Erratum: Acquired antibiotic resistance genes: an overview

Dr. Marilyn C. Roberts and Dr. Stefan Schwarz have contacted the authors of the original publication with several comments and suggestions to better harmonize the correct nomenclature of the antibiotic resistance genes, as the gene names were not always correctly presented in the various tables given. Authors often pick their own gene names which in many cases have been approved for use for other genetically distinct genes or give names to determinants which were already given an approved designated name. Therefore, we (Dr. Marilyn C. Roberts and Dr. Stefan Schwarz and Dr. Henk J. M. Aarts on behalf of the authors of the original publication) would like to present here the correct nomenclature and mechanistic features of the antibiotic resistance genes belonging to the following classes: Aminoglycosides (Table 1), Phenicols (Table 3), Macrolides–Lincosamides– Streptogramin B (Table 4), Quinolones (Table 5), Tetracyclines (Table 6), and Trimethoprim (Table 7). In addition some additional information is given on the various classes of antibiotic resistance genes as also a section regarding the antibiotic class Oxazolidinones has been added. Table 2 was correctly displayed by van Hoek et al. (2011) but has been updated. To the subsection dealing with the “Resistance mechanisms” of the AMINOGLYCOSIDES we would like to add that to date six additional methylases have been reported, i.e., npmA, rmtA, rmtB, rmtC, rmtD, and rmtE (Courvalin, 2008; Doi et al., 2008; Davis et al., 2010). Futhermore, that within the three major classes (AAC, ANT, and APH) an additional subdivision can be made based on the enzymes’ target sites within the aminoglycoside molecules: i.e., there are four acetyltransferases: AAC(1), AAC(2′), AAC(3), and AAC(6′); five nucleotidyltransferases: ANT(2′′), ANT(3′′), ANT(4′), ANT(6), and ANT(9); and seven phosphotransferases: APH(2′′), APH(3′), APH(3′′), APH(4), APH(6), APH(7′′), and APH(9). To the subsection β-LACTAM, Resistance, mechanisms we would like to add that in recent years acquired genes encoding ESBLs have become a major concern (Bradford, 2001). Over time, the genes for the parent enzymes blaTEM−1, blaTEM−2, and blaSHV−1 have undergone point mutations which resulted in amino acid substitutions that changed the substrate spectrum to that of ESBLs, starting with blaTEM−3 and blaSHV−2 (Bradford, 2001). Because chloramphenicol is not an actual antibiotic class the subsection of CHLORAMPHENICOL should be called PHENICOLS. Concerning the history of PHENICOLS, it is worthwhile to know the first antibiotic, chloramphenicol, originally referred to as chloromycetin, was isolated already in 1947 from Streptomyces venezuelae (Ehrlich et al., 1947). Besides the inactivating enzymes (chloramphenicol acetyltransferases), there are also reports on other phenicol resistance systems, such as the inactivation by phosphotransferases, mutations of the target site, permeability barriers, and efflux systems (Schwarz et al., 2004). Of the latter mechanism, cmlA and floR are the most commonly known genes in Gram-negative bacteria (Bissonnette et al., 1991; Briggs and Fratamico, 1999). The macrolides (subsection MACROLIDES – LINCOSAMIDES – STREPTOGRAMIN B) have a similar mode of antibacterial action, comparable antibacterial spectra and in part overlapping binding sites at the ribosome as two other antibiotic classes, i.e., lincosamides and streptogramin antibiotics (comprising streptogramin A and B compounds that act synergistically). Consequently, these antibiotics, although chemically distinct, have been clustered together as MLS antibiotics (Roberts, 1996). Macrolides, lincosamides and streptogramins all inhibit protein synthesis by binding to the 50S ribosomal subunit of bacteria (Weisblum, 1995; Roberts, 2002). To Resistance mechanisms of the subsection MACROLIDES–LINCOSAMIDES– STREPTOGRAMIN B. Shortly after the introduction of erythromycin into clinical setting in the 1950s, bacterial resistance to this antibiotic was reported for the first time in staphylococci (Weisblum, 1995). Since then a large number of bacteria have been identified that are resistant to MLS due to the presence of various different genes. The resistance determinants responsible include rRNA methylases that modify the ribosomal target sites, ABC transporters, and efflux proteins of the Major Facilitator Superfamily, as well as genes for inactivating enzymes (Roberts et al., 1999; Roberts, 2008). The latter group can be further