PANRE & PANRE-LA (Intervention Complex) Practice Exam
Observation for another 7 days
Observation for another 7 days is inappropriate because the patient already has persistent symptoms (>10 days) that indicate bacterial infection rather than viral infection. Viral sinusitis usually resolves within 7-10 days with supportive therapy such as analgesia, decongestants, hydration, and saline irrigation.
Amoxicillin-clavulanate for 10-14 days
Levofloxacin for 10-14 days
Levofloxacin for 10-14 days is an alternative option for patients with penicillin allergy but not the first-line choice because of its broader spectrum of activity and potential adverse effects, such as tendon rupture and QT prolongation.
Intranasal corticosteroids for 4 weeks
Intranasal corticosteroids for 4 weeks (choice D) are not recommended as monotherapy for acute bacterial sinusitis because they do not have antibacterial activity and may delay resolution of infection. They may be used as adjunctive therapy to reduce inflammation and improve drainage in patients with chronic or recurrent sinusitis.
Endoscopic sinus surgery
Endoscopic sinus surgery is reserved for patients with complications of acute bacterial sinusitis such as orbital cellulitis, intracranial abscess, or osteomyelitis; or patients with chronic or recurrent sinusitis that fails medical therapy.
A 25-year-old woman presents to your clinic with a 2-day history of dysuria, frequency, urgency, and suprapubic pain. She denies fever, chills, flank pain, vaginal discharge, or hematuria. She is sexually active with one male partner and uses oral contraceptives. Her last menstrual period was 2 weeks ago. Her vital signs are normal. Urinalysis shows positive leukocyte esterase and nitrites. Urine culture is pending. What is the most appropriate initial treatment for this patient?
Ciprofloxacin 500 mg orally twice daily for 3 days
Ciprofloxacin is a fluoroquinolone antibiotic that has good activity against most gram-negative bacteria causing UTIs. However, it is not a first-line agent for uncomplicated cystitis due to increasing resistance rates (>20%) and potential adverse effects such as tendon rupture, QT prolongation, and Clostridioides difficile infection. Fluoroquinolones should be reserved for complicated UTIs or patients with allergies or contraindications to other agents.
Levofloxacin 750 mg orally once daily for 5 days
This option is another fluoroquinolone antibiotic that has the same disadvantages as ciprofloxacin and is not a first-line agent for uncomplicated cystitis.
Nitrofurantoin 100 mg orally twice daily for 5 days
Trimethoprim-sulfamethoxazole (TMP-SMX) 160/800 mg orally twice daily for 3 days
This option is a combination antibiotic that was previously a first-line agent for uncomplicated cystitis. However, it is now recommended only if the local resistance rate of E. coli to TMP-SMX is <20% and the patient has no risk factors for resistance (such as recent antibiotic use, travel to areas with high resistance, or health care exposure) . TMP-SMX also has more adverse effects than nitrofurantoin or fosfomycin such as hypersensitivity reactions, hematologic abnormalities, hyperkalemia, and C. difficile infection. Additionally, TMP-SMX should be avoided in patients with sulfa allergy or G6PD deficiency.
No antibiotic therapy until urine culture results are available
This is inappropriate for patients with symptomatic acute cystitis who have positive urinalysis findings suggestive of bacterial infection. Delaying antibiotic therapy may increase the risk of complications such as pyelonephritis (upper UTI involving the kidney), urosepsis (bacteremia from UTI), or renal scarring. Empirical antibiotic therapy should be initiated promptly based on local resistance patterns and adjusted if needed when urine culture results are available.
Order a D-dimer test
Ordering a D-dimer test is not appropriate in this case because it has low specificity for PE and may be elevated in other conditions such as malignancy or inflammation. A negative D-dimer test can help rule out PE in patients with low clinical probability, but this patient has a high clinical probability. B) Ordering a chest X-ray is not appropriate in this case because it has low sensitivity for PE and may be normal or show nonspecific findings such as atelectasis or pleural effusion. A chest X-ray may be useful to rule out other causes of dyspnea such as pneumonia or pneumothorax, but it cannot confirm or exclude PE.
Order a chest X-ray
Ordering a chest X-ray is not appropriate in this case because it has low sensitivity for PE and may be normal or show nonspecific findings such as atelectasis or pleural effusion. A chest X-ray may be useful to rule out other causes of dyspnea such as pneumonia or pneumothorax, but it cannot confirm or exclude PE.
Order a computed tomography pulmonary angiography (CTPA)
Ordering a CTPA is the preferred diagnostic test for PE in most cases because it has high sensitivity and specificity for detecting pulmonary artery occlusion. However, in patients with hemodynamic instability due to massive PE, CTPA may cause further delay in treatment and worsen outcomes. Therefore, CTPA should be deferred until after thrombolytic therapy is initiated.
Start anticoagulation therapy
Starting anticoagulation therapy is an essential part of management for all patients with suspected or confirmed PE because it prevents further clot formation and propagation. However, anticoagulation alone may not be sufficient to dissolve large clots that cause massive PE and hemodynamic compromise. Therefore, anticoagulation should be combined with thrombolytic therapy in these cases.
Start thrombolytic therapy
This stage would require an FEV1 ≥ 80% predicted, which is higher than the patient’s value.
This stage would require an FEV1 30-49% predicted, which is lower than the patient’s value.
This stage would require an FEV1 < 30% predicted, which is much lower than the patient’s value.
This is not a valid stage according to the GOLD system. It may refer to a terminal condition that requires palliative care or hospice.
- Mild: FEV1 ≥ 80% predicted
- Moderate: 50% ≤ FEV1 < 80% predicted
- Severe: 30% ≤ FEV1 < 50% predicted
- Very severe: FEV1 < 30% predicted
Psychotherapy alone is unlikely to be effective in treating SAD, although it may be helpful as an adjunct to medication and light therapy. Therefore, this answer choice is incorrect.
Selective serotonin reuptake inhibitor (SSRI) alone
SSRIs are effective in treating SAD, but the most effective treatment for SAD is a combination of light therapy and medication. Therefore, this answer choice is not the best option.
Light therapy alone
Light therapy alone may be effective in some cases, but the combination of light therapy and medication is generally considered to be the most effective treatment for SAD. Therefore, this answer choice is not the best option.
Psychotherapy and SSRI
The combination of psychotherapy and medication is generally effective in treating major depressive disorder, but for major depressive disorder with seasonal pattern, the most effective treatment is a combination of light therapy and medication. Therefore, this answer choice is not the best option.
Light therapy and SSRI
- Serum glucose: 450 mg/dL
- Serum sodium: 140 mEq/L
- Serum potassium: 4.5 mEq/L
- Serum bicarbonate: 12 mEq/L
- Serum ketones: Positive
- Urine glucose: Positive
- Urine ketones: Positive
Type 1 diabetes mellitus
Type 1 diabetes mellitus is a chronic autoimmune disease that causes destruction of pancreatic beta cells and loss of insulin production. It typically presents in children or young adults with symptoms of hyperglycemia such as polyuria, polydipsia, polyphagia, and weight loss. However, type 1 diabetes mellitus alone does not explain the acidosis and ketosis seen in this patient.
Type 2 diabetes mellitus
Type 2 diabetes mellitus is a chronic metabolic disorder that causes insulin resistance and relative insulin deficiency. It usually affects older adults who are obese or have other risk factors such as hypertension, dyslipidemia, or family history. The symptoms of hyperglycemia are similar to those of type 1 diabetes mellitus, but less severe. Type 2 diabetes mellitus rarely causes DKA unless there is severe stress or infection.
Hyperosmolar hyperglycemic state
Hyperosmolar hyperglycemic state (HHS) is another serious complication of type 2 diabetes mellitus that occurs when there is profound dehydration and hyperglycemia due to inadequate insulin action. Unlike DKA, HHS does not cause significant acidosis or ketosis because there is enough residual insulin to prevent lipolysis. The presentation of HHS includes extreme hyperglycemia (>600 mg/dL), hyperosmolarity (>320 mOsm/kg), dehydration, and altered mental status.
Maturity-onset diabetes of the young
Maturity-onset diabetes of the young (MODY) is a rare form of monogenic diabetes that results from mutations in genes involved in beta cell function or development. It usually manifests before age 25 with mild hyperglycemia that can be controlled with oral hypoglycemic agents or diet alone. MODY does not cause DKA unless there is severe stress or infection.
- Hyperglycemia (>250 mg/dL)
- Acidosis (pH <7.3 or bicarbonate <18 mEq/L)
- Ketosis (serum or urine ketones positive)
Start heparin infusion and adjust warfarin dose
Heparin infusion and warfarin dose adjustment are indicated for patients with confirmed deep vein thrombosis (DVT) who have subtherapeutic INR levels. However, this patient has not yet been diagnosed with DVT and needs further diagnostic testing before initiating anticoagulation therapy.
Order duplex ultrasonography of the lower extremities
Administer tissue plasminogen activator (tPA)
tPA is a thrombolytic agent that dissolves blood clots by activating plasminogen into plasmin. Plasmin degrades fibrin, which forms the meshwork of clots. tPA may be used for patients with massive or life-threatening DVT who have contraindications to anticoagulation or who have failed anticoagulation therapy. However, it carries a high risk of bleeding complications and should not be used without confirming DVT diagnosis first.
Perform venography of the left leg
Venography is an invasive procedure that involves injecting contrast dye into a vein and taking X-ray images to visualize any obstruction or narrowing in the venous system. It was once considered the gold standard for diagnosing DVT but has been largely replaced by duplex ultrasonography due to its higher cost, invasiveness, discomfort, and risk of allergic reactions or nephrotoxicity from contrast dye.
Apply compression stockings and elevate the leg
Compression stockings are elastic garments that apply graduated pressure on the legs to improve venous return and prevent edema formation. They may be used as an adjunctive treatment for patients with confirmed DVT, along with anticoagulation therapy. Elevation of the leg can also reduce swelling and pain by decreasing hydrostatic pressure in the veins. However, these interventions do not address the underlying cause of DVT or prevent clot propagation or embolization. They should not be used as the sole therapy for suspected or confirmed DVT without diagnostic testing or anticoagulation therapy.
A 65-year-old man presents to his primary care provider with complaints of intermittent claudication in his left calf. He says that he feels pain and cramping in his leg after walking for about 10 minutes, which is relieved by resting. He has a history of hypertension, hyperlipidemia, and smoking. On physical examination, his left lower extremity pulses are diminished compared to the right. His ankle-brachial index (ABI) is 0.7 on the left and 1.0 on the right. What is the most likely cause of his symptoms?
Vasculitis is an inflammation of blood vessels that can cause narrowing or occlusion of arteries. However, vasculitis usually affects younger patients and causes other systemic symptoms such as fever, weight loss, rash, joint pain, etc. Vasculitis can also affect multiple organs such as kidneys, lungs, eyes etc.
Trauma can cause injury to blood vessels that may result in reduced blood flow to an extremity. However, trauma usually causes acute onset of symptoms such as pain, swelling, bruising, bleeding, etc. Trauma can also be associated with fractures, dislocations, nerve damage etc.
Radiation exposure can cause damage to blood vessels that may lead to stenosis or occlusion over time. However, radiation exposure usually affects patients who have received radiation therapy for cancer or other conditions. Radiation exposure can also cause other complications such as skin changes, fibrosis, necrosis etc.
Muscle strain is an injury to muscle fibers that causes pain and stiffness in the affected area. However, muscle strain usually occurs after excessive or unusual physical activity such as lifting heavy objects or sports. Muscle strain can also be associated with swelling, redness, warmth, etc.
Nasal endoscopy is a procedure that involves inserting a flexible tube with a camera into the nose to visualize the nasal cavity and sinuses. It may be useful for diagnosing conditions such as nasal polyps, tumors, foreign bodies, or fungal infections. However, it is not necessary for diagnosing allergic rhinitis which can be based on history and physical examination alone.
Skin prick testing
Serum IgE level
Serum IgE level is a blood test that measures the amount of immunoglobulin E (IgE), an antibody that mediates allergic reactions. It may be elevated in patients with allergic rhinitis but it is not specific for any particular allergen. Therefore, it cannot help identify what causes allergic rhinitis in this patient.
Nasal smear for eosinophils
Nasal smear for eosinophils is a test that involves collecting a sample of nasal secretions and staining it for eosinophils, a type of white blood cell that is involved in allergic inflammation. It may be positive in patients with allergic rhinitis but it is not specific for any particular allergen. Therefore, it cannot help identify what causes allergic rhinitis in this patient.
CT scan of sinuses
CT scan of sinuses is an imaging test that uses X-rays to create detailed pictures of the sinuses. It may be useful for diagnosing conditions such as chronic sinusitis, nasal polyps, tumors, or fungal infections. However, it is unnecessary for diagnosing allergic rhinitis, which can be based on history and physical examination alone.
- Serum creatinine: 1.8 mg/dL (normal range: 0.6–1.2 mg/dL)
- Blood urea nitrogen: 28 mg/dL (normal range: 7–20 mg/dL)
- Urinalysis: trace proteinuria, no hematuria or casts
Stage 1 CKD is incorrect because it requires an eGFR of ≥90 mL/min/1.73 m^2 with evidence of kidney damage such as albuminuria or hematuria. The patient has an eGFR of approximately 34 mL/min/1.73 m^2 and trace proteinuria.
Stage 2 CKD is incorrect because it requires an eGFR of 60–89 mL/min/1.73 m^2 with evidence of kidney damage such as albuminuria or hematuria. The patient has an eGFR of approximately 34 mL/min/1.73 m^2 and trace proteinuria.
Stage 3a CKD is incorrect because it requires an eGFR of 45–59 mL/min/1.73 m^2. The patient has an eGFR of approximately 34 mL/min/1.73 m^2.
Stage 4 CKD is incorrect because it requires an eGFR of 15–29 mL/min/1.73 m^2. The patient has an eGFR of approximately 34 mL/min/1.73 m^2.
- Stage G1 | ≥90 mL/min/1.73 m^2 | Normal or high GFR with evidence of kidney damage such as albuminuria or hematuria
- Stage G2 |60–89 mL/min/1.73 m^2 | Mildly decreased GFR with evidence of kidney damage
- Stage G3a |45–59 mL/min/1.73 m^2 | Mildly to moderately decreased GFR
- Stage G3b |30–44 mL/min/1.73 m^2 | Moderately to severely decreased GFR
- Stage G4 |15–29 mL/min/1.73 m^2 | Severely decreased GFR
- Stage G5 |<15 mL/min/1.73 m^2 or dialysis-dependent| Kidney failure
Osteoporosis is not typically associated with obesity, but rather with conditions such as hyperthyroidism, malabsorption syndromes, and chronic use of corticosteroids.
Gout is associated with hyperuricemia, which can be exacerbated by obesity, but it is not a direct consequence of obesity itself.
Chronic obstructive pulmonary disease (COPD)
Chronic obstructive pulmonary disease (COPD) is typically associated with smoking and environmental exposures, and while obesity can contribute to COPD, it is not the most likely comorbidity in this case.
Non-alcoholic fatty liver disease (NAFLD)
Iron-deficiency anemia can be associated with chronic gastrointestinal bleeding, which is not typically associated with obesity.
CT scan of the sinuses
Magnetic resonance imaging (MRI) of the sinuses
MRI of the sinuses is not the preferred initial diagnostic test for chronic sinusitis. It is reserved for cases where there is suspected intracranial extension of sinusitis or suspected complications such as abscess or osteomyelitis.
Plain radiography of the sinuses
Plain radiography of the sinuses is not useful in the diagnosis of chronic sinusitis. It can only identify significant structural abnormalities and is less sensitive than CT scan.
Transillumination of the sinuses
Transillumination of the sinuses is an outdated diagnostic test for sinusitis and has low diagnostic accuracy.
Laboratory tests for allergies
Laboratory tests for allergies may be useful in identifying underlying allergic rhinitis that may contribute to chronic sinusitis. However, it is not the most appropriate diagnostic test for chronic sinusitis.
Escherichia coli is a gram-negative bacillus that can cause urinary tract infections (UTIs), intra-abdominal infections, septicemia, and meningitis. It is not a common cause of SSTIs.
Streptococcus pyogenes can also cause cellulitis, erysipelas, necrotizing fasciitis, and toxic shock syndrome. It is a possible cause of SSTIs but less likely than S. aureus in this patient.
Pseudomonas aeruginosa is a gram-negative bacillus that can cause pneumonia, UTIs, septicemia, and infections in immunocompromised patients. It can also cause SSTIs in patients with burns or wounds exposed to contaminated water. It is not a likely cause of this patient’s infection.
Clostridium perfringens is a gram-positive bacillus that can cause gas gangrene, food poisoning, and enterocolitis. It can cause SSTIs in patients with trauma or surgery involving devitalized tissue. It is not a likely cause of this patient’s infection.
A 35-year-old man who recently moved from New York to Arizona presents to the clinic with fever, cough, chest pain, and weight loss for the past two weeks. He has no significant past medical history and does not smoke or use drugs. He works as a construction worker and has been exposed to dust at his job site. His vital signs are normal except for a temperature of 38.2°C (100.8°F). His physical examination reveals crackles in the right lower lung field. A chest radiograph shows a right lower lobe consolidation with a small cavity. What is the most likely causative organism of this patient's condition?
Mycobacterium tuberculosis is incorrect because it is a bacterial infection that causes chronic granulomatous inflammation of the lungs and other organs. Tuberculosis can present similarly to coccidioidomycosis but it is less common in the United States and more likely to affect immunocompromised patients or those with risk factors such as exposure to endemic areas or infected individua]. Tuberculosis can be diagnosed by sputum acid-fast bacilli smear and culture or nucleic acid amplification test.
Histoplasma capsulatum is incorrect because it is another systemic fungal infection that causes pulmonary and extrapulmonary manifestations similar to coccidioidomycosis but it is endemic in regions along the Ohio and Mississippi River valleys rather than in arid regions like Arizona. Histoplasma capsulatum exists as yeast in tissue rather than spherules like Coccidioides immitis. Histoplasma capsulatum can be diagnosed by urine antigen test or fungal culture from respiratory specimens.
Blastomyces dermatitidis is incorrect because it is another systemic fungal infection that causes pulmonary and extrapulmonary manifestations similar to coccidioidomycosis but it is endemic in regions around the Great Lakes and Mississippi River rather than in arid regions like Arizona. Blastomyces dermatitidis also exists as yeast in tissue rather than spherules like Coccidioides immitis. Blastomyces dermatitidis can be diagnosed by fungal culture from respiratory specimens or skin biopsy.
Staphylococcus aureus is incorrect because it is a bacterial infection that can cause secondary pneumonia following viral respiratory infections such as influenza. Staphylococcus aureus pneumonia typically affects patients with underlying lung diseases such as cystic fibrosis or chronic obstructive pulmonary disease. Staphylococcus aureus pneumonia can cause]necrotizing pneumonia with multiple cavities on chest radiograph. Staphylococcus aureus can be diagnosed by sputum Gram stain and culture or blood culture.
See C for explanation
Within 24 hours after delivery
See C for explanation
Within 1-2 weeks after delivery
Within 6 months after delivery
See C for explanation
More than a year after delivery
See C for explanation
Admit to intensive care unit for intravenous thrombolysis
Intravenous thrombolysis with tissue plasminogen activator (tPA) is indicated for patients with acute ischemic stroke who present within 4.5 hours of symptom onset and have no contraindications. However, this patient does not have an acute ischemic stroke because his symptoms resolved completely within an hour and his head CT scan was negative for infarction. Therefore, he does not qualify for intravenous thrombolysis.
Admit to stroke unit for aspirin and clopidogrel
Discharge home with aspirin and outpatient evaluation
Discharging this patient home with aspirin only would be inappropriate because he has a moderate risk of developing a stroke within the next few days. He needs more aggressive antiplatelet therapy with aspirin and clopidogrel as well as close monitoring in a hospital setting.
Perform carotid ultrasound and magnetic resonance angiography
Performing carotid ultrasound and magnetic resonance angiography may be useful to evaluate the source of embolism in this patient but they are not urgent tests that need to be done immediately. They can be performed after initiating antiplatelet therapy and stabilizing the patient’s blood pressure. Furthermore, these tests do not alter the initial management strategy which is based on clinical criteria rather than imaging findings.
Perform echocardiogram and Holter monitor
Performing echocardiogram and Holter monitor may also be helpful to identify potential cardiac sources of embolism such as atrial fibrillation or valvular disease in this patient but they are not essential tests that need to be done right away. They can be done after starting antiplatelet therapy and controlling the patient’s blood pressure. Moreover, these tests do not change the initial management plan which is based on clinical criteria rather than imaging results.
Azithromycin is incorrect because it has poor activity against S. pneumoniae, which accounts for about 30% of AOM cases.
Ceftriaxone is incorrect because it is a parenteral antibiotic that should be reserved for patients who cannot tolerate oral antibiotics or have failed initial therapy.
Myringotomy is incorrect because it is a surgical procedure that involves making an incision in the tympanic membrane to drain fluid from the middle ear. It is indicated for patients with chronic otitis media with effusion (OME), which is a persistent accumulation of fluid in the middle ear without signs of infection.
Observation is incorrect because it may be an option for selected patients older than 2 years with mild symptoms and no risk factors for complications, but not for this patient who has severe symptoms and recurrent infections.
- Serum glucose: 900 mg/dL
- Serum sodium: 150 mEq/L
- Serum potassium: 4.0 mEq/L
- Serum bicarbonate: 18 mEq/L
- Serum osmolality: 350 mOsm/kg
- Urine ketones: negative
Intravenous insulin infusion
Insulin infusion is not the first-line treatment for HHS, as it can worsen dehydration, hypokalemia, and cerebral edema if given before adequate fluid replacement. Insulin should be started after fluid resuscitation at a low dose to avoid rapid drops in serum glucose and osmolality.
Intravenous normal saline infusion
Intravenous sodium bicarbonate infusion
Sodium bicarbonate infusion is not indicated for HHS unless there is severe acidosis (pH <7.0). The patient’s serum bicarbonate level is mildly low (18 mEq/L), but not enough to warrant bicarbonate therapy. Moreover, sodium bicarbonate can increase serum osmolality and worsen cerebral edema.
Intravenous potassium chloride infusion
Intravenous potassium chloride infusion is unnecessary for HHS unless there is hypokalemia (<3.5 mEq/L). The patient’s serum potassium level is normal (4.0 mEq/L), so potassium supplementation is not required. However, potassium levels should be monitored closely during fluid and insulin therapy, as they may drop rapidly due to intracellular shifts.
Subcutaneous insulin glargine injection
Insulin glargine injection is a long-acting insulin that provides basal coverage for up to 24 hours. It is not suitable for treating acute hyperglycemia in HHS, as it has a slow onset of action and cannot be titrated easily according to blood glucose levels. Moreover, subcutaneous insulin administration may be unreliable in patients with poor perfusion due to dehydration.
Cognitive-behavioral therapy (CBT)
Cognitive-behavioral therapy (CBT) is a psychotherapy technique that can be used as an adjunct to pharmacotherapy in the treatment of major depressive disorder. However, it is not the most appropriate initial treatment for the patient in this case.
Electroconvulsive therapy (ECT)
Electroconvulsive therapy (ECT) is reserved for patients who have not responded to pharmacotherapy or who are experiencing severe symptoms such as suicidal ideation. It is not the most appropriate initial treatment for the patient in this case.
Lithium is used in the treatment of bipolar disorder and is not indicated for the treatment of major depressive disorder.
Mindfulness-based stress reduction (MBSR)
Mindfulness-based stress reduction (MBSR) is a non-pharmacological approach that can be used as an adjunct to pharmacotherapy in the treatment of major depressive disorder. However, it is not the most appropriate initial treatment for the patient in this case.
Mycoplasma pneumoniae is a cause of atypical pneumonia that affects younger adults or children. It usually occurs in outbreaks in close-contact settings such as schools or military barracks. It presents with gradual onset of low-grade fever, dry cough, headache, and malaise. The physical examination may be normal or reveal scattered crackles. The chest X-ray may show interstitial infiltrates or patchy areas of consolidation. The diagnosis can be made by serology or polymerase chain reaction (PCR). The treatment is macrolides or doxycycline.
Pseudomonas aeruginosa is a cause of hospital-acquired or ventilator-associated bacterial pneumonia that affects immunocompromised patients or those with structural lung disease such as cystic fibrosis. It presents with high fever, productive cough with greenish sputum, hemoptysis, and dyspnea. The physical examination may reveal signs of consolidation similar to S.pneumoniae but also cyanosis and clubbing due to chronic hypoxia. The chest X-ray may show multifocal infiltrates with cavitation. The diagnosis can be made by sputum culture showing gram-negative rods that produce blue-green pigment and have a fruity odor. The treatment is broad-spectrum antibiotics such as piperacillin-tazobactam or cefepime plus an aminoglycoside.
Legionella pneumophila is a cause of atypical pneumonia that affects older adults or those with underlying medical conditions such as COPD, diabetes, renal failure, malignancy, or immunosuppression. It usually occurs after exposure to contaminated water sources such as air conditioners, cooling towers, showers, fountains, etc. It presents with high fever, chills, cough, dyspnea, and gastrointestinal symptoms such as diarrhea, nausea, vomiting, and abdominal pain. The physical examination may reveal signs of consolidation similar to S.pneumoniae but also relative bradycardia and hyponatremia due to inappropriate antidiuretic hormone secretion. The chest X-ray may show patchy infiltrates that involve both lungs. The diagnosis can be made by urine antigen test, sputum culture, or PCR.
Staphylococcus aureus is not the most likely cause of pneumonia in this patient. The most common cause of bacterial pneumonia is Streptococcus pneumoniae (pneumococcus), especially in patients with underlying chronic conditions such as COPD and diabetes mellitus. Staphylococcus aureus pneumonia is more often seen in young children, post-viral infections, or hospital-associated settings. It can also cause severe complications such as necrotizing pneumonia, bacteremia, or sepsis.
Prescribe lifestyle modification focused on weight reduction and increased physical activity
Initiate metformin therapy for hyperglycemia
Metformin therapy is indicated for hyperglycemia in patients with type 2 diabetes. However, in this patient, the fasting glucose is only mildly elevated and does not meet the criteria for diabetes.
Prescribe a statin for hyperlipidemia
Statin therapy is indicated for patients with hyperlipidemia and an increased risk of cardiovascular disease. However, in this patient, the LDL cholesterol level is not reported, and the primary intervention should be lifestyle modifications.
Start antihypertensive therapy with a thiazide diuretic
Antihypertensive therapy is indicated for patients with elevated blood pressure. However, lifestyle modifications should be attempted first before initiating medication therapy.
Refer the patient for bariatric surgery
Bariatric surgery is indicated for patients with severe obesity (BMI ≥40 kg/m2) or BMI ≥35 kg/m2 with significant comorbidities. Although the patient in the scenario has a BMI of 32 kg/m2, the primary intervention should be lifestyle modifications before considering bariatric surgery.
Topical corticosteroids are not appropriate for impetigo as they can exacerbate the infection by suppressing the immune response and promoting bacterial growth.
Oral antihistamines are used to treat allergic reactions and are not effective in treating bacterial skin infections such as impetigo.
Oral doxycycline can be used to treat impetigo, but it is not the initial treatment of choice. Oral antibiotics are reserved for cases of extensive or severe impetigo or for patients who cannot tolerate topical antibiotics.
Oral acyclovir is an antiviral medication used to treat viral skin infections such as herpes simplex virus (HSV). It is not effective in treating bacterial skin infections such as impetigo.
Iodine deficiency can lead to hypothyroidism, but it is a relatively rare cause in the United States due to widespread iodine supplementation.
Pituitary adenoma is a rare cause of hypothyroidism and is more commonly associated with hyperthyroidism due to excess thyroid-stimulating hormone (TSH) secretion.
Thyroid cancer is not a common cause of hypothyroidism. While some types of thyroid cancer can lead to decreased thyroid hormone production, the majority of thyroid cancers do not affect thyroid function.
Graves' disease is a common cause of hyperthyroidism, not hypothyroidism. In Graves' disease, the immune system stimulates the thyroid gland to produce excess thyroid hormone, leading to hyperthyroidism symptoms such as weight loss, heat intolerance, and tachycardia.
Discontinue LABA and continue medium-dose ICS
Discontinuing LABA and continuing medium-dose ICS is not an appropriate step-down option for this patient. This would correspond to step 3 of the asthma treatment algorithm which still involves a relatively high dose of ICS. Moreover, discontinuing LABA abruptly may increase the risk of exacerbations or loss of control due to withdrawal effects. Therefore, if LABA is discontinued, it should be done gradually and under close monitoring.
Discontinue ICS and continue LABA
Discontinuing ICS and continuing LABA is not an appropriate step-down option for this patient. This would correspond to step 2 of the asthma treatment algorithm which involves low-dose ICS alone or alternative controllers such as leukotriene receptor antagonists or chromones. However, discontinuing ICS may lead to worsening inflammation, symptoms, lung function, and quality of life due to loss of steroid effects. Therefore, if ICS is discontinued, it should be done gradually and under close monitoring. Furthermore, using LABA alone without concomitant ICS may increase the risk of severe exacerbations or death due to paradoxical bronchoconstriction or masking effects. Therefore, LABA should never be used as monotherapy for asthma.
Reduce ICS dose by 50% and continue LABA
Reducing ICS dose by 50% and continuing LABA is not an appropriate step-down option for this patient. This would correspond to step 3 of the asthma treatment algorithm which still involves a relatively high dose of ICS plus LABA. Moreover, reducing ICS dose by more than one level at a time may increase the risk of exacerbations or loss of control due to insufficient anti-inflammatory effects. Therefore, if ICS dose is reduced, it should be done gradually by one level at a time every 2–3 months until reaching a low-dose level.
Reduce both ICS and LABA doses by 50%
Reducing both ICS and LABA doses by 50% is not an appropriate step-down option for this patient. This would correspond to step 2–3 depending on whether low- or medium-dose level was reached after reduction. However, reducing both components simultaneously may increase the risk of exacerbations or loss of control due to insufficient anti-inflammatory and bronchodilator effects. Therefore, if both components are reduced, it should be done sequentially rather than simultaneously, starting with reducing LABA first followed by reducing ICS after achieving good control.
Switch to low-dose ICS/formoterol as needed
Antibiotics are incorrect because they are not effective for OME unless there is a superimposed acute infection.
Antihistamines are incorrect because they have no proven benefit for OME and may cause sedation and dryness.
Decongestants are incorrect because they have no proven benefit for OME and may cause adverse effects such as hypertension, insomnia, and irritability.
Steroids are incorrect because they have no proven benefit for OME and may cause systemic side effects such as weight gain, immunosuppression, and growth retardation.
Acute coronary syndrome
Acute coronary syndrome is unlikely in this patient given her young age, lack of cardiac risk factors, normal vital signs and electrocardiogram.
Asthma can cause shortness of breath and chest tightness, but it is usually associated with wheezes on auscultation and triggered by allergens or irritants.
Pulmonary embolism can present with sudden onset dyspnea and chest pain, but it often causes hypoxia, tachypnea, and hypotension as well as abnormal findings on electrocardiogram (e.g., S1Q3T3 pattern) or chest radiograph (e.g., Hampton’s hump).
Thyrotoxicosis can cause palpitations and anxiety, but it also typically causes weight loss, heat intolerance, tremor, and exophthalmos, as well as abnormal thyroid function tests.
Increased protease activity
Decreased surfactant production
Decreased surfactant production is not a mechanism for emphysema but rather for atelectasis or respiratory distress syndrome. Surfactant is a phospholipid-protein complex that reduces surface tension at the air-liquid interface within the alveoli. Surfactant deficiency causes increased alveolar collapse especially during expiration leading to hypoxemia and hypercapnia.
Increased alveolar-capillary permeability
Increased alveolar-capillary permeability is not a mechanism for emphysema but rather for acute respiratory distress syndrome (ARDS). ARDS is a condition characterized by diffuse alveolar damage due to various insults such as sepsis, trauma, or aspiration. The damage causes increased leakage of fluid, protein, and inflammatory cells into the alveolar space impairing gas exchange. ARDS presents with acute onset of dyspnea, hypoxemia, and bilateral infiltrates on chest x-ray.
Decreased mucociliary clearance
Decreased mucociliary clearance is not a mechanism for emphysema but rather for chronic bronchitis which is another type of COPD. Chronic bronchitis is characterized by chronic productive cough for at least 3 months in each of 2 consecutive years. Smoking impairs mucociliary clearance by damaging cilia and increasing mucus production. This leads to mucus accumulation, bacterial colonization, and recurrent infections. Chronic bronchitis presents with cough, sputum production, wheezes, crackles, cyanosis, edema, and signs of right heart failure due to chronic hypoxia and pulmonary hypertension.
Increased pulmonary vascular resistance
Increased pulmonary vascular resistance is not a mechanism for emphysema but rather a complication that may occur due to chronic hypoxia-induced vasoconstriction or destruction of pulmonary capillaries. Increased pulmonary vascular resistance may lead to pulmonary hypertension and cor pulmonale which are late manifestations of COPD. Cor pulmonale presents with right ventricular hypertrophy or dilation, jugular venous distension, hepatomegaly, ascites, and peripheral edema.
Refer him for coronary angiography
This is an invasive procedure that involves inserting a catheter into the coronary arteries to visualize any blockages or narrowing. It is not indicated for asymptomatic patients with coronary artery disease (CAD), unless they have high-risk features such as diabetes with renal impairment, left main or multivessel disease, or reduced left ventricular function.
Prescribe him a statin and an aspirin
Advise him to quit smoking and exercise regularly
This is an important part of lifestyle modification for patients with CAD, but it is not sufficient by itself. Smoking cessation reduces the risk of myocardial infarction (MI), stroke, and death by about 50% within one year. Physical activity improves cardiovascular fitness, lowers blood pressure, enhances insulin sensitivity, and reduces inflammation. However, these interventions should be combined with pharmacological therapy for optimal outcomes.
Order an electrocardiogram (ECG) and an echocardiogram
These are non-invasive tests that can assess the electrical activity and structural function of the heart respectively. They are useful for diagnosing CAD in symptomatic patients or those with abnormal findings on physical examination. However, they are not routinely indicated for screening asymptomatic patients with CAD unless they have specific indications such as family history of sudden cardiac death or arrhythmias. Echocardiogram may also be helpful to evaluate left ventricular function before starting beta-blockers.
Start him on a beta-blocker and an ACE inhibitor
These are antihypertensive drugs that can lower blood pressure and reduce cardiac workload in patients with CAD. Beta-blockers block beta-adrenergic receptors in the heart and reduce heart rate, contractility, and oxygen demand ACE inhibitors inhibit angiotensin-converting enzyme (ACE), which converts angiotensin I to angiotensin II, a potent vasoconstrictor that also stimulates aldosterone secretion. Aldosterone increases sodium reabsorption, water retention, and blood volume. Both beta-blockers and ACE inhibitors have been shown to improve survival and prevent MI in patients with CAD who have reduced left ventricular function or previous MI[ However], they are not first-line agents for primary prevention of CAD in asymptomatic patients without these conditions.
Spironolactone is a potassium-sparing diuretic that is used in patients with advanced heart failure to reduce the risk of hospitalization and improve survival.
Digoxin is a cardiac glycoside that is used to control heart rate in patients with heart failure and atrial fibrillation but does not improve mortality.
Furosemide is a loop diuretic that is used to treat volume overload in patients with heart failure but does not improve mortality.
Verapamil is a calcium channel blocker that is contraindicated in systolic heart failure due to its negative inotropic effects.
Panic disorder is characterized by recurrent unexpected panic attacks that cause fear of having another attack or avoidance of situations that might trigger an attack. Panic attacks are sudden episodes of intense fear or discomfort that peak within minutes and are accompanied by at least 4 physical or cognitive symptoms such as palpitations, sweating, trembling, shortness of breath, chest pain, nausea, dizziness, derealization/depersonalization, fear of losing control or dying. The patient does not report having panic attacks.
Obsessive-compulsive disorder (OCD) is characterized by recurrent obsessions (intrusive thoughts or images that cause anxiety) and/or compulsions (repetitive behaviors or mental acts that aim to reduce anxiety). The patient does not report having obsessions or compulsions.
Post-traumatic stress disorder
Post-traumatic stress disorder (PTSD) is characterized by exposure to a traumatic event that involved actual or threatened death, serious injury, or sexual violence, and subsequent re-experiencing, avoidance, negative alterations in cognition and mood, and increased arousal related to the event. The patient denies any history of trauma.
Generalized anxiety disorder
Adjustment disorder is characterized by emotional or behavioral symptoms that develop within 3 months of an identifiable psychosocial stressor and cause significant impairment in social, occupational, or other areas of functioning. The symptoms usually resolve within 6 months after the termination of the stressor unless it has chronic consequences. The patient’s anxiety is not related to any specific stressors and has lasted longer than 6 months.
Administer intravenous alteplase
Administer intravenous heparin
Intravenous heparin administration is not recommended for acute ischemic stroke because it does not improve outcomes and may increase the risk of bleeding complications.
Perform carotid endarterectomy
Carotid endarterectomy is a surgical procedure that removes plaque from the carotid artery to prevent recurrent strokes in patients with significant carotid stenosis (>70%) who are asymptomatic or have had a transient ischemic attack (TIA) or minor stroke within the past 6 months. It is not indicated for patients with acute ischemic stroke who have not been stabilized medically.
Perform mechanical thrombectomy
Mechanical thrombectomy is an endovascular procedure that uses a catheter-based device to remove large vessel occlusions in patients with acute ischemic stroke who have a large penumbra (area of potentially salvageable brain tissue). It can be performed within 24 hours of symptom onset if intravenous alteplase is contraindicated or ineffective. However, it should not delay or replace intravenous alteplase if eligible.
Start oral aspirin
Oral aspirin is recommended for secondary prevention of ischemic stroke after initial treatment with intravenous alteplase or mechanical thrombectomy. It can also be used as initial treatment for patients who present more than 24 hours after symptom onset or who have contraindications to intravenous alteplase. However, it should not be given within 24 hours of receiving intravenous alteplase because it may increase the risk of bleeding complications.
ACE inhibitor alone
ACE inhibitors help to relax blood vessels by blocking the formation of a hormone that narrows them. They may be used as an initial antihypertensive treatment in the general nonblack population. They are always used in combination with lifestyle modifications.
Calcium channel blocker alone
Calcium channel blockers help relax blood vessels by preventing calcium from entering them. They may be used as an initial antihypertensive treatment in the general black population. They are always used in combination with lifestyle modifications.
Thiazide diuretic alone
Thiazide diuretics help remove sodium and water from the body by increasing urine output. They may be used as an initial antihypertensive treatment in the general nonblack and black populations, but only in combination with lifestyle modifications.
Thiazide diuretic + ACE inhibitor
This is a combination of two drugs that have different mechanisms of action to lower blood pressure. It may be used as an initial antihypertensive treatment in patients with stage 2 hypertension (systolic blood pressure ≥ 160 mm Hg or diastolic blood pressure ≥ 100 mm Hg), but only in combination with lifestyle modifications.
A 42-year-old woman with a history of GERD presents to your clinic for follow-up. She has been taking omeprazole 20 mg daily for the past 6 months and reports significant improvement in her heartburn and regurgitation symptoms. She has also made lifestyle modifications such as avoiding spicy and fatty foods, quitting smoking, and elevating the head of her bed. She asks you if she can stop taking omeprazole or reduce the dose. What is the most appropriate next step in management?
Continue omeprazole 20 mg daily indefinitely
This option may expose the patient to unnecessary risks of long-term PPI use without attempting a trial of dose reduction or discontinuation.
Discontinue omeprazole and monitor symptoms
This option may cause rebound acid hypersecretion and recurrence of GERD symptoms due to abrupt withdrawal of PPI therapy.
Switch to famotidine 20 mg twice daily
Immediately switching to an H2 blocker (such as famotidine) may not provide adequate symptom control for GERD, as H2 blockers are less potent than PPIs in suppressing gastric acid secretion. Slowly taper off the PPI first over 2-4 weeks (the higher the dose, the longer the taper). If symptoms return, it would be appropriate to start again with an H2 blocker. If long-term treatment is needed, H2 blockers allow better absorption of nutrients than PPIs and so potentially have fewer long-term adverse effects. If symptoms are still difficult to control, consider adding the PPI back at the lowest effective dose.
Taper omeprazole to every other day for 4 weeks
Perform an upper endoscopy
This option is not indicated for patients with uncomplicated GERD who have responded well to medical therapy. Endoscopy is reserved for patients who have alarm features such as dysphagia, odynophagia, weight loss, and anemia.
Administer intramuscular penicillin G benzathine
Administer oral amoxicillin-clavulanate
Oral amoxicillin-clavulanate is an alternative antibiotic for patients with GAS pharyngitis who are allergic to penicillin. However, it has more side effects (such as diarrhea or rash) than penicillin and does not offer any advantage over penicillin in terms of efficacy or spectrum
Administer oral azithromycin
Oral azithromycin is another alternative antibiotic for patients with GAS pharyngitis who are allergic to penicillin. However, it has less activity against GAS than penicillin and may increase the risk of macrolide resistance
Order a throat culture for confirmation
Ordering a throat culture for confirmation is not necessary because the rapid antigen test for GAS has high specificity (>95%) and can reliably diagnose GAS pharyngitis without further testing. Throat culture may be indicated if the rapid antigen test is negative, but there is high clinical suspicion for GAS infection.
Order an antistreptolysin O (ASO) titer
Ordering an antistreptolysin O (ASO) titer is not useful for diagnosing acute GAS pharyngitis because it measures antibodies that develop after several weeks of infection. ASO titer may be helpful for confirming past exposure to GAS in patients with suspected rheumatic fever or glomerulonephritis.
Creatinine kinase-MB (CK-MB)
Creatinine kinase (CK) is an enzyme found in various tissues, including skeletal and cardiac muscle. CK-MB is a specific isoform of CK found predominantly in cardiac muscle cells. Elevated levels of CK-MB can be seen in the early stages of AMI, but CK-MB is less specific for the diagnosis of AMI compared to troponin.
Myoglobin is a protein found in skeletal and cardiac muscle cells. Elevated myoglobin levels can be seen within 1-3 hours after the onset of symptoms, but myoglobin is less specific for the diagnosis of AMI compared to troponin. Elevated myoglobin levels can also be seen in other conditions that cause muscle injury, such as rhabdomyolysis.
C-reactive protein (CRP)
C-reactive protein (CRP) is an acute-phase protein that is elevated in response to tissue injury, inflammation, and infection. While elevated CRP levels can be seen in patients with AMI, CRP is not specific for the diagnosis of AMI and cannot be used as a diagnostic tool on its own.
Brain natriuretic peptide (BNP)
Brain natriuretic peptide (BNP) is a hormone released by the heart in response to increased pressure and volume in the cardiac chambers. Elevated BNP levels can be seen in patients with heart failure and other cardiac conditions, but BNP is not specific for the diagnosis of AMI.
Oral oseltamivir and inhaled albuterol
Oral oseltamivir and inhaled albuterol is incorrect because it does not address the patient's hypoxemia that requires oxygen therapy. Inhaled albuterol may provide some symptomatic relief for bronchospasm but does not treat the underlying viral infection.
Intravenous ceftriaxone and azithromycin
Intravenous ceftriaxone and azithromycin is incorrect because it is an empirical antibiotic regimen for bacterial pneumonia but not for viral pneumonia caused by influenza viruses. Antibiotics are not indicated unless there is evidence of a secondary bacterial infection such as persistent or worsening fever, leukocytosis, purulent sputum, or cavitation on chest radiograph.
Intravenous methylprednisolone and salbutamol
Intravenous methylprednisolone and salbutamol is incorrect because it is a treatment for acute exacerbation of asthma but not for influenza pneumonia. Corticosteroids may worsen viral replication and increase the risk of complications in patients with influenza pneumonia. Salbutamol (or albuterol) may provide some symptomatic relief for bronchospasm but does not treat the underlying viral infection.
Intravenous oseltamivir and oxygen therapy
Oral amoxicillin-clavulanate and montelukast
Oral amoxicillin-clavulanate and montelukast is incorrect because it is a treatment for chronic asthma control but not for influenza pneumonia. Amoxicillin-clavulanate is an antibiotic that has no activity against influenza viruses. Montelukast is a leukotriene receptor antagonist that reduces inflammation in asthma but has no effect on viral infections. Neither drug addresses the patient's hypoxemia which requires oxygen therapy.
Streptococcus pneumoniae is a common cause of pneumonia and meningitis, but it is not a frequent cause of erysipelas.
Staphylococcus aureus is a common cause of skin and soft tissue infections, but it is less common than S. pyogenes in causing erysipelas.
Pseudomonas aeruginosa is a gram-negative bacillus that is associated with infections in immunocompromised patients, but it is not a typical cause of erysipelas.
Haemophilus influenzae is a gram-negative coccobacillus that can cause respiratory tract infections, but it is not a common cause of erysipelas.
Middle cerebral artery
The common presentation of an MCA stroke includes sudden onset of contralateral hemiparesis (weakness on one side of the body) and sensory loss, particularly in the face and arm. Other symptoms may include aphasia (difficulty with language), if the dominant hemisphere is affected, or neglect and spatial awareness difficulties if the non-dominant hemisphere is affected.
Posterior cerebral artery
Posterior cerebral artery occlusion typically presents with visual field defects.
Anterior cerebral artery
Anterior cerebral artery occlusion typically presents with contralateral hemiparesis with loss of sensibility in the foot and lower extremity, sometimes with urinary incontinence.
Posterior inferior cerebellar artery
Posterior inferior cerebellar artery occlusion typically presents with ipsilateral ataxia and Horner’s syndrome.
Barium enema is an imaging test that involves injecting a contrast agent (barium sulfate) into the rectum and taking X-rays of the colon. It can show structural abnormalities such as diverticula, strictures, masses, or volvulus. However, it is less sensitive and specific than colonoscopy for detecting colorectal malignancy. Therefore, it is not the preferred test for this patient.
Thyroid function tests
Thyroid function tests are blood tests that measure the levels of thyroid hormones (T3, T4) and thyroid-stimulating hormone (TSH). They can help diagnose thyroid disorders such as hypothyroidism or hyperthyroidism. Hypothyroidism can cause constipation due to decreased gastrointestinal motility. However, this patient has no other signs or symptoms of hypothyroidism such as fatigue, cold intolerance, dry skin, hair loss, or bradycardia. Therefore, thyroid function tests are not necessary for this patient.
Stool osmolarity is a test that measures the concentration of solutes in stool water. It can help differentiate between osmotic diarrhea (high stool osmolarity) and secretory diarrhea (low stool osmolarity). However, this test is not useful for evaluating constipation which is defined by infrequent or difficult defecation.
Dietary modification is a nonpharmacological measure that involves increasing fiber and fluid intake to improve stool consistency and frequency. It may be effective for patients with primary constipation which has no identifiable organic cause. However, this patient has chronic constipation which requires further evaluation before initiating treatment.
A 35-year-old man visits his allergist for evaluation of his chronic nasal symptoms. He says that he has been suffering from sneezing, runny nose, and nasal congestion for more than six months. He also complains of frequent headaches and sinus infections. He has tried various over-the-counter medications but none of them have provided adequate relief. He has a history of asthma and eczema since childhood. On physical examination, he has dark circles under his eyes, a transverse nasal crease, and pale boggy nasal mucosa with clear discharge. Which of the following is the most appropriate initial treatment for this patient?
Oral antihistamines are effective for mild to moderate allergic rhinitis. They block histamine receptors and reduce symptoms such as sneezing, rhinorrhea, and itching. However, they have less effect on nasal congestion than intranasal corticosteroids. First-generation antihistamines may also cause sedation or anticholinergic side effects.
Decongestant nasal sprays
Decongestant nasal sprays are useful for short-term relief of nasal congestion due to allergic rhinitis. They act by constricting blood vessels in the nasal mucosa and reducing edema. However, they should not be used for more than three to five days because they can cause rebound congestion (rhinitis medicamentosa).
Leukotriene receptor antagonists
Leukotriene receptor antagonists are oral medications that block leukotriene receptors and reduce inflammation in allergic rhinitis. They may be used as an alternative or adjunctive therapy to intranasal corticosteroids or antihistamines. However, they are less effective than intranasal corticosteroids as monotherapy for allergic rhinitis.
Immunotherapy is a long-term treatment that involves exposing the patient to gradually increasing doses of allergens to induce tolerance and reduce symptoms. It may be considered for patients with severe allergic rhinitis who do not respond well to pharmacotherapy or who have significant adverse effects from medications. However, it is not an initial treatment option because it requires several months to years to achieve optimal results.
Age of onset over 40 years old
Type 2 diabetes is more commonly seen in individuals over 40 years old.
Elevated C-peptide levels
Elevated C-peptide levels indicate the presence of endogenous insulin production, which is more commonly seen in type 2 diabetes.
Positive islet cell antibodies
While obesity can be a risk factor for type 2 diabetes, it is not a key diagnostic criterion for type 1 diabetes.
Family history of type 2 diabetes
While family history can be a risk factor for type 2 diabetes, it is not a key diagnostic criterion for type 1 diabetes.
A 32-year-old female with a history of recurrent episodes of cellulitis presents with erythema and edema of her left lower leg. She has been treated for cellulitis multiple times in the past with antibiotics. On examination, the area is tender, warm to touch, and has small vesicles on the surface. Gram stain and culture of the vesicular fluid are negative. What is the most likely cause of this patient's cellulitis?
Group A streptococcus
Group A streptococcus and B) Staphylococcus aureus are common bacterial causes of cellulitis, but the presence of vesicles and negative culture makes these less likely.
Group A streptococcus and B) Staphylococcus aureus are common bacterial causes of cellulitis, but the presence of vesicles and negative culture makes these less likely.
Pseudomonas aeruginosa is a common cause of skin infections in individuals who have been in contact with contaminated water, but it typically causes more severe infections and is associated with necrotizing fasciitis rather than cellulitis.
Haemophilus influenzae is a rare cause of cellulitis and is typically associated with underlying immunodeficiency or malignancy.
A 65-year-old man with a history of hypertension and peptic ulcer disease presents to your clinic for a routine follow-up. He reports feeling well and has no complaints. His medications include lisinopril and omeprazole. His vital signs are normal. A complete blood count (CBC) shows:
- Hemoglobin: 10 g/dL (normal: 13-17 g/dL)
- Hematocrit: 30% (normal: 40-50%)
- Mean corpuscular volume (MCV): 70 fL (normal: 80-100 fL)
- Red cell distribution width (RDW): 18% (normal: 11-15%)
- White blood cell count: 6 x 10^9/L (normal: 4-11 x 10^9/L)
- Platelet count: 250 x 10^9/L (normal: 150-450 x 10^9/L)
Chronic kidney disease
Chronic kidney disease can cause normocytic anemia due to reduced production of erythropoietin by the kidneys. The MCV would be normal (80-100 fL).
Folate deficiency can cause macrocytic anemia due to impaired DNA synthesis in red blood cell precursors. The MCV would be high (>100 fL).
Thalassemia trait can cause microcytic anemia due to reduced synthesis of alpha or beta globin chains that form hemoglobin. However, thalassemia trait usually has a normal or low RDW (<15%) because red blood cells are uniformly small. Thalassemia trait also has a genetic basis and is more common in people of Mediterranean, African, or Southeast Asian descent.
Vitamin B12 deficiency
Vitamin B12 deficiency can also cause macrocytic anemia due to impaired DNA synthesis in red blood cell precursors as well as neurological symptoms such as peripheral neuropathy, ataxia, dementia, or psychosis. The MCV would be high (>100 fL).