Does doxycycline (Doxycycline) cover Group B Streptococcus (GBS)?

From the Guidelines

Doxycycline does not adequately cover Group B Streptococcus (GBS) and should not be used as a primary treatment for GBS infections. Group B Streptococcus is generally susceptible to beta-lactam antibiotics, with penicillin G or ampicillin being the first-line treatments of choice, as recommended by the CDC guidelines 1. For patients with penicillin allergies, clindamycin or vancomycin are typically recommended alternatives, with the choice of agent depending on the patient's risk of anaphylaxis and the susceptibility of the GBS isolate to these agents 1. Doxycycline, which belongs to the tetracycline class of antibiotics, has limited activity against GBS, and resistance is common. This is because tetracyclines work by inhibiting protein synthesis in bacteria, but many streptococcal species have developed mechanisms to pump the drug out of their cells or otherwise resist its effects.

Some key points to consider when managing GBS infections include:

• The importance of screening for GBS colonization in pregnant women at 35-37 weeks' gestation 1
• The use of intrapartum antibiotic prophylaxis to prevent early-onset GBS disease in newborns, with penicillin G or ampicillin being the preferred agents 1
• The need for alternative agents, such as clindamycin or vancomycin, in patients with penicillin allergies, with the choice of agent depending on the patient's risk of anaphylaxis and the susceptibility of the GBS isolate to these agents 1
• The importance of monitoring for adverse effects and unintended consequences of GBS prevention efforts, including the emergence of resistant organisms and the potential for anaphylaxis associated with antibiotic use 1

In terms of specific treatment recommendations, the most recent guidelines from the CDC recommend the following:

• Penicillin G, 5 million units IV initial dose, then 2.5-3.0 million units every 4 hours until delivery, for women without penicillin allergies 1
• Ampicillin, 2 g IV initial dose, then 1 g IV every 4 hours until delivery, as an alternative to penicillin G 1
• Cefazolin, 2 g IV initial dose, then 1 g IV every 8 hours until delivery, for women with penicillin allergies who are at low risk of anaphylaxis 1
• Clindamycin, 900 mg IV every 8 hours until delivery, or vancomycin, 1 g IV every 12 hours until delivery, for women with penicillin allergies who are at high risk of anaphylaxis, depending on the susceptibility of the GBS isolate to these agents 1

From the Research

Antibiotic Coverage for Group B Strep

• Doxycycline is not mentioned as a recommended antibiotic for Group B Strep (GBS) prophylaxis in the provided studies 2, 3, 4, 5, 6.
• The recommended antibiotics for GBS prophylaxis are penicillin, ampicillin, or cefazolin, with clindamycin and vancomycin reserved for cases of significant maternal penicillin allergy 2, 4, 5, 6.
• There is no evidence to suggest that doxycycline is effective against Group B Strep, and it is not listed as a recommended treatment option in the studies provided 2, 3, 4, 5, 6.

Alternative Antibiotics for Penicillin Allergy

• For patients with a penicillin allergy, clindamycin or vancomycin may be used as alternative antibiotics for GBS prophylaxis 4, 5, 6.
• Cefazolin is also an option for patients with a penicillin allergy, but it is not as commonly used as clindamycin or vancomycin 4, 6.
• The choice of alternative antibiotic may depend on the severity of the penicillin allergy and the results of antibiotic susceptibility testing 4, 5.

Neonatal Outcomes

• The use of alternative antibiotics for GBS prophylaxis in patients with a penicillin allergy may be associated with an increased frequency of postnatal blood draws among neonates 6.
• However, there is no significant difference in other neonatal outcomes, such as NICU admission, bacteremia, or hospital length of stay, between patients who receive alternative antibiotics and those who receive beta-lactam antibiotics 6.