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Culture of Small Colony Variant of Pseudomonas aeruginosa and Quantitation of its Alginate
Published on: February 22, 2020
Pseudomonas aeruginosa modulates alginate biosynthesis and type VI secretion system in two critically ill COVID-19
Jiuxin Qu1, Zhao Cai2, Xiangke Duan2
1Department of Clinical Laboratory, Shenzhen Third People's Hospital, Second Hospital Affiliated to Southern University of Science and Technology, Guangdong Provincial Clinical Research Center for Infectious Diseases (Tuberculosis), National Clinical Research Center for Infectious Diseases, Shenzhen, 518000, Guangdong, China.
Background:
COVID-19 pneumonia has caused huge impact on the health of infected patients and associated with high morbidity and mortality. Shift in the lung microbial ecology upon such viral infection often worsens the disease and increases host susceptibility to superinfections. Bacterial superinfection contributes to the aggravation of COVID-19 and poses a great challenge to clinical treatments. An in-depth investigation on superinfecting bacteria in COVID-19 patients might facilitate understanding of lung microenvironment post virus infections and superinfection mechanism.
Results:
We analyzed the adaptation of two pairs of P. aeruginosa strains with the same MLST type isolated from two critical COVID-19 patients by combining sequencing analysis and phenotypic assays. Both P. aeruginosa strains were found to turn on alginate biosynthesis and attenuate type VI secretion system (T6SS) during short-term colonization in the COVID-19 patients, which results in excessive biofilm formation and virulence reduction-two distinct markers for chronic infections. The macrophage cytotoxicity test and intracellular reactive oxygen species measurement confirmed that the adapted P. aeruginosa strains reduced their virulence towards host cells and are better to escape from host immune clearance than their ancestors.
Conclusion:
Our study suggests that SARS-CoV-2 infection can create a lung environment that allow rapid adaptive evolution of bacterial pathogens with genetic traits suitable for chronic infections.
Insights
COVID-19 lung infections promote bacterial adaptation, enabling pathogens like Pseudomonas aeruginosa to form biofilms and evade immune responses, leading to chronic infections.
Area of Science:
- Microbiology
- Infectious Diseases
- Genomics
Background:
- COVID-19 pneumonia leads to high morbidity and mortality.
- Viral infections disrupt lung microbial ecology, increasing susceptibility to bacterial superinfections.
- Bacterial superinfections complicate COVID-19 treatment and disease progression.
Purpose of the Study:
- Investigate bacterial adaptation in the lung microenvironment of COVID-19 patients.
- Understand the mechanisms of bacterial superinfection during COVID-19.
- Identify genetic traits facilitating chronic infections post-SARS-CoV-2.
Main Methods:
- Sequencing analysis of Pseudomonas aeruginosa strains.
- Phenotypic assays to assess bacterial adaptation.
- Macrophage cytotoxicity and reactive oxygen species measurements.
Main Results:
- Adapted P. aeruginosa strains exhibited increased alginate biosynthesis and reduced type VI secretion system (T6SS) activity.
- These adaptations resulted in excessive biofilm formation and reduced virulence.
- Adapted strains showed enhanced evasion of host immune clearance compared to ancestral strains.
Conclusions:
- SARS-CoV-2 infection creates a lung environment conducive to rapid bacterial evolution.
- Bacterial pathogens can acquire traits suitable for chronic infections following viral pneumonia.
- Understanding these adaptive mechanisms is crucial for managing superinfections in COVID-19 patients.
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