Antibacterial activity of Eugenia uniflora L. leaves extracts against clinical isolates of Streptococcus agalactiae

WINNIK, D.; BOBADILLA, F.; NOVOSAK, M.; KACHUK, A.; LACZESKI, M.; QUIROGA, M.

Santiago de Chile

Congreso; XXIV Congreso Latinoamericano de Microbiología; 2018

Sociedad Latinoamericana de Microbiología-Sociedad de Microbiología de Chile

Streptococcus agalactiae (GBS) causes invasive diseases in human and is a pathogen that affects livestock and fish.Streptococcosis is considered a destructive disease as it can cause massive fish death and is responsible for large economic losses worldwide. The most common strategy for the treatment of infectious diseases is the use of antibiotics.However, drug resistance has become an increasingly serious problem, what makes the development of alternative antibiotics a very urgent issue. Based on folk medicine in the Guaranitic region of South America, Eugenia uniflora L. (?pitanga?) leaves are commonly used for antihypertensive, diuretic and antimicrobial purposes. The aim of this study was to search for antimicrobial activity of leaf extracts of Eugenia uniflora L. against clinical isolates of GBS. The extracts were prepared from leaves collected in Oberá, Misiones Province, Argentina. They were obtained by controlled digestion at 37°C for 24 h and 48 h using water and ethanol, respectively. The antimicrobial activity was tested against fifteen strains of GBS, using the disc diffusion method and the Minimum Inhibitory Doses (MID) were calculated. The ethanolic extract was used to determine the Minimum Inhibitory Concentration (MIC) and the Minimum Bactericidal Concentration (MBC) by the broth dilution method. Aqueous and ethanolic extracts of pitanga showed the same inhibitory activity by the disc diffusion method (median MID= 3 mg disco-1, range =2) without significant differences (P-value = 0.57). The ethanolic extract inhibited the development of GBS at a MIC value of 1.4 mg mL-1 (SD=0.69) and a MBC value of 5.3 mg mL-1 (SD=2.65). The MBC/MIC ratio was 4.33 (SD=2.62). We conclude that the ethanolic extract of E. uniflora L. has antimicrobial activity against GBS. This activity would be bacteriostatic according to the values obtained and the available bibliography. These results indicate the need to continue with the studies to identify and characterize responsible metabolites that could represent new sources to develop products with application in human and animal medicine.