Avaliação da atividade antimicrobiana de Lactobacillus spp. sobre bactérias isoladas do útero de éguas: estudo in vitro

Abstract

The indiscriminate use of antimicrobials in the treatment of bacterial endometritis in mares has contributed to the increase in bacterial resistance, thereby encouraging the search for alternative therapeutic strategies. In this context, the use of lactic acid bacteria (LAB) for the prevention and control of dysbiosis associated with vaginitis and endometritis is widely described in humans and cattle, with more recent studies in equines. Thus, the present study evaluated, in vitro, the effect of Lactobacillus acidophilus (LA01), L. plantarum (LP09), L. rhamnosus GG (LRGG), and L. delbrueckii (LD327), tested individually and in combination (LA01+LP09 and MIX4), against bacteria isolated from the uterus of mares with and without active endometritis, including Acinetobacter baumannii, four strains of Escherichia coli, Enterobacter cloacae, Streptococcus equi, Staphylococcus warneri, Actinobacillus equi, Klebsiella pneumoniae, Pasteurella aerogenes, and Pseudomonas aeruginosa. The assays were performed using spot formation on MRS agar, chloroform inactivation, and subsequent inoculation of the pathogenic strains, with inhibition zones evaluated after 24 hours of incubation at 37 °C. The results demonstrated moderate to strong antimicrobial activity for most of the LAB tested, with inhibition halos ≥15 mm, with L. rhamnosus GG standing out for presenting the largest and broadest spectrum of inhibition (>20 mm). The other strains showed more selective activity, whereas MIX4 inhibited almost all microorganisms, except Staphylococcus warneri. Therefore, probiotic strategies associated with clinical protocols based on laboratory testing appear promising for the treatment and prevention of equine endometritis, contributing to greater therapeutic efficacy, reproductive safety, and control of antimicrobial resistance.