title: Antibiotic susceptibility of members of the Lactobacillus acidophilus group using broth microdilution and molecular identification of their resistance determinants.
abstract: The range of antibiotic susceptibility to 13 antibiotics in 101 strains of the Lactobacillus acidophilus group was examined using the lactic acid bacteria susceptibility test medium (LSM) and broth microdilution. Additionally, microarray analysis and PCR were applied to identify resistance genes responsible for the displayed resistant phenotypes in a selection of strains. In general, narrow as well as broad unimodal and bimodal MIC distributions were observed for the Lactobacillus acidophilus group and the tested antimicrobial agents. Atypically resistant strains could be determined by visual inspection of the obtained MIC ranges for ampicillin, chloramphenicol, clindamycin, erythromycin, quinupristin/dalfopristin, streptomycin and tetracycline. For most of these atypically resistant strains underlying resistance determinants were found. To our knowledge erm(A) was detected in lactobacilli for the first time within this study. Data derived from this study can be used as a basis for reviewing present microbiological breakpoints for categorization of susceptible and resistant strains within the Lactobacillus acidophilus group to assess the safety of microorganisms intended for use in food and feed applications.
authors.affiliation: BOKU - University of Natural Resources and Life Sciences, Department of Food Sciences and Technology, Institute of Food Sciences; Muthgasse 18, A-1190 Vienna, Austria.
authors.forename: Sigrid
authors.initials: S
authors.lastname: Mayrhofer
authors.forename: Angela H A M
authors.initials: AH
authors.lastname: van Hoek
authors.forename: Christiane
authors.initials: C
authors.lastname: Mair
authors.forename: Geert
authors.initials: G
authors.lastname: Huys
authors.forename: Henk J M
authors.initials: HJ
authors.lastname: Aarts
authors.forename: Wolfgang
authors.initials: W
authors.lastname: Kneifel
authors.forename: Konrad J
authors.initials: KJ
authors.lastname: Domig
mesh_terms: D000900:Anti-Bacterial Agents / Q000494:pharmacology*; D024881:Drug Resistance, Bacterial / Q000235:genetics*; D004917:Erythromycin; D007779:Lactobacillus acidophilus / Q000187:drug effects* / Q000235:genetics*; D008826:Microbial Sensitivity Tests; D013752:Tetracycline
chemical_list: D000900:Anti-Bacterial Agents; D004917:Erythromycin; D013752:Tetracycline