Meropenem Coverage for Haemophilus influenzae
Yes, meropenem provides excellent coverage against Haemophilus influenzae, including beta-lactamase-producing and beta-lactamase-negative ampicillin-resistant strains. 1, 2
Evidence for Meropenem Activity Against H. influenzae
- Meropenem is highly active against H. influenzae with MIC50 of 0.06 μg/ml and MIC90 of 0.25 μg/ml, making it 8-16 times more potent than imipenem against this pathogen 3
- The FDA label specifically indicates meropenem for the treatment of bacterial meningitis caused by Haemophilus influenzae, confirming its effectiveness against this organism 4
- Meropenem is 4-64 fold more active than imipenem against gram-negative bacteria, including H. influenzae 5
- Studies have shown meropenem to be particularly effective against beta-lactamase-negative ampicillin-resistant (BLNAR) strains of H. influenzae, with an MIC90 of 0.5 mg/L 2
Clinical Applications
- Meropenem is FDA-approved for bacterial meningitis caused by H. influenzae in pediatric patients 3 months of age and older 4
- For treatment of H. influenzae meningitis, the recommended pediatric dose is 40 mg/kg every 8 hours (maximum 2 grams every 8 hours) 4
- In community-acquired pneumonia guidelines, meropenem is recognized as an excellent β-lactam that is adequate for most H. influenzae infections 6
- Meropenem may be preferred when there is concern for relatively unusual CAP pathogens alongside H. influenzae 6
Comparative Efficacy
- While meropenem is highly effective against H. influenzae, it is considered a broad-spectrum agent that should be reserved for specific situations rather than routine use 6
- In murine bronchopneumonia models caused by both ampicillin-susceptible and BLNAR H. influenzae, meropenem showed excellent efficacy, second only to cefotaxime 2
- Against beta-lactamase-producing strains of H. influenzae, meropenem has been shown to be approximately 10 times more active than imipenem 7
Mechanism of Action Against H. influenzae
- Meropenem's bactericidal activity results from inhibition of cell wall synthesis by binding to penicillin-binding proteins 4
- Its high activity against H. influenzae is explained by ease of entry into bacteria combined with good affinity for essential penicillin binding proteins 1
- Meropenem is stable to all serine-based beta-lactamases, including those produced by H. influenzae, contributing to its effectiveness 1
Clinical Considerations
- For empiric therapy of community-acquired pneumonia where H. influenzae is a concern, guidelines suggest several options, with carbapenems like meropenem being particularly valuable when there are concerns about resistant pathogens 6
- When using disk diffusion testing for H. influenzae susceptibility to meropenem, a zone diameter of ≥17 mm indicates susceptibility (MIC ≤4 μg/ml) 3
- Despite excellent activity against H. influenzae, meropenem should be used judiciously to prevent development of resistance 6
Meropenem represents a highly effective option for treating H. influenzae infections, particularly in cases involving resistant strains or serious infections such as meningitis, where its excellent penetration and potent activity make it a valuable therapeutic option.