Genomic insights of predominant international high-risk clone ST2 Acinetobacter baumannii isolates in Saudi Arabia

Abstract

Objectives

Carbapenem-resistant Acinetobacter baumannii (CRAB), particularly the globally prevalent ST2 clone, poses significant threats in the Gulf Cooperation Council region through extensive drug resistance, high virulence, and efficient gene transfer. This study investigates the epidemiological and genomic characteristics of CRAB in the Jazan region, using whole genome sequencing to understand its transmission and genetic determinants.

Methods

Sixty-five clinical A. baumannii isolates exhibiting phenotypic resistance to carbapenems (meropenem, imipenem, and ertapenem) were collected from various tertiary hospitals in the Jazan region. The presence of prevalent carbapenemase genes among these isolates was examined using two sets of multiplex polymerase chain reaction (PCR). Forty-eight isolates confirmed as carbapenemase producers were selected for WGS analysis.

Results

Among the 65 clinical CRAB isolates, the adult ICU exhibited the highest prevalence of CRAB (76.9%). Multiplex PCR identified 48 (73.8%) isolates as carbapenemase producers, all harboring bla_OXA-51-like genes. Specifically, bla_OXA-23 was detected in 39 isolates (60%), bla_NDM in 8 (12.3%), and bla_OXA-24 in one isolate. These 48 carbapenemase-producing isolates also carried virulence-associated genes related to adherence, biofilm formation, immune evasion, iron acquisition and regulation, and serum resistance. Whole-genome sequencing (WGS) revealed that 39 (81.2%) of the carbapenemase-positive isolates belonged to ST2, followed by ST85 and ST107, with the KL152 locus as the most common capsule type.

Conclusions

The study indicates a significant rise in the ST2 clone in the Arabian Gulf, particularly in Saudi Arabia, and underscores the need for ongoing surveillance of less common clones such as ST85 and ST107 to manage public health risks effectively.