Table 5. Presence and transfer of mcr genes in E. coli and Salmonella (n = 1,619).
| Bacteria | Country | mcr-gene | Sample source | MIC (µg/mL) | No. of isolates (%) | Transferability* |
|---|---|---|---|---|---|---|
| E. coli (n = 988) | Thailand (n = 508) | mcr-1 | Pig | 8 | 4 | - |
| Pig carcass | 0.5, 8 | 3 | + (1) | |||
| Pork | 4 | 1 | + (1) | |||
| mcr-3 | Pig | 4–8 | 6 | - | ||
| Pig carcass | 0.5 | 1 | - | |||
| Pork | 8 | 1 | + (1) | |||
| mcr-1/ mcr-3 | Pig | 1 | 2 | - | ||
| Subtotal | 18 (4%)† | |||||
| Lao PDR (n = 351) | mcr-1 | Pig | 8 | 3 | - | |
| Pig carcass | 4–8 | 6 | - | |||
| Pork | 4–8 | 2 | - | |||
| mcr-3 | Pig | 4–8 | 5 | + (1) | ||
| Pig carcass | 2–8 | 3 | - | |||
| Pork | 0.5–4 | 2 | - | |||
| Subtotal | 21 (6%)† | |||||
| Cambodia (n = 129) | mcr-1 | Pig | 8–16 | 10 | - | |
| Pig carcass | 8 | 1 | - | |||
| Pork | 4–8 | 2 | - | |||
| mcr-3 | Pig | 4 | 3 | - | ||
| Pork | 0.5 | 1 | - | |||
| mcr-5 | Pork | 2 | 1 | - | ||
| Subtotal | 18 (14%)‡ | |||||
| Grand total | 57 (6%)§ | |||||
| Salmonella (n = 631) | Thailand (n = 276) | mcr-1 | Pig | 1 | 1 | - |
| mcr-3 | Pig | 1–8 | 3 | + (2) | ||
| Pork | 1–2 | 2 | - | |||
| Subtotal | 6 (2.2%) | |||||
| Cambodia (n = 118) | mcr-3 | Pig | 0.5–4 | 4 | + (1) | |
| Pork | 4 | 1 | - | |||
| Subtotal | 5 (4.2%) | |||||
| Grand total | 11 (2.8%)∥ | |||||
MIC, minimum inhibitory concentration.
*The number indicates the colistin-resistant isolate that can transfer mcr; †,‡Values for E. coli from different countries bearing a different superscript in the same column are significantly different (p ≤ 0.05); §,∥Values for E. coli and Salmonella bearing a different superscript in the same column are statistical different (p ≤ 0.05).