MINIMUM INHIBITORY CONCENTRATION Cymbopogon citratus ESSENTIAL OIL AGAINST Streptococcus suis TYPE II

Streptococcus suis serotype 2 is an important swine pathogen associated with arthritis, meningitis, pericarditis, pneumonia, septicemia, sudden death and also associated with human diseases. Streptococcus suis is emerging as a threat to animal health worldwide including in Brazil where serotype 2 is most prevalent in the South and Southeast. Several virulence factors have been proposed to be involved in the pathogenesis of infection. The most important of these is the capsular polysaccharide, which confers anti-phagocytic properties to the pathogen. In addition, the bacterial cell wall and modifications of its components, such as N-deacetylation of peptidoglycan and D-alanylation of lipoteichoic acids, also contribute to the virulence of Streptococcus suis. The objective of this study was to determine the minimum inhibitory concentration of the essential oil of Cymbopogon citratus against 3 strains of Streptococcus suis Type II. The experiment was carried out at the Laboratory of Veterinary Microbiology and Packaging Analysis Laboratory of the IFC-Campus Concordia. The chemical composition of the OE was performed by gas chromatography coupled to the mass spectrometer and three isolates of Streptococcus suis Type 2 from pigs with systemic diarrhea were used. The main compounds of the EO were mirceno with 17.08%, neral 29.89% and geraniol 40.40%. For the Minimum Inhibitory Concentration (MIC) test, the inoculum carpet was performed with the final concentration of 108 CFU mL-1. The EO was diluted in 100% PA ethanol (Merck, Germany) in concentrations: 50%; 25%; 12.5%; 6.25%; 3.125%; 1.56%; 0.78% and 0.39%; 5 μl of EO was used for filter paper disks (N. 103) with 6 mm diameter. The negative control was prepared using only the solvent (ethanol). The discs were placed on Mueller Hinton medium (MH) plates containing 5% sheep blood containing the carpet of the microorganisms and incubated at 37 ° C for 24 hours. The inhibitory halos were measured with pachymeter. Different concentrations were determined as inhibitory minimums among the isolates. For isolate 1, MIC was 6.25%, for isolates 2 and 3 inhibitory halos were obtained from the concentration of 12.5%. Thus, Streptococcus suis presented sensitivity to the EO of Cymbopogon citratus, making possible from these preliminary results, to carry out more detailed and applied studies.