Microbial adhesion capacity. Influence of shear and temperature stress

Environmental parameters dictate the conditions for both biofilm formation and deconstruction. The aim of this study is to analyse the impact of hydrodynamic and thermodynamic effects on bacterial detachment. Escherichia coli grown on two stainless steel metal surfaces with different roughness (brushed with roughness of 0.05 μm and electropolished with roughness of 0.29 μm) are exposed to laminar and turbulent (shower) flows of phosphate buffered saline media at temperatures of 8, 20 and 37 °C. Results show that the turbulent flow removes significantly more bacterial cells than laminar flow (p <0.05) on both materials. This indicates that the shear force determines the rate of detached bacteria. It is also observed that detachment of cells is more efficient on brushed than on electropolished contact surfaces because on the latter surface, fewer cells were attached before exposure. Moreover, we demonstrate that the temperature of the washing agent has an impact on bacterial detachment. At the same flow conditions, the exposure to higher temperature results in greater detachment rate.     

Efficacy of sodium dodecyl sulphate and natural extracts against E. coli biofilm

The aim of this study was to determine and compare the efficacy of a standard cleaning agent, sodium dodecyl sulphate, and natural extracts from pomegranate peel grape skin and bay laurel leaf against E. coli biofilm. The biofilm was exposed for 10 minutes to three different concentrations of each tested compound. The results show that bay laurel leaf extract is the most efficient with 43% biofilm biomass reduction, followed by pomegranate peel extract (35%); sodium dodecyl sulphate and grape skin extract each have 30% efficacy. Our study demonstrated that natural extracts from selected plants have the same or even better efficacy against E. coli biofilm removal from surfaces than the tested classical cleaning agent do. All this indicates that natural plant extracts, which are acceptable from the health and environment points of view, can be potential substitutes for classical cleaning agents.     

Study of the impact of cranberry extract on the virulence factors and biofilm formation by Enterococcus faecalis strains isolated from urinary tract infections

Drinking of cranberry fruit juice and application of commercial preparations containing the cranberry extracts are recommended in the prevention and treatment of urinary tract infections (UTIs), especially in women with recurrent UTIs. Many studies focus on the activity of cranberries against uropathogenic Escherichia coli (E. coli) strains. However, the knowledge of the cranberry effect on Gram-positive Enterococcus faecalis (E. faecalis) is limited. Therefore, the aim of our study was to establish the activity of commercial concentrated cranberry extract on the growth, virulence factors and biofilm formation of E. faecalis strains isolated from urine. Minimal inhibitory concentrations (MICs) of cranberry extract were determined by the broth microdilution method. Disc diffusion method was used to determine antimicrobial susceptibility. The impact of cranberry extract on bacterial survival, hydrophobicity, synthesis of lipase, lecithinase, DNase, hemolysin, gelatinase and biofilm mass was determined. Results show that cranberry extract inhibits the growth, enzymatic activities of bacteria and limits biofilm formation. The antibacterial activities of the studied cranberry extract confirm that it could be successfully used in prevention of UTIs caused by E. faecalis.     

<Emphasis Type="Italic">Enterococcus hirae</Emphasis> biofilm formation on hospital material surfaces and effect of new biocides

Background

Nowadays, the bacterial contamination in the hospital environment is of particular concern because the hospital-acquired infections (HAIs), also known as nosocomial infections, are responsible for significant morbidity and mortality. This work evaluated the capability of Enterococcus hirae to form biofilm on different surfaces and the action of two biocides on the produced biofilms.

Methods

The biofilm formation of E. hirae ATCC 10541 was studied on polystyrene and stainless steel surfaces through the biomass quantification and the cell viability at 20 and 37 °C. The effect of LH IDROXI FAST and LH ENZYCLEAN SPRAY biocides on biomasses was expressed as percentage of biofilm reduction. E. hirae at 20 and 37 °C produced more biofilm on the stainless steel in respect to the polystyrene surface. The amount of viable cells was greater at 20 °C than with 37 °C on the two analyzed surfaces. Biocides revealed a good anti-biofilm activity with the most effect for LH ENZYCLEAN SPRAY on polystyrene and stainless steel at 37 °C with a maximum biofilm reduction of 85.72 and 86.37%, respectively.

Results

E. hirae is a moderate biofilm producer depending on surface material and temperature, and the analyzed biocides express a remarkable antibiofilm action.

Conclusion

The capability of E. hirae to form biofilm can be associated with its increasing incidence in hospital-acquired infections, and the adoption of suitable disinfectants is strongly recommended.

     

Factors associated with post-treatment E. coli contamination in households practising water treatment: a study of rural Cambodia

The purpose of this study was to assess factors associated with Escherichia coli (E. coli) contamination in rural households in Cambodia that have adopted household water treatment. The following factors were significantly associated (α < 0.05) with apparent E. coli contamination: cleaning the drinking vessel with untreated water, not drying the cup (with a cloth), accessing treated water by the use of a scoop (ref: using a tap), having more than one untreated water storage container, having an untreated water storage container that appeared dirty on the outside, and cows living within 10 m of the household. This study provides further evidence confirming previous studies reporting an association between inadequate cleanliness of water storage containers and household drinking water contamination, and identifies practical recommendations statistically associated with reduced post-treatment E. coli contamination in the household setting in rural Cambodia.     

Contamination of public whirlpool spas: factors associated with the presence of Legionella spp., Pseudomonas aeruginosa and Escherichia coli

This work explores the factors associated with contamination of public spas by Legionella spp., Pseudomonas aeruginosa and Escherichia coli. Physicochemical and microbiological parameters were measured in water samples from 95 spas inQuébec, Canada. Spa maintenance was documented by a questionnaire. Legionella spp. were detected in 23% of spas, P. aeruginosa in 41% and E. coli in 2%. Bacteria were found in concerning concentrations (Legionella spp. ≥ 500 CFU/l, P. aeruginosa ≥ 51 CFU/100 ml or E. coli ≥ 1 CFU/100 ml) in 26% ofspas. Observed physicochemical parameters frequently differed from recommended guidelines. The following factors decreased the prevalence of concerning microbial contamination: a free chlorine concentration ≥ 2 mg/l or total bromine ≥ 3 mg/l (p = 0.001), an oxidation–reduction potential (ORP) > 650 mV (p = 0.001), emptying and cleaning the spa at least monthly (p = 0.019) and a turbidity ≤ 1 NTU (p = 0.013). Proper regulations and training of spa operators are critical for better maintenance of these increasingly popular facilities.     

Detection and source tracking of Escherichia coli,harboring intimin and Shiga toxin genes,isolated from the Little Bighorn River,Montana

The Little Bighorn River flows through the Crow Indian Reservation in Montana. In 2008, Escherichia coli concentrations as high as 7179 MPN/100 ml were detected in the river at the Crow Agency Water Treatment Plant intake site. During 2008, 2009, and 2012, 10 different serotypes of E. coli, including O157:H7, harboring both intimin and Shiga toxin genes were isolated from a popular swim site of the Little Bighorn River in Crow Agency. As part of a microbial source tracking study, E. coli strains were isolated from river samples as well as from manure collected from a large cattle feeding operation in the upper Little Bighorn River watershed; 23% of 167 isolates of E. coli obtained from the manure tested positive for the intimin gene. Among these manure isolates, 19 were identified as O156:H8, matching the serotype of an isolate collected from a river sampling site close to the cattle feeding area.     

Natural and synthetic plant compounds as anti-biofilm agents against Escherichia coli O157:H7 biofilm

Escherichia coli is a common gram-negative bacterium found in the gut and intestinal tract of warm-blooded animals including humans. An evolved seropathotype E. coli O157:H7 (STEC) came into existence in 1982, since then it has been evolved as a stronger and more robust drug-resistant pathotype of E. coli. This drug resistance is due to horizontal gene transfer, natural gene evolution for survival, and most of the cases due to the ability of STEC to switch to the biofilm growth mode from planktonic lifestyle. During the growth in biofilm mode, Escherichia coli O157:H7 opts more robust ability to grow in adverse environments i.e., in presence of antibiotics and other antimicrobial chemicals. Due to the biofilm matrix, the microbial community acquires drug resistance. This makes the treatment of diseases caused by E. coli O157:H7 a complex challenge. To address the illnesses caused by this biofilm-forming pathogen, there are several possible strategies such as antibiotic therapies, synthetic antimicrobial chemicals, adjunct therapy of synergistic effect of multiple drugs, and more importantly plant originated compounds as a new anti-biofilm candidate. The present review summarizes various phytochemicals and their derivatives reported in the last decade mostly to eliminate the biofilm of STEC. The review will progressively reveal the antibiofilm mechanism of the phytochemicals against STEC and to be a potential candidate for the development of the future antibacterial drugs to STEC induced infections.     

中试循环输水管道系统中建立嗜肺军团菌生物膜

目的模拟医院供水系统,建立代表上海地区自来水特征的新型中试循环输水管道系统,研究军团菌定植供水系统的能力;评估水流的停滞和层流状态对嗜肺军团菌生物膜的影响。方法采用培养技术和共聚焦激光扫描显微镜动态监测嗜肺军团菌进入生物膜达到稳态的过程。结果军团菌黏附和进入生物膜后开始增殖,第5周达到稳态,95.8%的嗜肺军团菌分布在生物膜内;管壁军团菌定植数量在层流状态明显高于停滞状态,平均值为7.8×104CFU/cm2和1.5×103CFU/cm2。结论中试循环输水管道中成功建立嗜肺军团菌生物膜;生物膜在军团菌增殖中起重要作用;水流停滞不会促进军团菌增殖。     

Multiple water source use in rural Vanuatu: are households choosing the safest option for drinking?

Households in low- and middle-income countries commonly make use of multiple water sources. However, it remains unclear to what extent their drinking water choices are optimal from a health perspective. This matched cohort study across 10 islands in Vanuatu examined communities with both a groundwater and rainwater source to determine whether their preferred drinking option was the safest in microbial terms. In communities that preferred to drink rainwater, 56.5% of rainwater sources had ‘high-risk’ or ‘very high risk’ Escherichia coli contamination (> 10 MPN/100 mL) compared with 26.1% of groundwater sources (p = 0.092). Moreover, a preference for drinking rainwater was significantly associated with rainwater sources having ‘high-risk’ or ‘very high risk’ levels of E. coli contamination (p = 0.045). Results show that communities do not necessarily choose the safest water source for drinking. Findings also highlight the need to bolster local capacity to manage water quality risks and for Sustainable Development Goal monitoring to distinguish between protected and unprotected rainwater tanks.     

Evaluation of the Colilert® Test for Detection of Verotoxin-Producing Escherichia coli in Water

ABSTRACT

The objective of this study was to estimate the sensitivity of the Colilert® test for detection of different isolates of Escherichia coli (E. coli) O157:H7 and other verotoxin-producing E. coli (VTEC) serotypes from water for potential on-farm food safety application. E. coli isolates evaluated were of human, bovine, porcine, or food origin. The sensitivity of the Colilert® test was 92% overall for the verotoxin-producing serotypes of E. coli. However, none of the E. coli O157:H7 isolates were identified as E. coli. No false-positive results for E. coli were detected. The Colilert® test could be used to screen water supplies for E. coli on the farm, however, an important pathogenic E. coli sero-type is not detected by the Colilert® test.     

Sanitizing alternatives for Escherichia coli and Salmonella typhimurium on bell peppers at household kitchens

Fresh fruits and vegetables are known to play an important role as carriers of disease-causing organisms in household kitchens. The aims of this study were to assess and compare the effectiveness of sodium hypochlorite, organic acid-based and silver-based products to reduce Escherichia coli and Salmonella typhimurium inoculated on individual bell pepper pieces. Inoculated bell pepper pieces (n = 5) were submerged in sodium hypochlorite, organic acid-based and silver-based product solutions, at the concentration specified in the product label for sanitization of fruits and vegetables. Sodium hypochlorite reduced E. coli and Salmonella typhimurium by 3.13 Log₁₀/25cm² and 2.73 Log₁₀/25cm², respectively. Organic-based and silver-based products reduced E. coli and S. typhimurium by 2.23 Log₁₀/25cm², 1.74 Log₁₀/25cm² and 2.10 Log₁₀/25cm², 1.92 Log₁₀/25cm², respectively. The results showed that greater attention is needed in selecting sanitizing products to kill or remove human pathogens from fresh produce to minimize risk of foodborne infections.     

The simultaneous mass and energy evaporation (SM2E) model

In this article, the Simultaneous Mass and Energy Evaporation (SM2E) model is presented. The SM2E model is based on theoretical models for mass and energy transfer. The theoretical models systematically under or over predicted at various flow conditions: laminar, transition, and turbulent. These models were harmonized with experimental measurements to eliminate systematic under or over predictions; a total of 113 measured evaporation rates were used. The SM2E model can be used to estimate evaporation rates for pure liquids as well as liquid mixtures at laminar, transition, and turbulent flow conditions. However, due to limited availability of evaporation data, the model has so far only been tested against data for pure liquids and binary mixtures. The model can take evaporative cooling into account and when the temperature of the evaporating liquid or liquid mixture is known (e.g., isothermal evaporation), the SM2E model reduces to a mass transfer-only model.     

Effect of Tidal Cycle on Escherichia coli Variability in a Tropical Estuary

A faecal indicator bacteria, Escherichia coli (E. coli), is widely used in monitoring health of estuaries, where tidal amplitude plays a critical role in its variability. Mahanadi estuary, formed at the mouth of a major tropical river Mahanadi, has large socio-economic importance. This anthropogenically stressed estuary remains understudied with respect to E. coli. Hence, this study addressed E. coli variability in Mahanadi estuary with novel sampling strategy that can be implemented at other tropical estuaries. The sampling strategy includes simultaneous measurements, at lesser-saline upper-estuary and higher-saline lower-estuary, over a tidal cycle. Although no significant variability of E. coli was observed between upper and lower-estuary, overall average count was higher during low tide and lower during high tide attributed to salinity fluctuations. Intermittent surpass of E. coli counts above recommended limits in Mahanadi estuary, indicated potential health risk, thus demands for frequent water quality monitoring and management strategies.

     

A Watershed Analysis of Seasonal Concentration- and Loading-based Results for <Emphasis Type="Italic">Escherichia coli</Emphasis> in Inland Waters

Fecal indicator bacteria, such as Escherichia coli, are frequently monitored in recreational waterbodies as indicators of potential fecal pathogen presence and exposure. The present watershed analysis investigated the influence of season on E. coli concentration (MPN/100 mL) and loading (MPN/day) measurements for inland waters at baseflow conditions. The master dataset collected during 2007–2012 for three watersheds included 896 E. coli (Colilert) samples with simultaneous flow taken for a subset (39?%) of samples. The outcomes for grouped watersheds were reflected in most cases for individual watersheds. Concentration- and loading-based results were highest in summer and spring, and lowest in the winter and fall, respectively. The comparison of these two measurement techniques (concentration and loading) highlight the impact of flow data during baseflow conditions for inland waters and reveal that caution should be used when inferring one method’s results from another.     

Quantification of genes encoding resistance to aminoglycosides, β-lactams and tetracyclines in wastewater environments by real-time PCR

In this study real-time PCR assays, based on the LUX?-technique, were developed for quantification of genes mediating resistance to aminoglycosides [aac(6´′)-Ie + aph(2´′´′)], β-lactams (mecA), and tetracyclines (tetA and tetB), for use in wastewater environments. The developed assays were applied on DNA extracted from three wastewater-associated environments: soil from an overland flow area treating landfill leachates, biofilm from a municipal wastewater treatment plant, and sludge from a hospital wastewater pipeline. The highest concentration of all genes was observed in the hospital pipeline and the lowest in the overland flow system. TetA and aac(6´′)-Ie + aph(2´′´′) could be detected in all environments. The tetB gene was detected in the overland flow area and the hospital wastewater pipeline and mecA was detected in the wastewater treatment plant and the hospital pipeline. The developed LUX? real-time PCR assays were shown to be fast and reproducible tools for detection and quantification of the four genes encoding antibiotic resistance in wastewater.     

CRISPR1上游侧翼序列用于大肠埃希菌和志贺菌鉴定的效果评价

目的 探讨基于成簇规律间隔的短回文重复序列（CRISPR）1上游侧翼序列对大肠埃希菌和志贺菌鉴定和评价效果。方法 通过BLAST重复序列识别并获得全基因组测序大肠埃希菌和志贺菌的CRISPRs和CRISPR相关基因（CRISPR-associated,cas）,并分析其种系;选取CRISPRs上、下游各500 bp侧翼序列,使用Clustal X进行序列比对;采用PCR方法扩增CRISPR1上游侧翼序列,以确定其对大肠埃希菌和志贺菌鉴定和评价效果。结果 73.4%（149/203）的大肠埃希菌存在I-E型CRISPR/Cas系统,包含了A、B1、D种系;8.4%（17/203）的大肠埃希菌存在I-F型CRISPR/Cas、17.2%（35/203）的大肠埃希菌不存在CRISPR/Cas,这2种大肠埃希菌均属于B2种系;9株志贺菌均存在I-E型CRISPR/Cas。在大肠埃希菌（B2种系外）、志贺菌CRISPR1上游和大肠埃希菌（B2种系）各存在61 bp侧翼序列,序列一致性为99%,且有种属特异性,PCR扩增此区域鉴定大肠埃希菌和志贺菌的灵敏度和特异度均>91%。结论 基于CRISPR1上游序列可用来鉴定大肠埃希菌和志贺菌,且具有很好的效果。     

上海市2012－2013年4种致泻性大肠埃希菌监测

目的 基于临床医院开展4种致泻性大肠埃希菌(DEC)人群监测,探讨公共卫生实验室对临床实验室需求的直接技术指导的实践模式。方法 设立哨点医院,以标准化方法筛选和鉴定DEC菌型;构建DEC流行特征基线;对疑似暴发病例开展基于实验室和流行病学调查。结果 2012－2013年选择上海地区4家哨点医院检测7 204份腹泻标本确认的712例DEC感染病例,阳性率为9.9%。其中肠致病性大肠埃希菌(EPEC)感染351例;肠产毒性大肠埃希菌(ETEC)感染292例;肠侵袭性大肠埃希菌(EIEC)感染32例;产志贺样毒素大肠埃希菌(STEC/EHEC)感染6例;DEC混合感染31例。EPEC感染以1～5岁儿童最多见,菌型均为aEPEC;ETEC流行峰值在8月,阳性率>20%,感染病例2012年聚集于1～28日龄和2013年的20～60岁人群(P< 0.05),菌型以耐热肠毒素(ST)型最多(59.6%),其次为不耐热肠毒素(LT)型(27.8%)和ST/LT型(12.6%);2013年儿童感染EIEC病例明显增加(P< 0.01);未监测到EHEC O157 : H7,但确认2例EHEC O26 : H11(eae-hlyA-stx1a)儿童病例;调查确认2012年上海地区15例新生儿ETEC聚集性感染病例与四川省自贡市新生儿病例属于同一克隆(STh-CS21-CFA/I-ClyA-EatA-ST2332- SHNL0005)。结论 上海地区DEC型谱特征已发生改变,ETEC对新生儿院内感染和食源性感染性腹泻构成潜在暴发风险,需加强实验室主动监测。     

Water quality at points-of-use in the Galapagos Islands

Piped drinking water is often considered a gold standard for protecting public health but research is needed to explicitly evaluate the effect of centralized treatment systems on water quality in developing world settings. This study examined the effect of a new drinking water treatment plant (DWTP) on microbial drinking water quality at the point-of-use on San Cristobal Island, Galapagos using fecal indicator bacteria total coliforms and Escherichia coli. Samples were collected during six collection periods before and after operation of the DWTP began from the freshwater sources (n = 4), the finished water (n = 6), and 50 sites throughout the distribution system (n = 287). This study found that there was a significant decrease in contamination by total coliforms (two orders of magnitude) and E. coli (one order of magnitude) after DWTP operation began (p < 0.001). However, during at least one post-construction collection cycle, total coliforms and E. coli were still found at 66% and 28% of points-of-use (n = 50), respectively. During the final collection period, conventional methods were augmented with human-specific Bacteroides assays – validated herein – with the goal of elucidating possible microbial contamination sources.Results show that E. coli contamination was not predictive of contamination by human wastes and suggests that observed indicator bacteria contamination may have environmental origins. Together these findings highlight the necessity of a holistic approach to drinking water infrastructure improvements in order to deliver high quality water through to the point-of-use.     

Antimicrobial activity of selected synbiotics targeted for the elderly against pathogenic Escherichia coli strains

The aim of the present study was to evaluate the antimicrobial activity of two synbiotic combinations, Lactobacillus fermentum with short-chain fructooligosaccharides (FOS-LF) and Bifidobacterium longum with isomaltooligosaccharides (IMO-BL), against enterohaemorrhagic Escherichia coli O157:H7 and enteropathogenic E. coli O86. Antimicrobial activity was determined (1) by co-culturing the synbiotics and pathogens in batch cultures, and (2) with the three-stage continuous culture system (gut model), inoculated with faecal slurry from an elderly donor. In the co-culture experiments, IMO-BL was significantly inhibitory to both E. coli strains, while FOS-LF was slightly inhibitory or not inhibitory. Factors other than acid production appeared to play a role in the inhibition. In the gut models, both synbiotics effectively inhibited E. coli O157 in the first vessel, but not in vessels 2 and 3. E. coli O86 was not significantly inhibited.