Klebsiella Pneumoniae Beta-Lactam Resistance from Environmental Surface Waters

Klebsiella pneumoniae is a gram-negative opportunistic pathogen causing infection in immunocompromised individuals frequently in the urinary and respiratory tracts. To treat an infection of this bacterium, beta-lactam antibiotics such as cefotaxime, ceftazidime, and cefoxitin are most commonly prescribed. Beta-lactam antibiotics are characterized as having beta-lactam rings that are hydrolyzed by beta-lactamase enzymes, which render the antibiotic ineffective against a given pathogen. One of the most prevalent and concerning beta-lactamases found around the world are known as extended-spectrum beta-lactamases which deactivate extended spectrum cephalosporins. As beta-lactam antibiotics continue to be a widely used treatment, the natural environment has become a reservoir for antimicrobial resistant Klebsiella pneumoniae. The aim of this study is to determine the prevalence of beta-lactam antibiotic resistance and ESBL production in Klebsiella pneumoniae acquired from aquatic environments. Water samples were collected in Orange County, California from 2011 to 2014. Water was filtered and plated on selection media containing antibiotics. Bacterial isolates were identified using matrix-assisted laser desorption/ionization time of flight (MALDI-TOF) mass spectrometry. Disk susceptibility tests were performed on each isolate and antibiotic resistance was determined according to Clinical Laboratory Standards Institute (CLSI) guidelines. 38 Klebsiella pneumoniae isolates were collected and beta-lactam resistance was found in 32% of isolates against cefotaxime with no observed resistance to ceftazidime. When clavulanic acid was combined with third generation cephalosporins, 37% of isolates tested positive for the presence of an extended spectrum beta-lactamase based on a zone of inhibition greater than or equal to 5 millimeters more than cefotaxime or ceftazidime alone. Cefoxitin and cefepime both resulted in 3% resistance. Beta-lactam antibiotic resistant and ESBL producing Klebsiella pneumoniae is present in aquatic environments of Orange County, California. Resistance is observed especially toward the third generation cephalosporin cefotaxime.