<i>Acinetobacter baumannii</i> Global Clone-Specific Resistomes Explored in Clinical Isolates Recovered from Egypt

• Main Authors: Samira M. Hamed (Author), Walid F. Elkhatib (Author), Hanka Brangsch (Author), Ahmed S. Gesraha (Author), Shawky Moustafa (Author), Dalia F. Khater (Author), Mathias W. Pletz (Author), Lisa D. Sprague (Author), Heinrich Neubauer (Author), Gamal Wareth (Author)
• Format: Book
• Published: MDPI AG, 2023-07-01T00:00:00Z.
• Subjects: article
• Online Access: Connect to this object online.

Summary

<i>Acinetobacter baumannii</i> (<i>A. baumannii</i>) is a highly problematic pathogen with an enormous capacity to acquire or upregulate antibiotic drug resistance determinants. The genomic epidemiology and resistome structure of 46 <i>A. baumannii</i> clinical isolates were studied using whole-genome sequencing. The isolates were chosen based on reduced susceptibility to at least three classes of antimicrobial compounds and were initially identified using MALDI-TOF/MS, followed by polymerase chain reaction amplification of <i>bla</i>_OXA-51-like genes. The susceptibility profiles were determined using a broth microdilution assay. Multi-, extensive-, and pan-drug resistance was shown by 34.8%, 63.0%, and 2.2% of the isolates, respectively. These were most susceptible to colistin (95.7%), amikacin, and trimethoprim/sulfamethoxazole (32.6% each), while only 26.1% of isolates were susceptible to tigecycline. In silico multi-locus sequence typing revealed 8 Pasteur and 22 Oxford sequence types (STs) including four novel STs (ST^Oxf 2805, 2806, 2807, and 2808). The majority of the isolates belonged to Global Clone (GC) 2 (76.4%), GC5 (19.6%), GC4 (6.5%), GC9 (4.3%), and GC7 (2.2%) lineages. An extensive resistome potentially conferring resistance to the majority of the tested antimicrobials was identified in silico. Of all known carbapenem resistance genes, <i>bla</i>_OXA-23 was carried by most of the isolates (69.6%), followed by IS<i>Aba1</i>-amplified <i>bla</i>_ADC (56.5%), <i>bla</i>_NDM-1 and <i>bla</i>_GES-11 (21.7% each), and <i>bla</i>_GES-35 (2.2%) genes. A significant correlation was found between carbapenem resistance and <i>carO</i> mutations, which were evident in 35 (76.0%) isolates. A lower proportion of carbapenem resistance was noted for strains possessing both <i>bla</i>_OXA-23- and <i>bla</i>_GES-11. Amikacin resistance was most probably mediated by <i>armA</i>, <i>aac(6')-Ib9</i>, and <i>aph(3')-VI</i>, most commonly coexisting in GC2 isolates. No mutations were found in <i>pmrABC</i> or <i>lpxACD</i> operons in the colistin-resistant isolates. Tigecycline resistance was associated with <i>adeS</i> (N268Y) and <i>baeS</i> (A436T) mutations. While the lineage-specific distribution of some genes (e.g., <i>bla</i>_ADC and <i>bla</i>_OXA-51-like alleles) was evident, some resistance genes, such as <i>bla</i>_OXA-23 and <i>sul1</i>, were found in all GCs. The data generated here highlight the contribution of five GCs in <i>A. baumannii</i> infections in Egypt and enable the comprehensive analysis of GC-specific resistomes, thus revealing the dissemination of the carbapenem resistance gene <i>bla</i>_OXA-23 in isolates encompassing all GCs.

Item Description

10.3390/antibiotics12071149
2079-6382