Activity of moxifloxacin and twelve other antimicrobial agents against 216 clinical isolates of Streptococcus pneumoniae.
BACKGROUND
An increased incidence of macrolide resistance in penicillin-resistant Streptococcus pneumoniae has been described.


METHODS
With this in mind, 216 S. pneumoniae isolates were evaluated for their in vitro susceptibility to a new fluoroquinolone, moxifloxacin, which was compared with penicillin, amoxicillin, cefuroxime, cefotaxime, ceftriaxone, erythromycin, clarithromycin, ciprofloxacin, sparfloxacin, ofloxacin, vancomycin and teicoplanin. A broth microdilution assay was performed in cation- adjusted Mueller-Hinton broth with 5% (v/v) lysed horse blood according to NCCLS guidelines.


RESULTS
Erythromycin resistance was observed in all the 22 penicillin-resistant S. pneumoniae (10.1%). All the penicillin- susceptible S. pneumoniae were susceptible to cephalosporins, whereas all the penicillin-resistant ones showed resistance to cefuroxime and only intermediate susceptibility to cefotaxime and ceftriaxone. The 216 tested strains were inhibited by sparfloxacin and moxifloxacin at concentrations of 0.12-0.5 mg/l and 0.06-0.25 mg/l, respectively, regardlesss of whether the strain was penicillin and/or erythromycin resistant. Seven penicillin-resistant strains displayed resistance to ofloxacin. All isolates were susceptible to vancomycin; teicoplanin MIC values ranged from 0.03 to 0.12 mg/l. The excellent in vitro activity of moxifloxacin against S. pneumoniae was not affected by penicillin and/or macrolides.


CONCLUSIONS
Moxifloxacin appears to be a promising choice for the treatment of pneumococcal infections, including situations where therapeutic choices are limited due to penicillin and macrolide resistance.
Esposito
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Clinica Malattie Infettive, Seconda Università degli Studi di Napoli, Ospedale Gesú e Maria, Via D. Contugno 1, I-80135 Napoli, Italy. silvanoesposito@libero.it
Noviello
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S
Ianniello
F
F
D000658:Amoxicillin / Q000494:pharmacology; D000900:Anti-Bacterial Agents / Q000494:pharmacology; D000890:Anti-Infective Agents / Q000494:pharmacology*; D001372:Aza Compounds; D002439:Cefotaxime / Q000494:pharmacology; D002444:Cefuroxime / Q000494:pharmacology; D002939:Ciprofloxacin / Q000494:pharmacology; D004917:Erythromycin / Q000494:pharmacology; D024841:Fluoroquinolones; D008826:Microbial Sensitivity Tests; D000077266:Moxifloxacin; D015242:Ofloxacin / Q000494:pharmacology; D011804:Quinolines; D013296:Streptococcus pneumoniae / Q000187:drug effects*; D017334:Teicoplanin / Q000494:pharmacology; D014640:Vancomycin / Q000494:pharmacology
D000900:Anti-Bacterial Agents; D000890:Anti-Infective Agents; D001372:Aza Compounds; D024841:Fluoroquinolones; D011804:Quinolines; D002939:Ciprofloxacin; D017334:Teicoplanin; D004917:Erythromycin; D014640:Vancomycin; D000658:Amoxicillin; D015242:Ofloxacin; D002439:Cefotaxime; D002444:Cefuroxime; C061363:sparfloxacin; D000077266:Moxifloxacin