Nosocomial spread of cephem-resistant Escherichia coli strains carrying multiple Toho-1-like beta-lactamase genes

• DOI: 10.1128/aac.41.12.2606
• Publication Date: 2018-10-09T00:27:29Z
• Authors: T Yagi; H Kurokawa; K Senda; S Ichiyama; H Ito; S Ohsuka; K Shibayama; K Shimokata; N Kato; M Ohta; Y Arakawa
• Keywords: Cephem; Beta-lactamase; Structural gene

Escherichia coli HKY56, which demonstrated resistance to various beta-lactams except carbapenems, was isolated from the throat swab of an inpatient in 1994. Conjugal transfer cephem HKY56 E. CSH2 not successful. Three cefotaxime-resistant clones harboring plasmid pMRE001, pMRE002, or pMRE003, each carried a 3.4-, 5.8-, 6.2-kb EcoRI fragment insert, respectively, were obtained HKY56. Although restriction analysis suggested their different origins, these showed similar profiles beta-lactams. The sequence 10 amino acid residues at N terminus beta-lactamase purified HB101(pMRE001) identical that Toho-1. This Toho-1-like beta-lactamase-1 (TLB-1) able hydrolyze cefoperazone and cefotaxime efficiently, but it failed cephamycins. A Toho-1-specific DNA probe hybridized with three distinct fragments derived chromosomal strain corresponded inserts by respectively. PCR Southern hybridization all six cephem-resistant strains, strains HKY273, HKY285, HKY288, HKY305, HKY316, HKY335, 1996 same hospital where had been isolated, also possessed multiple (TLB) genes, patterns quite among isolates. fingerprinting observed pulsed-field gel electrophoresis revealed isolates tested, genetic background. These findings carry chromosomally multiplied TLB genes may have proliferating transmitted patients hospital.