Open AccessTLA-1: a New Plasmid-Mediated Extended-Spectrum β-Lactamase from Escherichia coli
Author(s) -
J. Silva,
Cecilia Aguilar,
Guadalupe Ayala,
Marco Antonio Juárez Estrada,
Ulises Garza–Ramos,
Roberto Lara-Lemus,
L. Ledezma
Publication year - 2000
Publication title -
antimicrobial agents and chemotherapy
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.07
H-Index - 259
eISSN - 1070-6283
pISSN - 0066-4804
DOI - 10.1128/aac.44.4.997-1003.2000
Subject(s) - aztreonam , microbiology and biotechnology , cefotaxime , ceftazidime , biology , imipenem , sulbactam , escherichia coli , chryseobacterium , cefoxitin , antibiotic resistance , pseudomonas aeruginosa , gene , genetics , bacteria , antibiotics , staphylococcus aureus , 16s ribosomal rna
Escherichia coli R170, isolated from the urine of an infected patient, was resistant to expanded-spectrum cephalosporins, aztreonam, ciprofloxacin, and ofloxacin but was susceptible to amikacin, cefotetan, and imipenem. This particular strain contained three different plasmids that encoded two β-lactamases with pIs of 7.0 and 9.0. Resistance to cefotaxime, ceftazidime, aztreonam, trimethoprim, and sulfamethoxazole was transferred by conjugation fromE. coli R170 toE. coli J53-2. The transferred plasmid, RZA92, which encoded a single β-lactamase, was 150 kb in length. The cefotaxime resistance gene that encodes the TLA-1 β-lactamase (pI 9.0) was cloned from the transconjugant by transformation toE. coli DH5α. Sequencing of thebla TLA-1 gene revealed an open reading frame of 906 bp, which corresponded to 301 amino acid residues, including motifs common to class A β-lactamases:70 SXXK,130 SDN, and234 KTG. The amino acid sequence of TLA-1 shared 50% identity with the CME-1 chromosomal class A β-lactamase fromChryseobacterium (Flavobacterium )meningosepticum ; 48.8% identity with the VEB-1 class A β-lactamase fromE. coli ; 40 to 42% identity with CblA ofBacteroides uniformis , PER-1 ofPseudomonas aeruginosa , and PER-2 ofSalmonella typhimurium ; and 39% identity with CepA ofBacteroides fragilis . The partially purified TLA-1 β-lactamase had a molecular mass of 31.4 kDa and a pI of 9.0 and preferentially hydrolyzed cephaloridine, cefotaxime, cephalothin, benzylpenicillin, and ceftazidime. The enzyme was markedly inhibited by sulbactam, tazobactam, and clavulanic acid. TLA-1 is a new extended-spectrum β-lactamase of Ambler class A.