Exploring the association between capsular types, sequence types, and carbapenemase genes in Acinetobacter baumannii

Area of Science:

• Medical Microbiology
• Infectious Diseases
• Genomics

Background:

• Acinetobacter baumannii is a primary cause of difficult-to-treat nosocomial infections.
• The rise of carbapenem resistance in A. baumannii poses a significant clinical challenge.
• Understanding the genetic basis of resistance, including carbapenemase genes, is crucial.

Purpose of the Study:

• To investigate the prevalence of major carbapenemase genes in carbapenem-resistant A. baumannii (CRAB) strains.
• To explore the associations between carbapenemase gene profiles, sequence types (ST types), and capsular types (K types).
• To provide epidemiological insights for monitoring CRAB dissemination.

Main Methods:

• Collection of 98 CRAB strains from two Taiwanese hospitals (2015-2017).
• Detection of class A, B, and D β-lactamase carbapenemase genes using polymerase chain reaction (PCR).
• Genotyping using Oxford multilocus sequence typing (MLST) and global optimal eBURST analysis for 59 strains.

Main Results:

• High prevalence of bla_OXA-51-like (99%), bla_OXA-23-like (77.6%), and bla_OXA-24-like (25.5%) genes.
• Regional variations in gene distribution: bla_OXA-23-like more common than bla_OXA-24-like, with higher bla_OXA-24-like in southern Taiwan (KCGMH).
• Significant associations found between bla_OXA gene patterns, ST types, and K types, with four major K types (KL2, KL10, KL22, KL52) clustering into CC208 and a unique Taiwanese CC549.

Conclusions:

• The study elucidates the genetic landscape of CRAB in Taiwan, highlighting key carbapenemase genes and their epidemiological links.
• Identified associations between specific carbapenemase genes, ST types, and K types provide valuable markers for tracking CRAB.
• Findings support enhanced surveillance and targeted interventions to control the spread of multidrug-resistant A. baumannii.