Table. Characteristics of mcr-1–positive Salmonella isolates from pigs at slaughter, China, 2013–2014*.
| Strain | Serovar | PFGE type | Sequence type | S1-PFGE, plasmid, kb | Colistin MIC, mg/L | Polymyxin B MIC, mg/L | Other antimicrobial drug resistance† | Resistance gene‡ |
|---|---|---|---|---|---|---|---|---|
| SH149 | Typhimurium | A5 | 34 | ≈180 | 2 | 4 | AMP, STR, GEN, FFC, SXT, TET | floR, oqxAB |
| SH143 | Typhimurium | A1 | 34 | ≈180 | 2 | 4 | AMP, STR, GEN, FFC, SXT, TET | floR, oqxAB |
| SH138 | Typhimurium | A1 | 34 | ≈180 | 2 | 4 | AMP, STR, GEN, FFC, SXT, TET | floR, oqxAB |
| SH93 | Typhimurium | A1 | 34 | ≈180 | 2 | 8 | FFC, SXT, TET | floR, oqxAB |
| SH33 | Typhimurium | A1 | 34 | ≈110 | 2 | 4 | AMP, STR, SXT, TET | oqxAB |
| SH137 | Typhimurium | A1 | 34 | ≈180 | 2 | 8 | AMP, STR, GEN, FFC, SXT, TET | floR, oqxAB |
| SA316 | Typhimurium | A1 | 34 | ≈180 | 2 | 8 | AMP, STR, GEN, FFC, SXT, TET | floR |
| SH127 | Typhimurium | A1 | 34 | ≈180 | 2 | 4 | AMP, STR, GEN, FFC, SXT, TET | floR, oqxAB |
| SH128 | Typhimurium | A1 | 34 | ≈180 | 2 | 4 | AMP, STR, GEN, FFC, SXT, TET | floR, oqxAB |
| SH133 | Typhimurium | A1 | 34 | ≈180 | 2 | 4 | AMP, STR, GEN, FFC, SXT, TET | floR, oqxAB |
| SH134 | Typhimurium | A1 | 34 | ≈180 | 2 | 4 | AMP, STR, GEN, FFC, SXT, TET | floR, oqxAB |
| SH17 | Typhimurium | A1 | 34 | ≈180 | 2 | 4 | AMP, STR, GEN, FFC, SXT, TET | floR, oqxAB |
| SH239 | Typhimurium | A1 | 34 | ≈180, ≈138 | 2 | 8 | AMP, STR, GEN, FFC, SXT, TET | floR |
| SH271 | Typhimurium | A1 | 34 | ≈180 | 2 | 8 | AMP, STR, GEN, FFC, SXT, TET | floR, oqxAB |
| SH83 | Typhimurium | A1 | 34 | ≈180 | 2 | 4 | AMP, STR, GEN, FFC, SXT, TET | floR, oqxAB |
| SH205 | Typhimurium | A1 | 34 | ≈180 | 2 | 8 | AMP, STR, GEN, FFC, SXT, TET | floR, oqxAB |
| SH39 | Typhimurium | A2 | 34 | ≈180 | 2 | 4 | AMP, STR, GEN, FFC, SXT, TET | floR, oqxAB |
| SH178 | Typhimurium | A1 | 34 | ≈180 | 2 | 4 | AMP, STR, GEN, FFC, SXT, TET | floR, oqxAB |
| SH175§ | Typhimurium | A4 | 34 | ≈180 | 2 | 8 | AMP, STR, GEN, FFC, SXT, TET | floR, oqxAB |
| SH36§ | Heidelberg | B | ND | ≈180 | 2 | 8 | STR, FFC, SXT | floR, oqxAB |
| Z4P319S§ | London | C | ND | ≈180 | 1 | 2 | AMP, STR, GEN, FFC,CIP, SXT, TET | floR, oqxAB |
*According to recommendations of the joint Clinical and Laboratory Standards Institute (CLSI)–European Committee on Antimicrobial Susceptibility Testing (EUCAST) and the Polymyxin Breakpoints Working Group (http://www.eucast.org/), the International Organization for Standardization standard broth microdilution method (20776–1) was used to determine colistin MICs for these strains. Antimicrobial susceptibility was determined and evaluated according to CLSI document no. M100-S25 (http://shop.clsi.org/site/Sample_pdf/M100S25_sample.pdf). Resistance to florfenicol was interpreted according to EUCAST clinical breakpoints and epidemiological cutoff values (>16 mg/L) (http://mic.eucast.org/Eucast2/). MICs of olaquindox for all isolates, except SH36, were >64 mg/L. AMP, ampicillin; CIP, ciprofloxacin; FFC, florfenicol; GEN, gentamicin; ND, not determined; STR, streptomycin; SXT, sulfamethoxazole/trimethoprim; TET, tetracycline. †Boldface indicates resistance phenotypes transferred to a recipient by transformation. ‡Boldface indicates resistance genes transferred to a recipient by transformation. §Original strains of transformants.