title: Multidrug-resistant phenotype and isolation of a novel SHV- beta-Lactamase variant in a clinical isolate of Enterobacter cloacae.
abstract: BACKGROUND
  ESBL-producing bacteria are a clinical problem in the management of diseases caused by these pathogens. Worldwide, systemic infections with BL enzymes are evolving by mutations from classical bla genes in an intensified manner and they continue to be transferred across species.
  
  
  RESULTS
  E.cloacae BF1417 isolate and its transconjugants gave positive results with the DDST, suggesting the presence of ESBL. Sequence analysis revealed a bla SHV-ESBL-type gene that differs from the gene encoding SHV-1 by five point mutations resulting in three amino acid substitutions in the coding region: C123R, I282T and L286P. This novel SHV-type enzyme was designated SHV-128. The conjugation tests and plasmid characterization showed that the bla SHV-128 is located on a conjugative plasmid IncFII type. Expression studies demonstrated that the above mutations participated in drug resistance, hydrolysis of extended spectrum β-lactam and the change of the isoelectric point of the protein.
  
  
  CONCLUSIONS
  These findings underscore the diversity by which antibiotic resistance can arise and the evolutionary potential of the clinically important ESBL enzymes. In addition, this study highlights the need for systematic surveillance of ESBL-mediated resistance as well as in clinical areas and communities.
authors.affiliation: Address: Laboratory of Biochemistry and Biotechnology, Faculty of Sciences of Tunis, 2092, El Manar II, Tunisia. boursaamel@yahoo.fr.
authors.forename: Amel
authors.initials: A
authors.lastname: Bourouis
authors.affiliation: Addresses: Laboratory of Microbiology, Military Hospital of Tunis, 1089, Monfleury, Tunisia. bouabidibourouis0812@gmail.com.
authors.forename: Mouhamed
authors.initials: M
authors.lastname: Ben Moussa
authors.affiliation: Address: Laboratory of Biochemistry and Biotechnology, Faculty of Sciences of Tunis, 2092, El Manar II, Tunisia. omrane.belhadj@fst.rnu.tn.
authors.forename: Omrane
authors.initials: O
authors.lastname: Belhadj
mesh_terms: D000900:Anti-Bacterial Agents / Q000494:pharmacology*; D001426:Bacterial Proteins / Q000235:genetics* / Q000378:metabolism; D001483:Base Sequence; D016972:Enterobacter cloacae / Q000187:drug effects* / Q000235:genetics* / Q000378:metabolism; D008826:Microbial Sensitivity Tests; D008969:Molecular Sequence Data; D016133:Polymerase Chain Reaction; D016415:Sequence Alignment; D018440:beta-Lactam Resistance; D001618:beta-Lactamases / Q000235:genetics* / Q000378:metabolism; D047090:beta-Lactams / Q000494:pharmacology*
chemical_list: D000900:Anti-Bacterial Agents; D001426:Bacterial Proteins; D047090:beta-Lactams; C054882:beta-lactamase PIT-2; D001618:beta-Lactamases