Dataset Information

Oligoribonuclease Contributes to Tolerance to Aminoglycoside and ?-Lactam Antibiotics by Regulating KatA in Pseudomonas aeruginosa.

ABSTRACT: Pseudomonas aeruginosa is an opportunistic bacterial pathogen and is intrinsically resistant to a variety of antibiotics. Oligoribonuclease (Orn) is a 3'-to-5' exonuclease that degrades nanoRNAs. The Orn controls biofilm formation by influencing the homeostasis of cyclic-di-GMP. Previously, we demonstrated that Orn contributes to the tolerance of P. aeruginosa to fluoroquinolone antibiotics by affecting the production of pyocins. In this study, we found that mutation in the orn gene reduces bacterial tolerance to aminoglycoside and ?-lactam antibiotics, which is mainly due to a defective response to oxidative stresses. The major catalase KatA is downregulated in the orn mutant, and overexpression of the katA gene restores the bacterial tolerance to oxidative stresses and the antibiotics. We further demonstrated that Orn influenced the translation of the katA mRNA and narrowed down the region in the katA mRNA that is involved in the regulation of its translation. Therefore, our results revealed a novel role of the Orn in bacterial tolerance to oxidative stresses as well as aminoglycoside and ?-lactam antibiotics.

SUBMITTER: Xia B

PROVIDER: S-EPMC6535506 | biostudies-literature | 2019 Jun

REPOSITORIES: biostudies-literature

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Oligoribonuclease Contributes to Tolerance to Aminoglycoside and β-Lactam Antibiotics by Regulating KatA in Pseudomonas aeruginosa.

Xia Bin B Li Mei M Tian Zhenyang Z Chen Gukui G Liu Chang C Xia Yushan Y Jin Yongxin Y Bai Fang F Cheng Zhihui Z Jin Shouguang S Wu Weihui W

Antimicrobial agents and chemotherapy 20190524 6

Pseudomonas aeruginosa is an opportunistic bacterial pathogen and is intrinsically resistant to a variety of antibiotics. Oligoribonuclease (Orn) is a 3'-to-5' exonuclease that degrades nanoRNAs. The Orn controls biofilm formation by influencing the homeostasis of cyclic-di-GMP. Previously, we demonstrated that Orn contributes to the tolerance of P. aeruginosa to fluoroquinolone antibiotics by affecting the production of pyocins. In this study, we found that mutation in the orn< ...[more]

PMID: 30936107

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Project description:Resistance to ?-lactam antibiotics is a frequent problem in Pseudomonas aeruginosa lung infection of cystic fibrosis (CF) patients. This resistance is mainly due to the hyperproduction of chromosomally encoded ?-lactamase and biofilm formation. The purpose of this study was to investigate the role of ?-lactamase in the pharmacokinetics (PK) and pharmacodynamics (PD) of ceftazidime and imipenem on P. aeruginosa biofilms. P. aeruginosa PAO1 and its corresponding ?-lactamase-overproducing mutant, PA?DDh2Dh3, were used in this study. Biofilms of these two strains in flow chambers, microtiter plates, and on alginate beads were treated with different concentrations of ceftazidime and imipenem. The kinetics of antibiotics on the biofilms was investigated in vitro by time-kill methods. Time-dependent killing of ceftazidime was observed in PAO1 biofilms, but concentration-dependent killing activity of ceftazidime was observed for ?-lactamase-overproducing biofilms of P. aeruginosa in all three models. Ceftazidime showed time-dependent killing on planktonic PAO1 and PA?DDh2Dh3. This difference is probably due to the special distribution and accumulation in the biofilm matrix of ?-lactamase, which can hydrolyze the ?-lactam antibiotics. The PK/PD indices of the AUC/MBIC and C(max)/MBIC (AUC is the area under concentration-time curve, MBIC is the minimal biofilm-inhibitory concentration, and C(max) is the maximum concentration of drug in serum) are probably the best parameters to describe the effect of ceftazidime in ?-lactamase-overproducing P. aeruginosa biofilms. Meanwhile, imipenem showed time-dependent killing on both PAO1 and PA?DDh2Dh3 biofilms. An inoculum effect of ?-lactams was found for both planktonic and biofilm P. aeruginosa cells. The inoculum effect of ceftazidime for the ?-lactamase-overproducing mutant PA?DDh2Dh3 biofilms was more obvious than for PAO1 biofilms, with a requirement of higher antibiotic concentration and a longer period of treatment.

Project description:Factor for inversion stimulation (Fis) is a versatile DNA binding protein that plays an important role in coordinating bacterial global gene expression in response to growth phases and environmental stresses. Previously, we demonstrated that Fis regulates the type III secretion system (T3SS) in Pseudomonas aeruginosa In this study, we explored the role of Fis in the antibiotic resistance of P. aeruginosa and found that mutation of the fis gene increases the bacterial susceptibility to ciprofloxacin. We further demonstrated that genes related to pyocin biosynthesis are upregulated in the fis mutant. The pyocins are produced in response to genotoxic agents, including ciprofloxacin, and the release of pyocins results in lysis of the producer cell. Thus, pyocin biosynthesis genes sensitize P. aeruginosa to ciprofloxacin. We found that PrtN, the positive regulator of the pyocin biosynthesis genes, is upregulated in the fis mutant. Genetic experiments and electrophoretic mobility shift assays revealed that Fis directly binds to the promoter region of prtN and represses its expression. Therefore, our results revealed novel Fis-mediated regulation on pyocin production and bacterial resistance to ciprofloxacin in P. aeruginosa IMPORTANCE Pseudomonas aeruginosa is an important opportunistic pathogenic bacterium that causes various acute and chronic infections in human, especially in patients with compromised immunity, cystic fibrosis (CF), and/or severe burn wounds. About 60% of cystic fibrosis patients have a chronic respiratory infection caused by P. aeruginosa The bacterium is intrinsically highly resistant to antibiotics, which greatly increases difficulties in clinical treatment. Therefore, it is critical to understand the mechanisms and the regulatory pathways that are involved in antibiotic resistance. In this study, we elucidated a novel regulatory pathway that controls the bacterial resistance to fluoroquinolone antibiotics, which enhances our understanding of how P. aeruginosa responds to ciprofloxacin.

Dataset Information

Oligoribonuclease Contributes to Tolerance to Aminoglycoside and ?-Lactam Antibiotics by Regulating KatA in Pseudomonas aeruginosa.

Publications

Oligoribonuclease Contributes to Tolerance to Aminoglycoside and β-Lactam Antibiotics by Regulating KatA in Pseudomonas aeruginosa.

Similar Datasets

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