Table 2.
Antibiotic resistance genes detected in wastewater treatment plants (Compiled from Rizzo et al., 2013; Pazda et al., 2019).
| Antibiotic class | Mechanism of action | Mechanism of bacterial resistance | Gene name a |
|---|---|---|---|
| Aminoglycosides | Inhibiting protein synthesis |
Drug modification by adenylation Drug modification by phosphorylation |
aad[A1, A2, A13, B] aph[A, A‐3, A‐6, 2]; str[A, B]; strB |
| Beta‐lactams | Interfering with the bacterial cell wall biosynthesis by inactivation of penicillin‐binding proteins |
Penicillin‐binding protein Inactivation by beta‐lactamases (Drug degradation) |
mecA amp[C, R]; bla[CIT, CMY, CTX, FOX, GES, IMP, NPS, OXA, PER, PSE, SHV, TEM, TLA, VEB, VIM]; cfx[A, A3] |
| Glycopeptides | Interfering with cell wall biosynthesis | Produces a modified peptidoglycan pentapeptide | vanA |
| Macrolides | Inhibiting early stages of protein synthesis (binding to the 50S bacterial ribosome subunit) |
Methylation of 23S rRNA target side Cleavage of the drug lactone ring Inactivation of macrolide phosphotransferases Active pumping of the drug |
erm[A, B, C, F, O] ere[A, A2, B] mph[(A), (B), BM] mef[A, E]; mel; msrA |
| Quinolones | Inhibiting bacterial DNA replication enzymes (DNA gyrase & topoisomerase IV) |
Modification of target enzymes DNA gyrase and topoisomerase IV protection Modification by acetylation |
gyr[A, B]; parC qnr[A, A3, B, B1, B2, B4, B5, D, S, S1, S2, VC] aacA6‐ib‐cr |
| Sulphonamides | Inhibiting the dihydropteroate synthase, enzyme involved in the folic acid synthesis | Competitive inhibitors of dihydropteroate synthase, enzyme involved in folic acid synthesis | sul[1, 2, 3, A] |
| Tetracyclines | Inhibiting bacterial protein synthesis (binding to the 30S ribosomal subunit and preventing the aminoacyl tRNA association) |
Ribosome protection Drug export by membrane associated proteins Enzymatic inactivation of the drug |
ortA, tet[B(P), M, O, Q, S, T, W, X] tet[A, A(C), A(P), B, C, D, E, G, H, J, K, L, V, Y, Z, 31, 35, 36, 39] tetX |
| Trimethoprim | Inhibiting Dihydrofolate reductase (DHFR) | Increased synthesis of DHFR | dfr[II, V, XIII, 13, 16, 17, A19, B2, A20, A3, A12, A13, A21, A22, A33, B1, B5, B6, B8, D, E]; dhfr[V, VII, VIII, IX, XII, XV, A1, A14] |
| Multidrug | Multidrug resistance | Accumulation of many genes encoding resistance to a single drug and multidrug efflux pumps operation | acr[B, D]; ade[A, J]; amrB; mdt[F, G, H, N, O]; mex[B, D, F, I, W, Y]; norM; orf11; qac[B, EΔ1, EΔ1‐01, F, G2, H]; sedY; sme[B, E] |
For simplicity, gene variations are presented within square brackets.