CH. 26 Antimicrobials LH

The nurse should question the prescription of tetracycline for which patient?

A 6-year-old patient with Haemophilus influenzae; Tetracycline is contraindicated in children younger than 8 years because it can cause permanent discoloration of the teeth. Tetracycline is used to treat rickettsiae.

superinfection

A ______ occurs when the antibiotic eliminates the normal bacterial flora. When these bacteria or fungi are killed by antibiotics, then other bacteria or fungi cause infection, which is known as ________.

normal bacterial flora

consists of certain bacteria and fungi that are needed to maintain normal function in various organs

Within which time frame would the nurse draw the trough level for a patient on antibiotic therapy?

10 minutes before administration of the intravenous antibiotic; Trough levels are drawn just before infusion. The nurse should document the time drug administration is started and completed and the exact time a peak and/or trough level is drawn.

Peak serum drug levels should be drawn ____ after the medication is infused.

30 to 60 minutes

The nurse is setting up an intravenous infusion pump to administer a dose of vancomycin to a patient. Which infusion rate would the nurse set the drug to infuse?

60-90 minutes; Rapid infusion of vancomycin results in red man syndrome, a response resulting in histamine release and chills, fever, tachycardia, pruritus, rash, or a red face, neck, upper body, back, and arms. It can be alleviated by the slow infusion of vancomycin over a 60- to 90-minute period. For this reason, the nurse should set the pump at 60 to 90 minutes. Rapid infusions at 30 to 45 minutes may also cause hypotension. Rates from 100 to 250 minutes are too long.

_____ are effective against Escherichia coli.

Aminoglycosides

macrolide admin. for upper resp tract infection

Azithromycin is the drug of choice for upper respiratory tract infection. For intravenous administration, 500 mg of powdered azithromycin should be diluted in 250 to 500 mL of fluid. The patient should take a full course of antibacterial drugs. The patient should not stop the medication if the symptoms subside. Azithromycin in oral form should be given with a full glass of water, not with fruit juice. Because high doses of azithromycin may damage the liver, signs of liver dysfunction should be monitored. Elevated liver enzymes and yellowish discoloration of eyes (jaundice) are the signs of liver dysfunction. Antacids should be administered 2 hours before or 2 hours after administration of the drug.

Which information would the nurse include when teaching a student nurse about the similarities and differences between the pharmacokinetics of amoxicillin and dicloxacillin?

Both amoxicillin and dicloxacillin have short half-lives, and so they are metabolized quickly in the body. Dicloxacillin is much more protein-bound than amoxicillin. Hence, greater drug toxicity may result when other highly protein-bound drugs are used with dicloxacillin than with amoxicillin. Sixty percent of amoxicillin is excreted in the urine, whereas dicloxacillin is excreted in bile and urine. Amoxicillin is well absorbed from the GI tract, whereas dicloxacillin is only partially absorbed. Amoxicillin is 20% protein bound and dicloxacillin is highly protein bound (approximately 95%).

pharmacokinetics of cephalosporin drugs

Cefazolin sodium of the cephalosporin group is administered through the IV or IM route, not through the oral route. Cephalexin is one of the few drugs in the cephalosporin group that can be administered orally. The half-life of the drugs belonging to the cephalosporins group is essentially very short. The protein-binding capacity of cefazolin sodium is greater than that of cefaclor. Approximately 60% to 80% of the drug remains unchanged when passed through urine.

Which advantage does clindamycin have over lincomycin?

Clindamycin and lincomycin are both lincosamides. Clindamycin is more widely prescribed because it has many advantages over lincomycin. It is more effective, and it has fewer toxic effects. It is better absorbed through the gastrointestinal tract, and it is active against most gram-positive organisms. It also maintains a higher serum drug concentration.

Which information would the nurse include when teaching a patient about the administration of aspirin and dicloxacillin?

Dicloxacillin is a penicillinase-resistant penicillin and its effect can increase with aspirin. The effect of dicloxacillin can decrease with acidic fruits or juices, like oranges or orange juice.

Which class of drug is effective against Shigella?

Fluoroquinolones

pharmacokinetics of antibacterials

It is imperative that the antibacterial drug has an affinity to the binding sites of the bacterial cell. The drugs with longer half-lives maintain a greater concentration at the binding site. Protein binding has no major influence on the effectiveness of most antibacterial drugs. The antibacterial drugs have to penetrate the bacterial cell wall in sufficient concentrations. This type of drug has a steady state only after the fourth or fifth half-life.

______ are effective against Streptococcus pneumoniae and Haemophilus influenza.

Ketolides

A patient asks the nurse, "Why should take my calcium supplements 2 hours after taking levofloxacin?" Which response by the nurse is correct?

Levofloxacin is a quinolone antibiotic. Calcium supplements interfere with levofloxacin absorption and reduce oral absorption of levofloxacin. Therefore the nurse instructs the patient to take calcium supplements at least 1 hour before or after taking levofloxacin to prevent this interaction. Nitrofurantoin interacts with levofloxacin and antagonizes its antibacterial activity. Oral anticoagulant and levofloxacin interaction affects the intestinal flora.

_____ are effective against Staphylococcus aureus-caused septicemia.

Lipopeptides

Which medication is contraindicated in the patient who has been prescribed ceftriaxone to avoid nephrotoxicity?

calcium salts; loop diuretics; aminoglycosides. Ceftriaxone is a third-generation cephalosporin. Drugs like calcium salts, loop diuretics, and aminoglycosides increase nephrotoxicity in the patient. The patient should not be prescribed any of these medications while he or she is taking ceftriaxone.

Which drug may cause a decrease in the excretion of cephalosporins?

Probenecid; when used with cephalosporins decrease the excretion of cephalosporins by increasing their reabsorption, which increases the risk for toxicity.

Which bacterium is sensitive to gentamicin?

Pseudomonas aeruginosa

Which intervention would be appropriate when caring for a patient prescribed penicillin G potassium?

Taking penicillin for a prolonged period may cause superinfections. Therefore monitoring for stomatitis, which is a type of superinfection, is required. Respiratory distress is a severe allergic reaction after a first or second dose of penicillin. Epinephrine is used to treat a severe allergic reaction that may occur with the use of penicillin. A culture and sensitivity test should be obtained before starting the therapy for effective treatment. Penicillins should be taken with food to avoid gastric irritation.

____ are contraindicated in women in the last trimester of pregnancy because they cause irreversible discoloration of the permanent teeth. Glycopeptides have no such side effect.

Tetracyclines

The nurse notes a patient's amikacin serum drug concentration is 2 mcg/mL. Which additional laboratory result would the nurse review?

Serum creatinine concentration; Amikacin is an aminoglycoside antibiotic. Aminoglycosides have the potential to cause nephrotoxicity, and thus the patient's serum drug concentrations should be monitored regularly. The usual serum drug concentration of aminoglycosides is expected to be ≤1 mcg/mL (considered as safe range). Concentrations higher than this may cause adverse effects. Therefore the nurse should check the serum creatinine concentration to evaluate proper renal function.

Urine output should be monitored when ____ is taken, because it may cause hematuria; An increase in muscle contractions may result in seizures, which may occur with ___

ceftriaxone

nursing assessment measures after admin of cephalosporin

The nurse should not just record the vital signs of the patient. Along with the vital signs, it is imperative for the nurse to report the urine output of the patient as well. The nurse should evaluate laboratory results, putting special emphasis on those that indicate renal and liver function. The nurse needs to report abnormal findings regarding patient vitals and urine output; generally, temperature would be elevated and urine output would be decreased. The effect of penicillins like amoxicillin and dicloxacillin are decreased with acidic fruits or juices. The nurse should not expect the effect of cephalosporins to be negatively affected by food in the GI tract. Cefadroxil is well absorbed by the gastrointestinal tract and not affected by food. The absorption of cefpodoxime is enhanced by food.

pharmacodynamics of antibacterials

The once-daily antibacterial dose has been effective against eradicating pathogens. A weekly dose would not be effective. Antibacterial drugs are used to achieve the minimum effective concentration (MEC), not the maximum effective concentration, to halt the growth of the microorganism. The ease of antibacterial drug dosing, administered once or twice daily, increases with the patient's adherence to the drug regimen. A continuous infusion regimen of an antibacterial drug is more effective than intermittent dosing in case of severe infections. The nurse should always remember that the duration of time for use of the antibacterial drug varies according to the type of pathogen, site of infection, and immunocompetence of the host.

Which drug may cause cardiac death when used in combination with erythromycin?

VERAPAMIL; When verapamil, a calcium channel blocker, is used in combination with erythromycin, the erythromycin blood concentration is increased and the risk for sudden cardiac death increases.

___ is used against drug-resistant Staphylococcus aureus.

Vancomycin

Which antibacterial medication is commonly given to treat antibiotic-associated pseudomembranous colitis due to Clostridium difficile?

Vancomycin; given orally is not absorbed systemically, but it is excreted in the feces. This property makes it useful in the treatment of antibiotic-associated pseudomembranous colitis due to C. difficile infection

Which complication would the nurse monitor for in a patient taking an anticoagulant who is prescribed amikacin for treatment of pneumonia?

abnormal bleeding; Anticoagulants are given to prevent the formation of a clot or thrombus. When they are combined with an aminoglycoside they cause anticoagulant toxicity by inhibiting the action of vitamin K in the body. Therefore the nurse should check for abnormal bleeding in a patient who is administered both amikacin and anticoagulants. Formation of a thrombus is prevented by anticoagulants, and their effects are not decreased by amikacin. Loss of consciousness is not caused by amikacin or by a drug interaction with anticoagulants. A burning sensation of the feet is a symptom of paresthesia, which is a rare side effect caused by prolonged use of amikacin but is not related to anticoagulants.

Amoxicillin and ampicillin are ______drugs.

aminopenicillin

Nephrotoxicity may be seen with high doses of _____

amphotericin B.

The medication meropenem treats which infection?

bacterial meningitis; Meropenem is used to treat susceptible intraabdominal infections like complicated appendicitis and peritonitis. Because it can cross the blood-brain barrier, meropenem is effective in treating bacterial meningitis. Other lactam drugs are effective for a variety of infections outside the central nervous system, such as cellulitis, pneumonia, and tooth abscess.

A patient with a Streptococcus infection has been prescribed amoxicillin. Which parameter would the nurse monitor in the patient?

bowel habits, sleep patterns; respiratory rate. Diarrhea may occur when using amoxicillin; therefore bowel habits should be monitored. Insomnia is a side effect of amoxicillin; therefore the nurse should monitor the sleep patterns of the patient to check if the patient is having sufficient sleep. Respiratory distress is a life-threatening adverse effect associated with an allergic reaction; therefore the nurse should monitor respiratory rate when administering amoxicillin.

A patient is diagnosed with a respiratory infection caused by staphylococci. Which penicillinase-resistant drug may be included in the prescription?

dicloxacillin; Penicillinase-resistant penicillins are antibiotics that are able to resist breakdown by the penicillin-destroying enzyme. These enzymes are commonly produced by bacteria such as staphylococci. Dicloxacillin is a penicillinase-resistant drug

A patient receiving amikacin is prescribed a loop diuretic. The nurse will primarily monitor for which type of complication?

hearing ability; When administered with aminoglycosides, loop diuretics may increase the risk for ototoxicity, so the nurse should monitor the patient's hearing ability.

The patient taking intravenous gentamicin has elevated blood urea nitrogen (BUN). Which action would the nurse take?

hold the med; Gentamicin has a high potential for nephrotoxicity and is thus contraindicated in patients with elevated renal function tests such as BUN and creatinine. The nurse should hold the medication and call the health care provider.

Which characteristic is common to both tetracyclines and glycopeptides?

inner ear damage; Vancomycin is a glycopeptide that may cause ototoxicity as a side effect. Ototoxicity results in damage to the auditory or vestibular branch of cranial nerve VIII. Damage to the latter causes temporary or permanent loss of balance. Minocycline is a tetracycline that can cause damage to the vestibular part of the inner ear, which may cause difficulty maintaining balance.

The serum levels of warfarin, theophylline, and carbamazepine increase when they are given with _____

macrolides.

A patient being treated for inflammatory bowel disease reports dizziness, headache, confusion, depression, weakness, and lack of sleep. Which medication would the nurse suspect as the cause of the patient's condition?

metronidazole; Metronidazole acts by impairing deoxyribonucleic acid function of susceptible bacteria in gastrointestinal infections such as inflammatory bowel disorders. The general side effects of metronidazole are dizziness, headache, confusion, depression, irritability, weakness, and lack of sleep.

Penicillin G is an example of a _____ penicillin.

natural

Aminoglycosides if used in conjugation with _______ will be rendered inactive.

penicillins

Potassium supplements increase the serum potassium level when taken with ______ but not with cephalosporins.

potassium penicillin G

Which laboratory value would the nurse assess to ensure safe administration of vancomycin to a patient?

renal function; Vancomycin is a tricyclic glycopeptide, which causes nephrotoxicity. Therefore the nurse should check the patient's renal function before administering vancomycin. Renal impairment may lead to severe toxicity. The dosing frequency of vancomycin is dependent on renal function. Therefore it is important to check the patient's renal function.

A patient who is on nonsteroidal antiinflammatory drug (NSAID) therapy is prescribed levofloxacin to treat a lower respiratory tract infection. Which complication would the nurse monitor the patient for?

seizures; Levofloxacin is the drug of choice for severe lower respiratory tract infections. Levofloxacin should not be administered with NSAIDs, because it may cause central nervous system reactions such as seizures.

Encephalopathy is an adverse effect of _____ and may not be seen when levofloxacin is administered along with NSAIDs.

streptomycin sulfate

Which medication would the nurse anticipate incorporating into the plan of care for a patient with acne?

tetracycline; Tetracycline is considered to be a drug of choice for the treatment of acne

Penicillins like amoxicillin and dicloxacillin have a decreased effect when taken with ______ and an increased effect when taken with ______

tetracycline; methotrexate.

Which rationale describes the reason the nurse administers intravenous vancomycin to a patient over 1 hour.

to prevent hypotension; Rapid infusion of vancomycin may precipitate hypotension and cause red man syndrome. Therefore intravenous infusion of vancomycin should be done slowly; edema may be observed because of nephrotoxicity when the drug is given in excess.

Too rapid an intravenous injection of ___ can cause a condition known as red man or red neck syndrome, which is a toxic drug effect characterized by red blotching of the face, neck, and chest.

vancomycin

Ototoxicity is an adverse effect of ____

vancomycin.