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Updated: Jul 13, 2026

Quantification of Plasmid-Mediated Antibiotic Resistance in an Experimental Evolution Approach
Published on: December 14, 2019
Broader distribution of plasmid-mediated quinolone resistance in the United States
A Robicsek1, D F Sahm, J Strahilevitz
1Division of Infectious Diseases, Massachusetts General Hospital, 55 Fruit Street, Boston, Massachusetts 02114-2696, USA.
Abstract:
The plasmid-encoded quinolone resistance gene qnrA confers low-level quinolone resistance, facilitating selection of higher-level resistance. Epidemiologic surveys for qnrA were extended to isolates of Enterobacter spp. and to quinolone-susceptible Enterobacteriaceae. Two (10%) of 20 ceftazidime-resistant quinolone-susceptible Klebsiella pneumoniae strains carried the gene, as did 12 (17%) of 71 ceftazidime-resistant Enterobacter strains from across the United States. One of these Enterobacter isolates was quinolone susceptible. Thus, qnrA is present in quinolone-resistant and quinolone-susceptible Enterobacter and Klebsiella strains in the United States.
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