title: Identification of fusB-mediated fusidic acid resistance islands in Staphylococcus epidermidis isolates.
abstract: To understand the high prevalence of fusB genes in fusidic acid-resistant Staphylococcus epidermidis, analysis of resistance elements in 34 isolates was performed. First, sequence analysis of the aj1-LP-fusB region indicated that at least three types were present. Type I contained full-length aj1, type II contained a partial aj1 truncated from nucleotide position 93 to 421, and type III contained a more truncated aj1 that retained only the last 37 bp. Isolates with type I or type II aj1 displayed slightly higher levels of resistance to fusidic acid (MICs, 8 to 32 μg/ml) than did those with type III aj1 (MICs, 4 to 16 μg/ml). Subsequent sequencing of the flanking regions of fusB from four selected isolates carrying different types of aj1-LP-fusB regions revealed that the fusB genes were all located on phage-related resistance islands (RIs), referred to as SeRI(fusB)(-2793), SeRI(fusB)(-704), SeRI(fusB)(-5907), and SeRI(fusB)(-7778), respectively. Among them, three islands (SeRI(fusB)(-2793), SeRI(fusB)(-704), and SeRI(fusB)(-5907)) were located downstream of groEL (corresponding to the 44-min position based on Staphylococcus aureus whole genomic sequences), and one (SeRI(fusB)(-7778)) was located downstream of rpsR (corresponding to the 8-min position). All of the RIs were inserted into integrase-recognized att sites. Among 34 isolates, the insertion sites of fusB RIs were mostly (28/34, 82%) located downstream of groEL and two were located downstream of rpsR, but four remained unidentified. The pulsotype distribution indicated that fusB-containing S. epidermidis isolates were heterogeneous. In conclusion, the fusB resistance determinant in S. epidermidis was highly associated with phage-related RIs. This is the first report of fusB RI in S. epidermidis.
authors.affiliation: Department of Clinical Laboratory Sciences and Medical Biotechnology, National Taiwan University College of Medicine, 1 Chang-Te Street, Taipei 100, Taiwan.
authors.forename: Hsiao-Jan
authors.initials: HJ
authors.lastname: Chen
authors.forename: Jui-Chang
authors.initials: JC
authors.lastname: Tsai
authors.forename: Wei-Chun
authors.initials: WC
authors.lastname: Hung
authors.forename: Sung-Pin
authors.initials: SP
authors.lastname: Tseng
authors.forename: Po-Ren
authors.initials: PR
authors.lastname: Hsueh
authors.forename: Lee-Jene
authors.initials: LJ
authors.lastname: Teng
mesh_terms: D000900:Anti-Bacterial Agents / Q000494:pharmacology*; D001426:Bacterial Proteins / Q000235:genetics; D024881:Drug Resistance, Bacterial / Q000235:genetics*; D005672:Fusidic Acid / Q000494:pharmacology*; D044404:Genomic Islands / Q000235:genetics*; D006761:Hospitals; D008826:Microbial Sensitivity Tests; D008969:Molecular Sequence Data; D016133:Polymerase Chain Reaction; D017422:Sequence Analysis, DNA; D013203:Staphylococcal Infections / Q000453:epidemiology* / Q000382:microbiology; D013204:Staphylococcus Phages / Q000235:genetics; D013212:Staphylococcus epidermidis / Q000187:drug effects / Q000235:genetics / Q000472:pathogenicity*; D013624:Taiwan / Q000453:epidemiology
chemical_list: D000900:Anti-Bacterial Agents; D001426:Bacterial Proteins; D005672:Fusidic Acid