NR 293: Pharmacology for Nursing Practice Midterm Exam Ultimate Review and Study Guide: Complete Exam Preparation, In- Depth Practice Tests, and Final Assessment Manual

A patient asks how a bacteriostatic antibiotic differs from a bactericidal antibiotic. Which response by the nurse is most accurate? A. Bacteriostatic drugs directly destroy bacterial cell walls. B. Bacteriostatic drugs slow bacterial growth, allowing host defenses to eliminate the organisms. C. Bacteriostatic drugs permanently prevent all microorganisms from reproducing. D. Bacteriostatic drugs are effective only against gram-positive organisms. Correct Answer: B. Bacteriostatic drugs slow bacterial growth, allowing host defenses to eliminate the organisms. Rationale: Bacteriostatic medications inhibit bacterial growth or reproduction, allowing the immune system to eliminate the infection. Bactericidal drugs directly kill susceptible bacteria. Bacteriostatic activity is not limited to gram-positive organisms and does not necessarily prevent reproduction permanently. The classification depends on the drug, concentration, and target organism. Question 2 A hospitalized patient has a temperature of 39.2°C, hypotension, and a suspected bloodstream infection. Blood cultures and intravenous antibiotics have been ordered. Which action should the nurse take first? A. Administer the antibiotic immediately and obtain cultures afterward. B. Obtain the ordered cultures before administering the first antibiotic dose. C. Wait for the culture results before starting antibiotic therapy. D. Administer an antipyretic and reassess the patient in one hour. Correct Answer: B. Obtain the ordered cultures before administering the first antibiotic dose. Rationale: Cultures should generally be collected before the first antibiotic dose because antimicrobial therapy can reduce the number of organisms and potentially produce false-negative results. Antibiotic therapy should not be unnecessarily delayed after cultures are obtained, particularly when sepsis is suspected. Waiting for final culture results would be unsafe, and an antipyretic does not treat the underlying infection. Question 3 A patient with severe pneumonia begins receiving broad-spectrum antibiotics before the causative organism has been identified. Which term best describes this treatment approach? A. Definitive therapy B. Prophylactic therapy C. Empiric therapy D. Antagonistic therapy Correct Answer: C. Empiric therapy Rationale: Empiric therapy is started before culture and sensitivity results are available. The choice is based on suspected organisms, infection site, severity of illness, and local resistance patterns. Definitive therapy is selected after the causative organism and its susceptibilities are identified. Prophylactic therapy is used to prevent infection, whereas antagonism refers to an interaction in which one antimicrobial reduces another's effectiveness. Question 4 Culture results identify methicillin-sensitive Staphylococcus aureus, and the provider changes the patient's broad-spectrum medication to a narrower antibiotic specifically effective against the organism. Which type of treatment is being implemented? A. Empiric therapy B. Definitive therapy C. Prophylactic therapy D. Suppressive therapy Correct Answer: B. Definitive therapy Rationale: Definitive therapy is tailored to the organism identified through culture and sensitivity testing. Narrowing antibiotic therapy reduces unnecessary antimicrobial exposure, toxicity, disruption of normal flora, and selection of resistant organisms. Empiric therapy is used before the organism is identified, while prophylactic therapy is intended to prevent infection. Question 5 A patient receives an antibiotic before abdominal surgery even though no infection is present. What is the primary purpose of this medication? A. To provide definitive treatment B. To prevent a likely postoperative infection C. To determine bacterial sensitivity D. To treat an undiagnosed viral infection Correct Answer: B. To prevent a likely postoperative infection Rationale: Prophylactic antibiotics are administered to prevent infection when there is a significant risk of bacterial contamination, such as during certain abdominal, orthopedic, or cardiac procedures. They are generally timed so that adequate tissue concentrations are present when the incision is made. Definitive therapy requires an established infection, and antibiotics do not determine sensitivity or treat viral infections. Question 6 Two antibiotics are administered together, and their combined effect is substantially greater than the sum of their individual effects. Which type of interaction has occurred? A. Antagonistic B. Potentiative or synergistic C. Additive only D. Prophylactic Correct Answer: B. Potentiative or synergistic Rationale: A potentiative or synergistic interaction occurs when two antimicrobial agents produce an effect greater than would be expected from simply adding their individual effects. An additive interaction produces an effect approximately equal to the combined effects of both drugs. Antagonism occurs when one medication interferes with or reduces the activity of another. Prophylaxis describes the purpose of treatment rather than a drug interaction. Question 7 Which mechanism best explains the antibacterial activity of sulfonamides? A. Inhibition of bacterial folic acid synthesis B. Destruction of bacterial DNA by free radicals C. Binding to ergosterol in the cell membrane D. Inhibition of bacterial cell-wall cross-linking Correct Answer: A. Inhibition of bacterial folic acid synthesis Rationale: Sulfonamides competitively inhibit an enzyme involved in bacterial folate production. Because bacteria must synthesize their own folic acid, this interference slows bacterial growth and is generally bacteriostatic. Ergosterol binding is associated with amphotericin B, while beta-lactam antibiotics inhibit bacterial cell-wall synthesis. Question 8 The nurse should question a prescription for trimethoprim-sulfamethoxazole for which patient? A. A 35-year-old with an uncomplicated urinary tract infection B. A 6-week-old infant with a bacterial infection C. A 48-year-old with normal renal function D. A 27-year-old with no medication allergies Correct Answer: B. A 6-week-old infant with a bacterial infection Rationale: Sulfonamides are generally contraindicated in infants younger than two months because displacement of bilirubin from albumin may increase the risk of kernicterus. They should also be avoided near term during pregnancy and used cautiously in patients with renal impairment or folate deficiency. In appropriate patients, an uncomplicated urinary tract infection may be an indication for therapy. Question 9 A patient taking a sulfonamide develops fever, painful oral lesions, and a widespread blistering rash. What is the nurse's priority interpretation? A. The patient is experiencing an expected photosensitivity reaction. B. The findings suggest Stevens-Johnson syndrome. C. The medication is causing harmless skin dryness. D. The patient has developed antibiotic-associated candidiasis. Correct Answer: B. The findings suggest Stevens-Johnson syndrome. Rationale: Fever, mucosal lesions, skin pain, blistering, and epidermal detachment may indicate Stevens-Johnson syndrome, a rare but potentially life-threatening reaction requiring immediate discontinuation and emergency evaluation. Photosensitivity typically causes an exaggerated sunburn-like reaction on exposed skin without extensive mucosal involvement. Candidiasis produces localized fungal symptoms and does not usually cause systemic illness with blistering. Question 10 Which instruction is most important for a patient taking a sulfonamide antibiotic to reduce the risk of crystalluria? A. Restrict fluids after 6:00 p.m. B. Drink adequate amounts of water throughout the day. C. Take the medication with an antacid. D. Increase intake of calcium-rich foods. Correct Answer: B. Drink adequate amounts of water throughout the day. Rationale: Adequate hydration promotes urine flow and decreases the precipitation of sulfonamide crystals in the urinary tract. Fluid restriction can increase the risk of crystalluria and renal injury. Antacids and calcium do not prevent crystal formation. Renal function and urine output should also be monitored when clinically indicated.