Microbiology
A 6-year-old boy is brought to the office due to persistent cough. His symptoms began with a mild, upper respiratory illness 2 weeks ago, but the cough has progressively worsened, and now spells of dry cough are often followed by vomiting. The patient has no chronic medical conditions but has not received childhood vaccinations due to parental beliefs. He recently returned from summer camp. On physical examinations, the patient is afebrile, and lungs are clear to auscultation. Testing of respiratory secretions shows gram-negative cocconacilli. Which of the following is most likely involved in the pathogenesis of this patient's symptoms?
A. Alveolar influx of polymorphonuclear leukocytes
B. Circulating endotoxin mediated vasodilation
C. Interfron-gamma-induced macrophage activation
D. Intracellular invasion of reticuloendothelial cells
E. Loss of ciliated respiratory epithalial cells
E. Loss of ciliated respiratory epithalial cells
Bordetella pertussis, a small, gram-negative coccobacillus, spreads rapidly via airborne droplets through communities with low rates of tetanus-diphtheria-pertussis vaccination.
A 38-year old man comes into the office due to pain in multiple joints. He has a 5-year history of lumbar pain and a 2-year history of bilateral knee pain. The patient works in construction and his pain is worst after a long day on his feet. He has taken ibuprofen intermittently, but the pain is no longer tolerable. The patient has a paternal aunt with osteoarthritis. Physical examination shows blue-black spots on his sclerae and diffuse darkening of the auricular helices. Which of the following is the most likely cause of this patient's arthritis?
A. Homogentisic acid dioxygenase deficiency
B. Hyperuricemia
C. Mulifactorial articular cartilage failure
D. Recent infection with Salmonella
E. Tyrosinase deficiency
A. Homogentisic acid dioxygenase deficiency
Alkaptonuria is a relatively benign childhood disorder that is marked by severe arthritis in adult life. THe autosomal-recessive disorder is caused by deficiency of homogentisic acid dioxyfenase, which normally metabolizes homogentisic acid into maleylacetoacetate.
A 68 year-old man comes to the office due to thigh and leg pain the worsens with exertion. He is unable to walk through the local mall with his wife without discomfort. Past medical history is significant for hypertension and diabetes mellitus. The patient smokes 2 packs of cigarettes a day and consumes alcohol occasionally. Physical examination of the extremities shoes weak dorsalis pedis pulses in both feet. Further evaluation confirms moderate peripheral arterial disease involving both lower extremities. Which of the following drugs would best provide symptomatic improvement due to direct dilation of arteries and inhibition of platelet aggregation?
A. Abciximab
B. Argatroban
C. Aspirin
D. Cilostazol
E. Heparin
F. Tissue plasminogen activator
G. Warfarin
D. Cilostazol
Cilostazol reduces platelet activiation by inhibiting platelet phosphodiesterase, the enzyme responsible for the breakdown of cAMP. It is also a direct arterial vasodilator.
A 32-year-old man is hospitalized due to naseau, vomitting, and severe abdominal pain. He has a history of heavy alcohol use and was admitted to the hospital for acute pancreatitis a year ago. He has continued to drink alcohol since his last hospitalization and has a party last weekend, during which he consumed an entire 750-mL bottle of liquor. Temperature is 38.3 C (100.9 F), blood pressure is 110/80 mm Hg, pulse is 104/min, and respirations are 20/min. Abdominal examination is notable for marked tenderness in the epigastric region. Serum lipase is 2,392 U/L. The patient is admitted and started intravenous fluids, analgesics, and antiemetics with subsequent improvement of his symptoms. His vital signs remain stable with adequate urine output. However, on the second day of hospitalization, the patient develops progressive shortness of breath and hypoxemia. Chest x-ray reveals new bilateral opacities. Which of the following parameters is most likely to be normal in this patient?
A. Capillary permeability
B. Lung compliance
C. Pulmonary capillary wedge pressure
D. Ventilation/perfusion matching
E. Work of breathing
C. Pulmonary capillary wedge pressure
This patient with pancreatitis has developed hypoxic respiratory failure with bilateral pulmonary infiltrates. Noncardiogenic pulmonary edema can be distinguished from cardiogenic pulmonary edema by a normal capillary wedge pressure.
A 29-year-old woman comes to the office due to depression. Since breaking up with her boyfriend last month, she has been extremely sad and has difficulty getting out of bed. She describes sleeping 16 hours a day, increased appetite, a 4.5-kg (10 lb.) weight gain, low energy, decreased concentration and loss of interest in socializing with her friends and family. Patient had 2 similar episodes at age 23 and 27. She also describes brief periods in the past, lasting several days, when she was uncharacteristically confident and optimistic, successfully juggled 3 part-time jobs, and felt well rested and energetic despite only sleeping 3-4 hours a night. The patient drinks a glass of wine several times a week but does not use tobacco or illicit drugs. Which of the following is the most likely diagnosis?
A. Adjustment disorder with depressed mood
B. Bipolar I disorder
C. Bipolar II disorder
D. Cyclothymic disorder
E. Recurrent major depressive disorder
C. Bipolar II disorder
This patient's current major depressive episode (greater than or equal to 2 weeks, depressed mood, low energy, hyperinsomnia, increased appetite, decreased concentration, loss of interest) and history suggestive of a hypomanic episode (increase activity, energy and confidence, decreased need for sleep) are consistent with a diagnosis of bipolar II disorder.
A 46-year-old woman comes to the office to be tested for HIV after one of her prior sexual partners found that he was HIV positive. She feels healthy and has no symptoms. The patient has never had a sexually transmitted infection and has no chronic medical conditions. She has had several sexual partners in her lifetime and uses condoms inconsistently. Physical examination shows no abnormalities. HIV antigen/antibody immunoassay and a confirmatory HIV-1 antibody test are positive. Further studies reveal plasma HIV viral load is >250,000 copies/mL and CD4 lymphocyte count is 150 cells/mm3 . After discussing the results and need for treatment, the patient agrees to start antiretrovial therapy. An additional medication to prevent opportunistic infections is also planned. This added treatment is most likely being used to prevent infection from which of the following pathogens?
A. Candida albicans
B. Cryptococcus neoformans
C. Cytomegalovirus
D. Mycobacterium avium-intracellular
E. Pneumocystis jirovecii
F. Toxoplasma gondii
E. Pneumocystis jirovecii
Patients with HIV have progressive impairment of the cell mediated immune response that puts them at risk for opportunistic infections (OIs) with bacterial, fungal and protozoal pathogens. OIs are associated with significant morbidity and mortality and also worsen HIV progression and viremia. Antimicrobial prophylaxis can decrease the risk of developing certain OIs and is recommended in addition to antiretroviral therapy for all patients with HIV who have CD4 counts <200mm3.
A 14-year-old boy is brought to the emergency department due to excessive urination and thirst. He has losr 4.5 kg (10 lb) in the last 3 weeks. The patient has no past medical problems. His father has type 1 diabetes mellitus. Physical examination shows dry mucous membranes. Laboratory studies reveal blood glucose of 455 mg/dL, normal anion gap, and hemoglobin A1c of 11.3%. The patient is diagnosed with type 1 diabetes, and treatment with insulin is initiated. In addition to lowering blood glucose, insulin decreases glycogen synthesis in hepatocytes. Activation of which if the following molecules most likely promotes his metabolic effect?
A. Janus kinase (JAK)
B. Lipoxygenase
C. Phospholipase C
D. Protein kinase A
E. Protein phosphatase
E. Protein phosphatase
P13K promotes glycogen synthesis by activating protein phosphatase, an enzyme that dephosphorylates glycogen synthase, leading to its activation
An 8-day-old boy is beeing evaluated in the neonatal intensive care unit. The patient was born at 27 weeks gestation and intubated at bith due to surfactant deficiency. Temperature is 37 C (98.6 F), blood pressure is 66/12 mm Hg, and pulse is 182/min. A continuous harsh murmur is heard at the left infraclavicular region. There are bounding femoral and palmar pulses. A drug with which of the following mechanisms of action is most appropriate for treating the cause of the patient's murmur?
A. Activation of phospholipase A2
B. Activation of prostacyclin receptors
C. Activation of prostaglandin E2
D. Inhibition of cyclooxygenase
E. Inhibition of lipoxygenase
F. Inhibition of prostaglandin D2 receptors
D. Inhibition of cyclooxygenase
This newborn has a continuous murmur, widened pulse pressure, and bounding pulses, findings characteristic of patent ductus arteriosus (PDA). Treatment of PDA includes nonsteriodial inflammatory drugs (NSAIDs), which inhibit cyclooxygenase.
A 57-year-old man is hospitalized for aspiration pneumonia. The patient was healthy and worked as an engineer without difficulty until about 4 months ago. Since that time, he has developed sever confusion, mood changes, and memory impairment and has to tale medical leave from work. The patient is now completely dependent on his wife for toileting, feeding and general self-care. Physical examination shows disorientation and sporadic, jerky extremity movements. During hospitalization, the patient lapses into a coma and dies. Postmortem examination of his brain shows widespread atrophy of the cerebral cortex and cerebellum. Histologic analysis of the patient's brain tissue would most likely show accumulation of which of the following?
A. Alpha-synuclein
B. Amyloid precursor protein
C. Phosphorylated tau
D. Protease-resistant protein
E. RNA virus
D. Protease-resistant protein
This previously healthy patient developed rapidly progressive dementia associated with myoclonus and brain atrophy.
A 38 year-old woman comes to the office due to worsening dysmenorrhea and tension headaches for the past 3 months. She was recently promoted to school principal and says "It is more stressful than I anticipated; I often have to work late to catch up in paperwork and am not sleeping very well." The patient is married and has no children. While answering questions regarding her sexual history, she bursts in to tears. When the physician asks the patient what is upsetting her, she covers her face and says she was sexually abused as a child. Which of the following is the most appropriate response to the patient?
A. "I appreciate you sharing this with me; would you consider talking to a therapist about this as well?"
B. "I can see this is upsetting for you; we can talk about this another time when you're ready"
C. "I understand how difficult this is to discuss; could you tell me about what happened?"
D. I'm very sorry this happened to you; do you often experience flashbacks or nightmares related to the abuse?"
E. "This must be very painful to talk about; I'm here to listen and help you through this"
E. "This must be very painful to talk about; I'm here to listen and help you through this"
Physicians must respond to revelations of sexual abuse with clear expressions of empathy and support.
A 43 year-old immigrant from southern Asia suffers from a cough that has lasted for several months duration. He comes to the clinic today because of recent onset hemoptysis. On further evaluation, he reports a 15-lb weight loss over the past 4 months. Sputum cultures grow acid-fast bacilli that are susceptible to most antimycobacterial drugs in vitro. Isoniazid monotherapy in this patient would most likely result in:
A. Bacteriocidal effect on only extracellular bacilli
B. Decreased transport protein expression on the cell surface
C. β-lactamase induction within bacterial cells
D. Rapid mycobacterial elimination from the body
E. Selective survival of bacterial cells secondary to gene mutation
E. Selective survival of bacterial cells secondary to gene mutation
This patient most likely has active tuberculosis, which should never be treated with drug monotherapy due to rapid emergence of antibiotic resistance in M. tuberculosis. Isoniazid resistance specifically occurs by two selective gene mutations. The first is a decrease in bacterial expression of the catalase-peroxidase enzyme that is required for isoniazid activation once the drug enters the bacterial cell. The second mechanism of resistance occurs through modification of the protein target binding site for isoniazid.
A 16 year-old boy is brought to the ED due to nosebleeds and worsening bruising. He first noticed mild bruising on his lower legs a couple of days ago, and since then, the bruises have progressed along the thighs and hips. Today, he developed epistaxis that was difficult to control with applied pressure. The patient has Crohn disease and has had multiple hospitalizations for complications. He takes no anticoagulants. Vital signs are normal. Scent blood oozes from the nares. Abdominal examination is unremarkable, and pulses are strong. Skin examination shows large ecchymoses distributes along the lower extremities. Lab results are as follows:
Platelets 230,000/mm3
PT 28 sec
Activated PTT 68 sec
Reversal of this patient's coagulation abnormalities is achieved with the intravenous administration of a medication. This treatment most likelt directly affected which of the following cellular processes?
A. Epigenetic modification
B. Posttranscriptional modification
C. Posttranslational modification
D. Transcription
E. Translation
C. Posttranslational modification
This patient with Crohn disease has epitaxis, bruising and prolonged PT and PTT that are corrected with an intravenous medication. This presentation is consistent with vitamin K deficiency.
A 45-year-old man who was recently started on medication for paroxysmal atrial fibrillation undergoes stress ECG testing. The patient exercises on a treadmill for 9 minutes and reaches 98% of age-predicted maximal heart rate without chest pain or ST-segment changes. His pre-test resting QRS complex duration is 95 msec (normal: 80-120 msec) and corrected QT (QTc) interval duration is 410 msec (normal ≤ msec). ECG findings recorded at his maximally achieved heart rate show a QRS complex duration of 125 msec and QTc interval duration of 400 msec. Based on the patient's test results, which of the following medications is most likely being used to treat his atrial fibrillation?
A. Atenlol
B. Digoxin
C. Defetilide
D. Flecainide
E. Verapamil
D. Flecainide
Flecainide is a class 1C antiarrhythmic that is typically used to treat supraventricular tachycardias such as those caused by atrial fibrillation.
A 34 year-old male who is being treated for acute leukemia develops oliguria. His serum creatinine level is 2.7 mg/dL. Renal biopsy reveals multiple uric acid crystals obstructung renal tubular lumen. The principal site of uric acid precipitation would be which of the following?
A. Proximal tubules due to high solute concentration
B. Proximal tubules due to impaired uric acid transport
C. Loop of Henle due to urine hyposmolarity
D. Distal tubules due to high urine flow rate
E. Collecting ducts due to low urine pH
E. Collecting ducts due to low urine pH
A 27 year-old woman is brought to the ED by her employer due to increaslingly paranoid and disorganized behavior over the past year. The patient works as a housekeeper and has had progressive difficulty performing her work responsibilities. She has become increasingly secretive over the past 6 months and recently started talking in a whisper because she believes that listening devices are planted in the walls. Over the past month, she started hiding food and personal posessions in closts and under beds. The patient does not use alcohol or illicit drugs. Vital signs are stable, and physical examination is unremarkable. During the interview, she changes topics frequently and rambles about voices harassing her. Which of the following additional mental status finding is most likely in this patient?
A. Decreased facial expressiveness
B. Euphoric mood
C. Fluctuating level of consciousness
D. Olfactory hallucinations
E. Pressured speech
F. Tactile hallucinations
A. Decreased facial expressiveness
This patient's paranoid delusions, disorganized speech and behavior, auditory hallucinations and 1-year history of functional decline are consistent with schizophrenia.
A 6-week-old girl is brought to the emergency department because of a 10-day history of coughing and choking spells. The child gasps for breath, experiences paroxysms of coughing during which her oxygen saturation drops to 86%, and vomits twice in the examination room. Laboratory studies show leukocytosis with 80% lymphocytes. Cultures of sputum on special media grow encapsulated, gram-negative rods. Which of the following additional findings is most likely to be seen?
A. Erythematous rash
B. Fibrinous pseudomembrane
C. Hypoglycemia
D. Koplik spots
E. Vesicular rash
C. Hypoglycemia
This child has whooping cough, or, more accurately if one goes by the chronology of the symptoms, "coughing whoop," inasmuch as the patient is subject to a series of coughing episodes that are followed by a rapid inspiration of air. The "whoop" is caused by the rapid passage of air through a narrowed airway. The infection of the respiratory tract by Bordetella pertussis causes a hyperreactivity of the respiratory apparatus; even the slightest stimulus will trigger a coughing episode. Patients with whooping cough characteristically have posttussive emesis (vomit after a coughing episode).
A 28-year-old man comes to his primary care doctor because of a 2-day history of red discoloration of his right eye and joint pains that first began in his right elbow and right shoulder. Ten days ago he was treated for a chlamydial urethritis with doxycycline; the urethral discharge initially got better, but now has returned. There is no history of arthritis.
Which of the following is the most likely diagnosis?
A. Gout
B. Polymyositis
C. Sacroiliitis
D. Septic arthritis
E. Systemic lupus erythematosus
C. Sacroiliitis
A 39-year-old man comes to the physician because of a 6-month history of progressive shortness of breath. He has had a cough productive of white sputum for 2 years. He smoked 1 pack of cigarettes daily for 16 years but quit 10 years ago. He is in mild respiratory distress with pursed lips and a barrel chest; he is using the accessory muscles of respiration. Breath sounds are distant and crackles are present in the lower lung fields bilaterally. Pulmonary function tests show a decreased FEV1:FVC ratio, increased residual volume, and decreased diffusion capacity. An x-ray of the chest shows hyperinflation and hypertranslucency of the lower lobes of both lungs. Which of the following is the most likely diagnosis?
(A) Asthma
(B) Bronchiectasis
(C) Chronic pulmonary fibrosis
(D) Cystic fibrosis
(E) Emphysema
(E) Emphysema