A 33-year-old woman, gravida 1 para 0, at 39 weeks gestation comes to the hospital for a scheduled elective induction. She has had no contractions, vaginal bleeding, or leakage of fluid. Fetal movement is normal. Her pregnancy has been uncomplicated except for a positive group B Streptococcus (GBS) rectovaginal culture at 36 weeks gestation with resistance to erythromycin. The patient has no chronic medical conditions and has had no prior surgeries. She developed a nonpruritic maculopapular rash after taking penicillin in her 20s. Vital signs are normal. Abdomen is soft, gravid, and nontender. The cervix is 1 cm dilated and 60% effaced with the fetal vertex at -2 station. Fetal heart rate tracing is category 1. Given this patient's penicillin allergy, which of the following is the most appropriate pharmacotherapy for this patient?

Question

A 33-year-old woman, gravida 1 para 0, at 39 weeks gestation comes to the hospital for a scheduled elective induction.  She has had no contractions, vaginal bleeding, or leakage of fluid.  Fetal movement is normal.  Her pregnancy has been uncomplicated except for a positive group B Streptococcus (GBS) rectovaginal culture at 36 weeks gestation with resistance to erythromycin.  The patient has no chronic medical conditions and has had no prior surgeries.  She developed a nonpruritic maculopapular rash after taking penicillin in her 20s.  Vital signs are normal.  Abdomen is soft, gravid, and nontender.  The cervix is 1 cm dilated and 60% effaced with the fetal vertex at -2 station.  Fetal heart rate tracing is category 1.  Given this patient's penicillin allergy, which of the following is the most appropriate pharmacotherapy for this patient?

Quizplus · Accepted Answer

11ec25c8_da3b_77ac_bc81_eb50e219ec3b_MD0003_00 Antenatal screening for group B Streptococcus (GBS) is generally performed at 36-38 weeks gestation, and patients with a positive culture require intrapartum antibiotic prophylaxis (IAP) to prevent early-onset neonatal GBS infection (Choice C). Intravenous penicillin and ampicillin are first-line agents because they reach high bactericidal concentrations in the amniotic fluid rapidly (eg, within 3-4 hours), have no fetal toxicity, and have a narrow spectrum of coverage, thereby minimizing bacterial resistance. In patients with a penicillin allergy, IAP is chosen based on risk for anaphylaxis. This patient's prior nonpruritic maculopapular rash is considered low risk for anaphylaxis, but the same rash may recur if she is administered penicillin. Therefore, cefazolin (a first-generation cephalosporin) is the most appropriate pharmacotherapy for this patient. Cephalosporins have a lower risk of cross-reactivity but achieve the same high bactericidal concentrations in the amniotic fluid without fetal toxicity. (Choices B and E) In GBS-positive patients with a severe penicillin allergy (ie, reactions with a high risk for anaphylaxis, such as respiratory distress or urticaria), dual sensitivity testing of GBS isolates to both clindamycin and erythromycin is performed because erythromycin resistance is associated with inducible clindamycin resistance. In patients who are sensitive to both, IAP is with clindamycin. In patients who are resistant to clindamycin or erythromycin or for whom sensitivities are unavailable, IAP is with vancomycin. However, because vancomycin does not reach bactericidal concentrations in the amniotic fluid, infants of patients treated with vancomycin may require additional neonatal observation and evaluation. This patient with a penicillin allergy that is low risk for anaphylaxis can receive cefazolin. (Choice D) Nearly all GBS isolates have resistance to trimethoprim-sulfamethoxazole (TMP-SMX). In addition, TMP-SMX is avoided in the final month of pregnancy because it increases the risk of neonatal kernicterus. Educational objective: Pregnant patients positive for group B Streptococcus (GBS) receive intrapartum antibiotic prophylaxis to prevent early-onset neonatal GBS disease. Patients with a penicillin allergy that is low risk for anaphylaxis receive cefazolin. References: Prevention of perinatal group B streptococcal disease--revised guidelines from CDC, 2010. (http://www.ncbi.nlm.nih.gov/pubmed/21088663)

A 33-Year-Old Woman, Gravida 1 Para 0, at 39 Weeks