HIGH INCIDENCE OF EXTENDED SPECTRUM BETA-LACTAMASES IN KLEBSIELLA PNEUMONIAE FROM ENVIRONMENTAL SURFACE WATERS
Kyle Kisor, Luis Mota-Bravo, Lili Mesak.
University of California, Irvine, Irvine, CA.
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 of extended spectrum are commonly prescribed. Since K. pneumonia is commonly found in the environment, we hypothesize that environmental strains may be an unexplored reservoir of antibiotic resistance genes, particularly extended spectrum beta-lactamases (ESBL). Water samples were collected in Orange County, California from 2011 to 2014. K. pneumonia strains 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. Thirty eight K. 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 3rd 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. In the presence of ESBLs, resistance to ciprofloxacin, tetracycline, gentamicin, sulfisoxazole, and trimethoprim were observed. Multidrug resistance defined as resistance to 3 or more classes of antibiotics was observed in all isolates which produced ESBLs. Aquatic environments are an important reservoir of antibiotic resistant determinants in ESBL producing K. pneumonia.