Susceptibility rates of clinically important bacteria collected from intensive care units against colistin, carbapenems, and other comparative agents: Results from surveillance of multicenter antimicrobial resistance in Taiwan (SMART)

Chih Cheng Lai, Ying Sheng Chen, Nan Yao Lee, Hung Jen Tang, Susan Shin Jung Lee, Chin Fu Lin, Po Liang Lu, Jiunn Jong Wu, Wen Chien Ko, Wen Sen Lee, Po Ren Hsueh

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Objectives: This study aimed to determine the in vitro susceptibility of commonly encountered Gram-negative bacilli (GNB) recovered from patients admitted to intensive care units (ICUs) in Taiwan against colistin, carbapenems, and other comparative agents. Methods: In total, 758 nonduplicate GNB isolates were obtained from clinical specimens of ICU patients at seven medical centers in 2016. Minimum inhibitory concentrations (MICs) were determined using the Vitek 2 susceptibility system. The reference broth-microdilution method was performed to determine MICs of colistin. Five main carbapenemase genes among carbapenem-non-susceptible GNB and mcr-1–mcr5 genes among colistin non-wild-type or-resistant isolates were determined. Results: After exclusion 38 Proteus mirabilis and 13 Morganella morganii spp. among 361 Enterobacteriaceae isolates, 34 (9.4%) isolates were carbapenem-insusceptible, 91.1% (n=31) were colistin wild type, and three and one Klebsiella pneumoniae isolates carried blaKPC and blaOXA48-like, respectively. Carbapenem-insusceptible isolates were found in 23.4% (30 of 128) and 63.0% (87 of 138) of isolates of the Pseudomonas aeruginosa and Acinetobacter baumannii complex, respectively. mcr-1 was detected in two (1.8%) Enterobacter cloacae isolates. Very major errors between two methods of susceptibility to colistin were found in 1.5% of K. pneumoniae, 27.5% of E. cloacae, 4.7% of P. aeruginosa, and 10.1% of A. baumannii complex isolates. Conclusion: In this study, 8.7% of Enterobacteriaceae isolates from ICUs were not susceptible to carbapenem, and blaKPC and blaOXA48-like were found among three and one carbapenem-insusceptible K. pneumoniae isolates, respectively. Colistin MICs determined by Vitek 2 were not reliable, especially for E. cloacae and A. baumannii complex isolates.

Original languageEnglish
Pages (from-to)627-640
Number of pages14
JournalInfection and Drug Resistance
Publication statusPublished - Jan 1 2019



  • A. Baumannii
  • Carbapenemase
  • Carbapenems
  • Colistin
  • Intensive care units
  • Mcr-1
  • P. Aeruginosa
  • Susceptibility

ASJC Scopus subject areas

  • Pharmacology
  • Infectious Diseases
  • Pharmacology (medical)

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