Table 2.
Antibiotic resistance mechanisms found in PPB, associated to the antibiotics used as PPPs.
| Antibiotic | Class of antibiotic (general mode of action) | ARG(s) or gene modification leading to resistance | Type of resistance | Antibiotic resistance phenotype | Reference(s) |
|---|---|---|---|---|---|
| Gentamicin | Aminoglycosides (protein synthesis inhibitors) | aacA3 | Gene acquisition (antibiotic inactivation) | aacA3 encodes the aminoglycoside-3’-N-acetyltransferase, which inactivates gentamicin | Xu et al. (2013) |
| Kasugamycin | Aminoglycosides | aac(2′)-IIa (acyltransferase) | Gene acquisition (antibiotic inactivation) | Acetylation of the 2′-amino residue of kasugamycin, which inactivates the antibiotic | Yoshii et al. (2012, 2015) |
| Deletion of opp and dpp (two permeases) | Deletion (reduced permeability) | Opp and Dpp are two major peptide ATP-binding cassette transporter systems. When deleted, kasugamycin cannot enter the cell | Ge et al. (2018) | ||
| Streptomycin | Aminoglycosides | strA-strB | Gene acquisition (antibiotic modification) | strA-strB encode phosphostranferases (aph(3″)-Ib and aph(6)-Id respectively) that modify streptomycin into a non-toxic form | Chiou and Jones (1993, 1995a), McManus et al. (2002), and Förster et al. (2015) |
| rpsL | Point mutation (modification of the antibiotic targets) | rpsL encodes the ribosomal protein S12. Point mutations occur at codon 43 or rarely at codon 88 or 128, which prevent streptomycin to bind the ribosome | Chiou and Jones (1995b), Barnard et al. (2010), Zhang et al. (2011), Förster et al. (2015), and Escursell et al. (2021) | ||
| aadA1, aadA2 | Gene acquisition (antibiotic modification) | aadA genes encode aminoglycoside adenylyltransferases inactivating streptomycin | Schnabel and Jones (1999) and Xu et al. (2013) | ||
| Zhongshengmycin | Aminoglycosides | NA | NA | Increasing fatty acid biosynthesis | Wang Q. et al. (2021) |
| Bismerthiazol | Thiadiazol (inhibitor of histidine utilization pathway and quorum sensing) | NA | NA | NA | Zhu et al. (2013) and Liang et al. (2018) |
| Oxolinic acid | Quinolones (inhibitors of nucleic acids synthesis) | GyrA83 mutation | Point mutation (modification of the antibiotic targets) | gyrA encodes the DNA gyrase subunit A. The exact mechanisms are not defined yet | Maeda et al. (2007b) |
| Oxytetracycline | Tetracyclines (protein synthesis inhibitors) | tetC | Gene acquisition (active elimination) | Efflux of the antibiotic through a pump | Herbert et al. (2022) |
| Shenqinmycin | Heterocyclic antibiotic (phenazine) secreted by Pseudomonas spp. (accumulation of reactive oxygen species) | NA | Probably point mutation | Reduction of reactive oxygen species (ROS) production and/or increasing ability to metabolize ROS. The exact mechanisms are not defined yet | Pan et al. (2018) |
NA, information not available.