Meropenem Coverage Against Corynebacterium
Meropenem demonstrates excellent activity against most Corynebacterium species, with the notable exception of C. jeikeium, where susceptibility is variable and some strains show resistance. 1
Spectrum of Activity
Meropenem exhibits strong bactericidal activity against the majority of clinically significant Corynebacterium species:
Most Corynebacterium species are highly susceptible to meropenem, with mean MICs ranging from 0.04-0.17 mg/L, which is well below clinically achievable concentrations. 1
Corynebacterium jeikeium represents a critical exception to this broad coverage. Among C. jeikeium isolates, strains have been identified that show susceptibility to meropenem but paradoxically demonstrate resistance to imipenem and other beta-lactams, indicating unpredictable susceptibility patterns. 1
The bactericidal activity of meropenem against susceptible Corynebacterium strains is comparable to imipenem, though killing kinetics may be slower for certain species like C. jeikeium compared to streptococci or staphylococci. 1
Comparative Activity
Meropenem's activity against Gram-positive organisms, including Corynebacterium, is slightly less than imipenem (typically 2-4 times less active), but this difference is generally not clinically significant for susceptible strains. 2, 1
The broad-spectrum carbapenem activity includes excellent coverage of Gram-positive pathogens, anaerobes, and Gram-negative organisms, making it suitable for empirical therapy when Corynebacterium is suspected as part of polymicrobial infections. 3, 2
Clinical Considerations and Pitfalls
The most important pitfall is assuming universal Corynebacterium coverage without susceptibility testing, particularly for C. jeikeium. This species is notorious for multidrug resistance and requires specific susceptibility confirmation before relying on meropenem therapy. 1
Standard dosing of meropenem (1 gram IV every 8 hours) achieves plasma and tissue concentrations that exceed the MICs for susceptible Corynebacterium species throughout the dosing interval. 4
For serious infections where C. jeikeium is isolated or suspected (particularly in immunocompromised patients with indwelling catheters), obtain susceptibility testing before assuming meropenem efficacy, as vancomycin may be required for resistant strains. 1
Meropenem's stability against serine-based beta-lactamases contributes to its reliable activity against most Corynebacterium species, but this does not extend to intrinsically resistant organisms. 4