Maternal bacteremia in intrapartum fever: the role of ampicillin resistance and prolonged membrane rupture—a retrospective comparative study

Archives of Gynecology and Obstetrics https://doi.org/10.1007/s00404-025-08030-6 RESEARCH Maternal bacteremia in intrapartum fever: the role of ampicillin resistance and prolonged membrane rupture—a retrospective comparative study Raneen Abu Shqara1,2 · Omer Saporta2 · Daniel Glikman2 · Lior Lowenstein1,2 · Maya Frank Wolf1,2 Received: 16 February 2025 / Accepted: 7 April 2025 © The Author(s) 2025 Abstract Objective Intrapartum fever (IPF) (≥ 38.0 °C), if treated inappropriately, can lead to maternal bacteremia. In a cohort of women with IPF, we investigated perinatal, obstetrical, and microbiological outcomes, comparing those with bacteremia to those with negative blood cultures. Methods A retrospective cohort study at a tertiary hospital (2010–2022) focused on women attempting vaginal delivery who were diagnosed with IPF. Outcomes were compared between those with bacteremia vs. negative blood cultures. After delivery, chorioamniotic swab cultures were obtained. Bacterial distribution and rates of ampicillin-resistant Enterobacteriaceae in blood and swab cultures were described. Women with Group B streptococcal colonization or prolonged rupture of membranes (ROM) received prophylactic ampicillin. The results were compared using univariate and multivariate analysis. Results Overall, 78 women had bacteremia, and 341 had negative blood cultures. Women with bacteremia had higher rates of endometritis (p = 0.016), Apgar-5 < 7 (p = 0.021) and umbilical cord pH < 7.1 (p = 0.008). In multivariate analysis, prolonged ROM (p = 0.028) and prophylactic ampicillin (p = 0.036) were linked to maternal bacteremia. Maternal bacteremia (p < 0.001) was associated with higher endometritis and NICU admission rates. Blood cultures and chorioamniotic swab cultures matched in 65.9% of cases. Ampicillin-resistant Enterobacteriaceae spp. were found in 70.2% of blood cultures and 90.6% of chorioamniotic swab cultures. The rate of Enterobacteriaceae-isolated maternal bacteremia was higher among preterm than term deliveries (p = 0.034); while the rate of GBS-isolated bacteremia was lower (p < 0.001). Conclusion Ampicillin-resistant Enterobacteriaceae rates in blood and chorioamniotic swab cultures were concerning. Prolonged ROM and prophylactic ampicillin were associated with higher maternal bacteremia rates. Appropriate use of intrapartum antibiotics is essential. Keywords Ampicillin · Bacteremia · Chorioamnionitis · Neonatal morbidity · Intrapartum fever · Enterobacteriaceae What does this study add to the clinical work This study highlights the high prevalence of ampicillin-resistant Enterobacteriaceae as a cause of maternal peripartum bacteremia. It identifies prolonged ROM and prophylactic ampicillin as risk factors for maternal bacteremia, emphasizing the need for judicious antibiotic use. * Raneen Abu Shqara 1 Department of Obstetrics & Gynecology, Raya Strauss Wing of Obstetrics and Gynecology, Galilee Medical Center, PO Box 21, 22100 Nahariya, Israel 2 Azrieli Faculty of Medicine, Bar Ilan University, Safed, Israel Vol.:(0123456789) Archives of Gynecology and Obstetrics Introduction The prevalence of intrapartum fever (IPF), defined as a body temperature ≥ 38.0 °C, varies widely [1, 2]. IPF may be associated with an infectious or noninfectious etiology, such as epidural analgesia and the use of prostaglandins. Risk factors for IPF include prolonged labor, prolonged rupture of membranes (ROM), preterm prelabor ROM (PPROM) and nulliparity [3]. True maternal sepsis is rare; only an estimated 1.4% of pregnant patients with term clinical chorioamnionitis develop severe sepsis [1]. Sepsis is currently defined as life-threatening organ dysfunction caused by a dysregulated host response to infection [4]. As the gold standard for diagnosing sepsis in pregnancy has not been determined, the diagnosis of bacteremia, according to a positive blood culture, might identify patients at risk of adverse outcomes [5–7]. Ashwal et al. reported a 4.5% rate of maternal bacteremia among patients with IPF [8]. A few studies focused on the microbiological origin of intrapartum bacteremia [9–11]. Enterobacteriaceaeassociated bacteremia was reported to occur predominantly in the third trimester of pregnancy and was most frequently associated with urinary infections, followed by genital ascending infections [9]. Rates of prematurity were substantially higher among patients with Gram-negative than Gram-positive isolated bacteremia [11]. Despite substantial advances in medical practice, maternal sepsis remains a major and potentially preventable cause of maternal mortality and morbidity worldwide [12]. Among patients with IPF and available blood culture results, we aimed to identify risk factors associated with bacteremia and to examine associations between maternal bacteremia and adverse perinatal and obstetrical outcomes. In addition, we sought to investigate the distribution of pathogens in chorioamniotic swab cultures in patients with positive and negative blood culture results, and to compare the rates of maternal bacteremia between patients with PPROM and preterm labor. Methods Study population This retrospective study included pregnant patients who attempted vaginal delivery in a tertiary university-affiliated hospital between January 2010 and January 2022. The Institutional Review Board of the Galilee Medical Center approved the study. Included were pregnant patients with a singleton pregnancy who attempted vaginal delivery, with a fever > 38 °C and an available blood culture result. Exclusion criteria were multiple pregnancy, major fetal anomalies, intrauterine fetal death and the absence of an available blood culture or other missing data. The data were extracted from our electronic medical records and a chart review was performed. Outcome measures Chorioamnionitis was defined as a maternal temperature greater than or equal to 39.0 °C, or maternal temperature of 38.0–38.9 °C and one additional clinical risk factor, such as maternal leukocytosis > 15,000/mm2, purulent cervical drainage and fetal tachycardia (> 160 beats/min) [13]. Endometritis was defined based on a fever ≥ 38 °C in the absence of any other cause, together with an associated clinical finding such as uterine tenderness, purulent lochia, tachycardia or abdominal pain. Early-onset sepsis (EOS) was defined as culture-proven sepsis during the 7 days from birth. PPROM was defined as ROM prior to 37 weeks of pregnancy. PPROM antibiotic treatment consisted of intravenous ampicillin (2 g every 6 h for 48 h), followed by oral amoxicillin (500 mg every 8 h) for an additional five days, and simultaneously with oral roxithromycin (150 mg twice daily for 7 days). The study had several objectives: (a) to compare the co-primary outcomes of puerperal endometritis and neonatal intensive care unit (NICU) admission between patients with positive and negative blood cultures (b) to identify clinical and obstetrical risk factors for bacteremia in pa (...truncated)