[Comparison of antimicrobial and bactericidal activities and postantibiotic effects of macrolides antibiotics against clinical isolates, and examination of shape alteration by scanning electron microscope].
We examined antibacterial activities of 4 kinds of macrolides (MLs), erythromycin (EM), clarithromycin (CAM), azithromycin (AZM) and rokitamycin (RKM), against 4 bacterial species of clinical strains isolated in 2004. Bacterial isolates used were 51 strains of methicillin-susceptible Staphylococcus aureus (MSSA), 20 of Streptococcus pyogenes, 68 of Streptococcus agalactiae, and 120 of Streptococcus pneumoniae. Macrolide resistance genes, ermB and mefE, in macrolide-resistant S. pyogenes and S. agalactiae, and all of pneumococci were analyzed by PCR. Antimicrobial activities against macrolide-susceptible MSSA of EM and CAM, were more potent than those of RKM. By contrast, against S. pneumoniae, RKM was more effective than EM, CAM and AZM. Against S. pyogenes and S. agalactiae, 4 antibiotics showed similar antimicrobial activities. Twelve, 1 and 2 strains of MSSA, S. pyogenes and S. agalactiae, respectively, were resistant to EM, CAM and AZM, whereas RKM was active to almost, but not quite, of them. Among 120 strains of S. pneumoniae, 76 (63.3%) were resistant to EM (MIC; > or = 0.5 microg/mL), and 23, 15 and 28 strains were highly resistant (MIC; > 128 microg/mL) to EM, CAM and AZM, respectively. By contrast, for RKM, there were far fewer resistant strains, and there was no highly resistant strain. PCR analyses of macrolide-resistant genes revealed that 1 resistant strain of S. pyogenes and 2 of S. agalactiae carried mefE and ermB, respectively. In the case of S. pneumoniae, 59, 19 and 5 strains, respectively, carried ermB, mefE and both ermB and mefe. We also studied about bactericidal activities and postantibiotic effects (PAE) of MLs using macrolide-susceptible, and ermB- and mefE-carrying S. pneumoniae, and observed morphological alterations of the strains treated with the drugs by a scanning electron microscope. It was demonstrated that RKM had superior bactericidal activities and PAE than other 3 drugs, and potent destructive effects to all of 3 strains.
Yano
Hisakazu
H
Department of Otolaryngology-Head and Neck Surgery, Tohoku University Graduate School of Medicine.
Kobayashi
Toshimitsu
T
Okitsu
Naohiro
N
Aoki
Akiko
A
Toriya
Minoru
M
Nakada
Yukiko
Y
Sagai
Hitoshi
H
Iyobe
Shizuko
S
Inoue
Matsuhisa
M
D017963:Azithromycin / Q000494:pharmacology*; D001426:Bacterial Proteins; D017291:Clarithromycin / Q000494:pharmacology*; D004305:Dose-Response Relationship, Drug; D024881:Drug Resistance, Bacterial / Q000235:genetics; D004917:Erythromycin / Q000494:pharmacology*; D006801:Humans; D018942:Macrolides / Q000494:pharmacology*; D008565:Membrane Proteins; D016106:Methicillin Resistance; D008780:Methyltransferases; D008855:Microscopy, Electron, Scanning; D015644:Miocamycin / Q000031:analogs & derivatives* / Q000494:pharmacology; D016133:Polymerase Chain Reaction; D013211:Staphylococcus aureus / Q000187:drug effects* / Q000302:isolation & purification / Q000648:ultrastructure; D013292:Streptococcus agalactiae / Q000187:drug effects* / Q000302:isolation & purification / Q000648:ultrastructure; D013296:Streptococcus pneumoniae / Q000187:drug effects* / Q000302:isolation & purification / Q000648:ultrastructure; D013297:Streptococcus pyogenes / Q000187:drug effects* / Q000302:isolation & purification / Q000648:ultrastructure
D001426:Bacterial Proteins; D018942:Macrolides; C431304:MefE protein, Streptococcus pneumoniae; D008565:Membrane Proteins; D015644:Miocamycin; D004917:Erythromycin; D017963:Azithromycin; D008780:Methyltransferases; C431709:ErmA protein, Bacteria; D017291:Clarithromycin; C033383:rokitamycin