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Antimicrobial activity and spectrum of sparfloxacin tested against erythromycin-resistant Streptococcus pneumoniae
1Department of Pathology, University of Iowa College of Medicine, Iowa City, USA.
Abstract:
Recognition of a worldwide increase of penicillin-resistant Streptococcus pneumoniae and cross-resistance to other classes of antimicrobials have placed a great urgency on the need for new antimicrobial agents. Sparfloxacin, a novel pyridone carboxylic acid fluoroquinolone derivative was evaluated and compared to six other compounds for antimicrobial activity against erythromycin-resistant pneumococci (50 strains). The Etest susceptibility testing method was used to inoculate Mueller-Hinton agar supplemented with 5% sheep blood. There was extensive cross-resistance between erythromycin, clarithromycin (94%), and azithromycin (100%), but no cross-resistance was detected between macrolides/azalides and sparfloxacin (all strains susceptible at < or = 1.0 mu g/ml). Sparfloxacin (MIC90, 1 mu g/ml) was four-fold more active than ciprofloxacin and ofloxacin (MIC90, 4 mu g/ml). Sparfloxacin appears to possess excellent in vitro activity against erythromycin-resistant S. pneumoniae that were often highly resistant to beta-lactams, and further studies are recommended to investigate its in vivo efficacy against these multi-resistant organisms.
Insights
Sparfloxacin shows excellent activity against penicillin-resistant Streptococcus pneumoniae, demonstrating no cross-resistance with macrolides. This novel fluoroquinolone offers a promising alternative for treating infections caused by multi-drug resistant bacteria.
Area of Science:
- Microbiology
- Infectious Diseases
- Pharmacology
Background:
- Increasing prevalence of penicillin-resistant Streptococcus pneumoniae necessitates novel antimicrobial agents.
- Cross-resistance to existing antibiotics, including macrolides, is a significant clinical challenge.
- Erythromycin-resistant S. pneumoniae strains often exhibit multi-drug resistance, including to beta-lactams.
Purpose of the Study:
- To evaluate the in vitro antimicrobial activity of sparfloxacin against erythromycin-resistant Streptococcus pneumoniae.
- To compare sparfloxacin's efficacy with other antimicrobial agents against these resistant strains.
- To investigate potential cross-resistance between macrolides/azalides and sparfloxacin.
Main Methods:
- Etest susceptibility testing was performed on 50 strains of erythromycin-resistant S. pneumoniae.
- Mueller-Hinton agar supplemented with 5% sheep blood was used for inoculation.
- Sparfloxacin was compared against six other antimicrobial compounds.
Main Results:
- No cross-resistance was observed between macrolides/azalides and sparfloxacin; all strains were susceptible to sparfloxacin (< or = 1.0 μg/ml).
- Sparfloxacin exhibited potent activity (MIC90, 1 μg/ml), being four-fold more active than ciprofloxacin and ofloxacin (MIC90, 4 μg/ml).
- Extensive cross-resistance was confirmed between erythromycin, clarithromycin (94%), and azithromycin (100%).
Conclusions:
- Sparfloxacin demonstrates excellent in vitro activity against erythromycin-resistant Streptococcus pneumoniae.
- The compound shows significant potential as a therapeutic option for infections caused by multi-resistant S. pneumoniae strains.
- Further in vivo studies are recommended to confirm sparfloxacin's efficacy against these challenging pathogens.