Brief reportAntimicrobial Susceptibility of Inpatient Urinary Tract Isolates of Gram-Negative Bacilli in the United States: Results from the Study for Monitoring Antimicrobial Resistance Trends (SMART) Program: 2009−2011
Introduction
Urinary tract infection (UTI) is one of the most common community- and hospital-associated bacterial infections routinely treated empirically.1 UTIs are responsible for >100,000 hospitalizations yearly in the United States, and 40% of hospital-associated infections are UTIs, mostly due to indwelling catheters.2, 3 The most common pathogens associated with UTIs are Enterobacteriaceae and include Escherichia coli, Klebsiella pneumoniae, Klebsiella oxytoca, Proteus mirabilis, Citrobacter, and Enterobacter species.4 Treatment of hospitalized patients with complicated infections has become more difficult due to increasing antimicrobial resistance, which is of particular concern with the β-lactam and β-lactamase inhibitors and fluoroquinolones.5, 6, 7 Monitoring the emergence of resistance plays a critical role in aiding health care providers in the treatment of complicated UTIs. The Study for Monitoring Antimicrobial Resistance Trends (SMART) surveillance study is an ongoing, multinational surveillance program that has monitored the susceptibilities of Gram-negative bacilli from intra-abdominal infections since 2002. Beginning in September 2009, SMART has also monitored the susceptibilities of Gram-negative bacilli from hospitalized patients with UTIs. The present report describes the in vitro susceptibility of Gram-negative bacilli isolated from inpatients within the United States with UTIs from 2009 to 2011.
Section snippets
Sample Collection
Twenty-four unique sites in the United States contributed to the SMART UTI study during 2009−2011. Each study site was requested to submit up to 50 nonduplicate, consecutive Gram-negative bacilli from male or female hospitalized patients with a clinical and microbiological diagnosis of UTIs. Up to 50 Gram-negative bacilli per site were obtained from hospitalized patients with UTIs. These isolates were categorized as community associated (isolated <48 hours from admission), hospital associated
Results
Through the SMART surveillance program 2,135 Gram-negative isolates were collected from hospitalized patients with UTI at 24 US sites from 2009 to 2011; 88.6% (n = 1,892) of these were Enterobacteriaceae. E coli was the most frequently isolated pathogen at 48.9% (n = 1,045), followed by K pneumoniae at 14.5% (n = 310); P mirabilis at 6.4% (n = 136), Enterobacter cloacae at 4.6% (n = 99), and K oxytoca at 2.5% (n = 54). P aeruginosa accounted for 9.6% (n = 204) of the isolates. Other
Discussion
The economic burden of UTIs continues to rise, in part due to the frequency of these infections and also to the impact of resistance on their diagnosis and treatment.10 Resistance of urinary tract pathogens can occur in ambulatory, institutionalized, and hospitalized patients. This long progression of resistance in E coli and K pneumoniae has complicated the selection of empirical treatment for these infections.5 CA and HA organisms are frequently resistant to β-lactam and β-lactamase inhibitor
Conclusions
When taken in context with other published data, an overall ESBL rate of 7%, as noted in this study from the United States, is low compared with rates approaching or exceeding 20% in Europe, Asia, and Latin America, but it is significant nonetheless. This article confirms the usefulness of alternative antimicrobials, including the carbapenems, that although not yet advocated as first-line empirical treatment, they cannot be ignored. This report is limited in (1) its lack of trending data, (2)
Conflicts of Interest
This work was supported by a grant from Merck & Company (Whitehouse Station, New Jersey). Dr. Bouchillon, Mr. Badal, and Dr. Hoban are employees of International Health Management Associates, Inc. (IHMA), which is a contract research organization under contract to conduct and manage the SMART program on behalf of Merck & Company. S. P. Hawser is the CEO of IHMA Europe Sárl, a wholly owned subsidiary of International Health Management Associates, Inc. The study sponsor was not involved in the
Acknowledgments
International Health Management Associates, Inc. is grateful for the contributions made by D. Sun and ProScience, Inc. in the preparation of this article.
Dr. Bouchillon had major responsibilities in the study design, table creations, data collection and interpretation, and writing. All other authors contributed equally to document review and editing.
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