Avaliação do efeito in vitro de metabólitos de bactérias ácido-láticas sobre bactérias patogênicas isoladas de éguas com endometrite

Abstract

Bacterial endometritis is very common in mares and is the main cause of subfertility in this species. The irrational and excessive use of antibiotics as treatment has led to widespread antimicrobial resistance. Therefore, alternative prophylaxis and treatment methods for this condition are necessary and are being researched, such as the use of lactic acid bacteria as probiotics. The use of Lactobacillus spp. has been gaining prominence, as these microorganisms can produce metabolites and suppressing pathogens present in equine endometritis. This study tested the inhibitory capacity of different strains of Lactobacillus spp., namely Lactobacillus acidophilus, Lactobacillus delbrueckii, Lactobacillus rhamnosus GG, and Lactiplantibacillus plantarum, evaluating, in vitro, the effect of their total metabolites on pathogenic microorganisms found in the uterine environment of mares with endometritis, such as Pasteurella aerogenes, Pseudomonas aeruginosa, and Staphylococcus warneri. To this end, lactic acid bacteria were cultivated and spots formed, which were subsequently inactivated, leaving their total metabolites. Then, after adding the pathogenic strains to the culture medium for their proliferation, they were inoculated onto the plates containing the spots. The in vitro suppressive effects of the probiotic strains on the pathogens were confirmed by the inhibition zones formed around the spots. It was concluded that, among the Lactobacillus spp., Lactobacillus delbrueckii showed the greatest inhibition over Pasteurella aerogenes (P<0.05), Lactobacillus acidophilus over Pseudomonas aeruginosa (P<0.05), and that Staphylococcus warneri was not inhibited by Lactobacillus rhamnosus GG, and its inhibition by the others showed no statistical difference (P>0.05). Except for the absence of inhibition of Lactobacillus rhamnosus GG over Staphylococcus warneri, all probiotics showed at least moderate suppression means. Pasteurella aerogenes was the most inhibited pathogenic bacteria, and Staphylococcus warneri the least inhibited. Lactobacillus delbrueckii had a very strong inhibitory capacity for all pathogenic bacteria, being considered the best probiotic. These promising results reinforce the ability of lactic acid bacteria to suppress pathogenic bacteria, making their use a potential alternative to conventional treatments, minimizing growing antibiotic resistance.