Antibiotic resistance in non-starter, wild strains of Streptococcus thermophilus, and molecular and genomic analysis of atypical resistances

Trabajo presentado en el 12th International Symposium on Lactic Acid Bacteria, celebrado en Egmond aan Zee (Holanda) del 27 al 31 de agosto de 2017Resistance to antibiotics in food-borne commensal and beneficial microorganisms is not of clinical concern. However, resistant populations could serve as reservoirs of resistance determinants, which could ultimately be transferred during food manufacture or food consumption to pathogens (Rossi et al., 2014). Streptococcus thermophilus is a thermophilic lactic acid bacteria (LAB) species of great industrial use; the second in economic importance after Lactococcus lactis (Parente and Cogan, 2004). S. thermophilus is used as a starter in the production of yoghurt along with Lactobacillus delbrueckii subsp. bulgaricus. In combination with other lactobacilli species, it is also used in the manufacture of Swiss (Emmenthal, Gruyère) and Italian (Grana, Parmesan, Provolone, Mozzarella, etc.) cheese varieties. Its use has recently been extended to cheeses made with mesophilic starters such as Cheddar, Gouda, Manchego and others. Although S. thermophilus has never been found among the microbiota components of traditional Spanish cheeses, our group has detected the presence of DNA from S. thermophilus in several cheese types using culture-independent microbial techniques. Detection of DNA remains of this species has allowed the development of selective enrichment strategies for isolation of S. thermophilus strains from raw milk and raw milk-made cheeses. In this communication we report on the resistance/susceptibility profiles of 41 S. thermophilus wild isolates to a set of antibiotics from different classes together with the characterization of the genetic basis of atypical resistancesPeer reviewe