In Vitro Interaction between Mycoplasma agalactiae and Small Ruminants' Endogenous Bacterial Strains of Enterococcus spp. and Coagulase-Negative Staphylococcus .

Recently, an antimicrobial effect on Mycoplasma agalactiae (Ma), the main etiological agent of contagious agalactia (CA), was reported in vitro with strains of Enterococcus spp. from ovine and caprine milk. The aim of this work was to evaluate the interaction of Ma with the same Enterococcus spp. isolated from other anatomical locations (vagina) and other bacterial populations present in milk, such as coagulase-negative staphylococci (CNS). The vaginal Enterococcus strains and the raw milk CNS were isolated from sheep and goats. Experimental in vitro conditions were prepared to assess the growth of Ma with and without the presence of these strains. The selected vaginal strains were identified as Enterococcus (E.) hirae and E. mundtii, and the strains of CNS were identified as Staphylococcus petrasii . Different interactions of Ma with ovine and caprine wild vaginal strains of Enterococcus and dairy strains of CNS are described for the first time: Ma can grow exponentially during 15 h with the selected strains, although with certain strains, its optimal growth can be negatively affected ( p < 0.05). The colonization and/or excretion of Ma could, therefore, be influenced by certain endogenous bacterial strains. Our results increase the knowledge about possible bacterial ecology dynamics surrounding CA.