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[Cefoperazone, cefsulodin and ceftazidime--3 cephalosporins active against Pseudomonas in comparison with their
Abstract:
This study compares the in vitro activity of three cephalosporins - ceftazidime, cefoperazone, cefsulodin and their monobactam analogues for 144 strains of Pseudomonas aeruginosa. Media variation studies are performed and the effect of human serum and anaerobic conditions on MIC is investigated. A significant inoculum effect is considered as a sign of instability against beta-lactamases. Ceftazidine inhibits nearly all pseudomonads at concentrations between 2 and 4 micrograms/ml being significantly more active than the other antibiotics tested. The level of activity of all monobactams tested is lower than that of the homologous cephalosporins. The counterpart of ceftazidine is also the most effective monobactam but the counterpart of cefsulodin shows no activity against pseudomonads.
Insights
Ceftazidime demonstrates superior in vitro activity against Pseudomonas aeruginosa compared to other cephalosporins and their monobactam analogues. This study highlights ceftazidime
Area of Science:
- Microbiology
- Pharmacology
- Infectious Diseases
Background:
- Pseudomonas aeruginosa is an opportunistic pathogen known for its resistance to antibiotics.
- Beta-lactam antibiotics, including cephalosporins and monobactams, are crucial for treating P. aeruginosa infections.
- Understanding the in vitro activity of these agents is essential for guiding clinical treatment.
Purpose of the Study:
- To compare the in vitro activity of ceftazidime, cefoperazone, cefsulodin, and their monobactam analogues against Pseudomonas aeruginosa.
- To investigate the impact of media composition, human serum, and anaerobic conditions on antibiotic efficacy.
- To assess the inoculum effect as an indicator of beta-lactamase instability.
Main Methods:
- In vitro susceptibility testing of 144 P. aeruginosa strains.
- Determination of Minimum Inhibitory Concentrations (MICs) for tested antibiotics.
- Evaluation of media variation, human serum presence, and anaerobic conditions on MIC values.
- Assessment of inoculum effect to identify beta-lactamase instability.
Main Results:
- Ceftazidime exhibited the highest in vitro activity, inhibiting most P. aeruginosa strains at concentrations of 2-4 µg/ml.
- All tested monobactam analogues showed lower activity than their corresponding cephalosporins.
- The monobactam analogue of ceftazidime was the most effective among the monobactams, while the cefsulodin analogue was inactive against P. aeruginosa.
Conclusions:
- Ceftazidime is a highly effective cephalosporin against Pseudomonas aeruginosa in vitro.
- Monobactam analogues generally display reduced activity compared to parent cephalosporins.
- The study underscores the importance of ceftazidime in treating P. aeruginosa infections, with specific monobactams showing limited utility.