1. Wisner, Kirsten MS, RNC, CNS

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Universal screening for maternal group B streptococcus (GBS) colonization at 35 to 37 weeks' gestation and intrapartum antibiotic prophylaxis in GBS-positive laboring women have been highly effective in reducing incidence of early-onset GBS disease in newborns (Centers for Disease Control and Prevention [CDC], 2010). However, compliance with important details in the CDC guideline regarding antimicrobial susceptibility testing in penicillin-allergic women remains unacceptably low (Paccione & Wiesenfeld, 2013; Pelaez, Gelber, Fox, & Chasen, 2009), even despite institutional efforts to improve adherence (Critchfield, Lievense, Raker, & Matteson, 2011). This leaves babies born to these women at risk of GBS infection. Lack of understanding about antibiotic resistance in GBS isolates may cause clinicians to mistakenly assume that a baby has been protected and fail to recognize signs and symptoms of GBS disease in babies whose mothers have been inadequately treated with an ineffective antibiotic. Here is brief summary of the 2010 CDC's recommendations for antimicrobial susceptibility testing in penicillin-allergic women and recommended antibiotic treatment regimens in this population.


Group B streptococcus isolates' resistance to erythromycin and clindamycin have risen. Resistance was estimated at 25% to 32% for erythromycin and 13% to 20% for clindamycin in reports published during 2006-2009, causing erythromycin to be removed from the treatment guidelines in 2010 (CDC, 2010).


Penicillin-allergic, GBS-positive women should be screened for the nature of the reported penicillin allergy, and cefazolin should be used as an alternative to penicillin or ampicillin in women at low risk for anaphylaxis. High risk for anaphylaxis is defined as having had anaphylaxis, angioedema, respiratory distress, or urticaria after administration of a penicillin or cephalosporin (CDC, 2010). Cross-reactivity to first-generation cephalosporins (e.g., cefazolin) is estimated at 1%, and anaphylactic reactions to cephalosporins are estimated to be very rare at <=0.1% (Paccione & Wiesenfeld, 2013). Many women reporting a penicillin allergy report side effects rather than true hypersensitivity and are eligible to receive cefazolin.


Antimicrobial susceptibility testing should be done on GBS isolates from penicillin-allergic women at high risk for anaphylaxis. These women should receive clindamycin for intrapartum antibiotic prophylaxis only if their GBS isolate demonstrates susceptibility to both clindamycin and erythromycin. If the isolate was susceptible to clindamycin but resistant to erythromycin, further testing for inducible resistance to clindamycin should be performed (CDC, 2010). Further guidance on appropriate laboratory protocols for GBS isolate testing can be found at


Vancomycin should be reserved for penicillin-allergic women at high risk for anaphylaxis when there is confirmed resistance to clindamycin per appropriate laboratory protocols, or if susceptibility to clindamycin is unknown.


Adherence to the CDC guidelines for antimicrobial susceptibility testing and use of appropriate antibiotics are suboptimal (Critchfield et al., 2011; Paccione & Wiesenfeld, 2013; Pelaez et al., 2009) because in these studies, many women eligible to receive cefazolin did not, clindamycin was administered without confirmation of antimicrobial susceptibility, and vancomycin was overused due to failure to perform susceptibility testing or because of a poor interpretation of the guidelines.


Perinatal nurses are uniquely positioned to mitigate harm to babies who have been inadequately protected from GBS infection by understanding appropriate prophylactic antibiotic use in GBS-positive, penicillin-allergic women and discussing this with obstetrical and pediatric providers. Adherence to important details in the CDC guidelines can be advanced by promoting awareness of them to physician, laboratory, and leadership colleagues.




Centers for Disease Control and Prevention. (2010). Prevention of perinatal group B streptococcal disease: Revised guidelines from CDC, 2010. MMWR, 59(RR-10), 1-36. Retrieved from[Context Link]


Critchfield A. S., Lievense S. P., Raker C. A., Matteson K. A. (2011). Group B Streptococcus prophylaxis in patients who report a penicillin allergy: A follow-up study. American Journal of Obstetrics and Gynecology, 204(2), 150-e8.e1-e8. doi:10.1016/j.ajog.2010.08.063 [Context Link]


Paccione K. A., Wiesenfeld H. C. (2013). Guideline adherence for intrapartum group B streptococci prophylaxis in penicillin-allergic patients. Infectious Diseases in Obstetrics and Gynecology, 2013, 917304. doi:10.1155/2013/917304 [Context Link]


Pelaez L. M., Gelber S. E., Fox N. S., Chasen S. T. (2009). Inappropriate use of vancomycin for preventing perinatal group B streptococcal (GBS) disease in laboring patients. Journal of Perinatal Medicine, 37(5), 487-489. doi:10.1515/JPM.2009.090 [Context Link]