title: Comparison of three test media for antimicrobial susceptibility testing of bifidobacteria using the Etest method.
abstract: The performance of three test media for antimicrobial susceptibility testing of bifidobacteria using the Etest was compared. All Bifidobacterium strains (n=42) displayed good growth on trypticase-phytone-yeast extract agar (TPY). Most strains showed good growth on lactic acid bacteria susceptibility test medium supplemented with cysteine (LSM+cys); Bifidobacterium bifidum showed moderate growth. Growth of seven strains was inadequate on Brucella blood agar (BRU) and an additional eight strains showed moderate growth. The minimum inhibitory concentrations (MICs) for tetracycline were highest on BRU and lowest on LSM+cys (agreement 57%), whereas the MICs for streptomycin were lowest on BRU and highest on TPY (agreement 40%). Occasional mismatches (agreement 71-91%) between the test media were also detected for the beta-lactam antibiotics. This study describes test medium-dependent variation of MICs and the applicability of LSM+cys for antimicrobial susceptibility testing of bifidobacteria.
authors.affiliation: VTT Technical Research Centre of Finland, P.O. Box 1000, FI-02044 VTT, Espoo, Finland. jaana.matto@vtt.fi
authors.forename: J
authors.initials: J
authors.lastname: Mättö
authors.forename: M-L
authors.initials: ML
authors.lastname: Suihko
authors.forename: M
authors.initials: M
authors.lastname: Saarela
mesh_terms: D001644:Bifidobacterium / Q000187:drug effects* / Q000254:growth & development; D003470:Culture Media; D008826:Microbial Sensitivity Tests
chemical_list: D003470:Culture Media