Prevention of Mastitis with Probiotics
by Anne Eglash MD, IBCLC, FABM
Anyone reading this knows that mastitis is a highly undesired event that lactating individuals would like to prevent. Pain during lactation is a top reason for prematurely weaning, as is low milk production, which often complicates advanced cases of mastitis. Mastitis is a risk factor for breast abscesses, which incur health care costs, painful and frightening procedures, and significantly increase the risk of premature weaning. A history of recurrent mastitis is a risk factor for lower intention to breastfeed/lactate.
The article for this week is a multicenter randomized double-blinded placebo-controlled trial involving the administration of ligilactobacillus salivarius PS2 vs placebo (formerly known as lactobacillus salivarius) to 328 subjects who are from Spain, Poland, Germany, or Austria. The subjects received either L salivarius PS2 or placebo daily from the 35th week of pregnancy until the 12th week postpartum. The researchers contacted the subjects within 7 days postpartum, at 6 weeks and 12 weeks postpartum. If a participant had symptoms of mastitis (breast pain, redness, engorgement, and/or fever), they were seen in the office and the mastitis was evaluated for a severity rating.
A total of 9.7% of all subjects developed mastitis, and mastitis was more common in the placebo group.
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Mastitis is considered one of the main reasons for unwanted breastfeeding cessation. This study aimed to investigate the preventive effect of the probiotic strain Ligilactobacillus salivarius PS2 on the occurrence of mastitis in lactating women. In this multicountry, multicenter, randomized, double-blind, placebo-controlled trial, 328 women were assigned to the probiotic or the placebo group. The intervention started from the 35th week of pregnancy until week 12 post-partum. The primary outcome was the incidence (hazard) rate of mastitis, defined as the presence of at least two of the following symptoms: breast pain, breast erythema, breast engorgement not relieved by breastfeeding, and temperature > 38 °C. The probability of being free of mastitis during the study was higher in the probiotic than in the placebo group (p = 0.022, Kaplan–Meier log rank test) with 9 mastitis cases (6%) vs. 20 mastitis cases (14%), respectively. The hazard ratio of the incidence of mastitis between both study groups was 0.41 (0.190–0.915; p = 0.029), indicating that women in the probiotic group were 58% less likely to experience mastitis. In conclusion, supplementation of L. salivarius PS2 during late pregnancy and early lactation was safe and effective in preventing mastitis, which is one of the main barriers for continuing breastfeeding.
The women given Ligilactobacillus salivarius PS2 had a 58% lower likelihood of developing acute mastitis (defined by at least 2 symptoms: fever, breast redness, pain and/or engorgement).
Among all participants with a diagnosis of mastitis, those who received probiotics were less likely to be given antibiotics for their mastitis (44%), as compared to those who received placebo (72.7%).
Although not clinically significant, the participants receiving the probiotics reported less severe symptoms of mastitis compared to those who received the placebo.
The mechanism of effect is not simply that ingestion of the probiotic increases L salivarius in the lactating breast. Human milk sample analysis from the ProPact Study found that treatment with a beverage with several probiotics given to pregnant and lactating women did not result in higher amounts of those probiotics in the milk. However, there were other changes, such as differences in the amount of staph and strep species in the milk, and less subacute mastitis during lactation.
The authors of this study hypothesize that L. salivarius may exert anti-inflammatory and immune-modulatory effects in the lactating breast. They discuss data from other studies showing such effects on human milk bacterial counts, white cell counts, and changes in levels of anti-inflammatory agents.
I don’t know if this exact preparation of L salivarius PS2 is commercially available, as it was made for this study by DuPont in Madison Wisconsin. It is quite possible that other forms of L salivarius may not be as effective.