Risk factors for treatment failure in lactational mastitis: a retrospective cohort study in China

Lactation mastitis is a common postpartum disease. Flucloxacillin is frequently used for treatment, but its efficacy is limited in some cases, potentially causing adverse outcomes such as premature cessation of breastfeeding. This study aimed to identify risk factors for poor treatment outcomes in lactational mastitis managed with flucloxacillin and provide evidence for precise clinical management. A retrospective cohort study was conducted from January to December 2022 at the Chongqing Health Center for Women and Children in China. It included 133 hospitalized patients with acute lactational mastitis treated with flucloxacillin, divided into effective treatment (n = 93) and treatment failure (n = 40) groups. Effective treatment was defined as clinical improvement characterized by a reduction in breast pain and swelling, along with normalization of body temperature within 48 hours of initiating flucloxacillin therapy. Treatment failure was defined as the absence of clinical improvement or worsening of symptoms, necessitating a change in the antimicrobial regimen. Data on patient demographic and clinical characteristics, laboratory findings, and treatment outcomes were collected and analyzed. Among 133 patients, 93 (69.9%) were effectively treated with flucloxacillin, while 40 (30.1%) experienced treatment failure. Binary logistic regression identified onset time ≥3 days (Adjusted OR 2.76, 95% CI 1.22, 6.28) and inflammation located in the nipple/areola area (Adjusted OR 3.28, 95% CI 1.27, 8.49) as independent risk factors for treatment failure. The treatment failure group had longer median fever duration (3 days vs. 1 day, p < 0.001), longer median hospital stay (7 days vs. 4 days, p < 0.001), higher median hospitalization costs (3868 yuan [US$553] vs. 2000 yuan [US$286], p < 0.001), and higher lactation suppression rates (20% vs. 2.2%, p = 0.001). Staphylococcus aureus was the predominant isolate, with a higher isolation rate in the treatment effective group (88% vs. 50%, OR 7.0, 95% CI 1.78, 27.42). The present study identified that treatment failure of flucloxacillin for acute lactational mastitis was significantly associated with disease onset ≥3 days, inflammation in the nipple/areola area, and non-Staphylococcus aureus infections. Early identification and intervention are essential for better outcomes. Developing guidelines that emphasize early intervention may contribute to reducing fever duration, patient discomfort, breastfeeding cessation rates, and healthcare burden.