Detection of a Lactobacillus substance that inhibits Escherichia coli

Recent studies have shown that certain lactobacilli strains have the ability to interfere with the adherence and growth of uropathogenic bacteria. This interaction is believed to be important in the maintenance of a normal urogenital flora and in the prevention of infection in females. In the present study, Lactobacillus casei ssp. rhamnosus GR-1 and Lactobacillus acidophilus 76 were found to exert an inhibitory effect on pyelonephritogenic mutant Escherichia coli Hu 734 and E. coli ATCC 25922. The bioactivity of the inhibitor produced by strain GR-1 was retained under pH buffered conditions and was bactericidal. The bioactive substance was heat labile, not precipitated by up to 80% ammonium sulphate, and extractable in chloroform. The data indicated that the inhibitor is not lactic acid or hydrogen peroxide and has a molecular weight greater than 12,000-14,000. Human urine supported production of the inhibitor and reduced and delayed outgrowth of the E. coli. The ability of L. casei GR-1 and possibly other lactobacilli strains to produce inhibitors of uropathogenic bacteria may have clinical importance and significance in the microbial ecology of the urogenital tract.     

Characterization of vaginal lactobacilli coaggregation ability with Escherichia coli

The coaggregation abilities of probiotic strains might enable it to form a barrier that prevents colonization by pathogenic bacteria. In the present study, the characterization of the coaggregation ability of 19 vaginal lactobacilli was studied. Coaggregation ability of all lactobacilli with Escherichia coli ATCC 11229 was positive. Only the highest coaggregation percentage of Lactobacillus acidophilus S1 was obtained with E. coli ATCC 11229 under both aerobic (71%) and anaerobic conditions (62%). The coaggregation abilities of strains occurred higher at acidic pH than at basic pH values. Moreover, the coaggregation abilities of tested strains against E. coli decreased after heat treatment (70 or 85 °C). Also, the relationship between hydrophobicity and coaggregation of strains was found to be significant. The effect of sonication, some enzymes (lipase and pepsin) and sodium periodate on coaggregation ability of L. acidophilus S1, which is one of the highest potentials on coaggregation ability, was investigated. Sodium periodate did not have a significant effect on coaggregation ability of L. acidophilus S1. The sonicated cell showed lower coaggregation than the control, the supernatant fluid of this sonicated cells showed similar coaggregation ability to the control. Coaggregation abilities of bacteriotherapeutic lactobacilli with pathogenic bacteria can be used for preliminary screening in order to identify potentially probiotic bacteria suitable for human use against urogenital tract infections.     

Coaggregation of urogenital bacteria in vitro and in vivo

The working hypotheses of the present study were that (1) bacterial coaggregates exist in the urogenital tract of healthy and infected women, and (2) coaggregation reactions can occur in vitro between members of the urogenital flora. Examination of urogenital specimens from 25 healthy women showed that lactobacilli were the dominant organisms colonizing the epithelia and coaggregating with other Gram-positive and Gram-negative bacteria. In vitro light and electron microscopic studies confirmed that members of the urogenital flora could coaggregate. An examination of specimens from 9 women with urinary tract infection showed the presence of autoaggregated uropathogens free-floating in the urine and attached to epithelial cells. The phenomenon of autoaggregation was also noted in vitro for various uropathogens, suggestive that this may represent a virulence factor. It is evident that bacterial cell-to-cell binding within a strain and among different genera occurs in the urogenital tract. Further studies of the mechanisms that maintain and disrupt these microbial interactions will help to improve our understanding of disease initiation.     

Factors affecting the coaggregation ability of vaginal Lactobacilli withCandida spp.

In this study, the capacity of 30 strains of lactobacilli to coaggregate withCandida albicans ATCC 10239,C. albicans AJD 180 andCandida krusei ATCC 6258 were studiedin vitro. A marked coaggregation withC. albicans was observed for two strains ofLactobacillus crispatus, a strain ofLactobacillus cellobiosus and a strain ofLactobacillus salivarius. Coaggregation occurred at a pH range from 3 to 7, some strains showing optimal binding at high and other strains at low pH. Treatment of lactobacilli at 70 or 85°C for 20 min or treatment of the bacteria with pepsin abolished their capacity of coaggregation. The results may be of importance when trying to establish probiotics for vaginal use.     

Activity of cecropin P1 and FA-LL-37 against urogenital microflora

Two mammalian antimicrobial peptides, FA-LL-37 and cecropin P1, were tested for activity against six uropathogens and five Lactobacillus strains by broth microdilution assay. Both peptides inhibited Escherichia coli at 25 microM (FA-LL-39), and 1.56 microM (cecropin P1), Pseudomonas aeruginosa (12.5 microM, and 25 microM), and Klebsiella pneumoniae, (50 microM, and 1.56 microM), but not Enterococcus faecalis and Staphylococcus epidermidis. FA-LL-37 acted bacteriocidally against E. coli and bacteriostatically against the other two Gram-negative organisms. Cecropin P1 was bacteriocidal to all susceptible bacteria. Lactobacilli were resistant to both peptides, with the exception of poultry isolate Lactobacillus fermentum B-54, which was susceptible to FA-LL-37 at 100 microM. The differential activities of these peptides toward Gram-negative uropathogens versus urogenital lactobacilli demonstrate their potential as a topical treatment for urinary tract infections. In addition, production of such peptides in vivo could be a natural mechanism to aid in the maintenance of the lactobacilli-dominated urogenital flora at the expense of pathogens.     

抑制E.coli的SOS应答对恩诺沙星抗药性的影响

通过敲除SOS应答启动蛋白基因rec A,探讨SOS应答对E.coli恩诺沙星抗药性的影响,并体外评价Rec A抑制剂和恩诺沙星联用对细菌协同抑制作用的影响.利用Red重组系统,构建E.coli ATCC 25922的rec A缺失菌株E.coli ATCC 25922/?rec A;在恩诺沙星压力下,利用荧光定量PCR测定SOS应答系统相关基因rec A和umu C表达量的变化.用微量肉汤稀释法测定恩诺沙星等常用抗生素对两个菌株的MIC变化;利用梯度平板法测定恩诺沙星对两个菌株抗药性变异的影响;合成Rec A抑制剂,并评估其与恩诺沙星联合抑制E.coli生长及其抗药性的作用.结果表明,E.coli ATCC 25922/?rec A菌株对恩诺沙星的最低抑菌浓度值降低至原始菌株的1/8;经药物处理后,在梯度平板上,rec A缺失菌株较野生型不易产生抗药性;荧光定量PCR表明,rec A缺失菌株或在Rec A抑制剂作用下,SOS应答系统受到一定的抑制.敲除rec A,使菌株对恩诺沙星的抗药性和抗药率均明显降低;Rec A抑制剂在一定程度上能抑制SOS应答,起到协同抑菌作用.     

蛇毒抗菌肽OH-CATH对大肠杆菌引起家兔泌尿系感染的保护作用

为探讨蛇毒抗菌肽OH-CATH对大肠杆菌标准株和临床耐药株引起家兔泌尿系感染的保护作用,该文利用大肠杆菌标准株(E.coli ATCC 25922)和耐头孢菌素大肠杆菌临床耐药株建立雄性家兔泌尿系感染模型.通过膀胱直接给药的方式,分别给予动物感染模型生理盐水、蛇毒抗菌肽OH-CATH及头孢哌酮舒巴坦,并于给药后第1、5、l0及14天留取家兔中段尿用于尿液培养.将动物膀胱标本行H-E染色石蜡切片及透射电镜观察.结果显示:使用蛇毒抗菌肽OH-CATH的大肠杆菌标准株和临床耐药株不同组别中段尿培养阳性率明显降低;给予头孢哌酮舒巴坦可降低大肠杆菌标准株(E.coli ATCC 25922)引起感染的阳性率,但对耐头孢菌素大肠杆菌引起的感染的阳性率则无明显作用(P＜0.05);使用蛇毒抗菌肽OH-CATH组炎症细胞浸润、坏死及钙化组织较其他组为少.该结果提示蛇毒抗菌肽OH-CATH对大肠杆菌标准株(E.coli ATCC 25922)及耐头孢菌素大肠埃希菌临床耐药株有稳定活性,对其引起的家兔泌尿系感染有较好的保护作用,并为临床日益严重的耐药病原菌感染的治疗提供了新的思路和方向.     

Glutathione transferase in bacteria: subunit composition and antigenic characterization

The presence of glutathione transferase (GST; EC 2.5.1.18) in Escherichia coli ATCC 25922, E. coli ATCC 25422, Proteus vulgaris ATCC 8427, Pseudomonas aeruginosa ATCC 27853, Klebsiella oxytoca CIP 666, K. oxytoca AF 101, Enterobacter cloacae CIP 6085, Serratia marcescens CIP 6755, and Proteus mirabilis AF 2924 was investigated. Using 1-chloro-2,4-dinitrobenzene as substrate, GST activity was found in the glutathione-(GSH-)affinity-purified fraction of all strains tested. SDS-PAGE analysis of GSH-affinity-purified enzyme indicated that the GSTs of all these bacteria are dimers of two identical subunits of Mr about 22,500. Rabbit antiserum directed against the major isoenzyme present in Proteus mirabilis AF 2924, Pm-GST-6.0, was used to investigate the antigenic properties of bacterial GSTs. Western blot analysis indicated that a GST antigenically identical to Pm-GST-6.0 is present in Enterobacter cloacae CIP 6085, Escherichia coli ATCC 25422 and Proteus vulgaris ATCC 8427, but absent in Escherichia coli ATCC 25922, Klebsiella oxytoca CIP 666, K. oxytoca AF 101 and Serratia marcescens CIP 6755. The presence of Pm-GST-6.0, but not mammalian GST, increased the MIC values of amikacin, ampicillin, cefotaxime, cephalothin and nalidixic acid for E. coli ATCC 25922. It is suggested that bacterial GST may represent a defense against the effects of antibiotics.     

Inhibition of in vitro growth of enteropathogens by new Lactobacillus isolates of human intestinal origin

Three human Lactobacillus strains, coded B21060, B21070 and B21190, have recently been isolated. The strains show a series of features (acid and bile resistance, adhesion to various types of mucosal cell) which make them particularly promising for the preparation of probiotic products. In the present study, the ability of the strains to inhibit the growth of pathogens in coculture was investigated. Lactobacilli were incubated simultaneously or after one overnight growth with enterotoxigenic Escherichia coli, Salmonella enteritidis or Vibrio cholerae. After 24 and 48 h, bacterial counts of the pathogens and of the lactobacilli were performed. The results showed that these Lactobacillus strains inhibited the in vitro growth of E. coli and S. enteritidis under both conditions. Moreover, a cumulative effect was observed for mixtures of lactobacilli. In contrast, no significant inhibition of Vibrio cholerae growth was observed, provided that the pH of the medium was kept constant. The presence of the pathogens did not affect the growth of the Lactobacillus strains. Moreover, each of the Lactobacillus strains showed coaggregation ability with two pathogenic E. coli strains, namely ATCC 25922 and ATCC 35401.     

Antibacterial activity of crude methanolic extract and its fractions of aerial parts of Anthemis tinctoria

The antibacterial activity of the methanolic extract and its fractions of aerial parts of Aniheinis tinctoria (Asteraceae) was investigated against representative gram-positive Staphylococcus aureus (ATCC 25923) and Enterococcus faecalis (ATCC 29212) and gram-negative strains Escherichia coli (ATCC 25922) and Pseudomonas aeruginosa (ATCC 27853). The activity was concentrated mainly in the dichloromethane (DCM) and hexane fractions of crude methanolic extract. The 5 mg of DCM extract per disk produced 15-16 mm of inhibition zone against S. aureus and P. aeruginosa, however, no activity was found against E. faecalis and E. coli. The hexane fraction showed activity against S. aureus, P. aeruginosa and E. faecalis. As DCM fraction showed the highest antibacterial activity in the disk diffusion assay, the minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) values of only this fraction was determined against S. aureus and P. aeruginosa. These values were found to be in the range of 1.25 to 10 mg/ml.     

Antibacterial activity of coumarins

The antibacterial activity of coumarin per se and other 45 coumarin derivatives was tested against strains of Bacillus cereus MIP 96016, Escherichia coli ATCC 25922, Pseudomonas aeruginosa ATCC 27853, and Staphylococcus aureus ATCC 25923. The inhibitory effects of coumarins were affected by their substitution patterns. Osthenol (44) showed the most effective antibacterial activity against Gram-positive bacteria with MIC values ranging between 125 and 62.5 microg/ml. These results suggested that the prenyl chain of 44 at position 8 and the presence of OH at position 7 of the benzenic ring are required for the antibacterial activity against these strains.     

Screening antimicrobial activity of various extracts of Artemisia dracunculus L

The antimicrobial activities of chloroform, acetone and two different concentrations of methanol extracts of Artemisia dracunculus L. were studied. These extracts were tested against nine bacteria and four yeasts strains by the disc diffusion method. The results indicated that the methanol extract of A. dracunculus is more effective against tested microorganisms than chloroform or acetone extracts. The chloroform and acetone extracts were inhibitory only towards Pseudomonas aeruginosa (ATCC 27853). While the methanol extract that was diluted with 10 ml distilled water showed inhibition zones against Shigella (RSHI), Listeria monocytogenes ATCC 7644, P. aeruginosa (ATCC 27853), the methanol extract that was diluted with 5 ml distilled water showed inhibition zones against two different strains of Escherichia coli (RSHI, ATCC 25922), Shigella (RSHI), L. monocytogenes (ATCC 7644), and P. aeruginosa ATCC 27853. The cells of microorganisms treated with plant extracts and normal microorganism cells were observed by scanning electron microscope. It was apparent that cells are damaged after treatment with A. dracunculus.     

人HMGB1酸性尾端对其抗菌活性的影响

为研究人高迁移率族蛋白B1(high-mobility group box-1HMGB1)酸性尾端对其抗菌活 性的影响,提取人外周血单个核细胞总RNA,经RT\|PCR扩增得到编码人HMGB1的cDNA及其缺失酸性尾端的突变体cDNA(mcDNA),原核表达载体pQE\|80L分别表达重组人HMGB1蛋白(rhHMGB1)及缺失酸性尾端的突变体蛋白(mrhHMGB1),经Ni^2+_- NTA亲和层析柱纯化两种蛋白.通过试管稀释法、琼脂扩散法两种体外抗菌实验观察,并比较rhHMGB1mrhHMGB1抗菌活性的差异.实验结果显示,rhHMGB1对大肠杆菌JM109、ATCC2592 2、DH5α有明确的抗菌活性,其抗菌活性强弱依次为JM109>ATCC25922>DH5α,而mrhHMGB1 对大肠杆菌JM109、ATCC25922、DH5α则均无抗菌活性.实验结果表明,人HMGB1的酸性尾端对其抗菌活性的发挥至关重要,此研究为进一步探讨人HMGB1抗菌功能的机制奠定了基础.     

4株羊瘤胃功能性细菌的筛选

通过DNS法测定羊瘤胃源功能性细菌产生的纤维素酶和淀粉酶的活力,福林酚法测定产生的蛋白酶的活力,检测细菌产生酶的特性。同时检测菌株的发酵液对大肠埃希菌(ATCC25922)、副溶血弧菌(ATCC17802)、藤黄八叠球菌(HY78)和产气杆菌(AS1489)等指示菌的抑制能力,分析它们的抑菌活性。结果表明,羊瘤胃源细菌C13产生的纤维素酶活力最高,产酶量也最高;而细菌C5产淀粉酶活力和蛋白酶活力最高,产生淀粉酶和蛋白酶的能力也最高。抑菌活性检测发现,细菌C9对副溶血弧菌(ATCC17802)有很高的抑制作用,而细菌C12对大肠埃希菌(ATCC25922)的抑制能力最明显。     

Antibacterial activity of ethanolic and aqueous extracts of Acacia aroma Gill. ex Hook et Arn

The purpose of the present study was to investigate the antibacterial activity of seven ethanolic extracts and three aqueous extracts from various parts (leaves, stems and flowers) of A. aroma against 163 strains of antibiotic multi-resistant bacteria. The disc diffusion assay was performed to evaluate antibacterial activity of the A. aroma crude extracts, against several Gram-positive bacteria (E. faecalis, S. aureus, coagulase-negative stahylococci, S. pyogenes, S. agalactiae, S. aureus ATCC 29213, E. faecalis ATCC 29212) and Gram-negative bacteria (E. coli., K. pneumoniae, P. mirabilis, E. cloacae, S. marcescens, M morganii, A. baumannii, P. aeruginosa, S. maltophilia, E. coli ATCC 35218, P. aeruginosa ATCC 27853, E. coli ATCC 25922). All ethanolic extracts showed activity against gram-positive bacteria. Among all obtained extracts, only leaf and flower fluid extracts showed activity against Gram-negative bacteria. Based on this bioassay, leaf fluid extracts tended to be the most potent, followed by flower fluid extracts. Minimal inhibitory concentration (MIC) values of extracts and antibiotics were comparatively determined by agar and broth dilution methods. Both extracts were active against S. aureus, coagulase-negative stahylococci, E. faecalis and E. faecium and all tested Gram-negative bacteria with MIC values from 0.067 to 0.308 mg/ml. In this study the minimal bactericidal concentration (MBC) values were identical or twice as high than the corresponding MIC for leaf extracts and four or eight times higher than MIC values for flower extracts. This may indicate a bactericidal effect. Stored extracts have similar antibacterial activity as recently obtained extracts. The A. aroma extracts of leaves and flowers may be useful as antibacterial agents against Gram- negative and Gram-positive antibiotic multi-resistant microorganisms.     

Structure-activity relationship of antibacterial chalcones

The antibacterial activity of 31 chalcones was tested against bacterial strains, Bacillus cereus ATCC 11778, Escherichia coli ATCC 25922, Pseudomonas aeruginosa ATCC 27853, and Staphylococcus aureus ATCC 25923. Some of the tested chalcones showed fair to significant activity against Gram-positive bacteria. By comparison of the results obtained, the antibacterial activity can be related to features such as the presence of a C-4 hydroxyl group, a C-4' oxygenated substituent or a C-3' isoprenoid side chain, while the C-2' hydroxyl group might have importance for the stability of the molecule. The inhibitory effect of chalcones on human pathogenic microorganisms can be correlated with the substitution patterns of the aromatics rings.     

Studies on antimicrobial activity, in vitro, of Physalis angulata L. (Solanaceae) fraction and physalin B bringing out the importance of assay determination

Complex physalin metabolites present in the capsules of the fruit of Physalis angulata L. have been isolated and submitted to a series of assays of antimicrobial activity against Pseudomonas aeruginosa ATCC 27853, Staphylococcus aureus ATCC 29213, S. aureus ATCC 25923, S. aureus ATCC 6538P, Neisseria gonorrhoeae ATCC 49226, Escherichia coli ATCC 8739; E. coli ATCC 25922, Candida albicans ATCC 10231 applying different methodologies such as: bioautography, dilution broth, dilution agar, and agar diffusion techniques. A mixture of physalins (pool) containing physalins B, D, F, G inhibit S. aureus ATCC 29213, S. aureus ATCC 25923, S. aureus ATCC 6538P, and N. gonorrhoeae ATCC 49226 at a concentration of 200 mg/microl, using agar dilution assays. The mixture was inactive against P. aeruginosa ATCC27853, E. coli ATCC 8739; E. coli ATCC 25922, C. albicans ATCC 10231 when applying bioautography assays. Physalin B (200 microg/ml) by the agar diffusion assay inhibited S. aureus ATCC 6538P by +/- 85%; and may be considered responsible for the antimicrobial activity.     

Antimicrobial activity of plant essential oils against bacterial and fungal species involved in food poisoning and/or food decay

The currative properties of aromatic and medicinal plants have been recognized since ancient times and, more recently, the antimicrobial activity of plant essential oils has been used in several applications, including food preservation. The purpose of this study was to create directly comparable, quantitative data on the antimicrobial activity of some plant essential oils prepared in the National Institute of Research-Development for Chemistry and Petrochemistry, Bucharest to be used for the further development of food packaging technology, based on their antibacterial and antifungal activity. The essential oils extracted from thyme (Thymus vulgaris L.), basil (Ocimum basilicum L.), coriander (Coriandrum sativum L.), rosemary (Rosmarinus officinalis L.), sage (Salvia officinalis L.), fennel (Foeniculum vulgare L.), spearmint (Mentha spicata L.) and carraway (Carum carvi L.) were investigated for their antimicrobial activity against eleven different bacterial and three fungal strains belonging to species reported to be involved in food poisoning and/or food decay: S. aureus ATCC 25923, S. aureus ATCC 6538, S. aureus ATCC 25913, E. coli ATCC 25922, E. coli ATCC 35218, Salmonella enterica serovar Enteritidis Cantacuzino Institute Culture Collection (CICC) 10878, Listeria monocytogenes ATCC 19112, Bacillus cereus CIP 5127, Bacillus cereus ATCC 11778, Candida albicans ATCC 10231, Aspergillus niger ATCC 16404, Penicillium spp. CICC 251 and two E. coli and Salmonella enterica serovar Enteritidis clinical isolates. The majority of the tested essential oils exibited considerable inhibitory capacity against all the organisms tested, as supported by growth inhibition zone diameters, MICs and MBC's. Thyme, coriander and basil oils proved the best antibacterial activity, while thyme and spearmint oils better inhibited the fungal species.     

Effect of oxygen on survival of faecal pollution indicators in drinking water

AIMS: The aim of this study was to determine the effect of oxygen on the survival of faecal pollution indicators including Escherichia coli in nondisinfected drinking water. METHODS AND RESULTS: Aerobic and anaerobic drinking water microcosms were inoculated with E. coli ATCC 25922 or raw sewage. Survival of E. coli was monitored by membrane filtration combined with cultivation on standard media, and by in situ hybridization with 16S rRNA-targeted fluorescent oligonucleotide probes. Anaerobic conditions significantly increased the survival of E. coli in drinking water compared with aerobic conditions. Escherichia coli ATCC 25922 showed a biphasic decrease in survival under aerobic conditions with an initial first-order decay rate of -0.11 day(-1) followed by a more rapid rate of -0.35 day(-1). In contrast, the first-order decay rate under anaerobic conditions was only -0.02 day(-1). After 35 days, <0.01% of the initial E. coli ATCC 25922 population remained detectable in aerobic microcosms compared with 48% in anaerobic microcosms. A poor survival was observed under aerobic conditions regardless of whether E. coli ATCC 25922 or sewage-derived E. coli was examined, and regardless of the detection method used (CFU or fluorescent in situ hybridization). Aerobic conditions in drinking water also appeared to decrease the survival of faecal enterococci, somatic coliphages and coliforms other than E. coli. CONCLUSIONS: The results indicate that oxygen is a major regulator of the survival of E. coli in nondisinfected drinking water. The results also suggest that faecal pollution indicators other than E. coli may persist longer in drinking water under anaerobic conditions. SIGNIFICANCE AND IMPACT OF THE STUDY: The effect of oxygen should be considered when evaluating the survival potential of enteric pathogens in oligotrophic environments.     

细菌对肉鸡肠粘液的粘附作用

研究两歧双歧杆菌、嗜酸乳杆菌、禽大肠杆菌O78、大肠杆菌 ATCC 25922、鸡白痢沙门氏菌和鼠伤寒沙门氏菌与肉鸡不同部位肠粘液糖蛋白的粘附性能,探讨两歧双歧杆菌和嗜酸乳杆菌对所试病原菌的抗粘附作用。结果表明：在不同的肠道部位,两歧双歧杆菌、嗜酸乳杆菌、鸡白痢沙门氏菌和鼠伤寒沙门氏菌与肠粘液糖蛋白均有不同的粘附作用,而禽大肠杆菌O78、大肠杆菌 ATCC 25922在各肠段粘液上的粘附性能则相近;在相同的肠道部位,所试益生菌的粘附能力大于病原菌;两歧双歧杆菌和嗜酸乳杆菌对所试病原菌的粘附有不同的阻断作用,同时二者有时还存在互补抗粘附作用。