title: Variations in IS6 promoters alter the expression of carbapenem resistance in related strains of Acinetobacter baumannii.
abstract: The aim of this work was to investigate the role of the IS6 family of insertion sequences present upstream of blaOXA-58in two clonally related carbapenem-resistant Acinetobacter baumannii isolates obtained from paediatric cancer patients in Egypt. To determine their relatedness, the isolates were typed by pulsed-field gel electrophoresis (PFGE), and the intrinsic blaOXA-51-likegene was amplified and sequenced. Minimum inhibitory concentrations (MICs) to imipenem and meropenem was determined according to British Society of Antimicrobial Chemotherapy (BSAC) guidelines. PCR and sequencing of blaOXA-58and the upstream and downstream regions was performed to determine the genetic environment. The two isolates were positive for the intrinsic blaOXA-64gene, and the MICs for isolates AB-14298 and AB-P67 were 8mg/L and 64mg/L for imipenem and 2mg/L and 16mg/L for meropenem, respectively. The blaOXA-58gene in AB-14298 was flanked by ISAba3 interrupted with IS1006, whereas AB-P67 had ISAba3 interrupted by IS1008, both belonging to the IS6 family of insertion sequences. In conclusion, both IS1006 and IS1008 provided suitable promoter sequences for expression of the downstream blaOXA-58gene.
authors.affiliation: Clinical Medicine, University of Sussex, Brighton, UK. Electronic address: l.al-hassan@bsms.ac.uk.
authors.forename: Leena
authors.initials: L
authors.lastname: Al-Hassan
authors.affiliation: Medical Microbiology, University of Edinburgh, Edinburgh, UK.
authors.forename: Andres
authors.initials: A
authors.lastname: Opazo
authors.affiliation: School of Medicine and Dentistry, University of Aberdeen, Aberdeen, UK.
authors.forename: Bruno S
authors.initials: BS
authors.lastname: Lopes
authors.affiliation: The Children's Cancer Hospital, 57357 Cairo, Egypt.
authors.forename: Hadir El
authors.initials: HE
authors.lastname: Mahallawy
authors.affiliation: Medical Microbiology, University of Edinburgh, Edinburgh, UK.
authors.forename: Sebastian G B
authors.initials: SG
authors.lastname: Amyes
keywords: Acinetobacter baumannii; Carbapenem resistance; Genetic environment; IS6 family; Insertion sequences; bla(OXA-58)