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Antibacterial activity of meropenem and selected comparative agents against anaerobic bacteria at seven North
W Sheikh1, D H Pitkin, H Nadler
1Zeneca Pharmaceuticals Group, Business Unit of Zeneca Inc., Wilmington, Delaware 19897.
Abstract:
The antibacterial activity of meropenem and comparative agents against approximately 1,000 anaerobes was determined using the disk dilution methods recommended by the National Committee for Clinical Laboratory Standards (NCCLS). The organisms represented 27 species of six genera and included the most common pathogens. Meropenem and imipenem were the most active drugs and were comparable in overall activity, generally exhibiting an MIC90 of < or = 1 micrograms/mL. In contrast, the MICs of cefoxitin, clindamycin, and metronidazole were 32, 16, and 2 micrograms/mL, respectively. Meropenem was two- to fourfold more active than imipenem against selected Bacteroides species, Clostridium species, and Fusobacterium species. At a concentration of 1 microgram/mL, meropenem was more active than imipenem against cefoxitin-resistant Bacteroides fragilis or Bacteroides thetaiotaomicron. At a concentration of < or = 0.5 micrograms/mL, meropenem was more active than imipenem against clindamycin-resistant Bacteroides distasonis. At a concentration of 2 micrograms/mL, meropenem was more active than imipenem against cefoxitin-resistant or clindamycin-resistant Clostridium difficile. Thus, meropenem's high potency and broad-spectrum activity against common, rare, and drug-resistant anaerobes confirms its utility in the treatment of mixed anaerobic and aerobic infections.
Insights
Meropenem demonstrates potent broad-spectrum antibacterial activity against a wide range of anaerobes, including drug-resistant strains. This study confirms its effectiveness, comparable to imipenem, for treating mixed anaerobic and aerobic infections.
Area of Science:
- Microbiology
- Infectious Diseases
- Pharmacology
Background:
- Anaerobic bacterial infections pose significant therapeutic challenges.
- Evaluating novel antibiotics against diverse anaerobic pathogens is crucial for effective treatment strategies.
Purpose of the Study:
- To assess the in vitro antibacterial activity of meropenem against a large collection of anaerobic bacteria.
- To compare meropenem's efficacy with other established antimicrobial agents.
Main Methods:
- Disk dilution method following National Committee for Clinical Laboratory Standards (NCCLS) guidelines.
- Testing against approximately 1,000 anaerobic isolates from 27 species and six genera.
- Determination of Minimum Inhibitory Concentration 90 (MIC90) values.
Main Results:
- Meropenem and imipenem exhibited potent activity (MIC90 ≤ 1 µg/mL) against most anaerobes.
- Meropenem showed enhanced activity compared to imipenem against specific Bacteroides, Clostridium, and Fusobacterium species.
- Meropenem was effective against strains resistant to cefoxitin, clindamycin, and metronidazole.
Conclusions:
- Meropenem possesses high potency and broad-spectrum activity against common, rare, and drug-resistant anaerobic bacteria.
- Its efficacy supports its use in treating mixed anaerobic and aerobic infections.
- Meropenem represents a valuable therapeutic option for anaerobic bacterial infections.