The development of ciprofloxacin resistance in Pseudomonas aeruginosa involves multiple response stages and multiple...

Area of Science:

• Microbiology
• Molecular Biology
• Genetics

Background:

• Antibiotic resistance is a growing global health threat.
• The precise mechanisms by which bacteria acquire drug resistance are not fully understood.
• Pseudomonas aeruginosa is an opportunistic pathogen known for its intrinsic and acquired resistance capabilities.

Purpose of the Study:

• To elucidate the multistage process of antibiotic resistance acquisition in Pseudomonas aeruginosa.
• To identify specific molecular pathways and proteins involved in the development of heritable drug resistance.
• To investigate the role of identified proteins in the emergence of the resistant phenotype.

Main Methods:

• Exposure of susceptible Pseudomonas aeruginosa to sub-inhibitory concentrations of ciprofloxacin.
• Characterization of bacterial populations across different stages of antibiotic exposure.
• Proteomic analysis to identify differentially expressed proteins and post-translational modifications in resistant cells.
• Gene disruption via transposon mutagenesis to assess the functional role of candidate proteins.
• Integration of proteomic data with computational modeling and genomic sequencing.

Main Results:

• A three-stage model of resistance development was identified: mass cell death (Stage I), survival of a non-growing population (Stage II), and emergence of a growing, highly resistant population (Stage III).
• Stage III cells exhibited up to 50-fold increase in heritable resistance to ciprofloxacin.
• Proteomic analysis revealed upregulation of phosphorylation in succinate-semialdehyde dehydrogenase (SSADH) and methylmalonate-semialdehyde dehydrogenase (MMSADH).
• A conserved protein of unknown function was also found to be upregulated.
• Disruption of genes encoding SSADH, MMSADH, or the unknown protein significantly impaired the development of Stage III resistance.

Conclusions:

• Heritable antibiotic resistance in Pseudomonas aeruginosa emerges through a multistage process involving distinct cellular responses to antibiotic pressure.
• Upregulation and phosphorylation of SSADH and MMSADH are critical for the development of Stage III resistance.
• The findings suggest that resistance development involves a combination of genomic mutations and the modulation of pre-existing cellular pathways.
• Targeting these identified pathways could offer novel strategies to combat antibiotic resistance.