Back to abstracts
Back to abstracts
ABSTRACT
Background
Acinetobacter baumannii (A. baumannii) is a multidrug-resistant pathogen of global interest especially in healthcare settings. This study aimed to investigate the antimicrobial susceptibility profiles, and whole genome characteristics of A. baumannii isolates at a tertiary laboratory in Gauteng in 2024.
Method
A. baumannii isolates recovered at the tertiary laboratory were further genotypically confirmed by PCR after routine diagnostics. Antimicrobial susceptibility testing was conducted using the VITEK®-2 system. Repetitive extragenic palindromic PCR (rep-PCR) was used to determine the genetic relatedness of the isolates. Ten isolates were selected for whole genome sequencing (WGS) using Oxford Nanopore Technologies MinION. The library was prepared using rapid barcoding kit following the NO-MISS protocol. Sequence analysis was performed on the cloud-based EPI2ME software. Consensus sequences were generated with Medaka, genome annotation was carried out using Prokka, and multi-locus sequence typing was performed using MLST, while drug resistance genes were identified using the ResFinder tool. The genome map was constructed using Proksee.
Result
A total of 116 A. baumannii isolates were confirmed by PCR. Majority of the isolates (96.6%) were multidrug-resistant. Antimicrobial susceptibility testing showed high resistance rates to most antibiotics, ranging from 83.6% to 94.8%, except for colistin (0.9%) and tigecycline (0.9%). Majority of isolates were from surgical (44%) and high care (29%) wards. Rep-PCR revealed clonal variation among A. baumannii isolates clustering in six groups. WGS identified 38 resistance genes with a high prevalence of β-lactamase genes including blaOXA-23, blaNDM, and blaADC. Various virulence genes were identified, including ompA, pgaA–D, bauA/C, and lpxA/C/D, which are associated with biofilm formation, iron acquisition, and immune evasion.
Conclusion
The study affirmed A. baumannii as a medically significant pathogen exhibiting a diverse genetic and antimicrobial resistant profile. It is thus paramount to continually monitor its strains to advise on infection control and management.