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Construction and Characterization of an lpxM-Deficient Acinetobacter baumannii Strain Using a pyrF/5-FOA
Can Gao1, Kun Jiang1, Jiaxin Qi1
1Department of Clinical Laboratory, Suining Central Hospital, Suining, Sichuan, People's Republic of China.
Aim:
Multidrug-resistant Acinetobacter baumannii (MDR-AB) is on the rise, making it challenging to achieve the desired therapeutic effects with existing conventional antibiotics. The search for new antibacterial targets has emerged as a significant research focus.
Purpose:
The lysophospholipid acyltransferases (LPLATs) proteins encoded by the lpxM gene play a pivotal role in the biosynthesis of lipopolysaccharides (LPS). LPS is a critical component of the outer membrane of the cell wall and is essential for the survival and drug resistance of Gram-negative bacteria. This study aims to investigate the effects of the lpxM gene on the growth and drug susceptibility of MDR-AB.
Methods:
The standard strain of Acinetobacter baumannii (A. baumannii, AB) AYE was selected as the target. The lpxM gene was knocked out using the pyrF/5-FOA-based counterselectable method. Subsequently, the growth status and the minimum inhibitory concentration (MIC) of the knockout strain against conventional antibiotics were compared.
Results:
The lpxM gene in AB AYE was successfully and fully knocked out. The absorbance value at OD600 for the lpxM knockout strain during the stable period was observed to be as low as 2.5, indicating a significant reduction in growth rate. Furthermore, the MIC of the knockout strain for imipenem decreased from 16 μg/mL to 1 μg/mL, and the MIC for ceftazidime decreased from 32 μg/mL to 16 μg/mL, enhancing antibiotic sensitivity.
Conclusion:
This study demonstrates that the deletion of the lpxM gene induces alterations in the growth and drug resistance of AB, providing a crucial foundation for further investigation into the mechanisms underlying LPS-mediated drug resistance and for the screening of effective auxiliary inhibitors targeting lpxM against MDR-AB.
Insights
Deleting the lpxM gene significantly reduces the growth and enhances antibiotic susceptibility in multidrug-resistant Acinetobacter baumannii (MDR-AB). This finding offers a new target for combating MDR-AB infections.
Area of Science:
- Microbiology
- Molecular Biology
- Drug Discovery
Background:
- Multidrug-resistant Acinetobacter baumannii (MDR-AB) poses a significant threat due to limited effective antibiotic options.
- Lipopolysaccharide (LPS) biosynthesis, involving lysophospholipid acyltransferases (LPLATs) encoded by lpxM, is crucial for Gram-negative bacterial survival and drug resistance.
Purpose of the Study:
- To investigate the impact of the lpxM gene on the growth and drug susceptibility of MDR-AB.
- To explore lpxM as a potential target for novel antibacterial strategies against MDR-AB.
Main Methods:
- Gene knockout of lpxM in Acinetobacter baumannii (AB) AYE using a pyrF/5-FOA-based counterselectable method.
- Comparative analysis of growth rates (OD600) and minimum inhibitory concentrations (MICs) of the lpxM knockout strain against conventional antibiotics.
Main Results:
- Successful and complete knockout of the lpxM gene was achieved.
- The lpxM knockout strain exhibited a significantly reduced growth rate (OD600 ~2.5).
- Antibiotic sensitivity was enhanced, with decreased MICs for imipenem (16 to 1 μg/mL) and ceftazidime (32 to 16 μg/mL).
Conclusions:
- Deletion of the lpxM gene significantly alters the growth and drug resistance profiles of AB.
- These findings provide a basis for understanding LPS-mediated drug resistance mechanisms.
- Targeting lpxM presents a promising strategy for developing auxiliary inhibitors against MDR-AB.
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