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Activity of colistin against Klebsiella pneumoniae from 2007 to 2009, including isolates resistant to carbapenems

Abstract number: P1625

Hawser S., Bouchillon S., Hoban D., Dowzicky M.

Background: Due to significant resistance to currently available therapies, successful treatment of infections due to Klebsiella pneumoniae is becoming limited. Moreover, a recent increase in the numbers of carbapenem-resistant isolates has been documented. The emergence of drug-resistant isolates has led in more recent years to the re-introduction of "salvage" therapies such as colistin (polymyxin E). This study investigated the activity of colistin against clinical isolates of K. pneumoniae originating from multiple infection sources that were collected during 2007–2009.

Methods: All isolates were collected during the T.E.S.T surveillance program (Tigecycline Evaluation and Surveillance Trial) and included infection sources such as blood or other normally sterile fluids, pneumonia, and non-catheter related urinary tract specimens. MICs were performed according to CLSI guidelines and interpreted using EUCAST breakpoints. A total of 280 clinical isolates were tested for their susceptibilities to colistin and additional comparator antimicrobial agents.

Results: See table.

Conclusions: These data show that colistin exhibited good in vitro activity against the majority of isolates, including carbapenem-resistant isolates. Only 8 isolates (2.9%) were resistant to colistin, though there was no apparent relationship between colistin resistance and resistance to other antimicrobials.

AntimicrobialModeMIC50MIC90%SMINMAX
Ceftazidime=0.5=0.51686.1=0.5>16
Colistin0.250.250.597.1=0.12>4
Ertapenem=0.03=0.03=0.0396.8=0.03>32
Gentamicin=0.25=0.25190.7=0.25>8
Imipenem0.250.250.598.9=0.034
Levofloxacin=0.25=0.25486.4=0.25>4
Piperacillin/Tazobactam44>6478.9=0.5>64
Tigecycline=0.5=0.5193.6=0.5>2
%S, percent susceptible using EUC AST breakpoints

Session Details

Date: 10/04/2010
Time: 00:00-00:00
Session name: Abstracts 20th European Congress of Clinical Microbiology and Infectious Diseases
Subject:
Location: Vienna, Austria, 10 - 13 April 2010
Presentation type:
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