Antimicrobial activity of commercial citrus-based natural extracts against Escherichia coli O157:H7 isolates and mutant strains

Due to increasing concerns about the development of antimicrobial resistance amongst pathogenic bacteria, alternative strategies have been sought that do not use antibiotics to reduce pathogenic bacteria from foods and patients. A natural compound that has potent antimicrobial properties is citrus peel, which contains a variety of essential oils that inhibit the growth of or kill pathogenic bacteria. In the present study, seven citrus-based natural antimicrobials were evaluated for their ability to inhibit the growth of the pathogen Escherichia coli O157:H7. Zones of inhibition of E. coli O157:H7 by the citrus-derived fraction (10 microL/6 mm disk) were determined by a disk-diffusion assay on Sorbitol-MacConkey agar. Inhibition zones were observed after 48 h lawn growth of E. coli O157:H7 cells at 37 degrees C. Two citrus-based fractions, orange CP VAL terpeneless FAB 968611 and Limonene 1x Dist FAB 955430, inhibited E. coli O157:H7 with inhibition zones of approx. 11-24 mm dia. The remaining other five citrus-derived extracts (orange oil FL VAL 1121 ARR 974760, Orange 5x Conc VAL 4121 ARR 968374, orange terpenes ESS 1120 ARR 986259, orange terpenes CP 1100 ARR 986255, and orange terpenes OEO HP 1100 ARR 986257) were noninhibitory to E. coli O157:H7, yielding no clear inhibition zones. These studies show that citrus-derived natural compounds differ in their inhibitory activity against E. coli O157:H7 and some have potential applications as inhibitory agents against E. coli O157:H7 in various pathogen reduction strategies.     

In vitro effects of food extracts on selected probiotic and pathogenic bacteria

A panel of 148 extracts from 37 food products was prepared using organic and aqueous solvents and both neutral and acidic conditions. The panel of food products tested included fruits, vegetables, grains, herbs and spices, most of which are common in a normal European-style diet. The impact of these extracts on the growth of selected probiotic bacteria (Lactobacillus reuteri, Lactobacillus rhamnosus, Bifidobacteria lactis) and pathogenic bacteria (Escherichia coli 0157:H7 and Escherichia coli LF82) was assessed using a standard minimum inhibitory concentration method. The results showed that aqueous extractions of garlic and black peppercorns significantly enhanced the growth of one strain of probiotic bacteria (L. reuteri) whilst inhibiting both pathogenic strains of E. coli at a 1:50 dilution. Aqueous extracts of banana, apple and orange all enhanced the growth of the three probiotic strains significantly, and inhibited the pathogens to approximately 80% of the controls (not significant). Both aqueous and organic extractions of ginger significantly inhibited the growth of one or both E. coli strains, respectively (also at the 1:50 dilution).     

The Alleviation of Gut Microbiota-Induced Depression and Colitis in Mice by Anti-Inflammatory Probiotics NK151, NK173, and NK175

Gut microbiota dysbiosis is strongly associated with psychiatric disorders and inflammatory bowel disease (IBD). Herein, we examined whether the fecal microbiota of IBD patients with depression (IBDD) and their gut microbiota culture (iGm) could cause depression and colitis in mice and anti-inflammatory probiotics could mitigate depression in iGm-transplanted or immobilization stress (IS)-exposed mice. Fecal microbiota transplantation (FMT) from IBDD patients, which exhibited Enterobacteriaceae-rich gut microbiota, and its gut microbiota culture (iGm) increased depression-like behaviors in mice. Their treatments heightened the blood lipopolysaccharide (LPS) level and colonic IL-1β and IL-6 expression. However, FMT from healthy volunteers or sulfasalazine treatment alleviated cGm-induced depressive-like behaviors and hippocampal and colonic inflammation in mice. Moreover, oral administration of Lactobacillus plantarum NK151, Bifidobacterium longum NK173, and Bifidobacterium bifidum NK175, which inhibited LPS-induced IL-6 expression in macrophages, alleviated cGm-induced depression-like behaviors, hippocampal NF-κB⁺Iba1⁺ cell numbers and IL-1β and IL-6 expression, blood LPS, IL-6, and creatinine levels, and colonic NF-κB⁺CD11c⁺ number and IL-1β and IL-6 expression in mice. Treatment with NK151, NK173, or NK175 mitigated immobilization stress (IS)-induced depressive-like behaviors, neuroinflammation, and gut inflammation in mice. NK151, NK173, or NK175 also decreased IS-induced blood LPS, IL-6, and creatinine levels. The transplantation of Enterobacteriaceae-rich gut microbiota can cause depression and colitis, as IS exposure, and anti-inflammatory NK151, NK173, and NK175, may alleviate stress-induced fatigue, depression, and colitis by regulating the expression of proinflammatory and anti-inflammatory cytokines through the suppression of gut bacterial LPS.     

Antimicrobial resistant pattern of Escherichia coli strains isolated from pediatric patients in Jordan

The present study was conducted to investigate antimicrobial resistant pattern of Escherichia coli (E. coli) strains isolated from clinical specimens of Jordanian pediatric patients during the period from January to December 2008. A total of 444 E. coli strains were isolated from clinical specimens and tested for their susceptibility to different antimicrobial drugs. Overall, high resistance rate was observed for ampicillin (84%), followed by amoxicillin-clavulanic acid (74.3%), cotrimoxazole (71%), nalidixic acid (47.3%), cephalothin (41%). Lower resistance rates were observed for amikacin (0%) followed by Cefotaxime (11%), Ceftriaxone (11.7%), ciprofloxacin (14.5%), Norfloxacin (16.5%), gentamicin (17.3%) cephalexin (20.9%), Ceftazidime (22.5%), cefixime (29.6%), and cefaclor (32.8%). Ampicillin, amoxicillin-clavulanic acid and cotrimoxazole were found to be ineffective at in vitro inhibition of the E. coli of pediatric origin. Amikacin was highly effective for E. coli with susceptibility rate of 100%. The majority of E. coli strains were susceptible to third generation cephalosporins and fluoroquinolones.     

235株血流感染大肠埃希菌耐药性分析

目的分析某院血流感染患者标本分离的大肠埃希菌耐药性,为临床合理应用抗菌药物提供依据。方法采用BacT/Alert全自动血培养仪、VITEK2细菌鉴定仪对患者血标本进行培养、鉴定;K-B药敏纸片测定法进行药敏试验并筛选出产超广谱β-内酰胺酶(ESBLs)细菌。结果 2009—2011年共分离血流感染大肠埃希菌235株,ESBLs阳性90株,阳性率38.30%。产ESBLs菌株对氨苄西林、头孢噻肟、头孢曲松100%耐药;对亚胺培南/西司他丁、美罗培南敏感率均为100%,对头孢美唑、阿米卡星敏感率90%。非产ESBLs菌株耐药率最高的是氨苄西林,达70.63%;对亚胺培南/西司他丁、美罗培南敏感率均为100%,对阿米卡星、头孢噻肟、头孢美唑敏感率95%。产ESBLs菌株的耐药率均明显高于非产ESBLs菌株。在含有β-内酰胺酶抑制剂的复合抗菌药物中,只有头孢哌酮/舒巴坦对产ESBLs大肠埃希菌的敏感率90%,哌拉西林/他唑巴坦和替卡西林/克拉维酸的敏感率均未超过80%。结论血流感染大肠埃希菌产ESBLs株的耐药性较高,临床用药应根据患者感染菌的耐药情况制定合理的个体化治疗措施。     

In vitro activity of levofloxacin against Escherichia coli strains in acute pyelonephritis, in France in 2005

The objective of this study was to assess the in vitro activity of levofloxacin compared to other antibiotics against Escherichia coli strains isolated from female patients with acute pyelonephritis in 23 French hospitals in 2005. Minimal inhibitory concentrations (MICs) were determined in a central laboratory, by agar dilution method in compliance with the recommendations of the Comité de l'antibiogramme de la Société fran?aise de Microbiologie (CA-SFM). The percentages of susceptible strains were calculated according to the European Committee on Antimicrobial Susceptibility Testing (EUCAST) breakpoints approved by the CA-SFM (2005) for ciprofloxacin, levofloxacin, and ofloxacin and according to the CA-SFM breakpoints for the other antibiotics. Amongst the 231 strains collected, 46.3% of strains were isolated from urinary samples, 10.8% from blood culture, and 42.9% from both. Concerning fluoroquinolones, the percentages of susceptibility were 93.1%, 90.5%, and 92.7% for levofloxacin, ofloxacin, and ciprofloxacin, respectively. For the other antibiotics, a higher percentage of susceptibility was observed with ceftriaxone (99.6%) and amikacin (94.8%), whereas a lower percentage of susceptibility was observed with amoxiclav (68.8%), and cotrimoxazole (65.4%). Levofloxacin exhibited a good in vitro activity against E. coli strains isolated from acute pyelonephritis with 93.1% of susceptible strains.     

Antibacterial activity of garlic powder against Escherichia coli O-157

The antibacterial activity of garlic powder against O-157 was tested by using garlic bulbs post-harvested 1 y. O-157 at 10(6-7) cfu/mL perished after incubation for 24 h with a 1% solution of garlic powder. The use of powder from fresh garlic was more effective for antibacterial activity than that from old garlic; the 1% solution of fresh garlic powder eradicating the O-157 in 6 h. The antibacterial activity was resistant to heat treatment of 100 degrees C for 20 min. The water-soluble components of garlic powder were fractionated into three fractions (Fr. 1-3) by Sephadex G-100 column chromatography, among which Fr. 3 showed antibacterial activity against O-157 but the other fractions were scarce in activity. The antibacterial activity was also shown against other types of pathogenic bacteria such as methicillin-resistant Staphylococcus aureus (MRSA), Salmonella enteritidis, and Candida albicans. Thus, the practical use of garlic powder is expected to prevent bacteria-caused food poisoning.     

Immunization with recombinant Lactobacillus casei strains producing K99, K88 fimbrial protein protects mice against enterotoxigenic Escherichia coli

To exploit a safe and effective vaccine for the prevention against K99 or K88 infections of enterotoxigenic Escherichia coli (ETEC), we have developed a mucosal delivery vehicle based on Lactobacillus casei CICC 6105 using poly-γ-glutamate synthetase A (PgsA) as an anchoring matrix. To evaluate the immunization effect of the recombinant strains (harboring plasmids pLA-K99-K88-LTB, pLA-K99, and pLA-K88), anti-ETEC K99 or K88 antibody responses, T-cell proliferation, and cytokines by intracellular staining (ICS) were investigated after specific pathogen-free (SPF) C57BL/6 mice orally inoculated with these recombinant strains. After oral vaccination into C57BL/6 mice, all recombinant strains were proved to be immunogenic and able to elicit high levels of mucosal immunoglobulin A (IgA) titers in bronchoalveolar lavage fluids, intestinal fluids and prominent systemic immunoglobulin G and IgG subclasses (IgG1, IgG2b, and IgG2a) responses in sera. Using the T-cell proliferation assay, the stimulation index (SI) of groups immunized with pLA-K99/L. casei and pLA-K88/L. casei reached to 2.73 and 2.64, respectively, versus 2.56 in a group immunized with pLA-K99-K88-LTB/L. casei. A detailed analysis of the cell-mediated immune responses by ICS showed the number of specific CD8(+) T cells expressing cytokines (IFN-γ, TNF-α, and IL-2) and granule-associated proteins (CD107a) was higher than that of specific CD4(+) T cells secreted by immune spleen cells upon restimulation in vitro with peptides. Next, the results showed that DCs activated in vitro with recombinant L. casei enhance specific T-cell proliferation and promote T cells to produce both Th1 and Th2 cytokines. More than 80% of the vaccinated mice were protected after challenge with a lethal dose of standard strains C83912 and C83902. These results demonstrate that recombinant L. casei can induce specific humoral and mucosal antibodies and cellular immune response against protective antigens upon oral administration.     

EcoR phylogenetic analysis and virulence genotyping of avian pathogenic Escherichia coli strains and Escherichia coli isolates from commercial chicken carcasses in southern Brazil

Escherichia coli strains designated as avian pathogenic E. coli (APEC) are responsible for avian colibacillosis, an acute and largely systemic disease that promotes significant economic losses in poultry industry worldwide because of mortality increase, medication costs, and condemnation of carcasses. APEC is a subgroup of extraintestinal pathogenic E. coli pathotype, which includes uropathogenic E. coli, neonatal meningitis E. coli, and septicemic E. coli. We isolated E. coli from commercial chicken carcasses in a Brazilian community and compared by polymerase chain reaction-defined phylogenetic group (A, B1, B2, or D) with APEC strains isolated from sick chickens from different poultry farms. A substantial number of strains assigned to phylogenetic E. coli reference collection group B2, which is known to harbor potent extraintestinal human and animal E. coli pathogens, were identified as APEC (26.0%) in both commercial chicken carcasses and retail poultry meat (retail poultry E. coli [RPEC]) (21.25%). The majority of RPEC were classified as group A (35%), whereas the majority of APEC were groups B1 (30.8) and A (27.6%). APEC and RPEC presented the genes pentaplex, iutA, hly, iron, ompT, and iss, but with different virulence profiles. The similarity between APEC and RPEC indicates RPEC as potentially pathogenic strains and supports a possible zoonotic risk for humans.     

Bacterial flora of Tasmanian SIDS infants with special reference to pathogenic strains of Escherichia coli.

The general bacterial flora of 38 Tasmanian SIDS infants was examined together with faecal flora of 134 comparison infants ranging in age from birth to 6 months. The microflora of all specimens received was investigated with special emphasis on the toxigenic Escherichia coli (TEC). Samples were examined for verocytotoxigenic E. coli, free faecal verocytotoxin (FVT), heat labile toxin (LT) and heat stable toxin (ST) producers with the use of a Vero cell assay and commercial kits. The findings of this study revealed a high isolation rate (39%) of TEC from SIDS infants as compared to 1.5% from the healthy comparison infants. Atypical E. coli strains were also identified during the study, including E. coli A-D. An analysis of the same specimens for rotaviral and adenoviral antigens indicated that 30% of the SIDS cases were positive as compared to 20% in the comparison group.     

Antimicrobial resistance and the ecology of Escherichia coli plasmids

Four hundred and seven clinical isolates of Escherichia coli were examined for the presence of plasmids. These isolates comprised 189 which were collected irrespective of antimicrobial resistance (VP) and 218 which were collected on the basis of high-level trimethoprim resistance (TPR). The VP isolates were divided into drug sensitive (VPS) and drug-resistant (VPR) subpopulations. Plasmids were detected in 88% of VP isolates (81% of VPS and 94% of VPR) and 98% of TPR isolates. The distribution of plasmids in both groups and subpopulations was very similar. However, there were small but statistically significant differences between the plasmid distributions. These showed that more isolates in the resistant groups harboured plasmids than in the sensitive subpopulation (VPS) and that the number of plasmids carried by resistant isolates was greater. Multiple drug resistance was significantly more common among TPR isolates than the VPR subpopulation and this was paralleled by increased numbers of plasmids. Fifty-eight per cent of VPR and 57% of TPR isolates transferred antimicrobial resistance and plasmids to E. coli K12. Of the R+ isolates, 60% carried small plasmids (MW less than 20Md) and 52% of these co-transferred with R-plasmids. These results are discussed.     

The occurrence of salmonellas, mycobacteria and pathogenic strains of Escherichia coli in pig slurry.

Ninety-eight samples of pig slurry from 54 farms were examined for the presence of salmonellas, porcine enteropathogenic strains of haemolytic Escherichia coli and mycobacteria. Salmonellas were isolated from 12 farms (22%) and enteropathogenic E. coli from 13 farms (24%). Pathogenic mycobacteria were not isolated. Salmonellas were isolated from 7 of 16 farms (44%) stocked with 'minimal disease' pigs compared with only 5 of 38 farms (13%) stocked with conventionally reared pigs. Conversely enteropathogenic coliforms were isolated from 3 of 16 farms (19%) stocked with 'minimal disease' pigs compared with 10 of 38 farms (26%) stocked with conventionally reared pigs.     

Antibacterial activity of 13 honeys against Escherichia coli and Pseudomonas aeruginosa

In this study the activity of 13 honeys, including three commercial antibacterial honeys, against Escherichia coli and Pseudomonas aeruginosa was determined. Antibacterial activity of the honeys was assayed using standard well diffusion methods. All honeys, and an artificial honey, were tested at four concentrations (10%, 5%, 2.5%, and 1% wt/vol) against E. coli and P. aeruginosa, and zones of inhibition were measured. All honeys tested had an inhibitory effect on the growth of E. coli and P. aeruginosa, with one honey still having activity against E. coli and three having activity against P. aeruginosa at 2.5%. No honey was active at 1% concentrations. E. coli was more susceptible to inhibition by the honeys used in this study than was P. aeruginosa. In this study we have demonstrated that several honeys, in addition to commercial antibacterial honeys, can inhibit E. coli and P. aeruginosa and may have potential as therapeutic honeys.     

In vitro study of the prebiotic xylooligosaccharide (XOS) on the growth of Bifidobacterium spp and Lactobacillus spp

Abstract

We recently demonstrated that XOS increased the counts of Bifidobacterium in vivo without increasing Lactobacillus in healthy adults. In the current study, we evaluated the effect of XOS on the growth of 35 Bifidobacterium and 29 Lactobacillus strains in in vitro conditions. Bacteria were identified by 16S rRNA sequence analysis. The growth stimulation was determined by agar dilution technique on plates containing two-fold serial dilutions of XOS (100–0.1?mg/ml). The growth of 86% of Bifidobacterium strains was stimulated at 1.56?mg/ml XOS and 100% at 6.25?mg/ml XOS. The growth of 38% of Lactobacillus strains was stimulated at 1.56?mg/ml XOS and 62% at 6.25?mg/ml XOS; 31% of Lactobacillus were not stimulated by XOS. Our results further suggest that XOS may be beneficial in stimulating intestinal Bifidobacterium without having much effect on Lactobacillus. The potential role for XOS in managing obesity should be investigated further.     

Antimicrobial resistance and the ecology of Escherichia coli plasmids.

Four hundred and seven clinical isolates of Escherichia coli were examined for the presence of plasmids. These isolates comprised 189 which were collected irrespective of antimicrobial resistance (VP) and 218 which were collected on the basis of high-level trimethoprim resistance (TPR). The VP isolates were divided into drug sensitive (VPS) and drug-resistant (VPR) subpopulations. Plasmids were detected in 88% of VP isolates (81% of VPS and 94% of VPR) and 98% of TPR isolates. The distribution of plasmids in both groups and subpopulations was very similar. However, there were small but statistically significant differences between the plasmid distributions. These showed that more isolates in the resistant groups harboured plasmids than in the sensitive subpopulation (VPS) and that the number of plasmids carried by resistant isolates was greater. Multiple drug resistance was significantly more common among TPR isolates than the VPR subpopulation and this was paralleled by increased numbers of plasmids. Fifty-eight per cent of VPR and 57% of TPR isolates transferred antimicrobial resistance and plasmids to E. coli K12. Of the R+ isolates, 60% carried small plasmids (MW less than 20Md) and 52% of these co-transferred with R-plasmids. These results are discussed.     

河南省76株E.Coli O_(157):H_7菌株药物敏感性研究

目的探讨我省E.ColiO157:H7菌株的药物敏感性特点。方法美国疾病预防控制中心和WHO非洲区合作编写的“痢疾和霍乱流行的实验室诊断方法”中介绍的琼脂平板扩散法。结果76株E.ColiO157:H7菌株对庆大霉素、头抱噻甲羧肟、多粘菌素B、氯霉素、氟哌酸、阿莫西林六种抗生素的耐药率均<5%。有毒力菌株与无毒力菌株对庆大霉素、强力霉素、复方新诺明、氯霉素、四环素的耐药率差别有统计学意义,无毒力菌株的耐药率高于有毒力菌株。结论实验结果显示临床治疗可参考使用头抱类、喹诺酮类和氯霉素类抗生素。     

In vitro activity of temocillin against extended-spectrum beta-lactamase-producing Escherichia coli and Klebsiella pneumoniae strains isolated from urinary tract infections in France

Objectives

Temocillin was introduced in 2015 in the French guidelines for the treatment of extended-spectrum beta-lactamase (ESBL)-producing Enterobacteriaceae urinary tract infections. Little susceptibility data is available. We investigated the in vitro activity of temocillin against ESBL-producing Enterobacteriaceae isolated from samples of cytobacteriological examinations of urine.