Characterization of porin expression in Klebsiella pneumoniae carbapenemase (KPC)-producing K. pneumoniae identifies isolates most susceptible to the combination of colistin and carbapenems

Jae H. Hong, Cornelius J. Clancy, Shaoji Cheng, Ryan K. Shields, Liang Chen, Yohei Doi, Yanan Zhao, David S. Perlin, Barry N. Kreiswirth, M. Hong Nguyen

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We characterized carbapenem resistance mechanisms among 12 Klebsiella pneumoniae carbapenemase (KPC)-producing K. pneumoniae (referred to here as KPC K. pneumoniae) clinical isolates and evaluated their effects on the activity of 2-and 3-drug combinations of colistin, doripenem, and ertapenem. All isolates were resistant to ertapenem and doripenem; 75% (9/12) were resistant to colistin. Isolates belonged to the ST258 clonal group and harbored blaKPC-2, blaSHV-12, and blaTEM-1. As determined by time-kill assays, doripenem (8 μg/ml) and ertapenem (2 μg/ml) were inactive against 92% (11/12) and 100% (12/12) of isolates, respectively. Colistin (2.5 μg/ml) exerted some activity (range, 0.39 to 2.5 log10) against 78% (7/9) of colistin-resistant isolates. Colistin-ertapenem, colistin-doripenem, and colistin-doripenem-ertapenem exhibited synergy against 42% (5/12), 50% (6/12), and 67% (8/12) of isolates, respectively. Expression of ompK35 and ompK36 porins correlated with each other (R2= 0.80). Levels of porin expression did not correlate with colistin-doripenem or colistin-ertapenem synergy. However, synergy with colistin-doripenem- ertapenem was more likely against isolates with high porin expression than those with low expression (100% [8/8] versus 0% [0/4]; P=0.002). Moreover, bactericidal activity (area under the bacterial killing curve) against isolates with high porin expression was greater for colistin-doripenem-ertapenem than colistin-doripenem or colistin-ertapenem (P < 0.049). In conclusion, colistin-carbapenem combinations may provide optimal activity against KPC K. pneumoniae, including colistin-resistant isolates. Screening for porin expression may identify isolates that are most likely to respond to a triple combination of colistin-doripenem-ertapenem. In the future, molecular characterization of KPC K. pneumoniae isolates may be a practical tool for identifying effective combination regimens.

Original languageEnglish
Pages (from-to)2147-2153
Number of pages7
JournalAntimicrobial agents and chemotherapy
Issue number5
Publication statusPublished - 01-05-2013
Externally publishedYes


All Science Journal Classification (ASJC) codes

  • Pharmacology
  • Pharmacology (medical)
  • Infectious Diseases

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