title: The effects of D-Tyrosine combined with amikacin on the biofilms of Pseudomonas aeruginosa.
abstract: The biofilm formation of microorganisms causes persistent tissue infections resistant to treatment with antimicrobial agents. Pseudomonas aeruginosa is commonly isolated from the airways of patients with chronic fibrosis (CF) and often forms biofilms, which are extremely hard to eradicate and a major cause of mortality and morbidity. Recent studies have shown that D-amino acids (D-AAs) inhibited and disrupted biofilm formation by causing the release of the protein component of the polymeric matrix. However, the effects of D-AAs combined with common antibiotics on biofilms have rarely been studied. The current study first determined whether D-AAs disrupted the biofilms of PAO1 and the clinical airway isolates of P. aeruginosa. It was then determined whether combinations of D-Tyr (the most effective one) and the antibiotic amikacin (AMK) enhanced the activity against these biofilms. The results of the current study showed that D-Tyr is the most effective among those that disassemble the D-amino acids (D-leucine, D-methionine, D-Tyrptophan, and D-tryptophan), and D-Tyr at concentrations higher than 5 mM significantly reduced the biofilm biomass of P. aeruginosa (p < 0.05) without influencing bacterial growth. It was also revealed that D-Tyr improved the efficacy of AMK to combat P. aeruginosa biofilms, as indicated by a reduction in the minimal biofilm-inhibiting concentration (MBIC50 and MBIC90) without a change in the minimal inhibitory concentration (MIC) of planktonic bacteria. Thus, the findings indicated that D-Tyr supplementation overcame the resistance of P. aeruginosa biofilms to AMK, which might be helpful for preventing AMK overuse when this specific D-Tyr is recommended for combatting these biofilms. Also, toxicity of the liver and kidney from AMK could be potentially mitigated by co-delivery with D-Tyr.
authors.affiliation: Department of Medicine Clinical Laboratory, The Third Xiangya Hospital of Central South University, Tong Zipo Road, Changsha 410013, Hunan, PR China.
authors.forename: Pengfei
authors.initials: P
authors.lastname: She
authors.affiliation: Department of Medicine Clinical Laboratory, The Third Xiangya Hospital of Central South University, Tong Zipo Road, Changsha 410013, Hunan, PR China.
authors.forename: Lihua
authors.initials: L
authors.lastname: Chen
authors.affiliation: Department of Medicine Clinical Laboratory, The Third Xiangya Hospital of Central South University, Tong Zipo Road, Changsha 410013, Hunan, PR China.
authors.forename: Hongbo
authors.initials: H
authors.lastname: Liu
authors.affiliation: Department of Medicine Clinical Laboratory, The Third Xiangya Hospital of Central South University, Tong Zipo Road, Changsha 410013, Hunan, PR China.
authors.forename: Yaru
authors.initials: Y
authors.lastname: Zou
authors.affiliation: Department of Medicine Clinical Laboratory, The Third Xiangya Hospital of Central South University, Tong Zipo Road, Changsha 410013, Hunan, PR China.
authors.forename: Zhen
authors.initials: Z
authors.lastname: Luo
authors.affiliation: Department of Medicine Clinical Laboratory, The Third Xiangya Hospital of Central South University, Tong Zipo Road, Changsha 410013, Hunan, PR China.
authors.forename: Asmaa
authors.initials: A
authors.lastname: Koronfel
authors.affiliation: Department of Medicine Clinical Laboratory, The Third Xiangya Hospital of Central South University, Tong Zipo Road, Changsha 410013, Hunan, PR China. Electronic address: wuyong_xy@126.com.
authors.forename: Yong
authors.initials: Y
authors.lastname: Wu
mesh_terms: D000583:Amikacin / Q000494:pharmacology*; D000900:Anti-Bacterial Agents / Q000494:pharmacology*; D018441:Biofilms / Q000187:drug effects*; D008826:Microbial Sensitivity Tests; D011550:Pseudomonas aeruginosa / Q000187:drug effects* / Q000502:physiology*; D014443:Tyrosine / Q000494:pharmacology*
chemical_list: D000900:Anti-Bacterial Agents; D014443:Tyrosine; D000583:Amikacin
keywords: Amikacin; Biofilm; Combination; Pseudomonas aeruginosa; d-Tyrosine; d-amino acid