A 36-year-old male with fluctuating levels of consciousness is brought to the emergency department by ambulance due to a fire in his home. He currently opens his eyes to voice, localizes painful stimuli, responds when asked questions, but is disoriented and cannot obey commands. The patient’s temperature is 99°F (37.2°C), blood pressure is 86/52 mmHg, pulse is 88/min, and respirations are 14/min with an oxygen saturation of 97% O2 on room air. Physical exam shows evidence of soot around the patient’s nose and mouth, but no burns, airway obstruction, nor accessory muscle use. A blood lactate is 14 mmol/L. The patient is started on intravenous fluids.
What is the next best step in management?
Q222
A 62-year-old woman presents with abdominal pain and blood in her urine. Since the acute onset of symptoms 3 days ago, there has been no improvement. She describes the pain as moderate, sharp and burning in character, non-radiating, and localized to the suprapubic region. She also has noted some mild urinary frequency and urgency for the past 5 days, which has been getting progressively worse. She denies any flank pain, fever, chills, night sweats, dysuria, or pain on urination. The patient has a history of an abdominal leiomyosarcoma, which was diagnosed 6 months ago. The course of her disease is complicated by hepatic metastases, for which she recently started receiving a new therapy. The patient reports a 15-pack-year smoking history, but no alcohol or recreational drug use. Her temperature is 37.0℃ (98.6℉), pulse is 84/min, respiratory rate is 18/min, and blood pressure is 110/75 mm Hg. On physical examination, there is some mild suprapubic tenderness to palpation. The remainder of the exam is unremarkable. Laboratory findings include a mild leukopenia of 3,000/mm3. A urine dipstick reveals 3+ blood. Which of the following best describes the medication that could have prevented this patient’s symptoms?
Q223
A 38-year-old woman presents to her primary care physician for a new patient appointment. She states that she feels well and has no current complaints. The patient recently started seeing a specialist for treatment for another medical condition but otherwise has had no medical problems. The patient lives alone and drinks 2 alcoholic beverages every night. She has had 3 sexual partners in her lifetime, uses oral contraceptive pills for contraception, and has never been pregnant. Physical exam reveals a pleasant, obese woman with normal S1 and S2 on cardiac exam. Musculoskeletal exam reveals swelling of the MCP and PIP joints of the hands as well as ulnar deviation of the fingers. Laboratory tests are ordered and results are below:
Serum:
Na+: 139 mEq/L
Cl-: 100 mEq/L
K+: 4.3 mEq/L
HCO3-: 25 mEq/L
BUN: 20 mg/dL
Glucose: 99 mg/dL
Creatinine: 1.1 mg/dL
Ca2+: 10.2 mg/dL
AST: 95 U/L
ALT: 68 U/L
Which of the following best explains this patient's abnormal laboratory values?
Q224
A 67-year-old man comes to the physician for a follow-up examination after he was diagnosed with mantle cell lymphoma. The physician recommends a chemotherapeutic regimen containing bortezomib. Which of the following best describes the effect of this drug?
Q225
A 55-year-old man with a history of fatigue and exertional dyspnea presents to the urgent care clinic following an acute upper respiratory illness. On physical examination, his pulses are bounding, his complexion is very pale, and scleral icterus is apparent. The spleen is moderately enlarged. Oxygen saturation is 79% at rest, with a new oxygen requirement of 9 L by a non-rebreather mask. Laboratory analysis results show a hemoglobin level of 6.8 g/dL. Of the following options, which hypersensitivity reaction does this condition represent?
Q226
A 35-year-old man is brought to the emergency department after experiencing a seizure. According to his girlfriend, he has had fatigue for the last 3 days and became confused this morning, after which he started having uncontrollable convulsions throughout his entire body. He was unconscious throughout the episode, which lasted about 4 minutes. He has not visited a physician for over 10 years. He has smoked one pack of cigarettes daily for 12 years. His girlfriend admits they occasionally use heroin together with their friends. His temperature is 38.8°C (101.8°F), pulse is 93/min, respirations are 20/min, and blood pressure is 110/70 mm Hg. The lungs are clear to auscultation and examination shows normal heart sounds and no carotid or femoral bruits. He appears emaciated and somnolent. There are multiple track marks on both his arms. He is unable to cooperate for a neurological exam. Laboratory studies show a leukocyte count of 3,000/mm3, a hematocrit of 34%, a platelet count of 354,000/mm3, and an erythrocyte sedimentation rate of 27 mm/h. His CD4+ T-lymphocyte count is 84/mm3 (normal ≥ 500). A CT scan of the head is shown. Which of the following is the most appropriate next step considering this patient's CT scan findings?
Q227
A 56-year-old man of Nepalese origin presents to a clinic complaining of skin rashes that have been troubling him for years. On examination, there are numerous poorly demarcated skin lesions present on all parts of the body. There is also evidence of significant facial thickening, eyebrow loss, and symmetrical sensory neuropathy in a ‘glove and stocking’ distribution. An examination of the hands reveals bilateral weakness. A skin biopsy is taken from one of the lesions, and the culture is positive for acid-fast bacilli. Which of the following pharmacological therapies is involved in the treatment of this condition?
Q228
A 64-year-old woman comes to the physician for her routine health maintenance examination. She feels well. She had cervical cancer and received radiotherapy 8 years ago. Her vital signs are within normal limits. On percussion, the spleen size is 15 cm. Otherwise, the physical examination shows no abnormalities. The laboratory test results are as follows:
Hemoglobin 10 g/dL
Mean corpuscular volume 88 μm3
Leukocyte count 65,000/mm3
Platelet count 500,000/mm3
Two images of the peripheral blood smear are shown on the image. Which of the following is the most appropriate next step in management?
Q229
A 65-year-old female patient with a past medical history of diabetes mellitus and an allergy to penicillin develops an infected abscess positive for MRSA on the third day of her hospital stay. She is started on an IV infusion of vancomycin at a dose of 1000 mg every 12 hours. Vancomycin is eliminated by first-order kinetics and has a half life of 6 hours. The volume of distribution of vancomycin is 0.5 L/kg. Assuming no loading dose is given, how long will it take for the drug to reach 94% of its plasma steady state concentration?
Q230
A 55-year-old man presents to the urgent clinic complaining of pain in his right foot. He reported that the pain is intense that he had to remove his shoe and sock, and rates the pain level as 6 out of 10. He does not report trauma or recent infection. The past medical history includes hypertension. The medications include hydrochlorothiazide, enalapril, and a daily multivitamin. The family history is noncontributory. He consumes alcohol in moderation. His diet mostly consists of red meat and white rice. The blood pressure is 137/85 mm Hg, heart rate is 74/min, respiratory rate is 12/min, and the temperature is 36.9°C (98.4°F). The physical examination demonstrates swelling, redness, and tenderness to palpation in the first metatarsophalangeal joint of his right foot. There are no skin lesions. The rest of the patient’s examination is normal. An arthrocentesis procedure is scheduled. Which of the following is the most likely pharmacological treatment for the presented patient?
Antimicrobials US Medical PG Practice Questions and MCQs
Question 221: A 36-year-old male with fluctuating levels of consciousness is brought to the emergency department by ambulance due to a fire in his home. He currently opens his eyes to voice, localizes painful stimuli, responds when asked questions, but is disoriented and cannot obey commands. The patient’s temperature is 99°F (37.2°C), blood pressure is 86/52 mmHg, pulse is 88/min, and respirations are 14/min with an oxygen saturation of 97% O2 on room air. Physical exam shows evidence of soot around the patient’s nose and mouth, but no burns, airway obstruction, nor accessory muscle use. A blood lactate is 14 mmol/L. The patient is started on intravenous fluids.
What is the next best step in management?
A. Methylene blue
B. Hyperbaric oxygen
C. Sodium thiosulfate and sodium nitrite
D. Intravenous epinephrine
E. 100% oxygen, hydroxycobalamin, and sodium thiosulfate (Correct Answer)
Explanation: ***100% oxygen, hydroxycobalamin, and sodium thiosulfate***
- This patient presents with signs of both **carbon monoxide poisoning** (fire exposure, disoriented, altered mental status) and **cyanide poisoning** (fire exposure, very high lactate, normal oxygen saturation despite altered mental status). This combination therapy directly addresses both.
- **100% oxygen** competes with carbon monoxide for hemoglobin binding and helps clear it, while **hydroxycobalamin** and **sodium thiosulfate** are antidotes for cyanide poisoning, converting cyanide into less toxic compounds.
*Methylene blue*
- **Methylene blue** is used to treat **methemoglobinemia**, a condition where iron in hemoglobin is oxidized, leading to impaired oxygen transport.
- The patient's symptoms (fire exposure, altered mental status, and a high lactate with normal SpO2) are not characteristic of methemoglobinemia, but rather strong indicators of carbon monoxide and cyanide poisoning.
*Hyperbaric oxygen*
- **Hyperbaric oxygen** is a treatment for severe carbon monoxide poisoning, but it is not the initial or sole treatment for a patient with suspected co-existing cyanide poisoning.
- While recommended for **severe CO poisoning**, it doesn't directly address cyanide toxicity, which is suggested by the metabolic acidosis with a high lactate level despite normal oxygen saturation.
*Sodium thiosulfate and sodium nitrite*
- This combination (the **Lilly kit**) is traditionally used to treat **cyanide poisoning**, with sodium nitrite inducing methemoglobinemia to sequester cyanide, and sodium thiosulfate aiding its excretion.
- The patient also requires treatment for **carbon monoxide poisoning**, and hydroxycobalamin is generally preferred over sodium nitrite as it does not induce methemoglobinemia, which can worsen hypoxia in CO poisoning.
*Intravenous epinephrine*
- **Epinephrine** is a powerful vasoconstrictor and bronchodilator primarily used to treat **anaphylaxis** or **cardiac arrest**.
- There is no indication of anaphylaxis or cardiac arrest in this patient, and epinephrine would not be an appropriate treatment for carbon monoxide or cyanide poisoning.
Question 222: A 62-year-old woman presents with abdominal pain and blood in her urine. Since the acute onset of symptoms 3 days ago, there has been no improvement. She describes the pain as moderate, sharp and burning in character, non-radiating, and localized to the suprapubic region. She also has noted some mild urinary frequency and urgency for the past 5 days, which has been getting progressively worse. She denies any flank pain, fever, chills, night sweats, dysuria, or pain on urination. The patient has a history of an abdominal leiomyosarcoma, which was diagnosed 6 months ago. The course of her disease is complicated by hepatic metastases, for which she recently started receiving a new therapy. The patient reports a 15-pack-year smoking history, but no alcohol or recreational drug use. Her temperature is 37.0℃ (98.6℉), pulse is 84/min, respiratory rate is 18/min, and blood pressure is 110/75 mm Hg. On physical examination, there is some mild suprapubic tenderness to palpation. The remainder of the exam is unremarkable. Laboratory findings include a mild leukopenia of 3,000/mm3. A urine dipstick reveals 3+ blood. Which of the following best describes the medication that could have prevented this patient’s symptoms?
A. Antifolate that inhibits dihydrofolate reductase, inhibiting purine production necessary for cell synthesis and division
B. Serine protease inhibitor that reduces the action of plasmin
C. A thiol given concurrently with an antineoplastic agent to help reduce inflammation of the transitional epithelium of the bladder (Correct Answer)
D. Agent that binds to an intracellular receptor and results in the transactivation of genes that promote gluconeogenesis and has anti-inflammatory effects
E. Small molecule tyrosine kinase inhibitor that inhibits bcr-abl tyrosine kinase, blocking cell proliferation and inducing apoptosis
Explanation: ***A thiol given concurrently with an antineoplastic agent to help reduce inflammation of the transitional epithelium of the bladder***
- This patient's symptoms (suprapubic pain, hematuria, urinary frequency, urgency, and leukopenia) are consistent with **hemorrhagic cystitis**, a known complication of **cyclophosphamide** (an antineoplastic agent) or ifosfamide therapy.
- **Mesna** (2-mercaptoethane sulfonate sodium) is a thiol compound administered with cyclophosphamide to detoxify its urotoxic metabolite, **acrolein**, thereby preventing hemorrhagic cystitis.
*Antifolate that inhibits dihydrofolate reductase, inhibiting purine production necessary for cell synthesis and division*
- This describes **methotrexate**, an antineoplastic agent that can cause nephrotoxicity and mucositis but is not primarily associated with hemorrhagic cystitis prevented by mesna.
- **Leucovorin** is the rescue medication given with methotrexate to reduce toxicity, not mesna.
*Serine protease inhibitor that reduces the action of plasmin*
- This describes antifibrinolytic agents like **tranexamic acid** or aminocaproic acid, which are used to prevent or treat bleeding by inhibiting fibrinolysis.
- While these might be used to manage severe bleeding, they do not prevent chemical irritation and inflammation of the bladder lining caused by chemotherapeutic agents.
*Agent that binds to an intracellular receptor and results in the transactivation of genes that promote gluconeogenesis and has anti-inflammatory effects*
- This describes **glucocorticoids** (e.g., prednisone, dexamethasone), which are anti-inflammatory and immunosuppressive agents.
- Glucocorticoids are not used to prevent hemorrhagic cystitis caused by cyclophosphamide, and their mechanism of action is distinctly different from mesna.
*Small molecule tyrosine kinase inhibitor that inhibits bcr-abl tyrosine kinase, blocking cell proliferation and inducing apoptosis*
- This describes **imatinib** or other BCR-ABL inhibitors used primarily in chronic myeloid leukemia (CML).
- This type of medication and its associated toxicities are unrelated to the patient's symptoms or the protective role of mesna.
Question 223: A 38-year-old woman presents to her primary care physician for a new patient appointment. She states that she feels well and has no current complaints. The patient recently started seeing a specialist for treatment for another medical condition but otherwise has had no medical problems. The patient lives alone and drinks 2 alcoholic beverages every night. She has had 3 sexual partners in her lifetime, uses oral contraceptive pills for contraception, and has never been pregnant. Physical exam reveals a pleasant, obese woman with normal S1 and S2 on cardiac exam. Musculoskeletal exam reveals swelling of the MCP and PIP joints of the hands as well as ulnar deviation of the fingers. Laboratory tests are ordered and results are below:
Serum:
Na+: 139 mEq/L
Cl-: 100 mEq/L
K+: 4.3 mEq/L
HCO3-: 25 mEq/L
BUN: 20 mg/dL
Glucose: 99 mg/dL
Creatinine: 1.1 mg/dL
Ca2+: 10.2 mg/dL
AST: 95 U/L
ALT: 68 U/L
Which of the following best explains this patient's abnormal laboratory values?
A. Viral infection
B. Medication (Correct Answer)
C. Obesity
D. Bacterial infection
E. Alcohol
Explanation: ***Medication***
- The AST and ALT elevations, along with the patient's rheumatological findings (**MCP and PIP joint swelling**, **ulnar deviation**), strongly suggest **rheumatoid arthritis**.
- A common treatment for rheumatoid arthritis is **methotrexate**, which is known to cause **elevated liver enzymes (AST, ALT)**.
*Viral infection*
- While viral infections can cause elevated transaminases, this patient presents with classic signs of **rheumatoid arthritis** without other typical symptoms of acute viral illness.
- The chronic nature of joint changes (ulnar deviation) makes an acute viral etiology for the liver enzyme elevation less likely as the primary cause.
*Obesity*
- Obesity is a risk factor for **non-alcoholic fatty liver disease (NAFLD)**, which can cause elevated AST and ALT.
- However, NAFLD typically causes more modest elevations, often with **ALT > AST**, and obesity alone does not explain the rheumatological findings.
*Bacterial infection*
- Bacterial infections can cause systemic inflammation and potentially affect liver enzymes, but this patient shows no signs of acute infection (e.g., fever, leukocytosis) and presents with chronic joint issues.
- The pattern of joint involvement and liver enzyme elevation is not typical for a bacterial infection.
*Alcohol*
- Chronic alcohol consumption (2 drinks/night) can lead to **alcoholic liver disease** and elevated AST and ALT, typically with an **AST:ALT ratio of 2:1 or greater**.
- While the patient drinks alcohol, the liver enzyme elevations are relatively mild, and her presentation also includes rheumatological symptoms that are not explained by alcohol alone; the AST:ALT ratio here is less than 2:1.
Question 224: A 67-year-old man comes to the physician for a follow-up examination after he was diagnosed with mantle cell lymphoma. The physician recommends a chemotherapeutic regimen containing bortezomib. Which of the following best describes the effect of this drug?
A. Crosslinking of purine bases
B. Preventing the relaxation of DNA supercoils
C. Inhibition of tyrosine kinase receptors
D. Accumulation of ubiquitinated proteins (Correct Answer)
E. Stabilization of tubulin polymers
Explanation: ***Accumulation of ubiquitinated proteins***
- **Bortezomib** is a **proteasome inhibitor**, specifically targeting the 26S proteasome, which is responsible for degrading ubiquitinated proteins.
- Its inhibition leads to the accumulation of various **ubiquitinated proteins**, including pro-apoptotic factors, ultimately inducing **apoptosis** in cancer cells.
*Crosslinking of purine bases*
- This mechanism is characteristic of **alkylating agents** such as cyclophosphamide or cisplatin, which form covalent bonds with DNA, preventing replication and transcription.
- **Bortezomib** does not directly crosslink DNA bases; its primary action is on protein degradation pathways.
*Preventing the relaxation of DNA supercoils*
- This describes the mechanism of **topoisomerase inhibitors**, such as etoposide (topoisomerase II) or irinotecan (topoisomerase I), which block DNA replication and repair.
- Bortezomib has a distinct mechanism involving proteasome inhibition, not direct interaction with DNA or topoisomerases.
*Inhibition of tyrosine kinase receptors*
- This is the action of **tyrosine kinase inhibitors**, a class of drugs like imatinib or gefitinib, that target specific signaling pathways involved in cell growth and proliferation.
- Bortezomib's anti-cancer effects are mediated through protein degradation pathways, not by inhibiting receptor tyrosine kinases.
*Stabilization of tubulin polymers*
- This mechanism is characteristic of **taxanes** (e.g., paclitaxel), which hyperstabilize microtubules, interfering with cell division.
- **Bortezomib** does not affect microtubule dynamics; its action is focused on the proteasomal degradation system.
Question 225: A 55-year-old man with a history of fatigue and exertional dyspnea presents to the urgent care clinic following an acute upper respiratory illness. On physical examination, his pulses are bounding, his complexion is very pale, and scleral icterus is apparent. The spleen is moderately enlarged. Oxygen saturation is 79% at rest, with a new oxygen requirement of 9 L by a non-rebreather mask. Laboratory analysis results show a hemoglobin level of 6.8 g/dL. Of the following options, which hypersensitivity reaction does this condition represent?
A. Type III–immune complex-mediated hypersensitivity reaction
B. Type I–anaphylactic hypersensitivity reaction
C. Type IV–cell-mediated (delayed) hypersensitivity reaction
D. Type II–cytotoxic hypersensitivity reaction (Correct Answer)
E. Type II and III–mixed cytotoxic and immune complex hypersensitivity reaction
Explanation: ***Type II–cytotoxic hypersensitivity reaction***
- The patient's symptoms, including **fatigue**, **exertional dyspnea**, **pale complexion**, **scleral icterus**, and **splenomegaly**, along with a **low hemoglobin** of 6.8 g/dL, strongly suggest **hemolytic anemia**.
- Following an **upper respiratory illness**, this presentation is consistent with **autoimmune hemolytic anemia (AIHA)**, where antibodies (mainly IgG or IgM) mistakenly target and destroy red blood cells, which is a classic example of a **Type II hypersensitivity reaction**.
*Type III–immune complex-mediated hypersensitivity reaction*
- This reaction involves the formation of **immune complexes** that deposit in tissues, leading to inflammation and damage, as seen in conditions like **serum sickness** or **lupus nephritis**.
- The patient's primary symptoms of **hemolysis** and **anemia** are not characteristic of immune complex deposition.
*Type I–anaphylactic hypersensitivity reaction*
- This type involves **IgE-mediated mast cell degranulation**, leading to rapid onset symptoms like **urticaria**, **angioedema**, **bronchospasm**, and **hypotension**.
- The patient's presentation of gradual onset fatigue, anemia, and icterus does not align with the acute, systemic allergic reaction seen in Type I hypersensitivity.
*Type IV–cell-mediated (delayed) hypersensitivity reaction*
- This reaction is mediated by **T cells** and **macrophages**, with a delayed onset (24-72 hours), as seen in **contact dermatitis** or **tuberculosis skin tests**.
- The patient's rapid development of severe anemia and an acute hemolytic picture is not consistent with a T-cell-mediated delayed reaction.
*Type II and III–mixed cytotoxic and immune complex hypersensitivity reaction*
- While some autoimmune conditions can involve elements of both Type II and Type III reactions, the overwhelming clinical picture in this patient points to direct **antibody-mediated destruction of red blood cells (Type II)**.
- There are no specific features mentioned, such as vasculitis or nephritis, that would strongly suggest **immune complex deposition** in addition to the prominent hemolytic anemia.
Question 226: A 35-year-old man is brought to the emergency department after experiencing a seizure. According to his girlfriend, he has had fatigue for the last 3 days and became confused this morning, after which he started having uncontrollable convulsions throughout his entire body. He was unconscious throughout the episode, which lasted about 4 minutes. He has not visited a physician for over 10 years. He has smoked one pack of cigarettes daily for 12 years. His girlfriend admits they occasionally use heroin together with their friends. His temperature is 38.8°C (101.8°F), pulse is 93/min, respirations are 20/min, and blood pressure is 110/70 mm Hg. The lungs are clear to auscultation and examination shows normal heart sounds and no carotid or femoral bruits. He appears emaciated and somnolent. There are multiple track marks on both his arms. He is unable to cooperate for a neurological exam. Laboratory studies show a leukocyte count of 3,000/mm3, a hematocrit of 34%, a platelet count of 354,000/mm3, and an erythrocyte sedimentation rate of 27 mm/h. His CD4+ T-lymphocyte count is 84/mm3 (normal ≥ 500). A CT scan of the head is shown. Which of the following is the most appropriate next step considering this patient's CT scan findings?
A. Pyrimethamine, sulfadiazine, and leucovorin (Correct Answer)
B. Trimethoprim-sulfamethoxazole
C. Albendazole
D. Glucocorticoids
E. CT-guided stereotactic aspiration
Explanation: ***Pyrimethamine, sulfadiazine, and leucovorin***
- The patient presents with **immunosuppression** (CD4+ count of 84/mm³), neurological symptoms including a seizure, and CT findings showing **multiple ring-enhancing lesions**, characteristic of **cerebral toxoplasmosis**.
- The recommended treatment for toxoplasmosis in immunocompromised patients is a combination of **pyrimethamine**, **sulfadiazine**, and **leucovorin** to mitigate the hematological side effects of pyrimethamine.
*Trimethoprim-sulfamethoxazole*
- While trimethoprim-sulfamethoxazole (TMP-SMX) is used for toxoplasmosis **prophylaxis** in HIV patients, it is not the first-line treatment for active cerebral toxoplasmosis due to lower efficacy compared to pyrimethamine/sulfadiazine.
- TMP-SMX is the preferred regimen for *Pneumocystis jirovecii pneumonia (PCP)* prophylaxis, which differs from the presentation here.
*Albendazole*
- **Albendazole** is an antihelminthic drug primarily used to treat infections caused by various parasitic worms, such as **neurocysticercosis**.
- The CT findings are more consistent with toxoplasmosis than neurocysticercosis, which often presents with calcified lesions in chronic cases or cysts in various stages.
*Glucocorticoids*
- **Glucocorticoids** (e.g., dexamethasone) are often used in conjunction with antimicrobial therapy for cerebral toxoplasmosis to reduce **cerebral edema** and mass effect, especially if there is significant inflammation or herniation risk.
- However, glucocorticoids alone are not a definitive treatment as they do not address the underlying parasitic infection and can exacerbate immunosuppression.
*CT-guided stereotactic aspiration*
- **Biopsy (CT-guided stereotactic aspiration)** is typically reserved for cases where the diagnosis of cerebral toxoplasmosis is uncertain, or if there is no clinical or radiological improvement after 1–2 weeks of empiric antitoxoplasmal therapy.
- Given the classic presentation in an immunocompromised patient, empiric treatment is the initial appropriate step, rather than immediate biopsy, to avoid invasive procedures if unnecessary.
Question 227: A 56-year-old man of Nepalese origin presents to a clinic complaining of skin rashes that have been troubling him for years. On examination, there are numerous poorly demarcated skin lesions present on all parts of the body. There is also evidence of significant facial thickening, eyebrow loss, and symmetrical sensory neuropathy in a ‘glove and stocking’ distribution. An examination of the hands reveals bilateral weakness. A skin biopsy is taken from one of the lesions, and the culture is positive for acid-fast bacilli. Which of the following pharmacological therapies is involved in the treatment of this condition?
A. Ketoconazole
B. Isoniazid
C. Dapsone (Correct Answer)
D. Flucloxacillin
E. Prednisone
Explanation: ***Dapsone***
- The presented symptoms (poorly demarcated skin lesions, facial thickening, eyebrow loss, symmetrical sensory neuropathy in a 'glove and stocking' distribution, bilateral weakness, and acid-fast bacilli on skin biopsy) are characteristic of **lepromatous leprosy**.
- **Dapsone** is a cornerstone medication in the multidrug therapy (MDT) for leprosy, commonly used in combination with rifampicin and clofazimine for 12 months in multibacillary disease.
- This is the primary **antimicrobial agent** targeting *Mycobacterium leprae*.
*Ketoconazole*
- **Ketoconazole** is an antifungal medication, primarily used for superficial and systemic fungal infections.
- It has no role in the treatment of leprosy, which is a bacterial infection caused by *Mycobacterium leprae*.
*Isoniazid*
- **Isoniazid** is a first-line antitubercular drug used to treat tuberculosis (TB).
- While both leprosy and TB are caused by mycobacteria, they require different treatment regimens, and isoniazid is not used in standard leprosy therapy.
*Flucloxacillin*
- **Flucloxacillin** is an antibiotic from the penicillin class, primarily used to treat infections caused by **Staphylococcus** bacteria.
- It is ineffective against *Mycobacterium leprae*, which requires specific antimycobacterial drugs.
*Prednisone*
- **Prednisone** is a corticosteroid used to reduce inflammation and suppress the immune system.
- While corticosteroids like prednisone may be used as **adjunctive therapy** to manage acute inflammatory reactions (e.g., **Type 1 reversal reactions or Type 2 lepra reactions/ENL**) that can occur during leprosy treatment, they are not a primary antimicrobial therapy and do not directly kill *Mycobacterium leprae*.
Question 228: A 64-year-old woman comes to the physician for her routine health maintenance examination. She feels well. She had cervical cancer and received radiotherapy 8 years ago. Her vital signs are within normal limits. On percussion, the spleen size is 15 cm. Otherwise, the physical examination shows no abnormalities. The laboratory test results are as follows:
Hemoglobin 10 g/dL
Mean corpuscular volume 88 μm3
Leukocyte count 65,000/mm3
Platelet count 500,000/mm3
Two images of the peripheral blood smear are shown on the image. Which of the following is the most appropriate next step in management?
A. Phlebotomy
B. Rituximab
C. Watchful waiting
D. Allogeneic stem cell transplantation
E. Dasatinib (Correct Answer)
Explanation: ***Dasatinib***
- The patient's presentation with **anemia**, **marked leukocytosis (65,000/mm³) with predominantly myeloid cells**, **thrombocytosis (500,000/mm³)**, and **splenomegaly (15 cm)** is highly suggestive of **Chronic Myeloid Leukemia (CML)**. The peripheral smear showing **myelocytes, metamyelocytes, and basophils** (indicated by arrows on the image) further supports this diagnosis.
- **Dasatinib** is a second-generation **tyrosine kinase inhibitor (TKI)** that targets the **BCR-ABL fusion protein**, which is the hallmark of CML. TKIs are the first-line treatment for CML.
*Phlebotomy*
- This is primarily used for **polycythemia vera** to reduce red blood cell mass and hematocrit.
- It is not indicated for CML, which is characterized by an overproduction of myeloid cells, not primarily red blood cells.
*Rituximab*
- **Rituximab** is a monoclonal antibody targeting the **CD20 antigen** on B-lymphocytes.
- It is used in the treatment of **B-cell non-Hodgkin lymphoma** and some autoimmune diseases, not CML.
*Watchful waiting*
- Given the patient's clear signs of **CML (leukocytosis, thrombocytosis, splenomegaly, and characteristic peripheral smear)**, active treatment is indicated, not watchful waiting.
- CML, if left untreated, progresses from the chronic phase to accelerated phase and then to **blast crisis**, which is rapidly fatal.
*Allogeneic stem cell transplantation*
- **Allogeneic stem cell transplantation** is a potentially curative treatment for CML.
- However, it is typically reserved for patients who have **failed TKI therapy** or have high-risk features, as **TKIs are the initial first-line treatment** due to their effectiveness and lower toxicity compared to transplantation.
Question 229: A 65-year-old female patient with a past medical history of diabetes mellitus and an allergy to penicillin develops an infected abscess positive for MRSA on the third day of her hospital stay. She is started on an IV infusion of vancomycin at a dose of 1000 mg every 12 hours. Vancomycin is eliminated by first-order kinetics and has a half life of 6 hours. The volume of distribution of vancomycin is 0.5 L/kg. Assuming no loading dose is given, how long will it take for the drug to reach 94% of its plasma steady state concentration?
A. 30 hours
B. 12 hours
C. 6 hours
D. 18 hours
E. 24 hours (Correct Answer)
Explanation: ***24 hours***
- For a drug eliminated by **first-order kinetics**, it takes approximately **4 half-lives** to reach **93.75%** of steady state concentration, which is conventionally rounded to **94%**.
- Since the half-life of vancomycin is **6 hours**, reaching 94% of steady state requires: 4 × 6 hours = **24 hours**.
- This follows the pharmacokinetic principle that each half-life brings the drug closer to steady state: 1 t½ = 50%, 2 t½ = 75%, 3 t½ = 87.5%, 4 t½ = 93.75%.
*30 hours*
- This duration represents **five half-lives** (5 × 6 hours), at which point approximately **96.875%** (often rounded to 97%) of steady state would be reached.
- This exceeds the 94% target specified in the question.
*18 hours*
- This duration represents **three half-lives** (3 × 6 hours), at which point approximately **87.5%** of steady state concentration would be reached.
- This falls short of the 94% target.
*12 hours*
- This duration represents **two half-lives** (2 × 6 hours), at which point approximately **75%** of steady state concentration would be reached.
- This is insufficient time to reach 94% of plasma steady state concentration.
*6 hours*
- This duration represents **one half-life**, at which point approximately **50%** of steady state concentration would be reached.
- This is far too short to achieve near-steady state levels.
Question 230: A 55-year-old man presents to the urgent clinic complaining of pain in his right foot. He reported that the pain is intense that he had to remove his shoe and sock, and rates the pain level as 6 out of 10. He does not report trauma or recent infection. The past medical history includes hypertension. The medications include hydrochlorothiazide, enalapril, and a daily multivitamin. The family history is noncontributory. He consumes alcohol in moderation. His diet mostly consists of red meat and white rice. The blood pressure is 137/85 mm Hg, heart rate is 74/min, respiratory rate is 12/min, and the temperature is 36.9°C (98.4°F). The physical examination demonstrates swelling, redness, and tenderness to palpation in the first metatarsophalangeal joint of his right foot. There are no skin lesions. The rest of the patient’s examination is normal. An arthrocentesis procedure is scheduled. Which of the following is the most likely pharmacological treatment for the presented patient?
A. Diclofenac alone (Correct Answer)
B. Allopurinol alone
C. Probenecid alone
D. Colchicine and celecoxib
E. Oral methylprednisolone and meloxicam
Explanation: - ***Diclofenac alone***
- This patient presents with a classic picture of **acute gout**: sudden onset of severe pain, swelling, redness, and tenderness in the **first metatarsophalangeal joint** (podagra), with a history of hypertension and diuretic use (hydrochlorothiazide), and a diet rich in red meat.
- **NSAIDs like diclofenac** are first-line treatment for acute gout attacks, as they effectively reduce pain and inflammation.
- *Allopurinol alone*
- **Allopurinol** is a **xanthine oxidase inhibitor** used for the **long-term prevention** of gout attacks by lowering uric acid levels. It is not indicated for the management of acute flare-ups.
- Initiating allopurinol during an acute attack can paradoxically **worsen the flare** by mobilizing uric acid crystals.
- *Probenecid alone*
- **Probenecid** is a **uricosuric agent** that increases uric acid excretion via the kidneys and is used for **long-term management** of gout in patients who are underexcretors of uric acid.
- Like allopurinol, it is **not used for acute gout attacks** and should not be initiated during a flare.
- *Colchicine and celecoxib*
- **Colchicine** is an effective treatment for acute gout, particularly if given within the first 24-36 hours of symptom onset, but it can cause **significant gastrointestinal side effects** (nausea, vomiting, diarrhea).
- **Celecoxib** is a **COX-2 selective NSAID** which is also effective in acute gout. However, combining colchicine with another NSAID like celecoxib for initial treatment might be an **overkill** in terms of side effects and typically **only one first-line agent (NSAID or colchicine) is sufficient.**
- *Oral methylprednisolone and meloxicam*
- **Oral methylprednisolone (corticosteroids)** are highly effective for acute gout, especially in patients with **contraindications to NSAIDs** or who have polyarticular involvement.
- **Meloxicam** is an NSAID, and while appropriate for acute gout, combining it with systemic corticosteroids (methylprednisolone) is **usually reserved for more severe cases** or when monotherapy is insufficient, due to increased risk of side effects.