Plasmid-borne macrolide resistance in Micrococcus luteus.
A plasmid designated pMEC2 which confers resistance to erythromycin, other macrolides, and lincomycin was detected in Micrococcus luteus strain MAW843 isolated from human skin. Curing of this approximately 4.2 kb plasmid from the host organism resulted in erythromycin sensitivity of the strain. Introduction of pMEC2 into a different M. luteus strain conferred erythromycin resistance upon this strain. Macrolide resistance in M. luteus MAW843 was an inducible trait. Induction occurred at subinhibitory erythromycin concentrations of about 0.02-0.05 micro g ml(-1). Erythromycin and oleandomycin were inducers, while spiramycin and tylosin exerted no significant inducer properties. With heterologous expression experiments in Corynebacterium glutamicum, using hybrid plasmid constructs and deletion derivatives thereof, it was possible to narrow down the location of the plasmid-borne erythromycin-resistance determinant to a region of about 1.8 kb of pMEC2. Sequence analysis of the genetic determinant, designated erm(36), identified an ORF putatively encoding a 281-residue protein with similarity to 23S rRNA adenine N(6)-methyltransferases. erm(36) was most related (about 52-54% identity) to erythromycin-resistance proteins found in high-G+C Gram-positive bacteria, including the (opportunistic) pathogenic corynebacteria Corynebacterium jeikeium, C. striatum, C. diphtheriae and Propionibacterium acnes. This is believed to be the first report of a plasmid-borne, inducible antibiotic resistance in micrococci. The possible role of non-pathogenic, saprophytic micrococci bearing antibiotic-resistance genes in the spreading of these determinants is discussed.
Liebl
Wolfgang
W
Institut für Mikrobiologie und Genetik, Georg-August-Universität, Grisebachstr. 8, D-37077 Göttingen, Germany1.
Kloos
Wesley E
WE
Department of Genetics, North Carolina State University, Raleigh, USA2.
Ludwig
Wolfgang
W
Lehrstuhl für Mikrobiologie, Technische Universität München, Freising-Weihenstephan, Germany3.
D000900:Anti-Bacterial Agents / Q000494:pharmacology*; D004269:DNA, Bacterial / Q000032:analysis; D024881:Drug Resistance, Bacterial / Q000235:genetics*; D004917:Erythromycin / Q000494:pharmacology*; D015964:Gene Expression Regulation, Bacterial; D005798:Genes, Bacterial; D008826:Microbial Sensitivity Tests; D016982:Micrococcus luteus / Q000187:drug effects / Q000235:genetics / Q000378:metabolism*; D008969:Molecular Sequence Data; D010957:Plasmids / Q000235:genetics*; D017422:Sequence Analysis, DNA
D000900:Anti-Bacterial Agents; D004269:DNA, Bacterial; D004917:Erythromycin