Background: Mastitis affects up to 33 percent of lactating mothers and is a common reason why women stop breastfeeding. It can also be difficult to treat because of its polymicrobial nature. Several strains of lactobacilli have shown promise as probiotic agents that might be useful in treating mastitis. Arroyo and colleagues compared the effectiveness of probiotic and antibiotic therapies in women with lactation-associated mastitis.

The Study: A total of 352 women with mastitis symptoms were randomized to receive one of three treatments: a daily capsule with 200 mg of a freeze-dried probiotic containing 9 log₁₀ colony-forming units (CFUs) per mL of Lactobacillus fermentum (CECT5716), a similar amount of Lactobacillus salivarius (CECT5713), or an antibiotic prescribed by their physician. Patients were followed for 21 days, with pain scores and breast milk samples obtained at the beginning and end of the study. All patients had breast inflammation, painful breastfeeding, and initial milk bacterial counts of more than 4 log₁₀ CFU per mL. Women with mammary abscesses, Raynaud syndrome, or any other breast-related pathology were excluded.

Results: Initial pain scores and bacterial counts were similar among the three groups. The three most common bacterial species identified were Staphylococcus epidermidis, Staphylococcus aureus, and Streptococcus mitis in statistically similar proportions among groups. By day 21, a greater bacterial reduction occurred in women receiving probiotics compared with antibiotics, with the greatest reduction in the L. salivarius group. Breast pain scores were also significantly lower in the probiotic groups, with complete recovery in 88 percent of the L. fermentum and 85 percent of the L. salivarius group by day 21, compared with 28.7 percent of the antibiotic group. Recurrence of mastitis was also significantly more common in the antibiotic group than in the L. fermentum or L. salivarius group (30.7, 10.5, and 7.1 percent, respectively).

Conclusion: The authors conclude that L. fermentum or L. salivarius is an effective alternative to antibiotics for the treatment of infectious mastitis during lactation.