Anti-infective drugs ( Chapters 83-94) Flashcards
The nurse has been caring for a patient who has been taking antibiotics for 3 weeks. Upon assessing the patient, the nurse notices the individual has developed oral thrush. What describes the etiology of the thrush?
a. Antibiotic resistance
b. Community-acquired infection
c. Nosocomial infection
d. Suprainfection
ANS: D
Oral thrush is a manifestation of a suprainfection. The development of thrush is not a symptom of antibiotic resistance. Oral thrush typically is not a community-acquired infection. The development of thrush is not a nosocomial infection.
The nurse is caring for a patient on a medical-surgical unit who has a fever of unknown origin. The prescriber has ordered a broad-spectrum antibiotic. Which intervention is the priority?
a. Administering the antibiotic immediately
b. Administering antipyretics as soon as possible
c. Delaying administration of the antibiotic until the culture results are available
d. Obtaining all cultures before the antibiotic is administered
ANS: D
It is essential that samples of exudates and body fluids (in this case, blood cultures) be obtained for culture before initiation of treatment. Administration of the antibiotic is important but not more important than obtaining specimens for culture. Antipyretics may be indicated, but the priority is obtaining specimens for culture. Treatment may be initiated before the test results are available.
The nurse is teaching a nursing student about the mechanism by which antimicrobial agents achieve selective toxicity. Which statement by the student indicates a need for further teaching?
a. “Some agents disrupt the bacterial cell wall.”
b. “Some agents act to block the conversion of para-aminobenzoic acid (PABA) to folic acid.”
c. “Some agents cause phagocytosis of bacterial cells.”
d. “Some agents weaken the cell wall, causing cell wall lysis.”
ANS: C
Antimicrobial agents do not cause phagocytosis of bacterial cells. They do disrupt and weaken the bacterial cell wall; because human cells do not have cell walls, antimicrobial agents are not toxic to human cells. Some agents block the conversion of PABA to folic acid; humans do not synthesize folic acid and are not harmed by this process.
A child has received amoxicillin (Amoxil) for three previous ear infections, but a current otitis media episode is not responding to treatment. The nurse caring for this child suspects that resistance to the bacterial agent has occurred by which microbial mechanism?
a. Alteration of drug target molecules
b. Antagonist production
c. Drug inactivation
d. Reduction of drug concentration at the site of action
ANS: B
Drug inactivation can occur when microbes produce drug-metabolizing enzymes. Penicillin-resistant organisms, including many that cause otitis media, produce penicillinase. Alteration of drug target molecules, drug inactivation, and reduction of the drug concentration occur with other antimicrobials.
A nursing student asks a nurse to clarify the differences between the mechanisms of spontaneous mutation and conjugation in acquired resistance of microbes. What will the nurse say?
a. Conjugation results in a gradual increase in resistance.
b. Conjugation results in random changes in the microbe’s DNA.
c. Spontaneous mutation leads to resistance to only one antimicrobial agent.
d. Spontaneous mutation can transfer DNA from one organism to another.
ANS: C
Spontaneous mutation generally confers resistance to only one drug. Conjugation can occur quickly; spontaneous mutation is gradual. Spontaneous mutation is random; conjugation is not. Conjugation can occur with the transfer of DNA from one organism to another.
A patient has a viral sinus infection, and the provider tells the patient that antibiotics will not be prescribed. The patient wants to take an antibiotic and asks the nurse what possible harm could occur by taking an antibiotic. Which response by the nurse is correct?
a. “Antibiotics are mutagenic and can produce changes that cause resistance.”
b. “Even normal flora can develop resistance and transfer this to pathogens.”
c. “Host cells become resistant to antibiotics with repeated use.”
d. “Patients who overuse antibiotics are more likely to have nosocomial infections.”
ANS: B
Antibiotics make conditions favorable for the overgrowth of microbes with acquired resistance. Normal flora, present at all times, can develop resistance and can transfer this resistance to pathogens if they occur. Even when pathogens are not present, antibiotic use can promote resistance in the future. Antibiotics are not mutagenic. Host cells are not affected. Antibiotic use does not increase the risk of nosocomial infection in a particular patient but does increase resistance in resident organisms in a particular hospital.
A patient with recurrent bacterial pneumonia is treated with an antibiotic that has worked previously but is not working to reduce symptoms in a current infection. The nurse caring for this patient understands that this is likely for which reason?
a. The antibiotic altered the genetic makeup of the bacterial strain causing this infection.
b. The antibiotic caused host cells to change and become more susceptible to bacterial effects.
c. The antibiotic caused a mutation of the organism leading to reduced drug sensitivity.
d. The antibiotic destroyed competing organisms that secrete substances toxic to the pathogen.
ANS: D
Antibiotics promote resistance by destroying sensitive organisms and eliminating the toxins they produce, which facilitates survival of resistant organisms. Antibiotics do not alter the genetic makeup of bacteria. The host cells are not affected. Antibiotics are not mutagenic.
A patient has a localized skin infection, which is most likely caused by a gram-positive cocci. Until the culture and sensitivity results are available, the nurse will expect the provider to order a _____-spectrum _____ agent.
a. broad; systemic
b. broad; topical
c. narrow; systemic
d. narrow; topical
ANS: D
When infections are treated before the causative agent has been identified, and after cultures have been obtained, antibiotics may be used based on the knowledge of which microbes are most likely to cause infection at that particular site. Because this is a localized infection, a topical agent is recommended. Unless the infection is very serious, a narrow-spectrum antibiotic is best.
A parent asks a nurse if the provider will prescribe an antibiotic for a child who attends school with several children who have strep throat. The child is complaining of a sore throat and has a fever. What will be the nurse’s response?
a. “Because strep throat is likely, your child should be treated empirically.”
b. “With good hand washing, your child should not get strep throat.”
c. “Your child probably has strep throat, so your provider will order an antibiotic.”
d. “Your child should come to the clinic to have a throat culture done today.”
ANS: D
Whenever possible, the infecting organism should be identified before antibiotics are started, even if there is a strong suspicion that a particular organism is present. The nurse is correct in telling the parent to bring the child to the clinic for a throat culture. Fever and sore throat have other causes, so it is not correct to treat this child empirically, especially because these symptoms are not severe or life threatening. Although good hand washing is always indicated, this child already has symptoms and needs to be evaluated. Antibiotics should not be started until indicated by cultures
An older adult patient with chronic obstructive pulmonary disease (COPD) develops bronchitis. The patient has a temperature of 39.5° C. The nurse will expect the provider to:
a. obtain a sputum culture and wait for the results before prescribing an antibiotic.
b. order empiric antibiotics while waiting for sputum culture results.
c. treat symptomatically, because antibiotics are usually ineffective against bronchitis.
d. treat the patient with more than one antibiotic without obtaining cultures.
ANS: B
Patients with severe infections should be treated while culture results are pending. If a patient has a severe infection or is at risk of serious sequelae if treatment is not begun immediately, it is not correct to wait for culture results before beginning treatment. Until a bacterial infection is ruled out, treating symptomatically is not indicated. Treating without obtaining cultures is not recommended.
Which methods have been identified for preventing antimicrobial resistance? (Select all that apply.)
a. Administering influenza vaccine
b. Stopping antibiotic therapy as soon as possible when treating infection
c. Treating bacterial colonization in asymptomatic patients
d. Using narrow-spectrum antibiotics when possible
e. Using national data to determine antimicrobial drug selection
ANS: A, B, D
Vaccines help prevent disease and thus reduce the need to use antimicrobial drugs. Discontinuing antibiotic therapy as soon as possible, such as when an infection has been fully treated or when an infection is unlikely, helps reduce exposure of normal flora and other microbes to antimicrobials. Narrow-spectrum antibiotics target the pathogen and are less likely to act against other microbes. It is not correct to treat bacterial colonization when patients are asymptomatic. Local data give clearer information on local trends in susceptibility and resistance and thus are more likely to guide antimicrobial drug selection correctly.
Which are benefits of using a combination of two or more antibiotics? (Select all that apply.)
a. Reduced cost
b. Reduced risk of suprainfection
c. Reduced toxicity
d. Reduced resistance
e. Reduced risk in severe infection
ANS: C, D, E
In some situations, an antibiotic combination can reduce toxicity, because the dosage of a more toxic agent can be reduced. Drug combinations can be used to suppress the emergence of resistant bacteria in the treatment of tuberculosis. With a severe infection, a combination of antibiotics is useful until culture results are known to ensure that all possible sources of infection are treated. Using multiple antibiotics is more costly and poses a greater risk of suprainfection.
The nurse is teaching a pharmacology refresher course to a group of nurses. A student asks what host factors affect the choice of agents in antimicrobial therapy. The nurse will tell the students that such host factors include what? (Select all that apply.)
a. Age
b. Gender
c. Immune system status
d. Infection site
e. Weight
ANS: A, C, D
Host factors, such as the patient’s age, immune status, and the site of the infection, affect the choice of antimicrobial therapy used to treat an infection. Gender and weight do not affect the choice of antimicrobial but may affect the dose and route of administration.
A nurse transcribes a new prescription for potassium penicillin G given intravenously (IV) every 8 hours and gentamicin given IV every 12 hours. Which is the best schedule for administering these drugs?
a. Give the penicillin at 0800, 1600, and 2400; give the gentamicin (Garamycin) at 1800 and 0600.
b. Give the penicillin at 0800, 1600, and 2400; give the gentamicin (Garamycin) at 1200 and 2400.
c. Give the penicillin at 0600, 1400, and 2200; give the gentamicin (Garamycin) at 0600 and 1800.
d. Give the penicillin every 8 hours; give the gentamicin (Garamycin) simultaneously with two of the penicillin doses.
ANS: A
Gentamicin should never be administered concurrently with penicillin, because they will interact, and the penicillin may inactivate the aminoglycoside. All the other options show concurrent administration.
A patient has an infection caused by Pseudomonas aeruginosa. The prescriber has ordered piperacillin and amikacin, both to be given intravenously. What will the nurse do?
a. Make sure to administer the drugs at different times using different IV tubing.
b. Suggest giving larger doses of piperacillin and discontinuing the amikacin.
c. Suggest that a fixed-dose combination of piperacillin and tazobactam (Zosyn) be used.
d. Watch the patient closely for allergic reactions, because this risk is increased with this combination.
ANS: A
When penicillins are present in high concentrations, they interact with aminoglycosides and inactivate the aminoglycoside; therefore, these two drugs should never be mixed in the same IV solution. The drugs should be given at different times with different tubing. In the treatment of Pseudomonas infections, extended-spectrum penicillins, such as piperacillin, usually are given in conjunction with an antipseudomonal aminoglycoside, such as amikacin; therefore, suggesting a larger dose of piperacillin and discontinuation of the amikacin is incorrect. Zosyn is not recommended. The risk of allergic reactions does not increase with this combination of drugs.
A nurse assisting a nursing student with medications asks the student to describe how penicillins (PCNs) work to treat bacterial infections. The student is correct in responding that penicillins:
a. disinhibit transpeptidases.
b. disrupt bacterial cell wall synthesis.
c. inhibit autolysins.
d. inhibit host cell wall function.
ANS: B
PCNs weaken the cell wall, causing bacteria to take up excessive amounts of water and subsequently rupture. PCNs inhibit transpeptidases and disinhibit autolysins. PCNs do not affect the cell walls of the host.
A child with otitis media has had three ear infections in the past year. The child has just completed a 10-day course of amoxicillin (Amoxil) with no improvement. The parent asks the nurse why this drug is not working, because it has worked in the past. What will the nurse tell the patient?
a. “Amoxicillin is too narrow in spectrum.”
b. “The bacteria have developed a three-layer cell envelope.”
c. “The bacteria have developed penicillin-binding proteins (PBPs) that have a low affinity for penicillins.”
d. “The bacteria have synthesized penicillinase.”
ANS: D
Beta-lactamases are enzymes that cleave the beta-lactam ring and render the PCN inactive. This resistance is common with organisms that cause ear infections. Amoxicillin is a broad-spectrum antibiotic. A three-layer cell envelope occurs in gram-negative bacteria. Some bacterial strains, including methicillin-resistant Staphylococcus aureus (MRSA), develop PBPs with a low affinity for penicillins. MRSA is not a common cause of otitis media.
A child with an ear infection is not responding to treatment with amoxicillin (Amoxil). The nurse will expect the provider to order:
a. amoxicillin–clavulanic acid (Augmentin).
b. ampicillin.
c. nafcillin.
d. penicillin G (Benzylpenicillin).
ANS: A
Beta-lactamase inhibitors are drugs that inhibit bacterial beta-lactamases. These drugs are always given in combination with a penicillinase-sensitive penicillin. Augmentin contains amoxicillin and clavulanic acid and is often used when patients fail to respond to amoxicillin alone. Ampicillin is similar to amoxicillin, but amoxicillin is preferred and, if drug resistance occurs, ampicillin is equally ineffective. Pharmaceutical chemists have developed a group of penicillins that are resistant to inactivation by beta-lactamases (e.g., nafcillin), but these drugs are indicated only for penicillinase-producing strains of staphylococci. Penicillin G would be as ineffective as amoxicillin if beta-lactamase is present.
A patient is receiving intravenous potassium penicillin G, 2 million units to be administered over 1 hour. At 1900, the nurse notes that the dose hung at 1830 has infused completely. What will the nurse do?
a. Assess the skin at the infusion site for signs of tissue necrosis.
b. Observe the patient closely for confusion and other neurotoxic effects.
c. Request an order for serum electrolytes and cardiac monitoring.
d. Watch the patient’s actions and report any bizarre behaviors.
ANS: C
Although penicillin G is the least toxic of all antibiotics, certain adverse effects may be caused by compounds coadministered with penicillin. When large doses of potassium penicillin G are administered rapidly, hyperkalemia can occur, which can cause fatal dysrhythmias. When penicillin G is administered IM, tissue necrosis occurs with inadvertent intra-arterial injection. Confusion, seizures, and hallucinations can occur if blood levels of the drug are too high. Bizarre behaviors result with large IV doses of procaine penicillin G.
A patient is about to receive penicillin G for an infection that is highly sensitive to this drug. While obtaining the patient’s medication history, the nurse learns that the patient experienced a rash when given amoxicillin (Amoxil) as a child 20 years earlier. What will the nurse do?
a. Ask the provider to order a cephalosporin.
b. Reassure the patient that allergic responses diminish over time.
c. Request an order for a skin test to assess the current risk.
d. Suggest using a desensitization schedule to administer the drug.
ANS: C
Allergy to penicillin can decrease over time; therefore, in patients with a previous allergic reaction who need to take penicillin, skin tests can be performed to assess the current risk. Until this risk is known, changing to a cephalosporin is not necessary. Reassuring the patient that allergic responses will diminish is not correct, because this is not always the case; the occurrence of a reaction must be confirmed with skin tests. Desensitizing schedules are used when patients are known to be allergic and the drug is required anyway.
A patient with no known drug allergies is receiving amoxicillin (Amoxil) PO twice daily. Twenty minutes after being given a dose, the patient complains of shortness of breath. The patient’s blood pressure is 100/58 mm Hg. What will the nurse do?
a. Contact the provider and prepare to administer epinephrine.
b. Notify the provider if the patient develops a rash.
c. Request an order for a skin test to evaluate possible PCN allergy.
d. Withhold the next dose until symptoms subside.
ANS: A
This patient is showing signs of an immediate penicillin allergy, that is, one that occurs within 2 to 30 minutes after administration of the drug. The patient is showing signs of anaphylaxis, which include laryngeal edema, bronchoconstriction, and hypotension; these must be treated with epinephrine. This is an emergency, and the provider must be notified immediately, not when other symptoms develop. It is not necessary to order skin testing. The patient must be treated immediately, and subsequent doses should not be given.
A patient has an infection caused by Streptococcus pyogenes. The prescriber has ordered dicloxacillin PO. What will the nurse do?
a. Administer the medication as ordered.
b. Contact the provider to suggest giving the drug IV.
c. Question the need for a penicillinase-resistant penicillin.
d. Suggest ordering vancomycin to treat this infection.
ANS: C
Penicillinase-resistant penicillins have been developed for use against penicillinase-producing strains of staphylococci. These drugs have a very narrow antimicrobial spectrum and should be used only for such infections. S. pyogenes can be treated with penicillin G. The nurse should question the order. It is incorrect to contact the provider to ask for IV dosing. This infection can be treated with penicillin G and not with vancomycin.
The parent of an infant with otitis media asks the nurse why the prescriber has ordered amoxicillin (Amoxil) and not ampicillin (Unasyn). What will the nurse tell the parent?
a. Amoxicillin is a broader spectrum antibiotic than ampicillin.
b. Amoxicillin is not inactivated by beta-lactamases.
c. Ampicillin is associated with more allergic reactions.
d. Ampicillin is not as acid stable as amoxicillin.
ANS: D
Amoxicillin and ampicillin are similar in structure and actions but differ primarily in acid stability. Amoxicillin is more acid stable and, when administered orally, results in higher blood levels than can be obtained with equivalent doses of ampicillin. The two drugs have the same spectrum, both are inactivated by beta-lactamases, and both can cause allergic reactions.
A patient with an infection caused by Pseudomonas aeruginosa is being treated with piperacillin. The nurse providing care reviews the patient’s laboratory reports and notes that the patient’s blood urea nitrogen and serum creatinine levels are elevated. The nurse will contact the provider to discuss:
a. adding an aminoglycoside.
b. changing to penicillin G.
c. reducing the dose of piperacillin.
d. ordering nafcillin.
ANS: C
Patients with renal impairment should receive lower doses of piperacillin than patients with normal renal function. Aminoglycosides are nephrotoxic. Penicillin G and nafcillin are not effective against Pseudomonas infections.