You will act as a medical professor who is an expert in teaching and preparing students for the USMLE Step 3 Examination. Create a table by summarizing the following information to show the high yeild concepts with an emphasis on microbiology and pharmacology concepts that are tested on the USMLE Step 3 Examination: 

This patient has fever >24 hours postpartum and uterine fundal tenderness, findings consistent with postpartum endometritis, the most common cause of postpartum fever.  Other presenting features include purulent vaginal discharge, boggy uterus, and increased vaginal bleeding.  Postpartum endometritis is a polymicrobial infection of the uterine decidua caused by ascending vaginal flora during labor, delivery, or the immediate postpartum period.  Therefore, infection is common in patients with prelabor rupture of membranes (ie, membrane rupture prior to the onset of contractions at ≥37 weeks gestation) or with protracted labor because both increase exposure of the uterine cavity to ascending bacteria.

Given the polymicrobial nature of postpartum endometritis, a broad-spectrum intravenous antibiotic regimen that includes penicillin-resistant anaerobic coverage is required.  The most appropriate therapy is clindamycin plus gentamicin.  Clindamycin covers aerobic gram-positive cocci and penicillin-resistant anaerobes (eg, Bacteroides fragilis).  Gentamicin covers gram-negative (eg, Escherichia coli) and some gram-positive (eg, Staphylococcus) bacteria.  Treatment is continued until the patient is afebrile for 24 hours.

(Choice A)  Ampicillin plus gentamicin is a broad-spectrum regimen commonly used to treat intrapartum intraamniotic infection.  However, postpartum endometritis involves significantly greater anaerobic activity, and this regimen does not cover penicillin-resistant anaerobes.  However, ampicillin-sulbactam is an acceptable alternate regimen.

Intraamniotic infection is a polymicrobial infection of the placenta, amniotic fluid, membranes, or fetus; it presents with fever, maternal and/or fetal tachycardia, and uterine tenderness. Neonatal/fetal complications include in utero meconium passage, Apgar scores <6, and respiratory distress (eg, tachypnea, nasal flaring, grunting).

(Choice B)  Cefoxitin plus doxycycline, which covers Neisseria gonorrhoeae and Chlamydia trachomatis, is used to empirically treat pelvic inflammatory disease, which is also a polymicrobial infection of the upper genital tract.  However, it is not appropriate therapy in this patient because of lack of sufficient anaerobic coverage.  In addition, doxycycline is avoided in pregnancy and while breastfeeding due to its potential teratogenic effects.

(Choice C)  In pregnant or breastfeeding patients, ceftriaxone plus azithromycin is the preferred regimen for the empiric treatment of acute cervicitis due to N gonorrhoeae and C trachomatis.  However, neither antibiotic has anaerobic coverage; therefore, this regimen would be inadequate to treat postpartum endometritis.

(Choice E)  Vancomycin is a narrow-spectrum antibiotic effective only against gram-positive organisms (eg, methicillin-resistant Staphylococcus aureus).  It is indicated for the treatment of breast abscesses and for group B Streptococcus prophylaxis in penicillin-allergic patients.