased. Which of the following is most likely associated with this patient's condition?

115) A 44-year-old male who has had an extensive small bowel resection for Crohn's disease has been on total parenteral nutrition for two years. He presented to the hospital with epigastric and right upper quadrant pain. He has been taking azathioprine. His vital signs are within normal limits. Physical examination shows mild right upper quadrant tenderness. An ultrasonogram shows several gallstones; an ultrasonogram performed two years ago did not demonstrate gall stones. Which of the following is the most likely cause of his gallstones?

116) A 35-year-old Caucasian male presents to the emergency department with two episodes of bloody vomiting which occurred one-half hour ago. He has a history of migraines. For the past two days, he has been having severe headaches and has taken 20 tablets of aspirin without relief. He then resorted to heavy drinking and forgot about the pain. He drinks alcohol "occasionally" and has been smoking 1 pack of cigarettes daily for the past 18 years. Which of the following is the most likely explanation for this patient's hematemesis?

117) A 29-year-old male with a 6-year history of HIV infection presents with chronic, severe diarrhea associated with malaise, nausea, anorexia and abdominal cramps. His last CD4 count was 80cells/mm3. A modified acid-fast stain of a stool specimen shows 4-6 mm oocysts. Which of the following is the most likely microorganism responsible for this condition?

118) A 45-year-old Caucasian male presents with a 2-year history of progressive heartburn which is most severe while supine. Over-the-counter antacids have not relieved his symptoms. Endoscopy shows a hiatal hernia. The patient is reluctant to accept any treatment. Which of the following is he at risk for if his condition is left untreated?

119) A 45-year-old male comes to the physician with a 6-month history of periodic abdominal pain. He tried several over-the-counter medications including H2 blockers and proton pump inhibitors with moderate success. Workup, including an upper GI series and endoscopy, showed multiple duodenal ulcers and a single jejunal ulcer. Test of the stool for occult blood is positive. Test of the stool for fat is positive. Which of the following is the best explanation for this patient's impaired fat absorption?

120) A 58-year-old man presents with a one-year history of diarrhea. The stools are watery and accompanied by abdominal cramps. He denies any fever, blood per rectum, or foul-smelling stools. He has also experienced frequent episodes of dizziness, flushing, wheezing, and a feeling of warmth. He has taken herbal medicines, which failed to relieve his symptoms. He is depressed about his illness, and feels hopeless about diagnosis and treatment. He appears ill. Auscultation of the chest shows a 2/6 systolic murmur over the left lower sternal border. Abdominal examination shows hepatomegaly 3cm below the right costal margin, mild shifting dullness, and no abdominal tenderness. Laboratory studies show: Hb 13.0gm/dl, MCV 90fl, WBC 6,100/cmm, Platelets 210,000/cmm, AST101 U/L, ALT 99 U/L, Alkaline phosphatase 400 mg/dl. This patient is at risk of developing a deficiency of which vitamin or mineral?

121) A 65-year-old Caucasian male presents to your office with a several month history of difficulty swallowing. He has noticed a right-sided neck mass which increases in size while drinking fluids. His past medical history is significant for hypertension, gastroesophageal reflux disease, and osteoarthritis of his right knee. His current medications include hydrochlorothiazide, ranitidine, and occasional naproxene. You order a barium examination of the esophagus to visualize the abnormality. Which of the following is the most important pathogenetic factor in the development of this patient's problem?

122) A 20-year-old male university student presents with a one-month history of 4 to 6 loose watery bowel movements per day with occasional tenesmus, urgency, and abdominal cramps. He also describes a two-week history of intermittent bright red blood per rectum. His appetite and energy levels are excellent and his weight is stable. He is otherwise healthy and takes no medications. His family history is unremarkable. He has not recently used antibiotics nor has he traveled outside the country. He does not use tobacco, alcohol or drugs. Sigmoidoscopy demonstrates mild erythema and rectal biopsy confirms acute mucosal inflammation. Which of the following is a potential complication of this condition requiring regular surveillance?

123) A 46-year -old alcoholic man comes to the emergency department because of several episodes of vomiting. The last episode of emesis contained blood. Five hours ago, he had a fatty meal and several alcoholic drinks. Two days ago, he had an upper GI tract endoscopy and abdominal ultrasound for the evaluation of dyspepsia. The endoscopy was unremarkable, and the ultrasound showed a hyperechogenic enlarged liver and stones in the gallbladder. His temperature is 36.6°C (97.9°F), blood pressure is 120/70 mm Hg, pulse is 95/min, and respirations are 15/min. Laboratory studies show: Hb 12.8 g/dl, WBC 5,400/cmm, BUN 26 mg/dl, Creatinine 1.1 mg/dl, AST 100 U/L, ALT 45 U/L, Bilirubin 0.7 mg/dl. Nasogastric suction shows normal stomach contents mixed with bright red blood. The rectal examination shows no melena. Which of the following is the most likely explanation for this patient's bloody vomiting?

124) A 53-year-old woman presents to your office with right-sided abdominal pain that started two days ago. She describes the pain as constant and burning in nature. There is no associated nausea, vomiting or diarrhea. The patient reports taking over-the-counter antacids and ibuprofen, which brought no relief. Her medical history is significant for breast cancer diagnosed one year ago, for which she underwent a modified radical mastectomy and is receiving chemotherapy, the last course of which was completed two months ago. On physical examination, her temperature is 36.7°C (98°F), blood pressure is 120/70 mm Hg, pulse is 80/min, and respirations are 16/min. Her lung fields are clear to auscultation and her abdomen is soft and non-distended. The liver span is 10 cm and the spleen is not palpable. Lightly touching the skin to the right of the umbilicus elicits intense pain. In one week the patient is most likely to develop:

125) A 20-year-old Caucasian male presents with lower abdominal pain for the past few hours. The pain first started around the umbilicus, but then shifted to the right lower abdominal area. He has had one episode of vomiting. Physical examination shows tenderness at McBurney's point. CT scan of the abdomen confirms the diagnosis of acute appendicitis. Which of the following explains the pathophysiology of the shifting of pain from the peri-umbilical area to the right lower quadrant in acute appendicitis?

126) A husband and wife present to the ED with 1 day of subjective fever, vomiting, watery diarrhea, and abdominal cramps. They were at a restaurant a day before for dinner and both ate the seafood special, which consisted of raw shellfish. In the ED, they are both tachycardic with temperatures of 99.8°F and 99.6°F for him and her, respectively. Which of the following is responsible for the majority of acute episodes of diarrhea?

127) A 21-year-old woman presents to the ED complaining of diarrhea, abdominal cramps, fever, anorexia, and weight loss for 3 days. Her BP is 127/75 mm Hg, HR is 91 beats per minute, and temperature is 100.8°F. Her abdomen is soft and nontender without rebound or guarding. WBC is 9200/μL, β-hCG is negative, urinalysis is unremarkable, and stool is guaiac positive. She tells you that she has had this similar presentation four times over the past 2 months. Which of the following extraintestinal manifestations is associated with Crohn disease but not ulcerative colitis?

128) A 67-year-old woman is currently postoperative day 8 after an emergent laparoscopic cholecystectomy for acute cholecystitis. On postoperative day 2 she spiked a temperature of 40°C (101.4°F) and began to complain of some shortness of breath. X-ray of the chest revealed right lower lobe pneumonia, and the patient was started on clindamycin. Today she is experiencing multiple episodes of foul-smelling, watery diarrhea that is green tinged but non-bloody. She also complains of lower abdominal cramping. Her temperature is 37.8°C (100°F), pulse is 90/min, respiratory rate is 15/min, and blood pressure is 110/70 mm Hg. Which of the following is the most likely explanation for these findings?

129) A 73-year-old woman presents to the emergency room with black tarry stools and symptoms of presyncope when standing up. Digital rectal examination confirms the presence of melena. She recently started using ibuprofen for hip discomfort. Upper endoscopy confirms the diagnosis of a gastric ulcer. Which of the following is the most likely explanation for the gastric ulcer?

130) A 77-year-old woman is brought to the emergency room because of nonspecific abdominal discomfort. She has no anorexia, fever, chills, or weight loss. Her abdomen is soft and non-tender on physical examination. Abdominal x-rays show lots of stool in the colon, but no free air or air-fluid levels. The amylase is 150 U/L (25–125U/L), and the rest of her biochemistry and complete blood count are normal. Which of the following conditions can cause a false positive elevation in the serum amylase?

131) A 76-year-old woman with a history of congestive heart failure, coronary artery disease, and an “irregular heart beat” is brought to the ED by her family. She has been complaining of increasing abdominal pain over the past several days. She denies nausea or vomiting and bowel movements remain unchanged. Vitals are HR of 114 beats per minute, BP 110/75 mm Hg, and temperature 98°F. On cardiac examination, her HR is irregularly irregular with no murmur detected. The abdomen is soft, nontender, and nondistended. The stool is heme-positive. This patient is at high risk for which of the following conditions?

132) A 78-year-old man with a history of atherosclerotic heart disease and congestive heart failure presents with increasing abdominal pain. The pain began suddenly a day ago and has progressively worsened since then. He denies nausea, vomiting, and diarrhea, but states that he had black tarry stool this morning. He denies any history of prior episodes of similar pain. Vitals are BP 120/65 mm Hg, HR 105 beats per minute, and temperature 99°F. The patient is at high risk for which of the following conditions?

133) A 29-year-old man with acquired immune deficiency syndrome (AIDS) comes to the emergency department because of progressively increasing abdominal discomfort. Examination shows voluntary guarding in the upper abdomen. His biochemistry is normal except for an elevated amylase at 370 U/L (25–125 U/L). Which of the following infections can trigger this disorder in AIDS patients?

135) A 33-year-old woman develops mild epigastric abdominal pain with nausea and vomiting of 2 days duration. Her abdomen is tender on palpation in the epigastric region, and the remaining examination is normal. Her white count is 13,000/mL, and amylase is 300 U/L (25–125 U/L). Which of the following is the most common predisposing factor for this disorder?

136) A 54-year-old man complains of burning epigastric pain that usually improves after a meal, and is occasionally relieved with antacids. On examination, he appears well and besides some epigastric tenderness on palpation, the rest of the examination is normal. Upper endoscopy confirms a duodenal ulcer. Which of the following statements concerning PUD is most likely correct?

137) A 60-year-old man with no past medical history undergoes upper endoscopy and biopsy for an upset stomach that is worsened by eating. He is found to have inflammation predominantly in the antrum of the stomach. Which of the following is the most likely etiology of this condition?

138) A 23-year-old woman presents to the ED complaining of pain with urination. She has no other complaints. Her symptoms started 3 week ago. During this time, she has been to the clinic twice, with negative urine cultures each time. Her condition has not improved with antibiotic therapy with sulfonamides or quinolones. Physical examination is normal. Wet mount showed epithelial cells. Which of the following organisms is most likely responsible for the patient’s symptoms?

141) A term boy with Apgar scores of 9 and 9 at 1 and 5 minutes has failed to pass meconium at 72 hours. He has had no episodes of emesis, and his abdomen is only mildly distended to palpation. The patient’s mother reports that her older son had the same problem at birth. A plain radiograph of the abdomen shows a small bowel obstruction with numerous air-filled loops of bowel. The patient is treated with a diatrizoate meglumine (Gastrografin) enema, with good results. Which of the following is the most likely mechanism for this infant’s acute intestinal problem?

142) You are working in the ED on a Sunday afternoon when four people present with acute-onset vomiting and crampy abdominal pain. They were all at the same picnic and ate most of the same foods. The vomiting began approximately 4 hours into the picnic. They deny having any diarrhea. You believe they may have “food poisoning” so you place IV lines, administer IV fluids, and observe. Over the next few hours, the patients begin to improve, the vomiting stops, and their abdominal pain resolves. Which of the following is the most likely cause of their presentation?

143) A 43-year-old man feels vaguely unwell. Physical examination is unremarkable except for evidence of scleral icterus. The skin appears normal. Which of the following is the most likely explanation for why early jaundice is visible in the eyes but not the skin?

144) A 56-year-old woman becomes the chief financial officer of a large company and, several months thereafter, develops upper abdominal pain that she ascribes to stress. She takes an over-the-counter antacid with temporary benefit. She uses no other medications. One night she awakens with nausea and vomits a large volume of coffee grounds-like material; she becomes weak and diaphoretic. Upon hospitalization, she is found to have an actively bleeding duodenal ulcer. Which of the following statements is true?

145) A 50-year-old man wants to talk to you about something, "absolutely confidential". After you assure him, he admits, "He is unable to get an erection and just can't have sex." He wants to figure it out quickly because "he simply can't live like this." He has never been diagnosed with diabetes and denies other complaints. He has a 2 pack/day history of smoking for 30 years. On examination, his BP: 158/90mm of Hg; Temperature: 37.1°C (98.8°F); RR 14/min; PR 82/min. There is upper body obesity, rounded face, increased fat around the neck, and thinning of arms and legs. You find his skin to be bruised, fragile and thin. Laboratory reveals the following results. Serum: Glucose 186 mg/dl, Sodium 142 mEq/L, Potassium 2.5 mEq/L, Bicarbonate 38 mEq/L. Chest X ray shows a large mass in left bronchus. What is the most likely cause of patient's condition?

146) A 66-year old female has been your patient for the last 8 years. She was diagnosed with colorectal carcinoma 2 years ago, and eventually underwent an endoscopic resection. Since then, she has been healthy, and has been coming to the office regularly for follow-up visits. She is very grateful, and has stated many times that she owes her life to you. You are currently a co-investigator of a retrospective observational study of patients with colon cancer, and you believe that including her medical information will be extremely beneficial. What course of action must you take so that you can include this patient's data in your study?

147) A 65-year-old woman comes to the office for a health maintenance visit. She has been your patient for the last 15 years. When you ask how she has been, she replies with, "Well, I'm very health-conscious now. I read all the health magazines regularly, and exercise for 30 minutes daily. I eat a lot of garlic to control my cholesterol, and drink cranberry juice to keep my kidneys strong. I don't smoke, but I drink alcohol during social events. I've been compliant with regular screening colonoscopies, mammograms, and pap smears. Doc, since my mother died from ovarian cancer, do you think I can have an abdominal ultrasound every 6 months, plus any additional necessary tests, so that any cancer can be detected early?" What is the best response to this patient's concerns?

148) A 22-year-old African-American man presents to the ER with fever, jaundice, abdominal pain, and dark urine. His heart rate is 100/min and blood pressure is 100/60 mmHg. Peripheral blood smear reveals bite cells and red blood cell inclusions seen after crystal violet staining. The patient most likely suffers from which of the following conditions?

149) A 34-year-old male is brought to the emergency department with altered mental status. His girlfriend reports that he has had fever and cough for the past two days. His past medical history is significant for abdominal trauma two years ago that required splenectomy and left-sided nephrectomy. On physical examination, his temperature is 39° C (102.2°F), blood pressure is 80/50 mm Hg, pulse is 110/min, and respirations are 32/min. Gram-positive cocci are cultured from his blood. Which of the following is most likely impaired in this patient?

150) A 43-year-old man presents to your office with low energy and increased fatigability. He also complains of daytime sleepiness and occasional headaches. He drinks two to three glasses of wine daily but does not smoke. He sleeps in a separate room from his wife because she finds his constant snoring annoying. On physical examination, his blood pressure is 160/100 mmHg and his heart rate is 80/min. His BMI is 31.5 kg/m2. His abdomen is soft and non-tender. The liver span is 10 cm and the spleen is not palpable. Laboratory findings are: Hematocrit 60%, WBC count 9,000/mm3, Platelets 190,000/mm3. Which of the following is most likely responsible for this patient's increased hematocrit?

151) A 6-year-old African-American child is brought in by his father for complaints of easy fatigability and pallor. These symptoms occurred after the son was treated with "some medication" for a recent diarrhea. Physical examination is normal except for pallor and multiple petechiae. Laboratory values are as follows: Hb 8.0 g/dL, WBC 12,000/cmm, Platelets 50,000/cmm, Blood glucose 118 mg/dL, Serum Na 135 mEq/L, Serum K 5.3 mEq/L, Chloride 110 mEq/L, Bicarbonate 18 mEq/L, BUN 38 mg/dL, Serum creatinine 2.5 mg/dL, Total bilirubin 3 mg/dL, Direct bilirubin 0.5 mg/dL, PT 12 seconds, APTT 30 seconds, LDH 900 IU/L, Reticulocyte count 6%. A peripheral blood smear reveals giant platelets and multiple schistocytes. What is the most likely underlying pathophysiology for this boy's pallor?

153) A 79-year-old woman presents to your office complaining of an intermittent skin rash over the last several months. She denies fever, headache, and recent weight loss. Her past medical history is significant for diet-controlled diabetes and right knee osteoarthritis treated with acetaminophen. Physical examination reveals several dark purple ecchymotic areas over the dorsum of both arms. Her abdomen is soft and non-tender. The liver span is 8 cm and the spleen is not palpable. Laboratory studies reveal: Hematocrit 47%, WBC count 5,800/mm3, Platelet count 220,000/mm3, Serum creatinine 0.8 mg/dL\, Fibrinogen 350 mg/dL, Prothrombin time 10 sec, INR 1.0, Partial thromboplastin time 25 sec. Which of the following is the most likely cause of this patient's complaint?

154) A 42-year-old woman is evaluated for chronic abdominal pain and fatigue. Her pain is epigastric, crampy, and sometimes awakens her from sleep. She denies any recent weight loss, nausea, or vomiting. Her diet consists mainly of fruits and vegetables. She also complains of a "strange appetite" for paper and ice that she has never had before. Upper gastrointestinal endoscopy reveals an ulcer located on the anterior wall of the duodenal bulb. Her unusual appetite is most directly related to:

155) A 22-year-old female presents to the emergency room with a nosebleed. A quick review of her records reveals that she presented with the same problem yesterday, at which time the bleeding was stopped with prolonged local pressure. On review of systems, the patient also reports easy bruising for the past several months. On physical examination, her heart and lungs appear normal. The liver span is 8 cm and the spleen is not palpable. There are scattered ecchymoses over her arms and legs. Laboratory findings include the following: Hematocrit 45%, Platelet count 9,000/mm3, Leukocyte count 5,500/mm3, Neutrophils 56%, Eosinophils 1%, Lymphocytes 33%, Monocytes 10%, Fibrinogen 250 mg/dL, Prothrombin time 13 sec. Which of the following is the most likely cause of this patient's condition?

156) A 66-year-old female comes for removal of a lipoma from her elbow. She wants the swelling out because it looks ugly when she wears sleeveless tops. Her only complaints are general malaise and fatigue for the past 8 months, which she attributes to her "being alone all the time." Her vital signs are within normal limits. Physical examination reveals mild pallor and both cervical and supraclavicular lymphadenopathy. Her preoperative blood count reveals the following: Hemoglobin 10.0 g/dL, Hematocrit 32%, Platelets 126,000/cmm, WBC 31,600/cmm. Leukocyte distribution: Segmented neutrophils 18%, Lymphocytes 77%, Bands 4%, Monocytes 1%. The pathologist reports the presence of "leukocytes that have undergone partial breakdown during preparation of a stained smear or tissue section, because of their greater fragility." Lymph node biopsy confirms the diagnosis. What is the correct statement about the above patient?

157) A 17-year-old male presents to clinic for routine check-up. He is a long distance runner and has beenachieving outstanding results recently. He is very proud of his athletic achievements, remarking that his effort "pays off." He does not smoke or consume alcohol. His family history is significant for diabetes mellitus in his mother and skin cancer in his father. Chest examination is normal. His liver span is 8 cm and his spleen is not palpable. His current laboratory findings include: Hematocrit 59%, WBC count 7,500/mm3, Platelet count 170,000/mm3, ESR 15 mm/hr. Which of the following is the most likely explanation for the high hematocrit in this patient?

158) A 65-year-old Caucasian male had undergone cardiac catheterization followed by aortic valve replacement for severe aortic stenosis and coronary artery bypass grafting for three-vessel disease. His postoperative course was complicated by atrial fibrillation and a urinary tract infection. His other medical problems include hypertension, diabetes, and hypercholesterolemia. He is also receiving heparin, ciprofloxacin, and amiodarone. On postoperative day five, he developed prolonged bleeding from the venipuncture site. His labs show: Hb 11.5 g/dL, MCV88 fl, Platelet count 50,000/cmm, Leukocyte count 7,500/cmm, Segmented neutrophils 68%, Bands 1%, Eosinophils 1%, Lymphocytes 24%, Monocytes 6%, Prothrombin time 12 sec (INR=1.0), Partial thromboplastin time 65 sec. His preoperative labs were unremarkable. What is the most likely cause of these findings in this patient?

159) A 62-year-old woman presents complaining of recurrent cough productive of yellow sputum. She was seen several weeks ago for similar complaints and was effectively treated with a course of azithromycin. Today she expresses frustration that she seems to keep getting sick with the same infection. On review of systems, the patient also reports recent-onset back pain for which she has been taking acetaminophen. Her past medical history is otherwise insignificant. She has never smoked cigarettes, and drinks alcohol only on rare social occasions. Physical examination reveals conjunctival pallor, a few scattered rales in the lungs bilaterally, and tenderness over the lumbar vertebrae. Laboratory analyses reveal: Hemoglobin 8.4 g/dL, Leukocyte count 5,500/mm3, Blood urea nitrogen 34 mg/dL, Creatinine 2.0 mg/dL, Calcium 10.9 mg/dL, Albumin 3.8 g/dL, Total protein 9.5 g/dL. This patient is at increased risk for recurrent infections because of which of the following abnormalities?

160) A 47-year-old man presents to your office complaining of occasional daytime headaches, dizziness and nausea. He has no significant past medical history. He works as a traffic controller in an underground parking lot. He does not smoke cigarettes, and consumes alcohol only on weekends. He is sexually active in a monogamous relationship with his wife and uses condoms for contraception. His cardiac exam is unremarkable. His abdomen is soft and non-tender. The liver span is 8 cm and the spleen is not palpable. Laboratory findings are: Hematocrit 59%, WBC count 7,000/mm3, Platelets 200,000/mm3. Which of the following is most likely responsible for this patient's increased hematocrit?

161) A 57-year-old Caucasian female is diagnosed with deep venous thrombosis of the right leg that was confirmed with Doppler ultrasonography. She was diagnosed with pneumonia and empyema one week earlier, and treated with chest tube, antibiotics and bed rest. On her 6th day of anticoagulation therapy, she develops right hemiparesis and slight motor aphasia. The laboratory findings are: Red blood cells 4.3 million/mm3, Hemoglobin 14.00 g/dL, White blood cells 7,000/cmm, Platelets 50,000/cmm, APTT 60 sec (N < 25-40 sec), Fibrin degradation products negative. The emergency head CT scan does not reveal blood in the subarachnoid space or brain parenchyma. Which of the following is the most probable cause of this patient's condition?

162) A 25-year-old African American woman presents with a photo distributed skin rash and arthralgias. She is found to have low-range proteinuria and abnormal urinary sediment. Renal biopsy findings are consistent with focal proliferative glomerulonephritis. Her complete blood count shows: Erythrocyte count 3.2 mln/mm3, Platelets 60,000/mm3, Leukocyte count 2,500/mm3. Which of the following is the most likely cause of these hematologic findings?

163) A 45-year-old Asian man presents to your office complaining of easy fatigability. He denies abdominal pain, distention, nausea, vomiting, or significant weight loss. His past medical history includes a gastrectomy for a non-healing gastric ulcer. He is not currently taking any medications. He quit smoking several years ago and does not use alcohol or illicit drugs. His vital signs are within normal limits. Physical examination reveals a shiny tongue and pale palmar creases. No lymphadenopathy, hepatomegaly, or splenomegaly is present. His blood hemoglobin level is 7.5 mg/dL and W8C count is 3,800/mm3. Stool tests for occult blood are repeatedly negative. This patient's condition involves which of the following pathophysiologic mechanisms?

164) A 23-year-old African American man is treated with an antibiotic for an uncomplicated urinary tract infection. Several days later, he presents to your office saying that his initial symptoms have improved but his urine now appears dark. He has no significant past medical history and does not use tobacco, alcohol, or illicit drugs. His temperature is 36.8°C (98.2°F), pulse is 88/min, respirations are 14/min, and blood pressure is 130/76 mmHg. Physical examination is within normal limits. The urine sample stains positive with Prussian blue and the sediment microscopy is unrevealing. What is the mechanism behind the cell damage responsible for this patient's current complaint?

165) A 6-year-old Caucasian boy is hospitalized for acute sinusitis that was accompanied with intensive nasal bleeding. Past medical history is significant for recurrent pulmonary infections and several hospitalizations for parenteral antibiotic therapy. The sweat chloride test is positive. The blood tests reveal a prothrombin time (PT) of 20 seconds. Which of the following coagulation factors is most likely to be deficient in this patient?

166) A 27-year-old man presents to the emergency department with unremitting nose bleeding. He reports having a similar bleeding episode one year ago that was stopped in the ER. He works as a computer programmer and has a sedentary lifestyle. He drinks alcohol on social occasions but does not smoke or use illicit substances. On physical examination, there are several ruby-colored papules on his lips that blanch partially with pressure. Digital clubbing is also present. His abdomen is soft and non-tender. The liver span is 8 cm and the spleen is not palpable. Laboratory findings are: Hematocrit 60%, WBC count 8,000/mm3, Platelets 180,000/mm3. Which of the following is most likely responsible for this patient's increased hematocrit?

167) A 14-year-old boy is brought by his mother because she noticed a change in his voice. He has been having frequent nosebleeds for the last month, and feels that his "left nose" is always congested. There is no history of trauma. He admits to using marijuana, in the absence of his mother. He is otherwise well, and does not take any medications. He actively participates in the school basketball tournaments. Physical examination reveals an intact nasal septum with a visible mass at the back of the left nostril. CT scan reveals an erosion of the adjacent bone. What is the most likely reason of this patient's nosebleeds?

168) A 34-year-old male who recently emigrated from Asia comes to the clinic and complains of a two-month history of exertional shortness of breath and easy fatigability. He has been taking isoniazid and rifampin for his tuberculosis, which was diagnosed four months ago. Due to his religious beliefs, he completely turned into a vegetarian for the last year. Physical examination reveals severe pallor. Peripheral smear shows macrocytosis with hypersegmented polymorphonuclear neutrophils. His WBC and platelet counts are within normal limits. This patient's most likely problem is due to which of the following?

169) A 72-year-old woman complains of fatigue, dyspepsia, and shortness of breath. Her daughter tells you that her mother also has some slight memory loss and occasionally complains of numbness in her legs. The laboratory tests you ordered show a hemoglobin of 10.2 g/dL and an MCV of 110. The most likely cause is:

170) A 23-year-old male comes to ER with five day history of diarrhea and abdominal pain. Initially, the diarrhea was watery occurring five-six times per day but yesterday he noticed blood in the stool which prompted his visit to ER. He describes his abdominal pain as colicky and severe. He also complains of nausea and decreased appetite but he has had no vomiting. His past medical history is insignificant and never had similar symptoms. He is not sexually active and he denies any illicit drug use. He has no history of recent travel. His father had colon cancer and his uncle died of liver cirrhosis. His temperature is 36.6°C (98.0°F), blood pressure is 123/82 mmHg and heart rate is 102/min. On examination, he has prominent periumbilical and right lower quadrant tenderness but no guarding or rebound. Rectal examination reveals brownish stool mixed with blood. Which of the following is the most likely diagnosis?

171) A 55-year-old Asian man with mitral stenosis secondary to rheumatic heart disease undergoes dental surgery for caries. Postoperatively, he does well and is discharged home. Two weeks later, he presents with fever, chills, fatigue, and feels "sick." Four out of four blood culture bottles are positive for gram-positive cocci. An echocardiogram is performed and shows mitral valve vegetations. Which of the following is the most likely causative organism of this patient's condition?

172) A 16-year-old Asian boy presents with a two-day history of fever, malaise, and painful enlargement of his parotid glands. He has no significant past medical history. He was born in India, and has not received any childhood vaccinations. He recently returned from a one-week vacation in India. His vital signs are stable, except for a mild fever. Examination shows bilateral parotid enlargement. The rest of the examination is unremarkable. Which of the following organs is most likely to be affected by this patient's illness?

173) A 29-year-old man returns home to Colorado after a diving trip to Honduras in Central America. He was gone for 6 days. The day he returns, he starts to develop diarrhea, abdominal cramping, and nausea. There is no mucus and blood in the stool. He has no other medical problems and does not take medications. He does not use tobacco, alcohol or drugs. His temperature is 37.2°C (98.9°F), blood pressure is 120/74 mm Hg, pulse is 80/min, and respirations are 15/min. There is no lymphadenopathy. Chest is clear to auscultation. Abdomen is soft and non-tender. There is no organomegaly. Bowel sounds are increased. Stool is negative for leukocytes and fecal occult blood. Which of the following is the most likely pathogen responsible for his symptoms?

1) A 31-year-old, HIV-infected man from New York presents to the ER with anorexia, malaise, night sweats, fever, and weight loss of 6.8kg (15 lb) over the past one month. He also has a cough productive of yellow sputum. He was diagnosed with HIV two years ago. When last checked two months ago, his CD4 count was 220/microL. He is not taking any medications. His temperature is 39.2°C (102.2°F), pulse is 96/min, and blood pressure is 120/80 mm Hg. Physical examination reveals rales in his right upper chest. Laboratory studies show: Hematocrit 30%, WBC count 3,400/microL, Neutrophils 86%, Bands 2%, Lymphocytes 4%, Monocytes 8%. PPD test shows 3 mm induration. Chest x-ray reveals a right upper lobe cavitation. Sputum examination shows partially acid-fast, filamentous, branching rods. Based on these findings, which of the following organism is the most likely cause of this patient's pulmonary disease?

2) A 45-year-old man comes to the office and complains of intermittent, bloody diarrhea and abdominal pain for the past month. During this time period, he has lost six pounds. He was diagnosed with HIV infection in the past, but has refused antiretroviral therapy. Laboratory results show a CD4 count of 50cells/μL. The stool examination is negative. Colonoscopy with biopsy shows multiple colonic ulcerations and mucosal erosions. The biopsy shows large cells containing eosinophilic intranuclear and basophilic intracytoplasmic inclusions. What is the most likely cause of this patient's diarrhea?

3) A 73-year-old diabetic man presents with low-grade fever, facial pain over his right maxilla, and bloody nasal discharge for the last three days. For the last day, he has had diplopia. He was diagnosed with diabetes mellitus 10 years ago. For the last year, he has been on insulin. His most recent hemoglobinA1C was 12.0. His temperature is 39.0°C (102.2°F), pulse is 88/min, and blood pressure is 130/76mm Hg. Examination shows right-sided nasal congestion and necrosis of the right nasal turbinate with tenderness over the right maxillary sinus. There is chemosis and proptosis of his right eye. CT scan shows opacification of the right maxillary sinus. Which of the following is the most likely causative organism?

4) A 43-year-old HIV-positive male presents to your office with several exophytic purple skin masses on his lower abdomen. Physical examination reveals tender hepatomegaly and an abdominal CT scan shows nodular, contrast-enhanced intrahepatic lesions of variable size. Liver biopsy is attempted but severe hemorrhage results. Which of the following is the most likely cause of this patient's condition?

6) A 75-year-old female nursing home resident complains of cough and fever. Her past medical history is significant for hypertension, myocardial infarction (experienced two years ago), and a traumatic right foot amputation. Her current medications are atenolol, hydrochlorothiazide, and aspirin. Her temperature is 39.4°C (103°F), pulse is 110/min, respirations are 22/min, and blood pressure is 110/76 mmHg. Crackles are present at right lung base. Chest x-ray reveals a right lower lobe infiltrate. Which of the following pathogens is the most likely cause of this patient's condition?

7) A 45-year-old man presents to the emergency room with a two-day history of fever, dyspnea, abdominal pain, and diarrhea. He has no chest pain, but complains of dry cough. His past medical history is significant for bone marrow transplantation for acute myeloid leukemia (AML) three months ago. His temperature is 39°C (102.2°F), blood pressure is 122/80 mm Hg, pulse is 98/min, and respirations are 22/min. Exam of the oropharynx reveals thrush. Lungs exam demonstrates bilateral diffuse rales. Heart sounds are regular. Nonspecific abdominal tenderness is present. The chest radiograph shows multifocal, diffuse patchy infiltrates. Which of the following is the most likely cause of this patient's current condition?

8) A 55-year-old woman presents with a three-week history of low-grade fever, weight loss of 4.5kg (10 lb), and malaise. She is known to have mitral valve prolapse, but is otherwise healthy. She underwent a tooth extraction one month ago. She denies alcohol, tobacco, and illicit drug use. Her temperature is 38.5°C (101.3°F), pulse is 90/min, respirations are 18/min, and blood pressure is 145/76 mm Hg. Her chest is clear to auscultation and percussion. Cardiac examination reveals a III/IV holosystolic murmur at the apex that radiates to the axilla. Chest x-ray is normal. Urinalysis is unremarkable. Blood cultures are drawn and empiric antibiotics are started. Echocardiogram shows mitral regurgitation with vegetation on the mitral valve. Which of the following organisms is the most likely cause of this patient's condition?

9) A 50-year-old man presents to the office with fatigue, malaise, and disabling joint pain in his fingers, wrists, shoulder, hips, knees, and ankles. His pain is severe and associated with a mild degree of morning stiffness for 10-15 minutes. He occasionally takes acetaminophen and ibuprofen for this pain. He has a 10-pack-year smoking history. He does not drink alcohol. Family history includes an uncle who died of liver cancer. On examination, there is grayish skin pigmentation, most prominent on the exposed parts. Abdominal examination is significant for liver enlargement 2 cm below the costal margin. Laboratory studies reveal the following: Hemoglobin 13.0 g/L, Leukocyte count 5,500/mm3, Serum creatinine 0.8 mg/dl, Blood glucose 218mg/dl, Aspartate aminotransferase (SGOT) 128 U/L, Alanine aminotransferase (SGPT) 155 U/L, Alkaline phosphatase 120 U/L , Serum iron 450 mol/L (50-170g/dL), Transferrin saturation of iron 62% (22-47%), Serum Ferritin 3000ng/L (15-200 ng/ml, males). X-ray of the joints shows narrowing of joint spaces and diffuses demineralization. This patient's condition makes him more vulnerable to which of the following infections?

10) A 19-year-old white male presents with nausea, vomiting, and abdominal cramps. He has had four episodes of vomiting over the last two hours. He has not had diarrhea or fever. Four hours ago, he ate a salad from a local restaurant. His pulse is 82/min, blood pressure is 120/80 mm Hg, and temperature is 37.2°C (99°F). Abdominal and rectal examinations are unremarkable. Which of the following is the most likely cause of this patient's symptoms?

11) A 72-year-old male presents with a two-day history of intense pain in his right ear, along with ear discharge. The pain is so severe that he is unable to sleep. It radiates to his temporomandibular joint and is aggravated by chewing. His disease has worsened despite the use of topical antibiotics. He takes metformin and enalapril. On physical examination, granulation tissue is noted in the lower part of his external auditory canal. Cranial nerves are intact. Oropharynx is clear without exudate. Which of the following is the most likely causative organism of this patient's ear condition?

12) A 26-year-old male presents to your office with periodic flank pain. He also noticed that his urine was red during the last several days. He is known to be HIV-positive. One month ago, he presented with thrush. At that time, he was found to have a CD4 count of 100, and was started on anti-retroviral therapy. His current CD4 count is 250. Physical examination reveals no oral cavity lesions. The lungs are clear on auscultation. The serum creatinine level is 2.2 mg/dl. Urinalysis shows hematuria and needle-shaped crystals in the sediment. Which of the following is the most likely cause of this patient's current condition?

13) A 12-year-old boy is brought to the emergency department because of severe pain near his left knee. He has sickle cell disease, and has been hospitalized previously for sickle cell crisis. Vital signs are notable for mild fever. Examination of the left lower extremity reveals a normal knee joint with marked tenderness and swelling over the proximal tibia. Labs show leukocytosis and elevated ESR. He is subsequently diagnosed with osteomyelitis. Which of the following organisms is the most likely cause of his condition?

14) A 67-year-old man presents to his primary care provider in January with fever and a productive cough. The patient had been seen ten days earlier with complaints of fever to 102°F (39.0°C), myalgias, rhinorrhea, and dry cough. At that time, his lung exam revealed occasional crackles. He was given a medication and told to follow up if his symptoms worsened. The symptoms did remit over the first five days, but he began to feel worse again two days ago. He smokes a half-pack of cigarettes per day and drinks alcohol several times a week. On exam today, his temperature is 102.3°F (39.3°C), and lung exam reveals increased tactile fremitus in the left lower lobe. What is the most likely pathogen responsible for his current condition?

15) A 33-year-old man presents with low-grade fever, abdominal cramps, and diarrhea for the past six hours. He has had eight episodes of loose, watery stool containing blood and mucus over this time period. Last night, he ate shrimp and crab meat at a local restaurant. His current pulse is 85/min, blood pressure is 110/80 mm Hg, and temperature is 37.7°C (99.9°F). There are no significant findings on abdominal or rectal examinations. Stool examination shows numerous red blood cells and leukocytes. Which of the following is the most likely causative organism of this patient's condition?

16) A 46-year-old farmer comes to the physician because of pain and swelling of his right heel. He accidentally stepped on a rusty nail while working 2 weeks ago. Although he applied over the-counter antibiotic cream locally and took acetaminophen orally, he continued to have pain at the site of the injury. He has no other medical problems and takes no medication. He has no known drug allergies. He smokes 2-3 cigarettes a day and drinks alcohol occasionally. His temperature is 38.3°C (101°F), blood pressure is 140/90 mm Hg, pulse is 84/min and respirations are 14/min. On examination, the right heel is swollen, red, and warm and tender to touch. A small puncture wound is visible. Laboratory reports show mild leukocytosis. X-ray of the right foot shows features suggestive of osteomyelitis. The most likely cause of the patient's symptoms is infection with which of the following?

17) A 31-year-old, HIV-infected man from New York presents to the ER with anorexia, malaise, night sweats, fever, and weight loss of 6.8kg (151b) over the past one month. He also has a cough productive of yellow sputum. He was diagnosed with HIV two years ago. When last checked two months ago, his CD4 count was 220/microL. He is not taking any medications. His temperature is 39.2°C (102.2°F), pulse is 96/min, and blood pressure is 120/80mm Hg. Physical examination reveals rales in his right upper chest. Laboratory studies show: Hematocrit 30%, WBC count 3,400/microL, Neutrophils 86%, Bands 2%, Lymphocytes 4%, Monocytes 8%. PPD test shows 3 mm induration. Chest x-ray reveals a right upper lobe cavitation. Sputum examination shows partially acid-fast, filamentous, branching rods. Based on these findings, which of the following organism is the most likely cause of this patient's pulmonary disease?

18) A 26-year-old man comes to his physician with a two-week history of fatigue, fever, muscle aches, and arthralgias. He denies any weight loss. His temperature is 37.7°C (99.9°F), blood pressure is 115/75 mm Hg, respirations are 14/min, and pulse is 75/min. Physical examination is unremarkable, except for splenomegaly. Laboratory studies show: Hemoglobin 13 gm/dL, WBC count 12,000/microL, Neutrophils 22%, Lymphocytes 70%, Monocytes 5%, Basophils 1%, Eosinophils 2%, Platelet count 220,000/microL. Peripheral blood smear shows large basophilic lymphocytes with a vacuolated appearance. Heterophile antibody test is negative. What is the most likely cause of this patient's symptoms?

19) A 27-year-old man presents with symptoms of fever, chills, malaise, and joint discomfort in his hands and knees. He looks unwell, his temperature is 39.4°C, blood pressure 115/70 mm Hg, pulse 110/min, head and neck is normal, and his jugular venous pressure (JVP) has a prominent c-v wave. There is also a 3/6 pan-systolic murmur heard at the right sternal border that increases with respiration. His lungs are clear, abdomen is soft, and hand joints are normal. He has multiple puncture sites on his forearms from injection drug use. Which of the following is the most likely causative organism?

20) A 73-year-old man from a nursing home develops headache, fever, cough, sore throat, malaise, and severe myalgia during a community outbreak affecting numerous other residents at the home. The symptoms gradually resolve after 3 days, and he starts feeling better but then there is a reappearance of his fever, with cough and yellow sputum production. On examination, his temperature is 38.5°C, pulse 100/min, respiration 24/min, oxygen saturation 88% and crackles in the right lower lung base, bronchial breath sounds and dullness on percussion. CXR reveals a new infiltrate in the right lower lobe. Which of the following is the most likely causative organism?

21) A 56-year-old man is having intermittent fevers and malaise for the past 2 weeks. He has no other localizing symptoms. Two months ago, he had valve replacement surgery for a bicuspid aortic valve. A mechanical valve was inserted and his postoperative course was uncomplicated. On examination, his temperature is 38°C, blood pressure 124/80 mm Hg, pulse 72/min, and head and neck are normal. There is a 3/6 systolic ejection murmur, the second heart sound is mechanical, and a 2/6 early diastolic murmur is heard. The lungs are clear and the skin examination is normal. Three sets of blood cultures are drawn and an urgent echocardiogram is ordered. Which of the following is the most likely causative organism?

22) A 25-year-old woman is admitted with fever and hypotension. She has a 3-day history of feeling feverish. She has no history of chronic disease, but she uses tampons for heavy menses. She is acutely ill and, on physical examination, found to have a diffuse erythematous rash extending to palms and soles. She is confused. Initial blood tests are as follows: White blood cell count: 22,000/μL, Na+: 125 mEq/L, K+: 3.0 mEq/L, Ca++: 8.0 mEq/mL, Activated partial thromboplastin time (PTT): 65 (normal 21 to 36), Prothrombin time (PT): 12s (normal < 15s), Aspartate aminotransferase: 240 U/L (normal < 40), Creatinine: 3.0 mg/dL, Antinuclear antibodies: negative, Anti-DNA antibodies: negative, Serologic tests for RMSF, leptospirosis, measles: negative. Which of the following best describes the pathophysiology of the disease process?