First survey of cultivable bacteria fromRhipicephalus sanguineus sensu latoand assessment of the antagonism against five microorganisms of clinical importance

Rhipicephalus sanguineus sensu lato (s.l.) is the most widespread tick in the world and is a well-recognized vector of many pathogens that affect dogs and, occasionally, humans. There is scarce information regarding bacterial endosymbionts with antagonistic activity against microorganisms of public health importance. The goal of this work was to analyse the internal cultivable microbiota associated with brown dog ticks and to assess the inhibitory activity of these microorganisms against five common clinical pathogens: Escherichia coli, Bacillus cereus, Salmonella enteritidis, Listeria monocytogenes, and Staphylococcus aureus. Seventy ticks were analysed from four sampling sites located in Nuevo León, Mexico. Bacteria were isolated and identified via the amplification and sequencing of a region of the 16S rDNA gene fragment. DNA sequence BLAST analyses grouped all the isolates into 14 strains, which belonged to 11 different species: Oceanobacillus iheyensis, Staphylococcus epidermidis, Staphylococcus saccharolyticus, Staphylococcus cohnii, Jeotgalicoccus halotolerans, Bacillus clausii, Bacillus megaterium, Serratia marcescens, Pseudomonas stutzeri, Acinetobacter lwoffii, and Micrococcus luteus. Two isolated strains of B. clausii exhibited antagonistic activity against gram-positive and gram-negative food-borne pathogens (Bacillus cereus, Listeria monocytogenes, and Staphylococcus aureus). To our knowledge, this is the first study to describe the inner cultivable microbiota of R. sanguineus s.l.