猪源大肠杆菌的生物膜形成能力和耐药性分析

Characteristics of Biofilm Formation and Drug Resistance Analysis of Escherichia coli Isolated from Pigs

为明确成膜大肠杆菌的耐药特征及其与生物膜形成能力的关系,本试验对广西南宁地区腹泻猪粪便样品中分离的506株大肠杆菌进行结晶紫染色检测其生物膜形成能力;随机挑选110株大肠杆菌进行药敏试验;进一步针对85株成膜大肠杆菌进行全基因组测序(WGS)并基于核心单核苷酸多态性(SNP)基因组构建系统发育进化树,进行克莱蒙分型(Clemon typing)、多位点序列分型(MLST)和Pearson相关系数分析。结果显示,387株(76.48%)大肠杆菌能够形成生物膜,其中,32株(6.32%)为强成膜菌。成膜大肠杆菌对β-内酰胺类、四环素类、酰胺醇类和喹诺酮类抗生素的耐药率都较高(78%~95%),且强成膜菌株对头孢噻呋、阿米卡星和多西环素等8种抗菌药的耐药率显著高于弱成膜和无成膜菌株(P<0.05)。系统发育进化树显示,强成膜菌株整体上遗传背景呈现多样性。强成膜菌株的克莱蒙分型主要是A型和B1型,MLST共35种,其中ST 1286和ST 648较为流行;基因分布特征分析结果显示,49株强成膜菌株携带floR、qnrS1和bla_(TEM-1B)等耐药基因以及bcsA、csg、filA和mrk等生物膜形成相关基因;基于Pearson相关系数分析结果发现,耐药基因bla_(OXA-10)(r=0.23,P=0.034)和菌毛基因mrk(r=0.44,P=2.10×10^(-5))检出与生物膜形成能力呈正向线性相关性。本试验明确了猪源大肠杆菌生物膜形成能力和强成膜大肠杆菌的耐药特征以及其复杂的种群结构,为成膜大肠杆菌的防控提供了科学依据。

To elucidate the antimicrobial resistance characteristics and relationship with biofilm formation ability of biofilm-forming Escherichia coli(E.coli),506 E.coli strains isolated from diarrhea pig fecal samples in Nanning,Guangxi were assessed for their biofilm formation ability using crystal violet staining.A total of 110 randomly selected strains were subjected to antimicrobial susceptibility testing.Additionally,whole-genome sequencing(WGS) was performed on 85 biofilm-forming E.coli strains,and a phylogenetic tree was constructed based on core single nucleotide polymorphisms(SNPs).Clemon typing,multilocus sequence typing(MLST),and Pearson correlation coefficient analysis were also conducted.The results revealed that 387 strains(76.48%) could form biofilms,with 32 strains(6.32%) categorized as strong biofilm formers.Biofilm-forming E.coli showed high resistance rates to β-lactams,tetracyclines,amphenicol,and quinolones(78%–95%),with strong biofilm formers exhibiting significantly higher resistance rates to ceftiofur,amikacin,and doxycycline compared to weak or non-biofilm formers(P<0.05).The phylogenetic tree indicated a diverse genetic background among strong biofilm-forming strains.Clemon typing classified these strains primarily as type A and B1,with MLST identifying 35 types,including predominant ST 1286 and ST 648.Analysis of gene distribution revealed that 49 strong biofilm-forming strains carried resistance genes such as floR,qnr S1,and blaT EM-1B,as well as biofilm-related genes including bcs A,csg,fil A,and mrk.Pearson correlation analysis showed a positive linear correlation between the presence of the resistance gene blaO XA-10( r = 0.23,P = 0.034) and the biofilm formation ability,and between the fimbrial gene mrk( r = 0.44,P = 2.10 × 10-5) and biofilm formation ability.This study clarified the biofilm formation capabilities and antimicrobial resistance characteristics of porcine E.coli,as well as the complex population structure of strong biofilm formers,providing scientific evidence for the control and prevention of biofilm-forming E.coli.