Meropenem Coverage of Gram-Negative Bacilli
Yes, Merrem (meropenem) provides excellent coverage against gram-negative bacilli and is specifically recommended for treating infections caused by these organisms, particularly those producing extended-spectrum β-lactamases or hyperproducing lactamases. 1
Spectrum of Activity Against Gram-Negative Organisms
Meropenem demonstrates superior activity against gram-negative bacilli compared to many other antibiotics:
- Meropenem is more active against Enterobacteriaceae and Pseudomonas aeruginosa compared to imipenem 2, 3
- It maintains activity against gram-negative organisms that are resistant to third-generation cephalosporins 4
- The drug has excellent gram-negative aerobic and anaerobic activity 4
Specific Clinical Indications
The Infectious Diseases Society of America specifically recommends meropenem for:
- Infections caused by gram-negative bacilli that produce extended-spectrum β-lactamases (ESBLs) 1
- Organisms that may hyperproduce lactamases, including Enterobacter species, Citrobacter species, and Serratia marcescens 1, 5
- Meningitis caused by gram-negative isolates resistant to standard therapy 1
Guideline-Supported Use
Major guidelines position meropenem as a Group 2 carbapenem with broad gram-negative coverage:
- Carbapenems including meropenem offer wide spectrum antimicrobial activity against gram-positive and gram-negative aerobic and anaerobic pathogens 6
- Group 2 carbapenems (imipenem/cilastatin, meropenem, doripenem) share activity against non-fermentative gram-negative bacilli 6
- For health care-associated infections, meropenem is recommended as part of empiric therapy to achieve coverage of likely gram-negative pathogens 6
Resistance Considerations
Important caveats regarding resistance patterns:
- Meropenem is stable to most β-lactamases including AmpC β-lactamases and extended-spectrum β-lactamases 7
- For carbapenem-resistant gram-negative bacilli (CRGNB), newer formulations like meropenem-vaborbactam are recommended for severe infections due to carbapenem-resistant Enterobacteriaceae (CRE) 1
- Resistance develops when bacteria acquire metallo-β-lactamases capable of degrading carbapenems or when changes in membrane permeability occur 7
Clinical Efficacy Data
Clinical trials demonstrate strong efficacy against gram-negative infections:
- Meropenem monotherapy was significantly more effective than ceftazidime-based combination treatments in patients with nosocomial lower respiratory tract infections caused by gram-negative organisms 3
- Treatment with meropenem as initial empirical monotherapy was effective in serious infections in ICU patients with gram-negative pathogens 3