Colistin Resistance in Acinetobacter baumannii MDR-ZJ06 Revealed by a Multiomics Approach.

Area of Science:

• Microbiology
• Genomics
• Proteomics

Background:

• Acinetobacter baumannii is a significant opportunistic pathogen known for developing multidrug resistance.
• Colistin is a last-resort antibiotic for treating infections caused by multidrug-resistant Acinetobacter baumannii (MDRAB).
• Emergence of colistin-resistant MDRAB poses a critical threat to public health.

Purpose of the Study:

• To investigate the molecular mechanisms underlying colistin resistance in MDRAB.
• To compare the genomic, transcriptional, and proteomic profiles of a colistin-susceptible MDRAB strain with an induced colistin-resistant strain.
• To understand the global gene expression changes associated with colistin resistance.

Main Methods:

• Genomic analysis to identify genetic mutations.
• Transcriptional analysis to assess gene expression levels.
• Proteomic analysis to evaluate protein expression, focusing on efflux pumps and metabolic enzymes.

Main Results:

• Genomic analysis revealed inactivation of the lpxC gene by ISAba1 insertion in the colistin-resistant strain, leading to lipopolysaccharide (LPS) loss.
• Transcriptional analysis indicated significant metabolic regulation in the colistin-resistant strain.
• Proteomic analysis showed increased expression of the RND efflux pump system and decreased expression of FabZ and β-lactamase.

Conclusions:

• The lpxC mutation is a key factor in establishing colistin resistance in MDRAB.
• LPS loss, resulting from the lpxC mutation, drives global alterations in gene expression.
• These adaptive changes include upregulation of efflux pumps and downregulation of specific enzymes, contributing to the bacterium's resistance phenotype.