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In-vitro activity of FCE 22101 and synergy studies with other antimicrobial agents
1Department of Medicine, College of Physicians & Surgeons, Columbia University, New York, NY 10032.
Abstract:
FCE 22101 is a penem antibiotic with broad in-vitro activity similar to that of imipenem, although less active against Pseudomonas aeruginosa. Combinations of FCE 22101 with ciprofloxacin or gentamicin against methicillin-resistant Staphylococcus aureus and methicillin-resistant Staph. epidermidis resulted in addition or indifference by the chequerboard method. The combination of FCE 22101 and gentamicin against Streptococcus faecalis was usually additive. Against Enterobacter cloacae FCE 22101 had MICs of 16 mg/l whilst in combination with gentamicin (0.25-0.12 mg/l) the MICs were reduced to less than 2 mg/l. Ciprofloxacin and FCE 22101 showed only addition against Enterobacter spp. similar results were obtained with the combinations of FCE 22101 and gentamicin or ciprofloxacin tested against Citrobacter freundii. With Serratia spp. FCE 22101 and gentamicin showed synergy, but FCE 22101 and ciprofloxacin showed indifference. Similar results were obtained with strains of Escherichia coli and Klebsiella, Proteus, and Providencia spp. FCE 22101 plus gentamicin, or aztreonam, against Ps. aeruginosa usually showed indifference, but with ciprofloxacin addition was the rule. In general the combination of FCE 22101 with other agents resulted in an additive rather than a synergistic effect.
Insights
FCE 22101, a penem antibiotic, shows broad in-vitro activity. Combinations with other antibiotics like gentamicin and ciprofloxacin generally resulted in additive effects against various bacteria, with some synergistic activity observed.
Area of Science:
- Microbiology
- Pharmacology
- Infectious Diseases
Background:
- FCE 22101 is a novel penem antibiotic.
- It exhibits broad-spectrum in-vitro activity, comparable to imipenem.
- Its activity against Pseudomonas aeruginosa is noted as less potent than imipenem.
Purpose of the Study:
- To evaluate the in-vitro activity of FCE 22101.
- To assess the effects of combining FCE 22101 with other antibiotics (ciprofloxacin, gentamicin, aztreonam).
- To determine the combined activity against a range of Gram-positive and Gram-negative bacteria, including resistant strains.
Main Methods:
- In-vitro susceptibility testing.
- Chequerboard titration method to assess antibiotic combinations.
- Determination of Minimum Inhibitory Concentrations (MICs).
Main Results:
- FCE 22101 demonstrated broad activity, though less against Pseudomonas aeruginosa.
- Combinations with ciprofloxacin or gentamicin showed additive or indifferent effects against methicillin-resistant Staphylococcus aureus and Staph. epidermidis.
- Synergistic effects were observed with gentamicin against Serratia spp., while combinations with ciprofloxacin were generally additive or indifferent across various bacterial species.
Conclusions:
- FCE 22101 possesses significant in-vitro antibacterial activity.
- Combination therapy with FCE 22101 and other agents primarily yields additive effects.
- The study highlights potential utility in specific bacterial infections, warranting further investigation.