Question 1

A patient is taking dicloxacillin (Dynapen)500 mg every 6 hours to treat a severe penicillinase-resistant infection.At a 1-week follow-up appointment,the patient reports nausea,vomiting,and epigastric discomfort.The primary care NP should:

A) change the medication to a cephalosporin.
B) decrease the dose to 250 mg every 6 hours.
C) reassure the patient that these are normal adverse effects of this drug.
D) order blood cultures, a white blood cell (WBC) count with differential, and liver function tests (LFTs).

Accepted Answer

When giving penicillinase-resistant penicillins,it is important to monitor therapy with blood cultures,WBC with differential cell counts,and LFTs before treatment and weekly during treatment.This patient may have typical gastrointestinal side effects,but the symptoms may also indicate hepatic damage.Changing the medication is not indicated,unless serious side effects are present.Decreasing the dose is not indicated.

Question 2

A sexually active woman is being treated for streptococcal pharyngitis.The patient takes oral contraceptive pills (OCPs).Which penicillin should the primary care NP prescribe for this patient?&#10;A) Ampicillin&#10;B) Penicillin V&#10;C) Penicillin G&#10;D) Dicloxacillin

Accepted Answer

Although penicillin V is the drug of choice,ampicillin and penicillin G can be used to treat streptococcal pharyngitis.Penicillin G is the only penicillin that does not interfere with OCPs.Dicloxacillin is not recommended to treat streptococcal pharyngitis.

Question 3

The primary care NP administers penicillin G (Bicillin)to a 75-year-old patient who has COPD and heart failure.The patient takes digoxin,warfarin,and spironolactone.To help prevent drug interactions,the NP should order:

A) serum electrolytes.
B) coagulation studies.
C) creatinine clearance.
D) liver transaminases aspartate aminotransferase and alanine aminotransferase.

serum electrolytes.

Accepted Answer

Penicillin G can cause hyperkalemia,which can increase digoxin toxicity,so serum electrolytes should be monitored.Penicillin G does not interact with warfarin or spironolactone.Coagulation studies,creatinine clearance,and LFTs are not indicated in this circumstance.

Question 4

A patient with otitis media is treated for 10 days with amoxicillin.At the follow-up visit,the primary care NP notes bilateral erythematous,bulging tympanic membranes.The NP should prescribe:&#10;A) intramuscular injection of penicillin G (Bicillin).&#10;B) amoxicillin for 10 more days.&#10;C) oral dicloxacillin (Dynapen) for 10 days.&#10;D) oral amoxicillin-clavulanate (Augmentin) for 10 days.

Accepted Answer

Antibiotic resistance to penicillins occurs through three mechanisms,the most important being bacteria producing b-lactamase,which breaks down the b-lactam ring and renders the penicillin inactive.Clavulanic acid,used in combination with penicillins,prevents this inactivation.The NP should prescribe amoxicillin-clavulanate.Giving 10 more days of amoxicillin would not be effective.Dicloxacillin is used when resistance is caused by penicillinase-resistant staphylococcal infection.Penicillin G is not used to treat otitis media.

Question 5

A patient with group A b-hemolytic streptococcal pharyngitis is treated with penicillin V.At a follow-up visit 2 weeks later,the patient presents with edema of the hands and feet,blood pressure of 140/85 mm Hg,and cola-colored urine.A urine dipstick shows proteinuria.The primary care NP should:

A) perform a repeat throat culture.
B) prescribe 10 more days of penicillin V.
C) obtain an ASO titer and creatinine clearance.
D) order oral amoxicillin-clavulanate for 14 days.

Accepted Answer

A minimum of 10 days of treatment is recommended for any infection caused by group A b-hemolytic streptococcus to prevent the occurrence of rheumatic fever or acute glomerulonephritis.This patient shows signs of acute glomerulonephritis,so the NP should obtain an ASO titer and creatinine clearance to help confirm the diagnosis.It is not necessary to repeat the throat culture.Treatment involves controlling blood pressure and maintaining renal function,not giving antibiotics.

Question 6

A patient was seen in a local emergency department and was treated empirically for pharyngitis with ampicillin and comes to the clinic 2 days later with an urticarial rash.The patient has no previous history of atopy and does not have respiratory symptoms.The primary care NP should suspect:

A) scarlatina.
B) mononucleosis.
C) serum sickness.
D) penicillin allergy.

Accepted Answer

A nonallergic urticarial rash occasionally occurs with ampicillin and is common in patients with mononucleosis.This patient has pharyngitis,which was not diagnosed by throat culture.The NP should suspect mononucleosis and a nonallergic rash.Serum sickness and penicillin allergy are possible but less likely.A scarlatiniform rash is not urticarial.

Question 7

A primary care nurse practitioner (NP)sees a 3-year-old child who has a history of recurrent otitis media.The child's parent tells the NP that the child is allergic to penicillin.The NP learns that the child developed an all-over rash 2 days after starting amoxicillin at age 2 years.The NP should:

A) order a penicillin skin test.
B) use cephalosporins when treating otitis media.
C) order penicillin desensitization so the child can take penicillin when needed.
D) use amoxicillin when needed because actual allergy correlates poorly with patient report.

Accepted Answer

Although it is true that patient report correlates poorly with actual allergy,there is a risk of life-threatening anaphylaxis with a true penicillin allergy.The NP should order a penicillin skin test to verify allergy.If the skin test is positive,the patient should avoid b-lactam antimicrobials.Penicillin desensitization can be used for penicillin-allergic patients who need penicillins.

Deck 59: Penicillins