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In vitro activity of cefdinir against respiratory pathogens isolated in Sicily with reference to beta-lactamase
G Blandino1, G Aleo, F Caccamo
1Institute of Microbiology, University of Catania, Italy.
Abstract:
The in vitro activity of cefdinir (CI-983, FK-482), an orally absorbed aminothiazolyl cephalosporin, was evaluated against all 287 strains of Haemophilus influenzae, Haemophilus parainfluenzae, Moraxella catarrhalis, Streptococcus pneumoniae and Streptococcus pyogenes in comparison with cefaclor, cefuroxime, amoxicillin, amoxicillin-clavulanic acid, erythromycin and cotrimoxazole. The bactericidal activity of cefdinir, cotrimoxazole, amoxicillin-clavulanic acid and erythromycin was determined against H. influenzae, M. catarrhalis and S. pneumoniae. With the exception of one beta-lactamase negative ampicillin-resistant strain of H. influenzae (resistant to all antibiotics tested), no resistance to cefdinir was observed (MIC < or = 1 mg/l). Cefdinir was active against H. influenzae, H. parainfluenzae and M. catarrhalis regardless of whether or not they produced beta-lactamase. In general, the inhibitory concentrations of cefdinir against H. influenzae, H. parainfluenzae and M. catarrhalis were similar to those of amoxicillin/clavulanic acid, one or two dilutions lower than those of cefuroxime and four dilutions lower than those of cefaclor and cotrimoxazole. Against S. pneumoniae and S. pyogenes cefdinir had the same activity as cefuroxime and amoxicillin but was more effective than the other antibiotics tested. Kinetic studies showed that cefdinir was rapidly bactericidal at concentrations 2 and 4 times the minimum inhibitory concentration (MIC): a reduction of 99.9% in CFU values was generally observed after 6-8 h.
Insights
Cefdinir, an oral cephalosporin, demonstrated potent in vitro activity against key respiratory pathogens, including Haemophilus influenzae and Streptococcus pneumoniae. It showed broad-spectrum efficacy with minimal resistance observed, proving rapidly bactericidal.
Area of Science:
- Microbiology
- Pharmacology
- Infectious Diseases
Background:
- The emergence of antibiotic resistance necessitates the evaluation of new antimicrobial agents.
- Cephalosporins are a critical class of antibiotics used to treat bacterial infections.
Purpose of the Study:
- To assess the in vitro antibacterial activity of cefdinir against common respiratory tract pathogens.
- To compare cefdinir's efficacy with existing antibiotics.
Main Methods:
- In vitro susceptibility testing of 287 bacterial strains including Haemophilus influenzae, Haemophilus parainfluenzae, Moraxella catarrhalis, Streptococcus pneumoniae, and Streptococcus pyogenes.
- Determination of bactericidal activity and minimum inhibitory concentrations (MICs) for cefdinir and comparator antibiotics.
Main Results:
- Cefdinir exhibited potent activity against all tested strains, with no observed resistance except in one beta-lactamase negative ampicillin-resistant H. influenzae strain.
- Activity was maintained against beta-lactamase producing strains of H. influenzae, H. parainfluenzae, and M. catarrhalis.
- Cefdinir demonstrated comparable or superior activity to other tested antibiotics like amoxicillin-clavulanic acid, cefuroxime, cefaclor, erythromycin, and cotrimoxazole.
- Cefdinir was rapidly bactericidal, achieving a 99.9% reduction in viable counts within 6-8 hours at concentrations 2-4 times the MIC.
Conclusions:
- Cefdinir is a highly active oral cephalosporin against key respiratory pathogens.
- Its broad spectrum of activity and rapid bactericidal effect suggest its potential as a valuable therapeutic option for respiratory tract infections.