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[Antibacterial effect of cefixime]
C J Soussy1, M Meyran, J Duval
1Service du Bactériologie, CHU Henri-Mondor, Créteil.
Abstract:
Cefixime (CFM) is a new hemi-synthetic orally active cephalosporin which exhibits a particular affinity for PBPs 3, 1a, 1bs. Its penetration through the Gram negative bacilli outer membrane is similar to that of third generation cephalosporins. The MICs were assessed by the agar dilution method against 2,489 bacterial strains collected in 10 hospitals. Against Enterobacteriaceae, MICs50 and 90 are respectively (mg/l): naturally non beta-lactamase-producing species: E. coli and Shigella: 0.25-0.5, Salmonella: 0.06 - 0.25, P. mirabilis: 0.008 - 0.0.32; chromosomal penicillinase producing species: Klebsiella: 0.06 - 2; chromosomal cephalosporinase producing species: E. cloacae and C. freundii: 1 - greater than 128, S. marcescens: 0.25 - 16, Proteus indole: + 0.06 - 4, P. stuartii: 0.032 - 0.5. CFM activity is not altered in strains producing an acquired penicillinase. On the other hand, CFM appears to be inactive against cephalosporinase hyperproducing mutants and its activity is variably decreased against expanded spectrum beta-lactamase producing strains. CFM is inactive against P. aeruginosa (MIC50 and 90: 64 - 128) and against A. baumannii (16 - 128). Haemophilus and gonococci, beta-lactamase producing or not, as well as meningococci, are highly susceptible to CFM (MIC 0.008 - 0.12). B. catarrhalis is usually inhibited by 0.03 to 0.5. CFM is moderately active against meticillin-sensitive staphylococci (MIC50 and 90: 1-64), and inactive against meticillin-resistant strains. Enterococci are usually resistant, whereas streptococci and pneumococci are inhibited by low concentrations: 0.08 to 1. CFM is a bactericidal antibiotic, as shown by MBC and killing curves determination. These antibacterial properties relate CFM to the third generation cephalosporins and position the compound in an excellent place among the orally active cephalosporins.
Insights
Cefixime (CFM) is a potent, orally active cephalosporin effective against many Gram-negative and Gram-positive bacteria. Its activity is comparable to third-generation cephalosporins, though reduced against certain resistant strains.
Area of Science:
- Pharmacology
- Microbiology
- Infectious Diseases
Background:
- Cefixime (CFM) is a novel orally administered cephalosporin antibiotic.
- It demonstrates significant affinity for penicillin-binding proteins (PBPs) 3, 1a, and 1bs.
- CFM exhibits outer membrane penetration characteristics similar to third-generation cephalosporins.
Purpose of the Study:
- To evaluate the in vitro antibacterial activity of Cefixime (CFM).
- To assess CFM's efficacy against a broad spectrum of bacterial pathogens.
- To compare CFM's activity with existing cephalosporins.
Main Methods:
- Minimum Inhibitory Concentrations (MICs) were determined using the agar dilution method.
- Testing was performed on 2,489 bacterial isolates from 10 different hospitals.
- Susceptibility testing included various species of Enterobacteriaceae, Haemophilus, Neisseria, Moraxella, Staphylococcus, Enterococcus, Streptococcus, and Streptococcus pneumoniae.
Main Results:
- CFM demonstrated potent activity against non-beta-lactamase-producing Enterobacteriaceae (e.g., E. coli, Salmonella) and Haemophilus species.
- Activity was reduced against strains producing cephalosporinases or extended-spectrum beta-lactamases.
- CFM was inactive against Pseudomonas aeruginosa and Acinetobacter baumannii but showed moderate activity against methicillin-susceptible Staphylococcus aureus.
Conclusions:
- Cefixime (CFM) exhibits broad-spectrum bactericidal activity, positioning it favorably among orally active cephalosporins.
- Its efficacy is comparable to third-generation cephalosporins, particularly against susceptible Gram-negative organisms.
- CFM's effectiveness may be limited in infections caused by bacteria with specific beta-lactamase resistance mechanisms.