Journal: Antibiotics
Article Title: In Vitro and In Vivo Evaluation of Nitroxoline as an Effective Antimicrobial Alternative to Poultry Production
doi: 10.3390/antibiotics15010062
Figure Lengend Snippet: NTX-resistant mutant selection and stability. ( a ) Spontaneous mutation frequency of NTX resistance in wild-type S. enterica and E. coli strains was measured at 2×, 4×, and 8× MIC (8, 16, and 32 mg/L) after 48 h incubation at 37 °C. The resistance of colonies was supported by their ability to grow on NTX-containing media at the indicated concentrations. The frequency of resistance was determined by dividing the number of resistant mutants by the total number of cells determined by using dilutions of the overnight culture on agar media. Data are presented as mean ± Standard Error of the Mean (SEM) from two technical replicates ( n = 2). No mutations were observed at the concentration of 4× or 8× MIC (16 and 32 µg/mL, respectively). ( b ) MIC fold changes in selected mutant relative to their parental strains from ( a ). Parent–mutant pairs are indicated by vertical dotted lines. ( c ) Serial passage induction of the resistance to NTX against reference (hollow circle) and wild-type (solid star) E. coli and S. enterica . The y axis is the MIC-fold change in the tested isolates. Data are presented as mean ± SEM from two biological replicates ( n = 2). ( d ) Stability of NTX resistance mutations in two mutants from E. coli ATCC 25922 (Mut ATCC-D13 and Mut ATCC-D14) and two mutants from E. coli DSM 103263 (Mut DSM-D8 and Mut DSM-D14) in the absence of NTX. Mutant stability was quantified as the percentage of mutants in the original bacterial population, calculated by dividing the viable mutant cell count resistant to NTX by the total population and multiplying by a factor of 100. Three biological and two technical replicates were performed for each strain. Data are presented as mean ± SEM ( n = 3 biological replicates, each with two technical replicates).
Article Snippet: Parental strains E. coli ATCC 25922 and E. coli DSM 103263 were patched on drug-free medium only as controls.
Techniques: Mutagenesis, Selection, Incubation, Concentration Assay, Cell Characterization
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