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<p><i>Escherichia coli</i> infections in lambs lead to substantial morbidity and significant economic losses within the global sheep industry and causes substantial economic losses. This study investigated antibiotic resistance in <i>E. coli</i> isolated from diarrheic sheep in the Ta’e Reclamation Area of Xinjiang, Northwest China, and examined the effects of D-amino acids on biofilm formation. A total of 73 isolates were subjected to phylogenetic grouping, antibiotic susceptibility testing, resistance gene detection, biofilm assays, and evaluation of D-amino acid effects. The isolates were classified into groups A (20.6%), B1 (46.6%), and D (32.8%). High resistance rates were observed for ampicillin (67.1%), tetracycline (56.2%), streptomycin (53.4%), and gentamicin (52.1%); 47.9% exhibited multidrug resistance. Sixteen resistance genes were identified, with <i>aph3’</i> (82.2%), <i>blaTEM</i> (75.3%), and <i>cmlA</i> (68.5%) being most prevalent. Biofilm formation occurred in 72.6% of isolates. D-methionine, D-leucine, D-tryptophan, and D-tyrosine significantly inhibited biofilm formation, an effect specific to D-enantiomers as confirmed by L-amino acid controls. Growth curve analysis revealed that D-tyrosine and D-tryptophan inhibited biofilm at concentrations that did not affect planktonic growth, whereas D-methionine and D-leucine exhibited growth-inhibitory effects at biofilm-suppressing concentrations. qPCR further demonstrated that D-tyrosine and D-tryptophan downregulated <i>luxS</i>, <i>csgD</i>, and <i>pgaC</i>. Overall, sheep-derived <i>E</i>. <i>coli</i> in Northwest China exhibit significant antibiotic resistance. D-amino acids inhibit biofilm formation and show synergistic effects with antibiotics, suggesting their therapeutic potential.However, the underlying regulatory mechanisms require further investigation.</p>

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D-amino acids inhibit biofilm formation in Escherichia coli and increase antibiotic susceptibility in multidrug-resistant bacteria

  • 期刊论文

  • 发表日期：

    2026年4月28日

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  • Jixue Wang,
  • Bin Yang,
  • Guofeng Xing,
  • Yao Zhao,
  • Zihao Wu,
  • Jing Li,
  • Meng Qi,
  • Jing Wu

摘要

Escherichia coli infections in lambs lead to substantial morbidity and significant economic losses within the global sheep industry and causes substantial economic losses. This study investigated antibiotic resistance in E. coli isolated from diarrheic sheep in the Ta’e Reclamation Area of Xinjiang, Northwest China, and examined the effects of D-amino acids on biofilm formation. A total of 73 isolates were subjected to phylogenetic grouping, antibiotic susceptibility testing, resistance gene detection, biofilm assays, and evaluation of D-amino acid effects. The isolates were classified into groups A (20.6%), B1 (46.6%), and D (32.8%). High resistance rates were observed for ampicillin (67.1%), tetracycline (56.2%), streptomycin (53.4%), and gentamicin (52.1%); 47.9% exhibited multidrug resistance. Sixteen resistance genes were identified, with aph3’ (82.2%), blaTEM (75.3%), and cmlA (68.5%) being most prevalent. Biofilm formation occurred in 72.6% of isolates. D-methionine, D-leucine, D-tryptophan, and D-tyrosine significantly inhibited biofilm formation, an effect specific to D-enantiomers as confirmed by L-amino acid controls. Growth curve analysis revealed that D-tyrosine and D-tryptophan inhibited biofilm at concentrations that did not affect planktonic growth, whereas D-methionine and D-leucine exhibited growth-inhibitory effects at biofilm-suppressing concentrations. qPCR further demonstrated that D-tyrosine and D-tryptophan downregulated luxS, csgD, and pgaC. Overall, sheep-derived E. coli in Northwest China exhibit significant antibiotic resistance. D-amino acids inhibit biofilm formation and show synergistic effects with antibiotics, suggesting their therapeutic potential.However, the underlying regulatory mechanisms require further investigation.