Medical Q&A : find your quiz answers here !

Which of the following is the most common cause of bacterial endocarditis?


A. Staphylococcus aureus
B. Streptococcus viridans
C. Enterococcus faecalis
D. Pseudomonas aeruginosa

The most common cause of bacterial endocarditis is:

A. Staphylococcus aureus
Explanation:
Staphylococcus aureus is the most common cause of acute bacterial endocarditis, especially in individuals with no prior heart disease, intravenous drug users, or those with implanted devices like prosthetic valves or pacemakers. It is a highly virulent organism that can infect normal heart valves and cause rapidly progressing, destructive infections. Staphylococcus aureus endocarditis is often associated with aggressive clinical presentations, including high fever, septic emboli, and heart failure.

Why Not the Others:

• B. Streptococcus viridans: While Streptococcus viridans is the most common cause of subacute bacterial endocarditis, particularly in patients with pre-existing valvular abnormalities (like rheumatic heart disease), it causes a more indolent course compared to Staphylococcus aureus. However, overall, Staphylococcus aureus surpasses it as the most common cause in the modern clinical context.
• C. Enterococcus faecalis: This organism can cause endocarditis, especially in older adults and those with underlying gastrointestinal or urinary tract infections, but it is less common compared to Staphylococcus aureus and Streptococcus viridans.
• D. Pseudomonas aeruginosa: This is a less common cause of endocarditis, typically seen in intravenous drug users and patients with prosthetic valves, but it is not the most frequent pathogen.

Thus, Staphylococcus aureus remains the leading cause of bacterial endocarditis, particularly in acute presentations and high-risk populations.

 

Which of the following is the primary treatment for acute exacerbation of chronic obstructive pulmonary disease (COPD)?

A. Antibiotics
B. Systemic corticosteroids
C. Bronchodilators
D. Oxygen therapy

The correct answer is C. Bronchodilators.

Explanation:
In acute exacerbations of chronic obstructive pulmonary disease (COPD), the primary goal is to relieve symptoms such as shortness of breath and wheezing, which result from increased bronchoconstriction and mucus production.

Bronchodilators are the first-line treatment as they help relax the muscles around the airways, open up the bronchi, and improve airflow. Short-acting bronchodilators, such as beta-2 agonists (e.g., albuterol) and anticholinergics (e.g., ipratropium), are commonly used for immediate symptom relief in acute settings.

Here's why the other options are not considered the primary treatment, though they may still play a role:

• A. Antibiotics: These are used if there's evidence of a bacterial infection, such as increased sputum purulence or signs of infection. They are not the primary treatment unless an infection is clearly suspected.
  
  
• B. Systemic corticosteroids: Corticosteroids reduce inflammation and are often used in conjunction with bronchodilators during an exacerbation to improve symptoms and shorten recovery time. However, they are not considered the first-line or primary treatment.
  
  
• D. Oxygen therapy: Supplemental oxygen is used if the patient is hypoxemic (low blood oxygen levels), but it's not the first-line treatment for resolving the acute bronchoconstriction associated with an exacerbation.
  

In summary, bronchodilators are the primary treatment because they provide the most immediate relief of bronchoconstriction during an acute COPD exacerbation.

 

Which of the following is the most common cause of secondary hyperlipidemia?

A. Hypothyroidism
B. Diabetes mellitus
C. Nephrotic syndrome
D. Obstructive liver disease

The correct answer is B. Diabetes mellitus.

Explanation:
Secondary hyperlipidemia refers to elevated levels of lipids in the blood caused by an underlying condition, rather than a primary genetic disorder.

• Diabetes mellitus is the most common cause of secondary hyperlipidemia. In individuals with poorly controlled diabetes, high blood sugar levels lead to an increase in free fatty acid release from adipose tissue, which promotes the liver to produce more very-low-density lipoprotein (VLDL), contributing to elevated triglycerides and cholesterol levels.
  
  
• Hypothyroidism (A): While hypothyroidism can lead to elevated cholesterol levels, it is not as common a cause of secondary hyperlipidemia as diabetes.
  
  
• Nephrotic syndrome (C): This condition is associated with significant lipid abnormalities, including elevated cholesterol and triglycerides, but it is less common than diabetes mellitus.
  
  
• Obstructive liver disease (D): This can also lead to lipid abnormalities, particularly elevated cholesterol, but again, it is a less frequent cause than diabetes.
  

Thus, diabetes mellitus is the most prevalent cause of secondary hyperlipidemia, especially due to its global prevalence and strong association with lipid metabolism dysfunction.

 

Which of the following is the primary cause of acute mesenteric ischemia?

A. Embolism
B. Thrombosis
C. Nonocclusive mesenteric ischemia
D. Venous thrombosis

The correct answer is A. Embolism.

Explanation:
Acute mesenteric ischemia is a condition caused by a sudden decrease in blood flow to the intestines, leading to tissue damage. The primary cause of acute mesenteric ischemia is embolism, which accounts for approximately 50% of cases.

• Embolism: The most common cause of acute mesenteric ischemia, often arising from cardiac sources such as atrial fibrillation, myocardial infarction, or valvular disease. The embolus typically lodges in the superior mesenteric artery (SMA), which supplies the majority of the intestines, leading to a sudden blockage and ischemia.
  
  
• Thrombosis (B): While thrombosis of the mesenteric arteries can cause ischemia, it usually develops more gradually and is often associated with chronic atherosclerotic disease, not acute events.
  
  
• Nonocclusive mesenteric ischemia (C): This form occurs due to severe vasoconstriction rather than an actual blockage and is seen in critically ill patients. It is less common compared to embolism.
  
  
• Venous thrombosis (D): Mesenteric venous thrombosis is a rare cause of acute mesenteric ischemia and tends to present more insidiously than arterial embolism.
  

Thus, embolism is the most frequent and critical cause of acute mesenteric ischemia, necessitating urgent diagnosis and treatment.

 

Which of the following is the most common cause of hepatomegaly in children?

A. Viral hepatitis
B. Glycogen storage disease
C. Congestive heart failure
D. Fatty liver disease

The most common cause of hepatomegaly in children is:

A. Viral hepatitis

Explanation:
Hepatomegaly, or the enlargement of the liver, can occur due to various causes, and these may differ based on the age of the child, geographical location, and underlying health issues. Here's a breakdown of why viral hepatitis is the most common cause in children:

• Viral hepatitis (A): It is one of the leading causes of hepatomegaly in children worldwide. Hepatitis A and B, in particular, are common viral infections affecting children, leading to liver inflammation and enlargement. Hepatitis A is often transmitted via the fecal-oral route, especially in regions with poor sanitation, while hepatitis B is transmitted through blood or body fluids. These viral infections are more common in pediatric populations compared to other causes of hepatomegaly.
  
  
• Glycogen storage disease (B): While this can lead to hepatomegaly, it is a rare condition and not the most common cause overall. Glycogen storage diseases are metabolic disorders affecting how the body processes and stores glycogen in the liver.
  
  
• Congestive heart failure (C): Although congestive heart failure can cause hepatomegaly due to venous congestion, it is less common in children than viral hepatitis. It is more typically seen in adults, especially those with chronic cardiovascular issues.
  
  
• Fatty liver disease (D): This condition, known as non-alcoholic fatty liver disease (NAFLD), is becoming more common due to the rising rates of obesity in children, but it still does not surpass viral hepatitis as the most frequent cause of hepatomegaly in children.
  

In conclusion, viral hepatitis is the most common cause of hepatomegaly in children, primarily due to its relatively higher prevalence in pediatric populations, especially in areas with poor vaccination coverage and sanitation.

 

Which of the following is the first-line treatment for generalized anxiety disorder (GAD)?

A. Benzodiazepines
B. Selective serotonin reuptake inhibitors (SSRIs)
C. Tricyclic antidepressants (TCAs)
D. Monoamine oxidase inhibitors (MAOIs)

The first-line treatment for generalized anxiety disorder (GAD) is:

B. Selective serotonin reuptake inhibitors (SSRIs)

Explanation:
Generalized anxiety disorder (GAD) is a common mental health condition characterized by excessive, uncontrollable worry about various aspects of life. Treatment usually includes psychotherapy and medications, with the goal of reducing anxiety symptoms.

SSRIs (such as sertraline, escitalopram, and paroxetine) are considered the first-line pharmacological treatment for GAD because:

• Efficacy: SSRIs are effective in reducing the symptoms of anxiety and have been shown to improve overall functioning in people with GAD.
• Favorable Side Effect Profile: Compared to other classes of medications, SSRIs tend to have fewer and more manageable side effects. They are generally better tolerated, especially for long-term use, which is often required for managing anxiety disorders.
• Non-addictive: SSRIs do not carry the same risk of dependency or abuse as some other medications like benzodiazepines, making them a safer choice for long-term management.

Other Options:

• A. Benzodiazepines: While effective in the short-term management of acute anxiety symptoms, benzodiazepines (e.g., alprazolam, lorazepam) are not recommended as a first-line treatment because of their potential for dependence, tolerance, and withdrawal issues. They are typically reserved for short-term use or as an adjunct in treatment-resistant cases.
  
  
• C. Tricyclic antidepressants (TCAs): While effective for anxiety, TCAs (e.g., imipramine, amitriptyline) are generally not the first-line treatment because they have more side effects (e.g., weight gain, dry mouth, constipation, and sedation) compared to SSRIs.
  
  
• D. Monoamine oxidase inhibitors (MAOIs): MAOIs (e.g., phenelzine) are typically reserved for treatment-resistant cases due to their risk of serious side effects and dietary restrictions. They are not used as first-line treatments for GAD.
  

Thus, SSRIs are the preferred initial pharmacological treatment for generalized anxiety disorder due to their effectiveness, safety profile, and tolerability.

 

Which of the following is the most common cause of acute otitis externa?


A. Pseudomonas aeruginosa
B. Staphylococcus aureus
C. Streptococcus pyogenes
D. Candida albicans

The most common cause of acute otitis externa (AOE) is A. Pseudomonas aeruginosa.

Explanation:
Acute otitis externa, also known as "swimmer’s ear," is an infection of the outer ear canal, typically resulting from water exposure, trauma, or skin irritation. The condition leads to inflammation and infection, and the most common pathogen responsible is Pseudomonas aeruginosa, a gram-negative bacterium. This organism thrives in moist environments, making it particularly problematic in cases where the ear is exposed to moisture, such as after swimming.

Staphylococcus aureus, while also a common skin bacterium, is less frequently the cause of acute otitis externa compared to Pseudomonas.

Streptococcus pyogenes and Candida albicans are not common pathogens in cases of acute otitis externa, with Streptococcus being more commonly associated with pharyngitis and cellulitis, and Candida being a fungal pathogen more related to chronic infections in immunocompromised individuals.

Therefore, the correct answer is A. Pseudomonas aeruginosa.

 

Which of the following is the primary cause of hemolytic uremic syndrome (HUS) in children?


A. Streptococcus pneumoniae
B. Escherichia coli O157
C. Shigella dysenteriae
D. Salmonella typhi

The primary cause of hemolytic uremic syndrome (HUS) in children is B. Escherichia coli O157.

Explanation:
Hemolytic uremic syndrome (HUS) is a serious condition that affects the kidneys and is often triggered by an infection. In children, the most common cause of HUS is infection with Escherichia coli O157 (E. coli O157), specifically a strain that produces Shiga toxin, also known as Shiga toxin-producing E. coli (STEC). This toxin damages the lining of small blood vessels, particularly in the kidneys, leading to hemolysis (destruction of red blood cells), kidney failure, and thrombocytopenia (low platelet count).

Other bacterial pathogens, such as Shigella dysenteriae, can also produce Shiga toxin and cause HUS, but E. coli O157is by far the most common cause, especially in children. Streptococcus pneumoniae and Salmonella typhi are not common causes of HUS.

Thus, the correct answer is B. Escherichia coli O157.

 

Which of the following is the most common cause of secondary osteoporosis?

A. Hyperparathyroidism
B. Hyperthyroidism
C. Cushing's syndrome
D. Glucocorticoid therapy

The most common cause of secondary osteoporosis is D. Glucocorticoid therapy.

Explanation:
Secondary osteoporosis occurs due to an underlying condition or medication that affects bone density. Among the listed options, glucocorticoid therapy is the most frequent cause of secondary osteoporosis. Long-term use of glucocorticoids, such as prednisone, can lead to significant bone loss by inhibiting bone formation, increasing bone resorption, and reducing calcium absorption, ultimately increasing the risk of fractures.

Other conditions like hyperparathyroidism, hyperthyroidism, and Cushing's syndrome can also contribute to bone loss, but they are less common causes of secondary osteoporosis compared to glucocorticoid use.

 

Which of the following is the primary treatment for acute decompensated heart failure?

A. Beta-blockers
B. ACE inhibitors
C. Diuretics
D. Digoxin
The correct answer is C. Diuretics.

Explanation: The primary treatment for acute decompensated heart failure (ADHF) is diuretics, specifically loop diuretics like furosemide. These medications are used to reduce the fluid overload that often accompanies ADHF by promoting sodium and water excretion through the kidneys, which helps to relieve symptoms like pulmonary edema and dyspnea.

• Beta-blockers (A) and ACE inhibitors (B) are important for the long-term management of heart failure, but they are typically not the first-line treatment in acute settings due to their potential to worsen hemodynamic instability.
  
  
• Digoxin (D) can be used in certain cases for rate control or to improve cardiac contractility, but it is not considered the primary treatment for acute decompensated heart failure.
  

 

Which of the following is the primary cause of hemolytic anemia in glucose-6-phosphate dehydrogenase (G6PD) deficiency?

A. Infections
B. Certain medications
C. Fava beans
D. All of the above

The correct answer is D. All of the above.

Explanation:

Glucose-6-phosphate dehydrogenase (G6PD) deficiency is a genetic condition that affects red blood cells, making them more susceptible to oxidative stress. The deficiency impairs the red blood cells' ability to deal with oxidative damage because the enzyme G6PD plays a key role in protecting them from oxidative injury by maintaining adequate levels of reduced glutathione.

Triggers for hemolytic anemia in individuals with G6PD deficiency include:

1. Infections: Infections are a common trigger because they generate oxidative stress in the body as the immune system fights off pathogens. The increased oxidative stress can overwhelm the red blood cells, leading to hemolysis.
   
   
2. Certain medications: Some drugs, particularly those with oxidant properties, can induce hemolysis in individuals with G6PD deficiency. Examples include certain antibiotics (like sulfa drugs), antimalarial medications (such as primaquine), and analgesics.
   
   
3. Fava beans: Ingestion of fava beans (a condition known as "favism") can cause hemolysis in susceptible individuals with G6PD deficiency due to high levels of oxidants present in the beans.
   

Thus, all of these factors—infections, certain medications, and fava beans—can act as triggers for hemolytic anemia in people with G6PD deficiency.

 

Which of the following is the most common presenting symptom of pulmonary embolism?

A. chest pain
B. Dyspnea
C. Hemoptysis
D. Syncope

The most common presenting symptom of pulmonary embolism is B. Dyspnea (shortness of breath).

Explanation:
Pulmonary embolism (PE) is a blockage in one of the pulmonary arteries in the lungs, typically caused by blood clots that travel to the lungs from the legs or other parts of the body (deep vein thrombosis). The clinical presentation can vary widely, but dyspnea (difficulty breathing) is the most frequent symptom.

Here's why:

• Dyspnea: This is the most common symptom due to the sudden obstruction of blood flow in the lungs, which impairs oxygenation and leads to shortness of breath.
• chest pain: This is also a common symptom, often described as sharp and pleuritic (worsening with deep breaths). However, it is less common than dyspnea.
• Hemoptysis: Coughing up blood is less frequent and typically seen in more severe cases where lung tissue damage (infarction) has occurred.
• Syncope: Fainting or near-fainting is rare and generally associated with massive pulmonary embolism, which causes significant obstruction and leads to a decrease in cardiac output.

Therefore, dyspnea is the most common presenting symptom, often accompanied by other symptoms like chest pain and tachycardia, depending on the severity and extent of the embolism.

 

Which of the following is the primary treatment for acute pancreatitis?

A. Antibiotics
B. Fluid resuscitation
C. Pancreatic enzyme replacement
D. Cholecystectomy

The correct answer is B. Fluid resuscitation.

Explanation:
The primary treatment for acute pancreatitis focuses on supportive care, particularly fluid resuscitation. This is essential to maintain hydration and stabilize blood pressure, as patients with acute pancreatitis often become hypovolemic due to third-space fluid losses (fluid leakage into the peritoneal cavity). Adequate fluid resuscitation helps to prevent complications such as kidney failure and organ dysfunction.

• A. Antibiotics are not typically given unless there is evidence of infection (e.g., infected pancreatic necrosis).
• C. Pancreatic enzyme replacement is not a primary treatment for acute pancreatitis but may be used in chronic pancreatitis to aid digestion.
• D. Cholecystectomy might be indicated in cases of gallstone pancreatitis but is not part of the acute management and is usually performed after the acute inflammation has subsided.

 

Which of the following is the most common cause of acute tubular necrosis (ATN)?

A. Ischemia
B. Nephrotoxins
C. Sepsis
D. Dehydration

The most common cause of acute tubular necrosis (ATN) is A. Ischemia.

Explanation:
Acute tubular necrosis (ATN) is primarily caused by either ischemia (lack of blood flow and oxygen to the kidneys) or nephrotoxins (toxins harmful to kidney cells). Among these, ischemia is the most common cause.

Ischemia can result from prolonged periods of low blood pressure (hypotension), major surgeries, sepsis, or severe dehydration, which reduce the blood supply to the kidneys and cause damage to the renal tubules.

While nephrotoxins (such as certain antibiotics or contrast dyes) and sepsis are also significant contributors to ATN, ischemia remains the leading cause, particularly in critically ill patients.

 

Which of the following is the first-line treatment for benign prostatic hyperplasia (BPH)?

A. Alpha blockers
B. 5-alpha-reductase inhibitors
C. Phosphodiesterase-5 inhibitors
D. Anticholinergics

The first-line treatment for benign prostatic hyperplasia (BPH) is A. Alpha blockers.

Explanation:

• Alpha blockers (such as tamsulosin, alfuzosin, and doxazosin) are typically considered the first-line treatment for BPH. These medications work by relaxing the smooth muscles in the bladder neck and prostate, making it easier to urinate. They provide quick relief from urinary symptoms.
  
  
• 5-alpha-reductase inhibitors (such as finasteride and dutasteride) are used to reduce the size of the prostate but take longer to show effects, usually several months. They are more effective in men with larger prostates.
  
  
• Phosphodiesterase-5 inhibitors (such as tadalafil) can be used in some cases of BPH, particularly when erectile dysfunction is also present, but they are not typically the first choice for treating BPH alone.
  
  
• Anticholinergics are generally used to treat overactive bladder symptoms but are not considered a first-line treatment for BPH as they can potentially worsen urinary retention in men with BPH.
  

 

Which of the following is the primary cause of viral encephalitis in the United States?

A. Herpes simplex virus
B. West Nile virus
C. Varicella-zoster virus
D. Enterovirus

The primary cause of viral encephalitis in the United States is A. Herpes simplex virus.

Explanation:

• Herpes simplex virus (HSV) is the most common cause of viral encephalitis in the United States, particularly HSV-1. HSV encephalitis typically affects the temporal lobe of the brain and can lead to severe neurological damage if not treated promptly. Early diagnosis and treatment with antiviral medications, such as acyclovir, are crucial for improving outcomes.
  
  
• West Nile virus is a significant cause of viral encephalitis in the U.S., especially during outbreaks, but it is not the primary cause overall. It tends to cause encephalitis more in older adults and immunocompromised individuals.
  
  
• Varicella-zoster virus can cause encephalitis, particularly in immunocompromised individuals or as a complication of herpes zoster (shingles), but it is less common than HSV.
  
  
• Enteroviruses are a common cause of viral meningitis but are less frequently responsible for encephalitis compared to HSV.
  

 

Which of the following is the most common cause of acute pyelonephritis?

A. Escherichia coli
B. Klebsiella pneumoniae
C. Proteus mirabilis
D. Pseudomonas aeruginosa

The most common cause of acute pyelonephritis is A. Escherichia coli.

Explanation:
Acute pyelonephritis is a bacterial infection of the kidney that typically arises from an ascending urinary tract infection (UTI). Escherichia coli (E. coli) is responsible for the majority (approximately 70-90%) of these infections, particularly in otherwise healthy individuals. This is because E. coli is a common inhabitant of the gastrointestinal tract and has virulence factors (such as fimbriae) that allow it to attach to and invade the urinary tract.

Other bacteria like Klebsiella pneumoniae, Proteus mirabilis, and Pseudomonas aeruginosa can also cause pyelonephritis, but they are less common. These organisms are more often associated with complicated UTIs, especially in people with structural abnormalities in their urinary tract or those with catheter use.

Why E. coli is most common:

• Fimbriae (Pili): These hair-like structures on the surface of E. coli enable it to adhere to the epithelial cells of the urinary tract.
• Urease production: Some strains can produce urease, which increases the pH of urine, aiding bacterial survival.
• Frequent urinary tract colonization: E. coli is a common cause of UTI due to its proximity to the urethra from the gastrointestinal tract.

In summary, while other organisms can cause acute pyelonephritis, E. coli is by far the most frequent culprit.

 

Which of the following is the first-line treatment for major depressive disorder?

A. Benzodiazepines
B. Selective serotonin reuptake inhibitors (SSRIs)
C. Tricyclic antidepressants (TCAs)
D. Monoamine oxidase inhibitors (MAOIs)

The first-line treatment for major depressive disorder (MDD) is:

B. Selective serotonin reuptake inhibitors (SSRIs)

Explanation:
SSRIs are commonly used as the first-line treatment for major depressive disorder due to their efficacy and relatively favorable side-effect profile compared to other classes of antidepressants. They work by increasing the availability of serotonin in the brain, which can help improve mood and emotional regulation. SSRIs are generally preferred because they are less likely to cause side effects like weight gain or sedation compared to older medications like Tricyclic antidepressants (TCAs) and Monoamine oxidase inhibitors (MAOIs).

Other options like TCAs and MAOIs are usually considered second-line treatments because they tend to have more severe side effects and require more careful monitoring. Benzodiazepines, on the other hand, are not typically used for depression but are used for anxiety disorders or as a short-term treatment for acute anxiety.

 

Which of the following is the primary cause of acute liver failure in the United States?

A. Viral hepatitis
B. Alcohol toxicity
C. Acetaminophen overdose
D. Autoimmune hepatitis

The primary cause of acute liver failure in the United States is C. Acetaminophen overdose.

Explanation:
Acetaminophen (paracetamol) overdose is the most common cause of acute liver failure in the U.S. This condition occurs when excessive amounts of acetaminophen are taken, leading to liver toxicity. The liver metabolizes acetaminophen into a toxic byproduct, which, when accumulated in large amounts, causes hepatocellular damage. Without prompt medical intervention, such as N-acetylcysteine (NAC) treatment, it can lead to fulminant liver failure. Other causes of acute liver failure include viral hepatitis, drug-induced liver injury, and autoimmune hepatitis, but acetaminophen overdose remains the leading cause.

 

Which of the following is the most common cause of acute pericarditis?

A. Viral infection
B. Bacterial infection
C. Fungal infection
D. Tuberculosis

The most common cause of acute pericarditis is:

A. Viral infection

Explanation:
Viral infections are the leading cause of acute pericarditis, particularly infections caused by viruses such as coxsackievirus, echovirus, and influenza. Other viruses like HIV, herpesvirus, and adenovirus can also lead to pericarditis. These infections trigger inflammation in the pericardium, the sac-like covering of the heart.

Other causes:

• Bacterial infection: Although bacterial pericarditis can occur, it is much less common than viral pericarditis and usually occurs as a complication of other infections like pneumonia or septicemia.
  
  
• Fungal infection: Fungal pericarditis is rare and usually occurs in immunocompromised individuals.
  
  
• Tuberculosis: Tuberculous pericarditis is more common in regions where tuberculosis is endemic but is not the most frequent cause of acute pericarditis in the general population.