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Updated: Mar 31, 2026

Author Spotlight: Advancing Antibiotic Resistance Research Using an Efflux-Deficient Bacterial Strain and a Single-Copy Gene Expression System
Published on: January 5, 2024
Molecular epidemiology and characterization of multiple drug-resistant (MDR) clinical isolates of Acinetobacter
Sherief El-Shazly1, Ali Dashti2, Leila Vali2
1Department 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.
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.
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