Activity of colistin against Enterobacteriaceae from 2007 to 2009, including drug-resistant isolates

Abstract number: P1628

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

Background: Due to significant resistance to currently available therapies, successful treatment of infections due to Enterobacteriaceae 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 old "salvage" therapies such as colistin (polymyxin E). This study investigated the activity of colistin against clinical isolates of Enterobacteriaceae 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. Colistin MICs were performed on a selection of clinical isolates and tested according to CLSI guidelines and interpreted using EUCAST breakpoints. A total of 1,360 clinical isolates were tested for their susceptibilities to colistin and comparator antimicrobial agents.

Results: See table.

Conclusions: These data show that colistin exhibited good in vitro activity against the majority of isolates, many of which were resistant to other antimicrobials. Overall, the percent susceptibilities for colistin ranged from 85.3% (E. cloacae) to 98.8% (E. coli).

Organism (n)MIC50MIC90MIC Range%S*
Enterobacter aerogenes (292)0.510.25–>495.2
Enterobacter cloacae (258)0.5>4=0.12–>485.3
Escherichia coli (254)0.50.5=0.12–>498.8
Klebsiella oxytoca (276)0.250.5=0.12–>497.5
Klebsiella pneumoniae (280)0.250.5=0.12–>497.1
*%S, percent of isolates susceptible using EUCAST breakpoints.

Session Details

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