Determination of MIC, MPC, and MSW of Ilex paraguariensis Against Non-Typhoidal Salmonella with Identification of the Mechanisms of Resistance and Pathogenicity Factors

Abstract Objective: This study investigated the antibacterial activity of Ilex paraguariensis extracts against 32 different strains of non-typhoidal Salmonella (NTS) through the determination of the Minimum Inhibitory Concentration (MIC), Mutant Prevention Concentration (MPC), Mutant Selection Window (MSW), and the detection of virulence genes by multiplex PCR assays. Results: The MIC values of Ilex paraguariensis against Salmonella spp. strains varied between 0.78 mg/ml and 6.25 mg/ml with a MIC 90 of 3.12 mg/ml. The highest MPC in this study was 48 mg/ml yielding a Mutant Selection Window of 41.75 mg/ml. The MSW values of the remaining strains varied between 1.56 and 8.87 mg/ml. Genes of pathogenicity detected in Salmonella spp. isolates were most commonly the stn, sdiA, invA, sopB, invH, and sopE genes. The antibacterial activity of Yerba Mate extracts was not affected by the antimicrobial resistance patterns or pathogenicity genes expressed. More work is needed to identify the active antibacterial compound(s) responsible for the antibacterial activity.