In vitro activity of beta-lactams, macrolides, telithromycin, and fluoroquinolones against clinical isolates of Streptococcus pneumoniae: correlation between drug resistance and genetic characteristics.
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.
Yamaguchi
Toshiyuki
T
Department of Infectious Disease and Infection Control, Saitama Medical School, 38 Morohongo, Moroyama-machi, Saitama 350-0495, Japan. toshi-ngs@umin.ac.jp
Hashikita
Giichi
G
Takahashi
Shun
S
Itabashi
Akira
A
Yamazaki
Tsutomu
T
Maesaki
Shigefumi
S
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*
D000890:Anti-Infective Agents; D001426:Bacterial Proteins; D024841:Fluoroquinolones; D048628:Ketolides; D018942:Macrolides; D047090:beta-Lactams; C106791:telithromycin