Pharmacotherapeutic group: antibacterials for systemic use, carbapenems
ATC code: J01DH02
Mechanism of action
Meropenem exerts its bactericidal activity by inhibiting bacterial cell wall synthesis in Gram-positive and Gram-negative bacteria through binding to penicillin-binding proteins (PBPs).
Pharmacokinetic/Pharmacodynamic (PK/PD) relationship
Similar to other beta-lactam antibacterial agents, the time that meropenem concentrations exceed the MIC (T>MIC) has been shown to best correlate with efficacy. In preclinical models meropenem demonstrated activity when plasma concentrations exceeded the MIC of the infecting organisms for approximately 40 % of the dosing interval. This target has not been established clinically.
Mechanism of resistance
Bacterial resistance to meropenem may result from: (1) decreased permeability of the outer membrane of Gram-negative bacteria (due to diminished production of porins) (2) reduced affinity of the target PBPs (3) increased expression of efflux pump components, and (4) production of beta-lactamases that can hydrolyse carbapenems.
Localised clusters of infections due to carbapenem-resistant bacteria have been reported in the European Union.
There is no target-based cross-resistance between meropenem and agents of the quinolone, aminoglycoside, macrolide and tetracycline classes. However, bacteria may exhibit resistance to more than one class of antibacterials agents when the mechanism involved include impermeability and/or an efflux pump(s).
Breakpoints
MIC (minimum inhibitory concentraztion) interpretive criteria for susceptibility testing have been established by the European Committee on Antimicrobial susceptibility Testing (EUCAST) for meropenem and are listed below:
https://www.ema.europa.eu/documents/other/minimum-inhibitory-concentration-mic-breakpoints_en.xlsx
The prevalence of acquired resistance may vary geographically and with time for selected species and local information on resistance is desirable, particularly when treating severe infections. As necessary, expert advice should be sought when the local prevalence of resistance is such that the utility of the agent in at least some types of infections is questionable.
The following table of pathogens listed is derived from clinical experience and therapeutic guidelines.
Commonly susceptible species
Gram-positive aerobes Enterococcus faecalis$
Staphylococcus aureus (methicillin-susceptible
)£Staphylococcus species (methicillin-susceptible) including
Staphylococcus epidermidisStreptococcus agalactiae (Group B)
Streptococcus milleri group (
S. anginosus,
S. constellatus, and
S. intermedius)
Streptococcus pneumoniaeStreptococcus pyogenes (Group A)
Gram-negative aerobes Citrobacter freundiiCitrobacter koseriEnterobacter aerogenesEnterobacter cloacaeEscherichia coliHaemophilus influenzaeKlebsiella oxytocaKlebsiella pneumoniaeMorganella morganiiNeisseria meningitidisProteus mirabilisProteus vulgarisSerratia marcescens
Gram-positive anaerobes Clostridium perfringensPeptoniphilus asaccharolyticusPeptostreptococcus species (including P. micros, P anaerobius, P. magnus)
Gram-negative anaerobes Bacteroides caccaeBacteroides fragilis group
Prevotella biviaPrevotella disiens Species for which acquired resistance may be a problem
Gram-positive aerobes Enterococcus faecium$†
Gram-negative aerobes Acinetobacter species
Burkholderia cepaciaPseudomonas aeruginosa Inherently resistant organisms
Gram-negative aerobes Stenotrophomonas maltophiliaLegionella species
Other micro-organisms Chlamydophila pneumoniaeChlamydophila psittaciCoxiella burnetiiMycoplasma pneumoniae
$ Species that show natural intermediate susceptibility
£ All methicillin-resistant staphylococci are resistant to meropenem
† Resistance rate ≥ 50% in one or more EU countries.
Glanders and melioidosis: Use of meropenem in humans is based on in vitro B.mallei and B. pseudomallei susceptibility data and on limited human data. Treating physicians should refer to national and/or international consensus documents regarding the treatment of glanders and melioidosis.