Is there a place for β-lactams in the treatment of multidrug-resistant/extensively drug-resistant tuberculosis? Synergy between meropenem and amoxicillin/clavulanate

Ximena Gonzalo, Francis Drobniewski*

*Corresponding author for this work

    Research output: Contribution to journalArticlepeer-review

    56 Citations (Scopus)


    Objectives: To: (i) assess if amoxicillin/clavulanate is a useful option for the management of multidrug-resistant/extensively drug-resistant tuberculosis (MDR/XDR-TB); (ii) assess if meropenem/clavulanate is active against Mycobacterium tuberculosis at concentrations achievable in vivo; and (iii) determine whether there was inhibition of meropenem/clavulanate activity in the presence of amoxicillin. Methods: Twenty-eight M. tuberculosis strains (7 susceptible, 2 monoresistant, 16 MDR and 3 XDR) were included in the study and tested against different concentrations of meropenem, meropenem/clavulanate, amoxicillin/meropenem, amoxicillin/clavulanate and amoxicillin/meropenem/clavulanate using the Bactec 960 MGIT( system. Results: All 28 strains were resistant to meropenem at the highest concentration tested (5 mg/L). Although 24 strains were susceptible to amoxicillin/clavulanate, 7 strains were susceptible only to 7.2/2.5 mg/L amoxicillin/clavulanate, 10 strains were susceptible to 3.6/2.5 mg/L amoxicillin/clavulanate, 6 strains were susceptible to 1.8/2.5 mg/L amoxicillin/clavulanate and 1 strain was susceptible to 0.9/2.5 mg/L amoxicillin/clavulanate. Therefore, 4/28 strains (14.29%) were resistant to the highest concentration of amoxicillin tested (7.2 mg/L); all of them were MDR. All of the 11 strains resistant to amoxicillin or susceptible only to 7.2 mg/L amoxicillin increased their susceptibility to amoxicillin/clavulanate after the addition of meropenem. The addition of clavulanate to meropenem reduced the MIC of meropenem by an average of over 1.8 dilutions. Conclusions: The combination of amoxicillin/clavulanate plus meropenem is active against MDR/XDR-TB in vitro, and this triple therapy could be a useful therapy for MDR/XDR-TB and possibly help to reduce the development of further resistance.The drug susceptibility technique used here is routinely used, with modification, in mycobacteriology laboratories.

    Original languageEnglish
    Article numberdks395
    Pages (from-to)366-369
    Number of pages4
    JournalJournal of Antimicrobial Chemotherapy
    Issue number2
    Publication statusPublished - Feb 2013

    Bibliographical note

    Funding Information:
    This study was supported by internal funding.

    Copyright 2013 Elsevier B.V., All rights reserved.


    • β;-lactamases
    • MDR/XDR-TB
    • Mycobacterium tuberculosis


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