title: In vitro activity of beta-lactams, macrolides, telithromycin, and fluoroquinolones against clinical isolates of Streptococcus pneumoniae: correlation between drug resistance and genetic characteristics.
abstract: The in vitro activity of antimicrobial agents against Streptococcus pneumoniae was determined using 16 strains of penicillin-susceptible S. pneumoniae (PSSP) and 26 strains of penicillin intermediately resistant S. pneumoniae (PISP) + penicillin-resistant S. pneumoniae (PRSP) in Japan. The minimum inhibitory concentrations (MICs) of potent antibiotics, including eight beta-lactams (benzylpenicillin, ampicillin, cefotiam, cefepime, cefditoren, faropenem, panipenem, and biapenem), three macrolides (erythromycin, clarithromycin, and azithromycin), telithromycin, and three fluoroquinolones (ciprofloxacin, levofloxacin, and gatifloxacin), were determined. Twenty-three strains exhibited genetic variations at pbp1a + pbp2x + pbp2b, which are genetic-PRSP (g-PRSP). g-PISP strains accounted for 62.5% (10/16) of the PSSP strains. The existence of an abnormal pbp gene conferred not only penicillin resistance but resistance to cephems; however, panipenem and biapenem had potent in vitro efficacy against alterations. Regarding the macrolide resistance mechanisms (mefA or ermB): 16 isolates had only mefA, 18 isolates had ermB, and 2 isolates had both mefA and ermB. There was no correlation between the existence of an abnormal pbp gene and the existence of the mefA gene or the ermB gene.
authors.affiliation: Department of Infectious Disease and Infection Control, Saitama Medical School, 38 Morohongo, Moroyama-machi, Saitama 350-0495, Japan. toshi-ngs@umin.ac.jp
authors.forename: Toshiyuki
authors.initials: T
authors.lastname: Yamaguchi
authors.forename: Giichi
authors.initials: G
authors.lastname: Hashikita
authors.forename: Shun
authors.initials: S
authors.lastname: Takahashi
authors.forename: Akira
authors.initials: A
authors.lastname: Itabashi
authors.forename: Tsutomu
authors.initials: T
authors.lastname: Yamazaki
authors.forename: Shigefumi
authors.initials: S
authors.lastname: Maesaki
mesh_terms: D000890:Anti-Infective Agents / Q000494:pharmacology*; D001426:Bacterial Proteins / Q000235:genetics; D024881:Drug Resistance, Bacterial / Q000235:genetics*; D024841:Fluoroquinolones / Q000494:pharmacology*; D006801:Humans; D048628:Ketolides / Q000494:pharmacology; D018942:Macrolides / Q000494:pharmacology*; D008826:Microbial Sensitivity Tests; D013296:Streptococcus pneumoniae / Q000187:drug effects* / Q000235:genetics; D047090:beta-Lactams / Q000494:pharmacology*
chemical_list: D000890:Anti-Infective Agents; D001426:Bacterial Proteins; D024841:Fluoroquinolones; D048628:Ketolides; D018942:Macrolides; D047090:beta-Lactams; C106791:telithromycin