Molecular epidemiology and characterization of multiple drug-resistant (MDR) clinical isolates of Acinetobacter baumannii

Sherief El-Shazly; Ali Dashti; Leila Vali; Michael Bolaris; Ashraf S Ibrahim

doi:10.1016/j.ijid.2015.10.016

Molecular epidemiology and characterization of multiple drug-resistant (MDR) clinical isolates of Acinetobacter baumannii

Int J Infect Dis. 2015 Dec:41:42-9. doi: 10.1016/j.ijid.2015.10.016. Epub 2015 Oct 27.

Authors

Sherief El-Shazly¹, Ali Dashti², Leila Vali², Michael Bolaris³, Ashraf S Ibrahim⁴

Affiliations

¹ 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.
² Department of Medical Laboratory Sciences, Faculty of Allied Health Sciences, Health Sciences Center, Kuwait University, Kuwait.
³ Division of Pediatric Infectious Diseases, Los Angeles Biomedical Research Institute at Harbor-University of California Los Angeles (UCLA) Medical Center, Torrance, California, USA.
⁴ 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.

Abstract

Objectives: 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.

Keywords: Acinetobacter baumannii; MLST; PFGE; β-lactamase.

Publication types

Research Support, N.I.H., Extramural

MeSH terms

Acinetobacter Infections / epidemiology
Acinetobacter Infections / microbiology*
Acinetobacter baumannii / genetics*
Acinetobacter baumannii / isolation & purification
DNA Transposable Elements
DNA, Bacterial / genetics
Drug Resistance, Multiple, Bacterial*
Electrophoresis, Gel, Pulsed-Field
Gene Expression Regulation, Bacterial
Genotype
Hospitals
Humans
Los Angeles / epidemiology
Molecular Epidemiology*
Multilocus Sequence Typing
Polymerase Chain Reaction
Sequence Analysis, DNA

Substances

DNA Transposable Elements
DNA, Bacterial

Abstract

Publication types

MeSH terms

Substances

Grants and funding