Disease relevance of smr

• Plasmid-borne smr gene causes resistance to quaternary ammonium compounds in bovine Staphylococcus aureus [1].
• The smr gene was subcloned and expressed in S. aureus and E. coli and its ability to confer the multidrug resistant phenotype was demonstrated for two different lipophilic cation classes: phosphonium derivatives and quarternary amines [2].

High impact information on smr

• The plasmid, designated pNVH99, has similarities to small, smr-containing staphylococcal plasmids previously found in human and food isolates. pNVH99 is a new member of the pC194 family of rolling-circle replication plasmids [1].
• Moreover, PCR amplification and Southern blot hybridization experiments failed to find genes phylogenetically related to the qacA and smr genes, encoding multidrug efflux systems previously described for the genus Staphylococcus [3].
• Although open reading frames (ORFs) of all the smr genes examined were identical to those reported previously (e.g., qacD in pSK41), smr gene cassettes were classified into three groups (types 1, 2, and 3) [4].
• We analyzed the genomic diversity of smr and its gene cassette, a structural unit containing smr and terminal direct repeats (DRs), in 22 clinical strains of Staphylococcus aureus isolated over 9 years in a Japanese hospital [4].
• Although MICs of antiseptics and ethidium bromide were generally the same among strains having type 1, 2, or 3 smr gene cassette, the type 1 cassette was detected most frequently [4].

Chemical compound and disease context of smr

• Susceptibilities to antiseptic agents and distribution of antiseptic-resistance genes qacA/B and smr of methicillin-resistant Staphylococcus aureus isolated in Asia during 1998 and 1999 [5].

Biological context of smr

• An open reading frame (ORF) similar to the QAC resistance genes qacC, ebr and smr previously reported from clinical staphylococcal strains was identified (qacC') [6].
• It was suggested by genomic comparison that type 2 and type 3 cassettes might have been derived from the type 1 cassette via insertion of foreign DNA sequence, and that the type 2 cassette might be a precursor form of some previously reported smr cassettes, such as those in pSK108 and pNVH99 [4].

Associations of smr with chemical compounds

• Our results indicated that four or more antiseptic-resistance genes exist in methicillin-resistant S. aureus and that antiseptic-resistant methicillin-resistant S. aureus strains without qacA and smr are widely spread in Japan [7].
• One QAC resistant strain harbouring the smr gene showed resistance to ampicillin, penicillin, tetracycline, erythromycin and trimethoprim [8].

Other interactions of smr

• The smr gene product (identical to products of ebr and qacC/D genes) was shown to be homologous to a new family of small membrane proteins found in Escherichia coli, Pseudomonas aeruginosa, Agrobacterium tumefaciens, and Proteus vulgaris [2].
• Twenty-four isolates hosting one of the genes qacA/qacB, smr, qacG or qacH, were subjected to species identification [8].

Analytical, diagnostic and therapeutic context of smr

• Plasmid analysis, PCR, and DNA sequencing revealed a novel plasmid of 2,239 bp containing the smr gene [1].

References