Award Date

5-1-2014

Degree Type

Thesis

Degree Name

Master of Public Health (MPH)

Department

Health Sciences

First Committee Member

Patricia Cruz

Second Committee Member

Mark Buttner

Third Committee Member

Timothy Bungum

Fourth Committee Member

Daniel Young

Number of Pages

62

Abstract

Carbapenems are β-lactam antibiotics reserved for the treatment of severe microbial infections, especially those targeting the Enterobacteriaceae. Introduced in the 1980s, carbapenems have been used successfully in hospitals, and in the 1990s resistance was discovered. Carbapenem resistance is conferred through the production of carbapenemases. In the U.S., the most common carbapenemase is Klebsiella pneumoniae carbapenemase (KPC). In 2012, the National Healthcare Safety Network reported a carbapenem resistance rate of 13.0% among Klebsiella pneumoniae infections, and indicated that the mortality rate associated with carbapenem resistant Enterobacteriaceae (CRE) infections ranged from 48.0-71.9%. According to the Food and Drug Administration (FDA), carbapenem resistance is observed when a pure culture has a minimum inhibitory concentration (MIC) ≥ 4 g/ml as determined through antibiotic susceptibility testing (AST).In 2012, a lower MIC for carbapenem antibiotics was established for KPCs by the Clinical and Laboratory Standards Institute (CLSI) (i.e., MICs 1 - 4 g/ml are designated resistant), but these criteria have not been endorsed by the FDA. Data are needed to determine the percentage of clinical isolates with carbapenem MIC between 1 and 4 g/ml that are truly resistant. Determining the presence of the KPC gene is important because the use of carbapenems in patients with MIC between 1- 4 g/ml may have poor clinical outcomes. Conversely, if lacking the KPC gene, carbapenems may still be indicated. The objectives of this study were to determine the presence of the KPC gene, the carbapenem AST profiles of clinical isolates, and the resistance rates based on the previous and current CLSI criteria. This study involved 56 suspected CRE clinical isolates from Las Vegas, Nevada, which were analyzed by culture, AST, and polymerase chain reaction to detect the KPC gene. The prevalence of the blaKPC gene in our CRE isolates was 83.3%, and the prevalence was 94.7% among our Klebsiella pneumoniae isolates. Our data showed no statistically significant difference between the previous and the current CLSI criteria in defining carbapenem resistance among the Enterobacteriaceae. The results from this study helped determine the prevalence of the KPC gene and antimicrobial susceptibility profiles among CRE isolates in Las Vegas. These may be useful in improving antibiotic stewardship in Nevada.

Keywords

Antibiotics; Beta lactam antibiotics; Drug resistance in microorganisms; Klebsiella pneumoniae

Disciplines

Microbiology | Molecular Biology | Public Health

Language

English


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