Table 1.
Bacterial strain characteristics and corresponding the MALDITet(X)-plus test results
| MIC | MS Ratio | |||||||||
|---|---|---|---|---|---|---|---|---|---|---|
| Species |
n |
genes |
TC(1s)a |
OTC(1s)a |
DOX(2s)a |
TGC(3s)a |
ERA(4s)a |
OMA(4s)a |
TGC |
OTC |
| Control strains | 4 | |||||||||
| E. coli-JM109-pBAD24-tet(X3) | 1 | tet(X3) | 64 | 128 | 32 | 4 | 4 | 16 | 0.5 ± 0.09 | 0.2283 ± 0.0503 |
| E. coli-JM109-pBAD24-tet(X4) | 1 | tet(X4) | 64 | 128 | 16 | 8 | 2 | 16 | 0.43 ± 0.11 | 0.2155 ± 0.013 |
| E. coli JM109 – pBAD24 | 1 | - | 2 | 2 | 0.5 | 0.03 | 0.008 | 0.125 | 0 ± 0 | 0.1346 ± 0.0629 |
| E. coli 25,922 | 1 | - | 2 | 2 | 0.5 | 0.03 | 0.06 | 0.25 | 0 ± 0 | 0.1221 ± 0.0498 |
| Test strains | 90 | |||||||||
| Non-Tet(X)-producers in tetracycline-resistant strains | 61 | |||||||||
| Acinetobacter spp. | 2 | tet(A) | >256 | >256 | 128–256 | 2–4 | 1–2 | 8 | 0 ± 0 | 0.0041 ± 0.0058 to 0.0151 ± 0.0132 |
| Acinetobacter spp. | 6 | tet(B) | >256 | >256 | 128–256 | 0.5–4 | 0.5–1 | 0.5–8 | 0 ± 0 | 0 ± 0 to 0.0463 ± 0.0208 |
| E. coli | 17 | tet(A) | 64->256 | 64->256 | 4->256 | 0.06–4 | 0.03–2 | 0.25–8 | 0 ± 0 | 0 ± 0 to 0.0189 ± 0.0157 |
| E. coli | 7 | tet(B) | 128->256 | 128->256 | 32->256 | 0.125–2 | 0.03–1 | 0.5–8 | 0 ± 0 | 0 ± 0 to 0.0158 ± 0.0224 |
| E. coli | 1 | tet(G) | 256 | 256 | 64 | 2 | 0.5 | 8 | 0 ± 0 | 0 ± 0 |
| E. coli | 4 | tet(M) | 128–256 | 128->256 | 32–64 | 0.125–0.5 | 0.125–0.25 | 2 | 0 ± 0 | 0 ± 0 |
| E. coli | 4 | tet(A)- tet(B) | 128->256 | >256 | 64–256 | 0.03–0.5 | 0.03–0.25 | 0.25–4 | 0 ± 0 to 0.0035 ± 0.005 | 0 ± 0 to 0.0111 ± 0.0157 |
| E. coli | 4 | tet(A)- tet(M) | 64–256 | 64->256 | 32->128 | 0.25–0.5 | 0.125–0.25 | 2–4 | 0 ± 0 to 0.0085 ± 0.0121 | 0 ± 0 to 0.0727 ± 0.0748 |
| K. pneumoniae | 3 | tet(A) | 128->256 | 256->256 | 32–256 | 0.5–4 | 0.125–2 | 4–8 | 0 ± 0 to 0.0033 ± 0.0047 | 0 ± 0 to 0.0518 ± 0.0309 |
| K. pneumoniae | 1 | tet(D) | 256 | >256 | 128 | 2 | 1 | 8 | 0 ± 0 | 0.0231 ± 0.0326 |
| K. pneumoniae | 3 | tet(A)- tet(D) | >256 | >256 | >256 | 1–2 | 1 | 8 | 0 ± 0 | 0.0128 ± 0.0137 to 0.0419 ± 0.0326 |
| S. enteritis | 5 | tet(B) | 64–256 | 128->256 | 8–64 | 0.5–2 | 0.06–0.5 | 1–4 | 0 ± 0 | 0 ± 0 |
| S. enteritis | 2 | tet(A)- tet(B) | 128 | >256 | 64 | 1 | 0.25 | 2 | 0.0003 ± 0.0004 to 0.0003 ± 0.0005 | 0 ± 0 to 0.0083 ± 0.0117 |
| S. enteritis | 1 | tet(B)- tet(D) | 256 | 128 | 64 | 1 | 0.25 | 4 | 0 ± 0 | 0 ± 0 |
| S. enteritis | 1 | tet(B)- tet(M) | 256 | >256 | 64 | 1 | 0.125 | 2 | 0 ± 0 | 0.0136 ± 0.0193 |
| Tetracycline-susceptible strains | 29 | |||||||||
| E. coli | 29 | non-tet(X)b | 0.5–1 | 1–2 | 1 | 0.125–0.5 | 0.03–0.06 | 0.25–1 | 0 ± 0 to 0.0018 ± 0.0025 | 0.0671 ± 0.0227 to 0.3897 ± 0.0184 |
TC, tetracycline; OTC oxytetracycline; DOX, doxycycline; TGC, tigecycline; ERA, eravacycline; OMA, omadacycline.
aThe number in parentheses indicates the generation of tetracycline.
bNon-tet(X) strains lack all tet genes as well as tet(X).