Antimicrobial Susceptibility Studies
Antimicrobial susceptibility of Enterobacteriaceae, including molecular characterization of extended-spectrum beta-lactamase–producing species, in urinary tract isolates from hospitalized patients in North America and Europe: results from the SMART study 2009–2010,☆☆,,★★

https://doi.org/10.1016/j.diagmicrobio.2012.05.024Get rights and content

Abstract

In 2009–2010, 3646 urinary tract isolates of Enterobacteriaceae spp. were isolated from hospitalized patients in North America and Europe. Extended-spectrum beta-lactamase (ESBL) production was detected in 8.5% and 8.8% of Escherichia coli and Klebsiella pneumoniae, respectively, in North America and in 17.6% and 38.9% for Europe, respectively. The carbapenems (ertapenem and imipenem) were the most active agents in vitro, with ampicillin–sulbactam the least active. Molecular characterization of about 50% of ESBL-positive isolates identified the presence of blaCTX-M genes in over 90% of Escherichia coli from both continents. blaKPC was more common in North American isolates of K. pneumoniae than in European isolates (21.4% versus 6.9%). blaTEM and AmpC genes were infrequent. Enterobacteriaceae spp. isolated from hospitalized patients with urinary tract infections in both North America and Europe are often resistant to commonly used antimicrobials with blaCTX-M genes common in both Escherichia coli and K. pneumoniae.

Introduction

Urinary tract infection (UTI) is a common cause for hospitalization and is also frequently acquired by patients hospitalized for other indications (Wagenlehner et al., 2008, Wagenlehner et al., 2011). Enterobacteriaceae are the family most commonly implicated including Escherichia coli, Klebsiella pneumoniae/oxytoca, and Proteus mirabilis (Alhambra et al., 2004, Mathai et al., 2001, Zhanel et al., 2010). Empirical antimicrobial therapy is guided by knowledge of the bacterial spectrum of UTI pathogens and the prevalence of antimicrobial resistance (Bader et al., 2010). Antimicrobial resistance varies by institution, country, and continent. Globally, resistance to commonly used oral and parenteral antimicrobials including aminoglycosides, third-generation cephalosporins, carbapenems, and beta-lactam/beta-lactamase inhibitor combinations is increasing (Meier et al., 2011, Perez et al., 2007). Over the past 10 years, the prevalence of extended-spectrum beta-lactamase (ESBL)–positive Enterobacteriaceae, as well as those now demonstrating carbapenem resistance, has increased dramatically (Hoban et al., 2010a, Hoban et al., 2010b). The Study for Monitoring Antimicrobial Resistance Trends (SMART) is an ongoing, multinational surveillance program that has monitored the susceptibilities of Gram-negative bacilli from intra-abdominal infections since 2002. SMART also began monitoring the susceptibilities of Gram-negative bacilli from hospitalized patients with UTIs in late 2009. This report describes the in vitro susceptibility of selected Enterobacteriaceae from UTI and the molecular characterization of a subgroup of ESBL-positive isolates from North America and Europe from 2009 to 2010.

Section snippets

Collection centers

Up to 50 Gram-negative bacilli per site from hospitalized patients with UTIs were obtained from hospitals in North America (2009: 29 sites; 2010: 31 sites) and Europe (2009: 39 sites; 2010: 43 sites).

Bacterial isolates

Each study site was requested to submit consecutive Gram-negative bacilli isolated from in-patients with UTIs. All isolates were deemed to be clinically significant (> 105 CFU/mL) by the participating site. Only 1 isolate per species per patient was accepted. Isolate inclusion was independent of

Results

In 2009–2010, 4004 Gram-negative bacilli were collected in the SMART program from hospitalized patients in North America and Europe with UTIs. Enterobacteriaceae comprised 3646 (91.1%) of these isolates. Escherichia coli (2,241, 61.5%), K. pneumoniae (604, 16.6%), K. oxytoca (107, 2.9%), and Proteus mirabilis (239, 6.6%) were the most common Enterobacteriaceae species. P. aeruginosa and Acinetobacter spp. represented 8.6% of the Gram-negative bacilli. The antimicrobial susceptibility profiles

Discussion

The spectrum of bacteria isolated from UTIs in hospitalized patients is very broad and includes both Gram-positive and Gram-negative pathogens. In a study examining causative pathogens in both Europe and North America (Gordon and Jones, 2003), typically Gram-negative species account for over 70% and are usually composed of Escherichia coli, Klebsiella spp., Pseudomonas spp., Proteus spp., Enterobacter spp., and Citrobacter spp. Recently, the epidemiology of complicated UTI pathogens in 7

Acknowledgments

The authors thank all the SMART investigators for their participation in this program.

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    Funding: The SMART surveillance program is funded by Merck & Co.

    ☆☆

    Conflict of Interest: D. Hoban, S. Hawser, R. Badal, C. Lascols, M. Hackel, and S. Bouchillon served as scientific advisors or consultants to Merck and received research support from Merck to conduct this study. L. Nicolle declares no conflicts.

    Transparency declaration: The authors are responsible for the work described in this article. All authors were involved in at least one of the following: conception, design, acquisition, analysis, and statistical analysis, interpretation of data, and drafting the manuscript and/or revising the manuscript for important intellectual content. All authors provided final approval of the version to be published.

    ★★

    Portions of the study were presented at the 51st Interscience Conference on Antimicrobial Agents and Chemotherapy (Chicago, IL, September 17–20, 2011) [Abstract No. E-1822] and 21st European Congress of Clinical Microbiology and Infectious Disease (Milan, Italy, May 7–10, 2011) [Abstract No. P566].

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