Ciprofloxacin and tetracycline susceptibility of lactobacilli isolated from indigenous children's feces

To investigate the frequency of ciprofloxacin and tetracycline resistance lactobacilli in children feces, a total of 160 feces samples were cultured on Lactobacilli-selective Rogosa agar supplemented with 0.1 mg/ml of cycloheximide and 0.5% of CaCO 3, and identified Lactobacillus species were identified by analysis of the PCR sequenced-16S rRNA gene through BLAST against the deposited GenBank database. In these samples, 96 isolates were obtained and identified as belonging to 6 species, including Lactobacilli plantarum, Lactobacilli helveticusi, Lactobacilli salivarius, Lactobacilli casei, Lactobacilli fermentum and Lactobacilli pentosus. Strain-subtyping of these isolates by repetitive extragenic palindromic (REP)-PCR demonstrated a notable genotypic biodiversity of 65.6%. Antimicrobial susceptibility of ciprofloxacin and tetracycline had a wide different minimum inhibitory concentration (MIC) values in these isolates. The MIC50 and MIC90 of ciprofloxacin both was 64 µg/ml for both, while the MIC50 and MIC90 of tetracycline were 128 and 512 µg/ml. These results indicate that high-level resistant activity of ciprofloxacin and tetracycline among Lactobacillus species in indigenous children’s intestines was prevalent in mountain district at the central area of Taiwan.