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[In vitro activity of imipenem against hospital bacteria]
1Service de bactériologie, Hôpital Henri-Mondor, Créteil.
Abstract:
Imipenem proved highly active against Enterobacteriaceae: the different bacterial groups exhibited similar mode MICs (0.12 to 0.25 micrograms/ml), except for Serratia (0.25-0.5 micrograms/ml), Proteus mirabilis (0.5 micrograms/ml), indole-positive Proteus (2 micrograms/ml) and Providencia (1 mu/ml). The MICs of cefotaxime-resistant strains (cephalosporinase hyperproducing or very broad spectrum betalactamase producing) were within the susceptibility range. Imipenem also exhibited satisfactory activity against Pseudomonas aeruginosa (mode MIC 1-2 micrograms/ml), although resistant strains by decrease of permeability were observed, and against Acinetobacter (mode MIC 0.25-0.5 micrograms/ml). The MICs ranged from 0.03 to 4 micrograms/ml (mode MIC 0.5) for Haemophilus and from 0.25 to 1 micrograms/ml for Neisseria gonorrhoeae, regardless of the betalactamase producing status. The MICs for N. meningitidis were less than 0.06 micrograms/ml. Methicillin-susceptible staphylococci had low MICs ranging from 0.008 to 0.5 micrograms/ml (mode MIC 0.016). The MICs for methicillin-resistant strains varied widely from 0.016 to 64 micrograms/ml and were higher after incubation at 30 degrees C. Streptococci and pneumococci were highly susceptible (usually 0.008 to 0.03 micrograms/ml). The MICs for enterococci varied from 0.12 to 32 micrograms/ml (mode MIC 1-2). With the exception of Clostridium difficile, anaerobic bacteria were inhibited by concentrations lower than 1 (mode MIC 0.06 for C. Perfringens and 0.03 for Bacteroides fragilis).
Insights
Imipenem demonstrates broad-spectrum antibacterial activity against numerous Gram-negative and Gram-positive pathogens. This carbapenem antibiotic shows potent efficacy, even against some resistant strains, highlighting its clinical potential.
Area of Science:
- Microbiology
- Pharmacology
- Infectious Diseases
Context:
- The emergence of antibiotic resistance necessitates the evaluation of novel antimicrobial agents.
- Carbapenem antibiotics, such as imipenem, are critical in treating severe bacterial infections.
Purpose:
- To assess the in vitro activity of imipenem against a wide range of clinically significant bacterial species.
- To determine the minimum inhibitory concentrations (MICs) of imipenem for various Gram-negative and Gram-positive bacteria, including resistant strains.
Summary:
- Imipenem exhibited high activity against Enterobacteriaceae, Pseudomonas aeruginosa, Acinetobacter, Haemophilus, Neisseria, and anaerobic bacteria.
- Methicillin-susceptible staphylococci, streptococci, and pneumococci were highly susceptible to imipenem.
- While generally effective, some resistance mechanisms were observed in Pseudomonas aeruginosa and methicillin-resistant staphylococci.
Impact:
- Imipenem's broad spectrum of activity supports its role as a valuable therapeutic option for complex bacterial infections.
- Understanding imipenem's susceptibility patterns is crucial for guiding empirical and targeted antibiotic therapy.
- This data contributes to the ongoing surveillance of antibiotic resistance and the effective use of carbapenems.