Comparison of synergism between colistin, fosfomycin and tigecycline against extended-spectrum β-lactamase-producing Klebsiella pneumoniae isolates or with carbapenem resistance

Yee Huang Ku, Chi Chung Chen, Mei Feng Lee, Yin Ching Chuang, Hung Jen Tang, Wen Liang Yu

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15 Citations (Scopus)


Purpose: To investigate the synergistic and bactericidal effects of antimicrobial combinations of any two of colistin, fosfomycin and tigecycline against the nine extended-spectrum β-lactamase (ESBL)-producing Klebsiella pneumoniae (KP) clinical isolates, including 4 carbapenem-susceptible strains and five imipenem and/or meropenem-resistant strains. Methods: In vitro synergism and bactericidal activity of combination of colistin, fosfomycin and tigecycline were evaluated by time-kill studies in standard inoculum of bacterial densities of a suspension containing 5 × 105 CFU/mL by using 1/2× MIC for each alone, and both 1/2× and 1/4× MIC for any two drugs. The settings of low MIC dosing were allowed to rapidly survey the most active drug combination. Results: The most active combination group was colistin plus tigecycline, showing synergy in 8 isolates and bactericidal activities in 6 isolates by using concentrations of 1/2× MIC and 1/4× MIC, respectively. The least active combination was tigecycline plus fosfomycin, which showed synergy in only 4 isolates and no bactericidal activities by using concentrations of 1/2× MIC and 1/4× MIC, respectively. Conclusions: The combination of tigecycline and colistin may be considered as a last-resort approach to the ESBL-producing KP infections, especially those isolates with carbapenem resistance.

Original languageEnglish
JournalJournal of Microbiology, Immunology and Infection
Publication statusAccepted/In press - 2017



  • Carbapenem resistance
  • Colistin
  • ESBL
  • Fosfomycin
  • Tigecycline

ASJC Scopus subject areas

  • Immunology and Allergy
  • Immunology and Microbiology(all)
  • Microbiology (medical)
  • Infectious Diseases

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