CONICET | Buscador de Institutos y Recursos Humanos

Yersinia enterocolitica is a Gram-negative coccobacillus belonging to Enterobactereaceae family. It is an important foodborne pathogen causing gastrointestinal disease in humans known as yersiniosis. Y. enterocolitica is widespread in the environment and animal populations. The main reservoir of human pathogenic Y. enterocolitica strains are pigs. So, contaminated pork and pork products are the most important source of infection. Due to the inappropriate use of antibiotics in the last years has allowed microorganisms evolve resistance to them, it is important to look for an alternative to battle against bacteria. Alkaloids are abundant secondary metabolites in plants and represent one of the most widespread classes of compounds endowed with multiple and varied pharmacological properties. With the intention of contributing to solve this global problem, in previous studies, we examined a set of aporphinoid alkaloids as possible effective antimicrobial agents on planktonic growth of Y. enterocolitica strain. We found that Pachypodanthine inhibited planktonic growth at 100 µM. The aims of this study are determinate the Minimal Inhibitory Concentration (MIC) and Minimal Bactericidal Concentration (MBC) and evaluate the growth inhibitory effect at 96 h of culture of Pachypodanthine on Y. enterocolitica bio-serotype B1A/O:7,8-8-8,19, isolated from pork sausage in our laboratory. The MIC and MBC was determined by the microdilution test in Moeller Hinton broth (MH) according to Clinical and Laboratory Standards Institute (CLSI), with 100 μM of initial concentration and subsequent serial dilutions in half, at 37 °C for 24 h. A growth curve was made with an starter inoculum at DO610 of 0.05 in trypticase soy broth (TSB) using the inhibitor at MIC concentration, growth control was maintained without alkaloid, a sterile control with uninoculated broth, and an inhibition control using 25 µg/ml of chloramphenicol were added. Aliquots of 0.1 ml were measured at OD655 after 3, 6, 18, 24, 48, 72 and 96 h of culture at 37°C using a microplate reader. Results show that MIC value was 100 µM, as this was the highest tested concentration it was not possible to obtain the MCB value. Its inhibition increased from 52.7 % at 24 h to 76.9 % at 96 h of culture with MIC value. In addition, we assayed MIC and MBC on different biotypes (B) of Y. enterocolitica strains, resulting for B1B strain 100 µM; for B2 and B3 strains 50 µM; and for B4 25 µM for both determinations in all cases. These results suggest that Pachypodanthine presents great inhibition of Y. enterocolitica B1A planktonic growth at 100 µM improving its effect until 96 h of culture, indicating that it does not degrade over time. Furthermore, this compound can inhibit planktonic growth of different Y. enterocolitica biotypes showing activity in almost all existing biotypes. We concluded that Pachypodanthine could be used as antimicrobial agent in the future to prevent intestinal diseases

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