TY - JOUR
T1 - In Vivo evolution of CMY-2 to CMY-33 β-lactamase in Escherichia coli sequence type 131
T2 - Characterization of an acquired extended-spectrum AmpC conferring resistance to cefepime
AU - Pires, João
AU - Taracila, Magdalena
AU - Bethel, Christopher R.
AU - Doi, Yohei
AU - Kasraian, Sara
AU - Tinguely, Regula
AU - Sendi, Parham
AU - Bonomo, Robert A.
AU - Endimiani, Andrea
N1 - Funding Information:
This work was supported by the Swiss National Science Foundation (SNF) (grant 32003B-153377 to A.E.). J.P. is a Ph.D. student (2014 to 2017) supported by the SNF. The research reported in this publication was also supported in part by the National Institute of Allergy and Infectious Diseases of the National Institutes of Health (grants R01AI063517 and R01AI100560 to R.A.B., and grants R21AI107302 and R01AI104895 to Y.D.); the Cleveland Department of Veterans Affairs, the Veterans Affairs Merit Review Program (award 1I01BX001974 to R.A.B.); and the Geriatric Research Education and Clinical Center VISN 10 (to R.A.B.). The content of this article is solely the responsibility of the authors and does not represent the official views of the National Institutes of Health or the Department of Veterans Affairs. We thank Sara Droz (Institute for Infectious Diseases, University of Bern) for providing the E. coli isolates (Ec-1 and Ec-2) and Thierry Parret and Gwendoline Boillat (Hôpital du Jura Bernois SA, St-Imier, Switzerland) for the clinical data regarding the patient.
Publisher Copyright:
Copyright © 2015, American Society for Microbiology. All Rights Reserved.
PY - 2015/12/1
Y1 - 2015/12/1
N2 - Cefepime is frequently prescribed to treat infections caused by AmpC-producing Gram-negative bacteria. CMY-2 is the most common plasmid-mediated AmpC (pAmpC) β-lactamase. Unfortunately, CMY variants conferring enhanced cefepime resistance have been reported. Here, we describe the evolution of CMY-2 to an extended-spectrum AmpC (ESAC) in clonally identical Escherichia coli isolates obtained from a patient. The CMY-2-producing E. coli isolate (CMY-2-Ec) was isolated from a wound. Thirty days later, one CMY-33-producing E. coli isolate (CMY-33-Ec) was detected in a bronchoalveolar lavage fluid sample. Two weeks before the isolation of CMY-33-Ec, the patient received cefepime. CMY-33-Ec and CMY-2-Ec were identical by repetitive extragenic palindromic-PCR (rep-PCR), being of hyperepidemic sequence type 131 (ST131) but showing different β-lactam MICs (e.g., cefepime MIC, 16 and ≤0.5 μg/ml for CMY-33-Ec and CMY-2-Ec, respectively). Identical CMY-2-Ec isolates were also found in a rectal swab. CMY-33 differs from CMY-2 by a Leu293-Ala294 deletion. Expressed in E. coli strain DH10B, both CMYs conferred resistance to ceftazidime (≥256 μg/ml), but the cefepime MICs were higher for CMY-33 than CMY-2 (8 versus 0.25 μg/ml, respectively). The kcat/Km or inhibitor complex inactivation (kinact)/Ki app (μM-1 s-1) indicated that CMY-33 possesses an extended-spectrum β-lactamase (ESBL)-like spectrum compared to that of CMY-2 (e.g., cefoxitin, 0.2 versus 0.4; ceftazidime, 0.2 versus not measurable; cefepime, 0.2 versus not measurable; and tazobactam, 0.0018 versus 0.0009, respectively). Using molecular modeling, we show that a widened active site (∼4-Å shift) may play a significant role in enhancing cefepime hydrolysis. This is the first in vivo demonstration of a pAmpC that under cephalosporin treatment expands its substrate spectrum, resembling an ESBL. The prevalence of CMY-2-Ec isolates is rapidly increasing worldwide; therefore, awareness that cefepime treatment may select for resistant isolates is critical.
AB - Cefepime is frequently prescribed to treat infections caused by AmpC-producing Gram-negative bacteria. CMY-2 is the most common plasmid-mediated AmpC (pAmpC) β-lactamase. Unfortunately, CMY variants conferring enhanced cefepime resistance have been reported. Here, we describe the evolution of CMY-2 to an extended-spectrum AmpC (ESAC) in clonally identical Escherichia coli isolates obtained from a patient. The CMY-2-producing E. coli isolate (CMY-2-Ec) was isolated from a wound. Thirty days later, one CMY-33-producing E. coli isolate (CMY-33-Ec) was detected in a bronchoalveolar lavage fluid sample. Two weeks before the isolation of CMY-33-Ec, the patient received cefepime. CMY-33-Ec and CMY-2-Ec were identical by repetitive extragenic palindromic-PCR (rep-PCR), being of hyperepidemic sequence type 131 (ST131) but showing different β-lactam MICs (e.g., cefepime MIC, 16 and ≤0.5 μg/ml for CMY-33-Ec and CMY-2-Ec, respectively). Identical CMY-2-Ec isolates were also found in a rectal swab. CMY-33 differs from CMY-2 by a Leu293-Ala294 deletion. Expressed in E. coli strain DH10B, both CMYs conferred resistance to ceftazidime (≥256 μg/ml), but the cefepime MICs were higher for CMY-33 than CMY-2 (8 versus 0.25 μg/ml, respectively). The kcat/Km or inhibitor complex inactivation (kinact)/Ki app (μM-1 s-1) indicated that CMY-33 possesses an extended-spectrum β-lactamase (ESBL)-like spectrum compared to that of CMY-2 (e.g., cefoxitin, 0.2 versus 0.4; ceftazidime, 0.2 versus not measurable; cefepime, 0.2 versus not measurable; and tazobactam, 0.0018 versus 0.0009, respectively). Using molecular modeling, we show that a widened active site (∼4-Å shift) may play a significant role in enhancing cefepime hydrolysis. This is the first in vivo demonstration of a pAmpC that under cephalosporin treatment expands its substrate spectrum, resembling an ESBL. The prevalence of CMY-2-Ec isolates is rapidly increasing worldwide; therefore, awareness that cefepime treatment may select for resistant isolates is critical.
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UR - http://www.scopus.com/inward/citedby.url?scp=84954484036&partnerID=8YFLogxK
U2 - 10.1128/AAC.01804-15
DO - 10.1128/AAC.01804-15
M3 - Article
C2 - 26392491
AN - SCOPUS:84954484036
SN - 0066-4804
VL - 59
SP - 7483
EP - 7488
JO - Antimicrobial agents and chemotherapy
JF - Antimicrobial agents and chemotherapy
IS - 12
ER -