In vitro biofilm formation by uropathogenic Escherichia coli and their antimicrobial susceptibility pattern

Objective:To detect in vitro biofilm formation of uropathogenic Escherichia coli(E.coli)(UPEC) strains isolated from urine specimens and also to determine their antimicrobial susceptibility pattern using 13 commonly used antibiotics.Methods:The present study comprised of 166 urine specimens collected from tertiary care hospitals in and around Coimbatore.South India. All the specimens were subjected to gram staining,bacterial culture and the E.coli strains were screened for biofilm formation using Tube Method(TM),Congo Red Agar(CRA) and Tissue Culture Plate method(TCP) respectively.Subsequently,the antimicrobial susceptibility test was performed by Kirby Bauer-disk diffusion method for the biofilm and non-biofilm producing E. coli strains.Results:Of the 100(60.2%) E.coli strains,72 strains displayed a biofilm positive phenotype under the optimized conditions in the Tube Method and the strains were classified as highly positive(17,23.6%),moderate positive(19.26.3%) and weakly positive(36.50.0%). similarly under the optimized conditions on Congo Red agar medium,biofilm positive phenotype strains were classified as highly positive(23,23%).moderate positive(37.37%) and weakly positive(40,40%).While in TCP method,the biofilm positive phenotype strains were also classified as highly positive(6.6%),moderate positive(80.80%) and weakly positive(14,14%),it didn’t not correlate well with the tube method for detecting biofilm formation in E.coli.The rates of antibiotic resistance of biofilm producing E.coli were found to be 100%for chloramphenicol and amoxyclav(amoxicillin and clavulanic acid),86%for gentamicin and cefotaxime.84%for ceftazidime,83%for cotrimoxazole and piperacillin/tazobactam,75%for tetracycline and 70% for amikacin,Conclusions:This study reveals the prevalence and antimicrobial susceptibility pattern of biofilm and non-biofilm producing uropathogenic E.coli strains.

The effect of matrine against biofilm formation in Escherichia coli

Objective:To investigate the effect of matrine against biofilm formation of Escherichia coli(E.coli)in the early stage.Methods:Biofilms of E.coli(ATCC25922)was induced by using a peritoneal dialysis catheter in 96-well plates.After treatment with matrine for 24 h,the formation of biofilm on the catheters was observed by scanning electron microscope.The expressions of the flagellar gene(fliC)and motility genes(motA and motB)were determined by qPCR,and the protein expression of fliC was detected by western blotting.Results:The biofilm formation of E.coli was suppressed by different concentrations(less than the minimal inhibitory concentration)of matrine,and the mRNA levels of motA and motB as well as the mRNA and protein expression levels of fliC were decreased in a dose-dependent manner.Conclusion:Matrine could inhibit biofilm formation of E.coli via downregulating the expression of motA,motB and fliC.

Role of Cell Surface Structures in Biofilm Formation by <i>Escherichia coli</i>

This study aims to understand the relationship between capabilities of Escherichia coli strains to form biofilm and serotype groups expressed on cell surface. Sixteen strains of E. coli were originally isolated from different food processing lines in different Moroccan cities. Strains serotyped based on their O (somatic), H (flagellar), and K (capsular) surface antigen profiles using different antiserums. Biofilm assays carried out in 96-well microtiter dishes using the method of O’Toole et al. Our results show that no clear relation observed between origin and serotype groups. In the other hand, we observed that not all studied strains were able to form biofilm. Furthermore, combination of antigens H40 and K11 appears to be involved in biofilm formation. In fact, the H antigen seems to be implicated in the placement of the bacterial cells near the surface and the K antigen may play a role in physicochemical interactions between bacteria and inert surface.

Biofilm formation in trimethoprim/sulfamethoxazole-susceptible and trimethoprim/sulfamethoxazoleresistant uropathogenic Escherichia coli

Objective: To compare bioi lm formation in trimethoprim/sulfamethoxazole(SXT)-susceptible Escherichia coli(E. coli)(SSEC) and SXT-resistant E. coli(SREC) isolated from patients with urinary tract infections, and study the motile ability and physical characteristics of the isolates.Methods: A total of 74 E. coli isolates were tested for antimicrobial susceptibility with the disc diffusion assay. Based on the SXT-susceptibility test, the E. coli isolates were divided into SSEC(N = 30) and SREC(N = 44) groups. All E. coli isolates were examined for motile ability by using a motility test medium, and for checking bioi lm formation a scanning electron microscope was used. Bacterial colony size was measured with a vernier caliper and bacterial cell length was measured under a light microscope. The bacterial growth rate was studied by plotting the cell growth(absorbance) versus the incubation time. Results: The frequencies of non-motility and biofilm formation in the SREC group were signii cantly higher than that in the SSEC group(P < 0.01). The SREC bacterial cell length was shorter than that in the SSEC group [(1.35 ± 0.05) vs.(1.53 ± 0.05) μm, P < 0.05)], whereas the bacterial colony size and mid-log phase of the growth curve were not signii cantly dif erent. Conclusions: The present study indicated that bioi lm formation and phenotypic change of uropathogenic E. coli can be attributed to the mechanism of E. coli SXT resistance.

In vitro biofilm formation in ESBL producing Escherichia coli isolates from cage birds

Objective:To determine biofilm and hydrophobicity formation ratios in extended spectrum beta lactamases(ESBL) synthesizing Escherichia coli isolates which were isolated from feces samples of 150 cage bird species randomly taken from pet shops in Hatay province,Turkey.Methods:In vitro biofilm production of 4 ESBL positive isolates were performed by Congo Red Agar(CRA),Standard Tube(ST) and Microtitre Plate(MP) methods while their hydrophobicity were examined by bacterial adhesion to hydrocarbon(BATH) test.Results:In the examined isolates,while biofilm production was found to be negative by CRA method,highest biofilm producing strain,among 4 bacteria was determined to be A42 by ST and MP methods.The Scanning Electron Microscopy(SEM) also displayed these confirmed findings.The hydrophobicity values of strains were determined to be between 22.45%and 26.42%.Conclusions:As a result,biofilm formation in cage bird feces originated ESBL positive Escherichia coli isolates was performed for the first time in Turkey.In order to present the relation between pathogenicity and biofilm production in animal originated ESBL positive isolates,further studies are required.

Disinfection Treatment of Heated Scallop-Shell Powder on Biofilm of <i>Escherichia coli</i>ATCC 25922 Surrogated for <i>E. coli</i>O157:H7

The ability of heated scallop-shell powder (HSSP) to disinfect Escherichia coli ATCC 25922 biofilm was investigated. On account of its cryotolerance and cell surface characteristics, the E. coli strain is reportedly a useful surrogate for E. coli O157: H7 in surface attachment studies. In this study, an E. coli ATCC 25922 biofilm was formed on a glass plate, and immersed in a slurry of HSSP. Following treatment, the disinfection ability of the HSSP toward the biofilm was non-destructively and quantitatively measured by conductimetric assay. The disinfection efficacy increased with HSSP concentration and treatment time. HSSP treatment (10 mg/mL, pH 12.5) for 20 min completely eliminated biofilm bioactivity (approximately 108 CFU/cm2 in non-treated biofilms). In contrast, treatment with NaOH solution at the same pH, and treatment with sodium hypochlorite (200 mg/mL) reduced the activity by approximately one to three log10. Fluorescence microscopy confirmed that no viable cells remained on the plate following HSSP treatment (10 mg/mL). Although alkaline and sodium hypochlorite treatments removed cells from the biofilm, under these treatments, many viable cells remained on the plate. To elucidate the mechanism of HSSP activity against E. coli ATCC 25922, the active oxygen generated from the HSSP slurry was examined by chemiluminescence analysis. The luminescence intensity increased with increasing concentration of HSSP slurry. The results suggested that, besides being alkaline, HSSP generates active oxygen species with sporicidal activity. Thus, HSSP treatment could also be effective for controlling biofilms of the toxic strain E. coli O157: H7, implicated in food poisoning.

Correlation of biofilm formation of uropathogenic Escherichia coli(UPEC) and fimbriae genotypes

Objective:In the present study we try to correlate between pathogenic intrinsic factor of Escherichia coli(E.coli) presented with different fimbria genotyes and biofilm formation with host immune factor entitled interleukin-6(IL-6) secretion as defense mechanism.Methods:A total of 91 pediatrics complaining of pyuria were included in the present study.In addition,20 healthy control children were included.Full microbiological study was performed for isolated E.coli.PapC alleles were studied by multiple alleles PCR and biofilm formation was studied.IL-6 was measured in urine.Results:IL-6 had statistically significant elevation in patients’urine compared to control.From biofilm study, it was found that 19 isolated E.coli had formed biofilm in vitro.Moreover,urine samples with positive biofilm formation of E.coli had statistically significant lower IL-6 secretion than those with negative E.coli for biofilms.The distribution of fimbria genotypes showed that the frequent genotype was for alleleⅠ(34.3%) followed by mixed allelesⅠandⅡ(24.1%).There was significant correlation between mixed alleles(Ⅰ&Ⅱ)and biofilm formation.Conclusion: The present study highlights the presence of significant strains of E.coli causing urinary tract infections capable of biofilm formation.Biofilm formation is associated with less innate immunity manifested by lower urinary IL- 6.The majority of isolates had fimbria genes.It appears that mixed allelesⅠandⅡhave prominent virulence effect with tendency for biofilm formation.

Effect of Human Insulin on the Formation of Catheter-Associated <i>E. coli</i>Biofilms

Biofilm formation is essential for the survival and growth of Escherichia coli?in catheter-associated infections. Individuals with type 2 diabetes mellitus can excrete insulin and/or glucose in their urine. This population also has an increased incidence of urinary tract infections. The focus of this study was to determine if the composition of Foley catheter material affects biofilm formation by E. coli in a model system for type 2 diabetes mellitus. Rubber (lubricious-coated), silicon-coated, silver-coated and nitrofurazone-coated catheter segments (5 mm;n = 6) were tested. Catheter segments were added to E. coli ATCC25922 (104 CFU/ml, final concentration) in artificial urine alone, or with insulin (40 μU/ml) and/or glucose (0.1%). After incubation (18 h, 37?C, in air and anaerobically) the level of catheter-associated biofilm was determined by crystal violet staining (Abs550nm). Statistical analysis was done by ANOVA with post-hoc analysis (Tukey). Neither nitrofurazone-coated nor silver-coated catheters supported the formation of E. coli biofilm, regardless of growth condition tested. In contrast, under aerobic biofilm formation on silicon catheters was significantly higher (p E. coli controls. Biofilm formation was also significantly increased

3种鸡源乳酸菌抑制大肠杆菌生物被膜形成的比较研究

试验旨在研究鼠李糖乳杆菌、戊糖片球菌和口乳杆菌3种鸡源乳酸菌对大肠杆菌生物被膜生成的影响。利用置片法对供试菌株培养48 h,定性观察细菌生长与生物被膜的形成;利用96孔微板法定量检测4种细菌生长的OD_(590)值,评价抑制生物被膜生成的效果。结果表明,大肠杆菌培养12 h开始形成生物被膜,24 h形成典型的生物被膜,并伴有交织链接的生物被膜骨架;3种乳酸菌培养36 h均未见生物被膜骨架,OD_(590)值显示鼠李糖乳杆菌生物被膜厚度优于戊糖片球菌、口乳杆菌。与大肠杆菌共培养发现,3种乳酸菌全菌液和上清液均能显著抑制大肠杆菌生物被膜的生成,抑制效果鼠李糖乳杆菌>口乳杆菌>戊糖片球菌。结果可为探索乳酸菌拮抗大肠杆菌感染机制提供参考。

鸡源大肠杆菌生物被膜形成与耐药性、毒力基因的关联性分析

旨在了解鸡源大肠杆菌临床分离株生物被膜形成能力与耐药性、毒力基因之间的关系。通过刚果红试验、结晶紫染色法测定生物被膜形成能力;采用微量肉汤稀释法检测分离株对阿莫西林、氟苯尼考、庆大霉素等8种抗菌药的耐药性;PCR检测常见耐药、毒力基因携带情况;采用实时荧光定量PCR检测毒力基因在生物被膜阳性菌中的表达量。结果表明,在51株分离株中,生物被膜阳性菌株比例为19.61%,阳性菌株中,OD_(600)最大值为2.233±0.702,最小值为0.374±0.099,其他介于1.455~1.604之间;耐药性检测显示,生物被膜阳性菌株对头孢喹肟、氟苯尼考、庆大霉素、阿米卡星、黏菌素的耐药率均高于阴性菌株,其中对阿米卡星和黏菌素差异显著(P<0.05),但对多西环素耐药率低于阴性菌株,差异显著(P<0.05),二者对阿莫西林+克拉维酸、恩诺沙星耐药率无差异;OD_(600)值最大的E13对8种测定药物全部耐药,6株OD_(600)值介于1.455~1.604的菌株对5种及以上抗菌药产生耐药性,OD_(600)值为0.374的菌株E39为敏感菌株。PCR结果显示耐药基因bla_(CTX-M-9)、bla_(CTX-M-U)、bla_(OXA-1)、mcr-1、rmtB、floR在生物被膜阳性菌株中的检出率高于阴性菌株,菌株E13同时携带9种耐药基因;共检出16种毒力基因,其中fimH、astA、aggR、irp1、iucD、fyuA、ybtA、ompA在生物被膜阳性菌株中的检出率高于阴性菌株,且阳性菌株毒力基因型复杂;以OD_(600)值为0.374的E39菌株为对照,OD_(600)值较大的生物被膜阳性菌株中,fimH、ompA、ompA、iucD、hlyF毒力基因表达呈现上调趋势。综上,与生物被膜阴性菌株相比,大肠杆菌生物被膜阳性菌株耐药更为严重,携带毒力基因型更加复杂多样,且毒力基因表达呈现上调趋势。

阿米卡星诱导对大肠埃希氏菌耐药性及生物被膜和外排泵活性的影响

为研究亚抑菌浓度阿米卡星诱导对大肠埃希氏菌敏感菌株耐药性、生物被膜形成能力及外排泵活性的影响,采用微量肉汤稀释法测定阿米卡星对6株菌株的最小抑菌浓度(MIC),并以0.5 MIC作为初始诱导浓度进行诱导,每隔5 d重新测定阿米卡星MIC,并调整诱导浓度,共计30 d,最后将诱导第30天菌株进行无药物压力稳定培养5 d,保存各诱导菌株及无药传代菌株共计210株,测定各诱导菌株药物敏感性、生物被膜形成能力及部分菌株外排泵活性变化。结果发现,随着诱导天数的增加,阿米卡星对6株分离菌株MIC逐渐升高,诱导菌株耐药性不断增强,其对诱导第30天菌株的MIC值为诱导前的8~32倍;经过5 d无药培养后,MIC测定结果与第30天基本保持一致;诱导后的菌株中,强成膜能力菌株占总数的5%,中成膜能力菌株为56.7%;以每5 d的生物被膜形成量平均值与原菌相比,结果发现,所有诱导菌株生物被膜形成量均显著增加(P<0.01),表明亚抑菌浓度阿米卡星诱导可促进大肠埃希氏菌生物被膜的形成;无药稳定培养5 d的菌株与诱导第30天菌株相比,生物被膜形成能力基本保持不变。荧光探针测定外排泵结果显示,诱导菌株外排泵活性显著受到抑制。以上研究结果表明,阿米卡星诱导促进菌株生物被膜的形成,抑制外排泵活性,使菌株的耐药性增强,研究结果可为氨基糖苷类药物用药提供理论依据。

河曲马源大肠杆菌耐药相关基因检测及外排泵抑制剂对其生物被膜的影响

[目的]了解河曲马源大肠杆菌的耐药情况,为兽医临床合理使用抗菌药物提供基础理论指导。[方法]采用细菌形态学、革兰染色镜检、16S rDNA序列分析等方法进行细菌分离鉴定。采用微量肉汤稀释法和PCR扩增方法对分离鉴定的大肠杆菌进行抗菌药物敏感性试验及耐药基因、整合酶基因、外排泵基因携带情况检测。同时,采用改良结晶紫半定量方法进行生物被膜形成能力测定。利用棋盘法测定13种外排泵抑制剂与多西环素联用对生物被膜的清除作用。[结果]分离株在伊红-美蓝琼脂培养基上为具有绿色金属光泽的紫黑色菌落,在大肠杆菌/大肠菌群显色培养基上为蓝色菌落,革兰染色镜检可见粉红色短杆状细菌。经16S rDNA测序比对与大肠杆菌高度相似的分离株为64株。64株大肠杆菌分离株对酰氨醇类、磺胺类及利福霉素类药物耐药率相对较高并出现多重耐药菌株,其中20.31%(13/64)表现出对5类抗菌药物耐药;检测到21个耐药基因、1个整合酶基因及6个外排泵基因为阳性;整合酶基因intl 1检出率为89.06%。生物被膜形成能力为强、中、弱及无成膜能力的大肠杆菌分别为8(12.50%)、34(53.13%)、20(31.25%)和2(3.12%)株。外排泵抑制剂与多西环素联合能增强对生物被膜的清除能力。[结论]河曲马源大肠杆菌耐药较为严重,应进一步加强青海省河南蒙古族自治县赛马的用药监管力度,减少或避免多重耐药菌株的出现及耐药性广泛传播。

杭州地区牛乳源大肠杆菌的分离鉴定及木糖醇联用抗菌肽对生物被膜形成的干预

旨在调查杭州地区牛乳源大肠杆菌的流行情况,并探究木糖醇联用抗菌肽对引起奶牛乳房炎的大肠杆菌生物被膜形成的影响。通过麦康凯选择性培养基分离、革兰染色、生化试验、PCR方法鉴定牛乳源大肠杆菌,并采用刚果红平板试验和结晶紫染色法评价大肠杆菌生物被膜形成能力,选取生物被膜形成能力强的典型菌株,采用内置载体片法构建生物被膜,测定木糖醇和抗菌肽联用对大肠杆菌生物被膜的最小抑菌浓度(MBIC)和最小杀菌浓度(MBEC),最后通过扫描电镜分析木糖醇联用抗菌肽对大肠杆菌生物被膜干预的影响。结果显示:杭州地区牛乳源大肠杆菌的分离率达49%,其中58.2%以上能形成生物被膜。当抗菌肽单独使用时,MBIC和MBEC较高;联用5%木糖醇后,MBIC和MBEC明显降低,表明可以减少抗菌肽的用量。另外,木糖醇和抗菌肽联用能明显降低生物被膜的形成,并且5%木糖醇能增强抗菌肽1037的杀菌作用。本研究表明,联用木糖醇和抗菌肽可能是一种有效的控制奶牛乳房炎的方法。

禽致病性大肠埃希氏菌生物被膜形成的调控机制研究进展

禽致病性大肠埃希氏菌能够引起禽类感染性细菌病,给禽类养殖业造成了重大的经济损失,并严重限制了禽类养殖业的健康发展。为了了解禽致病性大肠埃希氏菌的感染机制,论文简述了生物被膜的形成过程及其危害。细菌生物被膜的形成不但增强细菌对抗菌药物的耐药性,而且导致宿主持续和反复性感染,同时还很难被预防、控制和清除。论文还分析了普遍存在于各类细菌中的重要调控系统——群体感应、双组份系统和第二信使的信号转导途径及其调控机制,并阐述了群体感应、双组份系统和第二信使以及两系统间的互作网络对细菌生物被膜的影响。因此,了解多系统共同调控生物被膜形成的分子机制或许可以作为破坏生物被膜形成的新策略,从而为控制由生物被膜引起的感染和抗菌药物耐药性提供研究方向。

大肠埃希菌裂解性噬菌体vB_EcoP-R1的特性及其抗细菌生物膜活性分析

目的从医院污水中分离大肠埃希菌特异性噬菌体,分析其生物学特性,并检测其对细菌生物膜的裂解作用。方法通过双层琼脂平板法分离纯化噬菌体,透射电镜观察其形态,并测定其一步生长曲线、体外裂解曲线、温度及酸碱稳定性。全基因测序分析噬菌体基因组组成及特性,结晶紫染色法评估噬菌体对宿主菌生物膜的清除效果。结果从医院污水中新分离1株大肠埃希菌特异性噬菌体,命名为vB_EcoP-R1;透射电镜下显示形态与尾病毒目足病毒科噬菌体成员相似,在-20~50℃的温度范围内以及在pH值5.0~11.0酸碱条件下能稳定存活。vB_EcoP-R1基因组全长为40875 bp,GC含量为49.94%,不含毒力基因和耐药基因。vB_EcoP-R1能够裂解临床分离的大肠埃希菌,且显示高度种属特异性。噬菌体作用于宿主菌预成形生物膜4 h后,对生物膜的清除率达到80.16%。结论vB_EcoP-R1是1株新的大肠埃希菌特异性噬菌体,裂解性强且种属特异性高,可裂解宿主菌已形成的生物膜,有望用于大肠埃希菌感染的替代治疗。

“黄金洗剂”逆转ESBLs+E.coli耐药性的体外实验研究

目的探讨中药“黄金洗剂”对产超广谱β-内酰胺酶的大肠埃希菌(ESBLs+E.coli)的体外抗菌效果及其逆转细菌耐药的部分机制。方法通过肉汤稀释培养法确定“黄金洗剂”对ESBLs+E.coli的最低抑菌浓度(MIC),然后应用改良Kirby-Bailer法分析“黄金洗剂”对ESBLs+E.coli耐药性的逆转效果,最后通过结晶紫染色分析生物膜形成能力和检测ESBLs酶活性来探讨“黄金洗剂”逆转细菌耐药的机制。结果“黄金洗剂”对ESBLs+E.coli的MIC为0.6 g/mL,其最佳抑菌条件是0.5 g/mL的药物浓度作用细菌24 h。此时“黄金洗剂”能够逆转细菌对第四代头孢菌素头孢吡肟的耐药性[(13.9±1.2)%],而对第三代头孢菌素头孢噻肟和头孢曲松的逆转率很低。进一步研究发现“黄金洗剂”能够逆转细菌耐药是因为该中药能够抑制生物膜形成,抑制ESBLs酶活性。结论“黄金洗剂”在0.5 g/mL条件下作用细菌24 h能够明显逆转细菌对头孢吡肟的耐药性,主要通过抑制细菌生物膜的形成和ESBLs的酶活性来实现。

新疆维吾尔自治区阿克苏地区某屠宰场羊源大肠杆菌MLST分型、耐药性分析和毒力基因检测

[目的]了解新疆维吾尔自治区阿克苏地区屠宰场羊源大肠杆菌的流行情况以及耐药性和毒力基因分布特征。[方法]从阿克苏地区某屠宰场采集健康羊的淋巴结、胴体拭子、粪便样本共30份,使用选择性培养基分离大肠杆菌,然后采用大肠杆菌特异性phoA基因对其进行分子生物学鉴定;利用PCR扩增及测序技术对大肠杆菌分离株进行多位点序列分型(multilocus sequence typing,MLST);采用K-B纸片扩散法开展分离菌株对抗菌药物的敏感性试验;应用PCR技术检测分离菌株的耐药基因和毒力基因携带情况;使用96孔板微量肉汤法测定分离菌株的生物被膜形成能力。[结果]从30份样本中分离得到14株大肠杆菌,分离率为46.67%;14株分离株分属于10个MLST型别;对复方新诺明(100%)、青霉素(85.71%)和四环素(50.00%)耐药率较高,9株菌具有多重耐药表型(64.29%);在14株大肠杆菌中检测到blaTEM(85.71%)、aph(3′)(71.43%)、tetA(64.29%)、sul1(57.14%)和sul2(57.14%)等12种耐药基因,并且8株菌携带Ⅰ型整合子int-Ⅰ基因(57.14%);在14株大肠杆菌中检测到fimH(100%)、yijP(92.86%)、mat(92.86%)、sheA(92.86%)、stx1(35.71%)和ibeB(28.57%)等10种毒力基因;10株大肠杆菌具有生物被膜形成能力(71.43%)。[结论]该屠宰场羊源大肠杆菌种内分型丰富,具有较强的耐药性,还可形成生物被膜,并且携带多种耐药基因和毒力基因,对动物性食品安全可能存在潜在威胁。

塑料包装材料表面大肠杆菌滋生影响因素研究

目的选择大肠杆菌为典型致病菌,分析不同塑料包装材料(聚乙烯、聚丙烯、聚酰胺、聚对苯二甲酸乙二酯)、营养状况与温湿度下包装表面大肠杆菌的滋生情况。方法通过正交试验法分析各因素对大肠杆菌在包装表面滋生的影响规律。着重研究不同塑料材料表面大肠杆菌生物膜附着的影响因素,通过相关性分析确定模型输入参数;并基于这些参数采用反向传播神经网络(BP神经网络)建立不同塑料材料表面大肠杆菌菌落数的预测模型。结果温度对大肠杆菌在材料表面的生长影响最大,其次为营养状况,材料和相对湿度的影响相对较小。塑料材料的水接触角、表面能、粗糙度和营养肉汤接触角是影响材料表面大肠杆菌生物膜附着的主要因素,基于这些因素建立的塑料材料表面大肠杆菌菌落数的神经网络预测模型的R^(2)超过0.95,具有极高的预测精度。结论该研究提出了塑料包装材料表面大肠杆菌滋生的关键环境控制因素,并为食品包装材料的选择提供了参考,从而为提升食品安全提供理论依据。

双组份系统调控禽致病性大肠杆菌生物被膜的研究进展

禽致病性大肠杆菌是一种典型的肠道外致病性大肠杆菌,能够引起各种肠道外疾病,给禽类养殖业造成重大的经济损失。生物被膜作为一种保护细菌的物理屏障用于抵御抗生素的损伤及逃避宿主的免疫系统,从而导致宿主持续和反复性感染。双组份系统是普遍存在于各类细菌中主要的信号传导系统,参与调控细菌抗生素耐药性和生物被膜的形成。为了解由生物被膜造成的禽致病性大肠杆菌感染机制,文章详述了生物被膜的形成过程,并综述了双组份系统调控生物被膜形成的分子机制,以期探寻阻断双组份系统信号转导的新方法以破坏生物被膜的形成作为控制禽致病性大肠杆菌感染的治疗策略,从而为防治由生物被膜引起的抗生素耐药性以及持续或反复性感染提供研究方向。

Pediococcus Acidilactici Inhibit Biofilm Formation of Food-Borne Pathogens on Abiotic Surfaces

In this study,we aimed to examine the inhibitory effect of PA003,a Pediococcus acidilactici that produces lactic acid and antimicrobial peptides pediocin,on pathogenic biofilm formation on abiotic surfaces.PA003 and pathogens(Escherichia coli,Salmonella enterica serovar Typhimurium,Staphylococcus aureus and Listeria monocytogenes) were used to evaluate auto-aggregation,hydrophobicity,biofilm formation and biofilm formation inhibition on stainless steel,polyvinyl chloride and glass slides in terms of exclusion,displacement and competition.The results showed the highest auto-aggregation abilities were observed for one of the E.coli strains EAggEC(E58595) and the highest hydrophobic strain was observed with EPEC(E2348/69)(51.9%).The numbers of biofilm cells of E.coli,S.Typhimurium,S.aureus and L.monocytogenes on stainless steel,polyvinyl chloride and glass slide coupons were effectively reduced by approximately 4log CFU/coupon.These results demonstrate that lactic acid bacteria can be used as an alternative to effectively control the formation of biofilms by food-borne pathogens.