Characterization of ermB gene transposition by Tn1545 and Tn917 in macrolide-resistant Streptococcus pneumoniae isolates

Naohiro Okitsu, Satoru Kaieda, Hisakazu Yano, Ryuichi Nakano, Yoshio Hosaka, Ryouichi Okamoto, Toshimitsu Kobayashi, Matsuhisa Inoue

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    43 Citations (Scopus)

    Abstract

    In Streptococcus pneumoniae, the ermB gene is carried by transposons, such as Tn917 and Tn1545. This study investigated the relationship between macrolide resistance and the presence of the ermB gene on Tn917 or Tn1545 in 84 Japanese pneumococcal isolates. Macrolide-resistant strains were classified into two groups as follows. Group 1 (19 strains) showed a tendency to high resistance to erythromycin (MIC at which 50% of isolates are inhibited, 4 mg/liter; MIC at which 90% of isolates are inhibited [MIC90], 128 mg/liter) but susceptibility to rokitamycin (MIC90, 1 mg/liter), with the ermB gene located on Tn1545. Group 2 (65 strains) showed a tendency to high resistance to both antibiotics (MIC90s for both erythromycin and rokitamycin, > 128 mg/liter), with the ermB gene located on Tn917. There were no strains with constitutive macrolide resistance in either group. All of the strains in group 2 had a deletion in the promoter region of ermB and an insertion of the TAAA motif in the leader peptide. The results of pulsed-field gel electrophoresis and serogrouping showed that Tn1545 spread clonally while Tn917 spread both horizontally and clonally. In conclusion, in Japanese macrolide-resistant S. pneumoniae isolates, the ermB gene is carried and spread primarily by Tn917.

    Original languageEnglish
    Pages (from-to)168-173
    Number of pages6
    JournalJournal of Clinical Microbiology
    Volume43
    Issue number1
    DOIs
    Publication statusPublished - 2005 Jan

    ASJC Scopus subject areas

    • Microbiology (medical)

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