Date of Award

5-13-2016

Degree Type

Thesis

Degree Name

Master of Public Health (MPH)

Department

Public Health

First Advisor

Dr. Lisa Casanova

Second Advisor

Dr. Christine Stauber

Abstract

Antibiotic resistance is a serious global public health problem. ESBLs are enzymes that destroy expanded-spectrum beta-lactam antibiotics rendering these drugs ineffective. Infection with ESBL-producing K.pneumoniae are hard to treat and result in longer hospital stay and higher mortality rates. The Clinical Laboratory Standard Institute (CLSI) have standard methods for detection of ESBL producing strains of bacteria in infected patients to guide antibiotic therapy, reduce the risk of mortality and risk of transmission. The presence of K.pneumoniae and E.coli which produce ESBLs have been confirmed in natural environments such as soil and water but no standard methods exist to identify directly and quantify these bacteria to understand the risk of human exposure in these settings. The purpose of this research is to assess the ability of an agar dilution method, using a differential agar Bio-Rad Rapid E.coli 2 agar utilized in environmental water quality studies, to identify correctly ESBL-producing K.pneumoniae. The minimum inhibitory concentration (MIC) of ceftriaxone antibiotic for wild-type ESBL producing K.pneumoniae isolates were compared on Mueller-Hinton broth (MHB) and Bio-Rad Rapid E.coli 2 agar. Using the MIC values, the isolates were classified as susceptible, intermediate or resistant. The MIC of wild-type strains of K.pneumoniae were above 4μg/mL for both methods on all susceptibility tests performed. The results of this research suggest that Bio-Rad Agar dilution method performed well, correctly identifying these strains as resistant to ceftriaxone, an indication of ESBL production. The Bio-Rad agar dilution method can be considered as a viable standard method for direct identification of ESBL-producing K.pneumoniae in natural environments.

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