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[Expression of Class I integrase gene in Acinetobacter baumannii and drug-resistance]
Le Li1, Zhong-di Xia, Zhao-hui Hu
1Derpartment of Microbiology, Xiangya School of Medicine, Central South University, Changsha 410078, China.
Objective:
To explore the expression level of class I integrase (intI 1) mRNA in Acinetobacter baumannii from biofilm cells and planktonic cultured cells ,and to analyze the drug-resistance of Class I integron positive strains.
Methods:
Acinetobacter baumannii were collected from hospitals,and Class I integron strains were screened by gene amplification. Total RNA of Class I integron positive strains was extracted, and the intI1 mRNA expression in the bioflim cells and planktonic cultured cells was measured by RT-PCR. Susceptibilities to antibiotics of Class I integron positive strains were also examined.
Results:
The intI1 gene mRNA was expressed under 2 conditions, and the mRNA expressed in the biofilm cells was about 4 times higher than that in the planktonic cultured cells. Among the 64 strains of Acinetobacter baumannii, 46 strains were Class I integron positive strains. The antibiotic resistance of intI1 gene cassette-positive strains was higher than that of gene cassette-negative strains.
Conclusion:
The intI1 gene mRNA can be up-regulated in Acinetobacter baumannii biofilm cells.Class I integron plays an important role in drug resistance. It is much easier to capture gene cassettes for bacteria under biofilm condition.
Insights
Class I integrase (intI1) mRNA expression is significantly higher in Acinetobacter baumannii biofilm cells compared to planktonic cells. This suggests Class I integrons play a key role in bacterial drug resistance.
Area of Science:
- Microbiology
- Molecular Biology
- Antimicrobial Resistance
Background:
- Acinetobacter baumannii is a significant nosocomial pathogen.
- Integrons are mobile genetic elements that contribute to antibiotic resistance.
- Class I integrons, mediated by the intI1 gene, are prevalent in clinical isolates.
Purpose of the Study:
- To quantify the expression of class I integrase (intI1) mRNA in Acinetobacter baumannii biofilms versus planktonic cultures.
- To investigate the association between Class I integron positivity and antibiotic resistance profiles in Acinetobacter baumannii.
Main Methods:
- Screening of Acinetobacter baumannii strains for Class I integrons using gene amplification.
- Quantification of intI1 mRNA levels in biofilm and planktonic cells via RT-PCR.
- Assessment of antibiotic susceptibility for Class I integron-positive and negative strains.
Main Results:
- intI1 mRNA expression was detected in both biofilm and planktonic cells.
- Biofilm cells exhibited approximately four times higher intI1 mRNA expression than planktonic cells.
- A higher prevalence of antibiotic resistance was observed in Class I integron-positive strains compared to negative strains.
Conclusions:
- Class I integrase (intI1) mRNA expression is upregulated in Acinetobacter baumannii biofilm environments.
- Class I integrons are crucial mediators of drug resistance in Acinetobacter baumannii.
- Biofilm formation may facilitate the acquisition of gene cassettes by bacteria, enhancing resistance.
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