Microbiology and Antibiotic Resistance in Peripartum Bacteremia

Abstract

Objective: To examine the microbiology and associated antibiotic resistance patterns among febrile peripartum women with positive blood cultures.

Methods: We conducted a retrospective cohort study in which we reviewed all bacteremia cases between 2009 and 2016 that occurred between 7 days before and 30 days after delivery. Institutional guidelines include obtaining blood cultures and promptly initiating intravenous antibiotics for all obstetric patients with fever of 100.4°F or higher. We describe antibiotic resistance patterns for the most frequently isolated organisms and perform univariate analyses regarding maternal and neonatal outcomes based on type of bacteremia.

Results: Among 56,835 deliveries, 3,797 (6.7%) obstetric patients had blood cultures drawn and 120 (3.2%) had documented bacteremia. The most commonly cultured organisms were Escherichia coli (17.5%, n=21), Bacteroides species (10.8%, n=13), Enterococcus species (10.8%, n=13), group B streptococci (10.8%, n=13), and group A streptococci (5.0%, n=6). E coli had high rates of resistance to ampicillin (n=17, 81.0%) and extended spectrum beta lactams (n=10, 47.6%). Gram-positive bacteremia was noted in 65/120 patients (54.2%), gram-negative bacteremia in 39/120 (32.5%), and anaerobic bacteremia in 16/120 (13.3%) (P=.02). Neonatal bacteremia was identified in 8/120 cases (6.7%), of which 7/8 (87.5%) were attributable to gram-negative bacteria and 1/8 (12.5%) were attributable to gram-positive bacteremia (P=.004). There were no differences in neonatal death or maternal intensive care unit admission.

Conclusion: Peripartum bacteremia is uncommon, with the most frequently isolated organism being E coli. The evolution of antibiotic resistance patterns in E coli at our institution may be of clinical significance in determining antibiotic choice for peripartum fever.