title: SHV-7, a novel cefotaxime-hydrolyzing beta-lactamase, identified in Escherichia coli isolates from hospitalized nursing home patients.
abstract: Four ceftazidime-resistant Escherichia coli strains were isolated from elderly nursing home patients in a New York hospital during 1993. Strains MCQ-2, MCQ-3, and MCQ-4 were determined to be identical by pulsed-field gel electrophoresis and plasmid profiles, whereas strain MCQ-1 was unique. Strain MCQ-1 was determined to produce a TEM-10 beta-lactamase. Strains MCQ-2, MCQ-3, and MCQ-4 were also noted to be resistant to cefotaxime. These three strains produced two beta-lactamases with pIs of 5.4 (TEM-1) and 7.6. beta-Lactamase assays revealed that the pI 7.6 enzyme hydrolyzed cefotaxime faster (at a relative hydrolysis rate of 30% compared with that of benzylpenicillin) than either ceftazidime or aztreonam (relative hydrolysis rates of 13 and 3.3%, respectively). Nucleotide sequencing of the gene encoding the pI 7.6 beta-lactamase from strain MCQ-3 revealed a blaSHV-type gene differing from the gene encoding SHV-1 at four nucleotides which resulted in amino acid substitutions: phenylalanine for isoleucine at position 8, serine for arginine at position 43, serine for glycine at position 238, and lysine for glutamate at position 240. This novel SHV-type extended-spectrum beta-lactamase is designated SHV-7.
authors.affiliation: Lederle Laboratories, Pearl River, New York, USA.
authors.forename: P A
authors.initials: PA
authors.lastname: Bradford
authors.forename: C
authors.initials: C
authors.lastname: Urban
authors.forename: A
authors.initials: A
authors.lastname: Jaiswal
authors.forename: N
authors.initials: N
authors.lastname: Mariano
authors.forename: B A
authors.initials: BA
authors.lastname: Rasmussen
authors.forename: S J
authors.initials: SJ
authors.lastname: Projan
authors.forename: J J
authors.initials: JJ
authors.lastname: Rahal
authors.forename: K
authors.initials: K
authors.lastname: Bush
mesh_terms: D000595:Amino Acid Sequence; D001483:Base Sequence; D002439:Cefotaxime / Q000378:metabolism*; D004926:Escherichia coli / Q000187:drug effects / Q000201:enzymology* / Q000235:genetics; D006801:Humans; D008826:Microbial Sensitivity Tests; D008969:Molecular Sequence Data; D009735:Nursing Homes; D010957:Plasmids; D001618:beta-Lactamases / Q000032:analysis* / Q000737:chemistry / Q000235:genetics
chemical_list: D001618:beta-Lactamases; D002439:Cefotaxime