ColE-type plasmid bearing bla_OXA-232 increases persister cell formation

Area of Science:

• Microbiology
• Molecular Biology
• Genetics

Background:

• Bacterial persister cells are a small subpopulation exhibiting high tolerance to antibiotics.
• Understanding factors influencing persister cell formation is crucial for combating antibiotic resistance.

Purpose of the Study:

• To investigate the impact of plasmids encoding carbapenemase genes on the formation of bacterial persister cells.
• To determine if specific carbapenemase genes or plasmid types influence persister cell frequency.

Main Methods:

• Transformation of Escherichia coli MG1655 with three different carbapenemase-encoding plasmids (blaNDM-1, blaKPC-2, blaOXA-232).
• Construction and transformation of gene-deletion variants of the ColE-type plasmid (pM5_OXA232).
• Assessment of persister cell formation against ciprofloxacin and amikacin, and measurement of relA and spoT gene expression.

Main Results:

• The ColE-type plasmid (pM5_OXA232) significantly increased persister cell formation compared to other plasmids.
• Deletions in specific genes (vbhA, hypothetical gene, mobile gene cassette) on pM5_OXA232 reduced persister cell formation.
• Expression patterns of relA and spoT correlated with persister cell formation rates, especially with ciprofloxacin exposure.

Conclusions:

• A small ColE-type plasmid carrying blaOXA-232 influences bacterial persister cell formation.
• This plasmid-mediated increase in persister cells may contribute to the dissemination of low-level carbapenemase resistance.