title: Molecular epidemiology and characterization of multiple drug-resistant (MDR) clinical isolates of Acinetobacter baumannii.
abstract: OBJECTIVE
  The aim of this study was to identify the genetic relatedness of multiple drug-resistant (MDR) Acinetobacter baumannii clinical isolates recovered from a hospital in Los Angeles.
  
  
  METHODS
  Twenty-one MDR A. baumannii isolates were collected and their antibiotic susceptibilities determined according to Clinical and Laboratory Standards Institute guidelines. Genes coding for antibiotic resistance were identified by PCR, and their identities were confirmed by DNA sequencing. Clonal relationships were studied by pulsed-field gel electrophoresis (PFGE) and multilocus sequence typing (MLST).
  
  
  RESULTS
  MDR consistently correlated with the presence of oxacillinases, mostly in the form of the plasmid-mediated OXA-23 enzyme, which was detected in 12 (57.1%) isolates. GES-type carbapenemases were found in 20 (95.2%) strains, AAC in all 21 (100%) strains, and PER in seven (33.3%) strains, and ISAba1 was detected in 16 (76.2%) isolates. The association between ISAba1 and resistance genes confirms insertion elements as a source of β-lactamase production. Of the 21 clinical isolates, five were found to be related to sequence type 1 (ST1) and 16 to ST2, as analyzed by MLST. PFGE demonstrated that the majority of clinical isolates were highly related (>85%).
  
  
  CONCLUSIONS
  This study supports a more complete understanding of genotyping of antibiotic resistance for better assessment of MDR strain transmission.
authors.affiliation: Department of Medical Laboratory Sciences, Faculty of Allied Health Sciences, Health Sciences Center, Kuwait University, Kuwait; Division of Adult Infectious Diseases, Los Angeles Biomedical Research Institute at Harbor-University of California Los Angeles (UCLA) Medical Center, 1124 West Carson St., St. John's Cardiovascular Research Center, Torrance, CA 90502, USA.
authors.forename: Sherief
authors.initials: S
authors.lastname: El-Shazly
authors.affiliation: Department of Medical Laboratory Sciences, Faculty of Allied Health Sciences, Health Sciences Center, Kuwait University, Kuwait.
authors.forename: Ali
authors.initials: A
authors.lastname: Dashti
authors.affiliation: Department of Medical Laboratory Sciences, Faculty of Allied Health Sciences, Health Sciences Center, Kuwait University, Kuwait.
authors.forename: Leila
authors.initials: L
authors.lastname: Vali
authors.affiliation: Division of Pediatric Infectious Diseases, Los Angeles Biomedical Research Institute at Harbor-University of California Los Angeles (UCLA) Medical Center, Torrance, California, USA.
authors.forename: Michael
authors.initials: M
authors.lastname: Bolaris
authors.affiliation: Division of Adult Infectious Diseases, Los Angeles Biomedical Research Institute at Harbor-University of California Los Angeles (UCLA) Medical Center, 1124 West Carson St., St. John's Cardiovascular Research Center, Torrance, CA 90502, USA; David Geffen School of Medicine at UCLA, Los Angeles, California, USA. Electronic address: ibrahim@labiomed.org.
authors.forename: Ashraf S
authors.initials: AS
authors.lastname: Ibrahim
mesh_terms: D000151:Acinetobacter Infections / Q000453:epidemiology / Q000382:microbiology*; D040981:Acinetobacter baumannii / Q000235:genetics* / Q000302:isolation & purification; D004251:DNA Transposable Elements; D004269:DNA, Bacterial / Q000235:genetics; D024901:Drug Resistance, Multiple, Bacterial; D016521:Electrophoresis, Gel, Pulsed-Field; D015964:Gene Expression Regulation, Bacterial; D005838:Genotype; D006761:Hospitals; D006801:Humans; D015141:Los Angeles / Q000453:epidemiology; D017720:Molecular Epidemiology; D058885:Multilocus Sequence Typing; D016133:Polymerase Chain Reaction; D017422:Sequence Analysis, DNA
chemical_list: D004251:DNA Transposable Elements; D004269:DNA, Bacterial
keywords: Acinetobacter baumannii; MLST; PFGE; β-lactamase