Indicator Of Bacterial Contamination Research Articles

A Label-Free and Ultrasensitive Prussian Blue-Based Dipstick Sensor for Bacterial and Biofilm Detection.

Water and food contamination has become the major contributor to infections and deaths. However, rapid and sensitive bacterial detection still remains an unmet demand that has attracted widespread attention. Often water and food samples are sent out for laboratory testing to detect the presence of contamination, which is time-consuming and laborious. Herein, we have developed a highly sensitive, tenable, affordable, and robust (STAR) paper-based colorimetric dipstick sensor based on the principle of Prussian blue (PB) synthesis as an indicator of bacterial contamination. In the presence of bacteria, it leads to the formation of PB, a dye that acts as a colorimetric indicator. The intensity of the PB is the direct measure of the degree of contamination. The fabrication of the STAR dipstick sensor involves a simple and cost-effective process. The STAR dipstick sensor is ultrasensitive and can detect up to 101 CFU/mL of bacteria within minutes of contact with the test sample. The STAR dipstick sensor is fabricated using biodegradable components, which is speculated to facilitate quick and environmentally friendly degradation after each use. The sensor has been validated for its properties and capabilities at different pH to detect both Gram-positive and Gram-negative bacterial strains in real-time samples. The stability and degradation were also monitored. Comprehensively, the proposed STAR dipstick sensor can serve as a point-of-care device to detect bacterial contamination in a swift and sensitive manner.

Calcium alginate gels-functionalized polyurethane foam decorated with silver nanoparticles as an antibacterial agent for point-of-use water disinfection

This paper reports the preparation of calcium alginate gels-functionalized PUF decorated with AgNPs (CA/PUF@Ag) by in situ reduction of Ag+ ions to form AgNPs with weakly reducing glycerol in CA/PUF composite. The water-adsorbing capacity, chemical structure, crystalline nature, elemental composition and morphologies of the composite were characterized. The Ag release behavior of CA/PUF@Ag was investigated. The inhibition zone test, time-dependent co-culture assay, test tube test, and antibacterial filtration experiment with Escherichia coli as an indicator of bacterial contamination were conducted to explore the antimicrobial efficacy. Results indicated that the CA/PUF@Ag prepared at 0.25 % w/v of SA could absorb more water with a higher swelling ratio of 8.0 g/g than that of PUF@Ag (6.0 g/g), which was subsequently squeezed by minimal pressure stimuli. The CA/PUF@Ag had a larger initial AgNPs loading amount (8.48 mg/g), lower Ag release concentration (44.35 μg/L) and lower Ag release rate (0.27 %) after 14 days tests than those of PUF@Ag (7.93 mg/g, 80.87 μg/L and 0.60 % respectively). The CA/PUF@Ag was highly reusable because bacterial cells in the squeezed water recovered from the composite were completely inactivated over five cycles of operation, and exhibited good antibacterial efficacy as an antibacterial filter in a flow test.

Detection of microbial contamination based on uracil-selective synthetic receptors

The here presented work is focused on the development of a method for detection of microbial contamination of food based on uracil-selective synthetic receptors. Because uracil may serve as an indicator of bacterial contamination, its selective and on-site detection may prevent spreading of foodborne diseases. The synthetic receptors were created by molecular imprinting. Molecularly imprinted polymers for selective uracil isolation were prepared by a non-covalent imprinting method using dopamine as a functional monomer. Detection of isolated uracil was performed by capillary electrophoresis with absorption detection (λ - 260 nm). The conditions of preparation of molecularly imprinted polymers, their binding properties, adsorption kinetics and selectivity were investigated in detail. Furthermore, the prepared polymer materials were used for selective isolation and detection of uracil from complex samples as tomato products by miniaturized electrophoretic system suggesting the potential of in situ analysis of real samples.

Development of dysbiosis in the organism of rats receiving a high-fat diet

Background. To determine the effect on the degree of dysbiosis in the organs and tissues of rats treated with high-fat diet (HFD) using fats with various fatty acid compositions.Methods. We used ordinary (high-linoleic) sunflower oil, high-oleic sunflower oil, butter, palm and coconut oils. Rats were fed with 15 % of each of the fats for 64 days. In the blood serum from v.cava and v. porta, in the liver, heart, brain, skeletal muscles and intestinal mucosa, urease activity (an indicator of bacterial insemination), lysozyme activity (a factor of non-specific immunity) were determined, and the degree of dysbiosis was calculated from the ratio of relative urease and lysozyme activities. Results. The activity of urease in the blood of v. porta increased in rats treated with HFD, and was significantly higher than in the blood of v.cava. In most of the studied tissues, urease activity increased after HFD, with the exception of rats receiving high-oleic sunflower oil (HOSO). In contrast, lysozyme activity was reduced in most tissues, with the exception of rats treated with HOSO. The degree of dysbiosis increased after HFD with the exception of rats treated with HOSO.Conclusion. HFD increases the translocation of bacteria from the intestine. The liver partially neutralizes the microflora coming from the intestines. In blood serum from v. cava and v. porta, urease activity (an indicator of bacterial contamination), lysozyme activity (nonspecific immunity factor) were determined in the liver, heart, brain, skeletal muscle and intestinal mucosa, and the degree of dysbiosis was calculated by the ratio of the relative activities of urease and lysozyme.Results. Blood urease activity v. porta was elevated in rats treated with HFD and was significantly higher than in blood v. cava. In most of the tissues studied, urease activity increased after HFD with the exception of rats treated with high oleic sunflower oil (HOSO), the development of dysbiosis in all tissues of the body. The exception is HOSO, which does not cause the development of dysbiosis and inflammation.

Efficacy of washing and disinfection in cattle markets in Ireland

BackgroundFew studies have reported on the effectiveness of the washing and disinfection methods used in cattle markets in Ireland. Purchasing cattle into recipient herds poses a high biosecurity risk due to the possibility of introducing disease. In Ireland, livestock markets are an important intermediary in the movement of cattle to new herds. Thus disease control strategies need to consider the disease risk associated with moving livestock through markets. Some cattle are also moved directly from markets for slaughter at abattoirs. Washing and disinfection at markets is utilised to reduce faecal contamination in markets, thereby reducing the risk of disease spread among animals and carcass contamination at slaughter. The primary objective of this study was to assess the efficacy of standard washing and disinfection techniques at markets in Ireland in reducing bacterial contamination on internal structures. Total viable counts (TVC) of colony forming units (CFU) were used as indicators of bacterial contamination, which could include pathogens of public and animal health concern. Four hundred and seventy nine samples were taken mainly from pen floors and the TVC enumerated for each sample.ResultsWashing and disinfection was effective at significantly reducing TVCs on floors and metal bars of market holding pens, but residual contamination remained. Washing market pens only (no disinfection), followed by a rest period between batches of cattle (6.5 days) was as effective at reducing TVCs as washing followed by disinfection and a shorter rest period (5.5 days).ConclusionsMarkets are a potential reservoir for microbial contamination with a resultant increased risk of disease spread by cattle moving through markets into new herds, and carcass contamination for cattle moving directly to slaughter. Therefore, market managers need clear advice and guidance on the development of hygiene programmes that are suitable for use in livestock markets.

БАКТЕРІАЛЬНЕ ЗАБРУДНЕННЯ МОЛОКА ЗА РІЗНИХ ТЕМПЕРАТУР І ТЕРМІНІВ ЗБЕРІГАННЯ

Research was conducted in the laboratory LILCO, Surgères, France. For the first experiment, 24 samples of cooled bulk tank goat milk were selected be transported within 2 – 3 hours at different temperatures. Then all samples were stored day at 4 °C. The indicators of bacterial contamination, fat, protein, freezing point, somatic cell count, urea were similar for different temperatures of transporting milk samples. Noted the big somatic cell count (> 2000 thousand / ml) at low bacterial contamination (19,6 × 103 CFU/mL) of goat milk. Samples of milk can be delivered to the laboratory for 2–3 hours at a temperature of 2, 10 or 20 °C if the milk immediately after milking cooled and stored in a tank at 4 °C.10 samples of cow's milk (non–cooled – 3 hours after milking, cooled – after a day) were also examined. Bacterial contamination of milk which has been cooled and being stored one day at 4 °C was in 4.6 times less (P < 0.01) than non–cooled milk, analyzed in 3 hours after milking. This proves that bacterial contamination of milk in Ukraine accordance with European requirements (up to 100 thousand. CFU/ml) is possible only when rapid cooling of milk after milking to 4 оС and storing it in the cooling tank.

Pollution characteristics of alluvial groundwater from springs and bore wells in semi-urban informal settlements of Douala, Cameroon, Western Africa

Alluvial groundwater from springs and bore wells, used as the major source of water for drinking and other domestic purposes in the semi-urban informal settlements of Douala, Cameroon, has been studied. Six representative springs, four bore wells and two hand dug wells, situated in the Phanerozoic basin were selected, from which a total of 72 water samples were analyzed for chemical characteristics and indicators of bacterial contamination. The results showed anthropogenic pollution, evident from high concentrations of organic (up to 94.3 mg NO3/l nitrate) fecal coliform and fecal streptococcus detected in the springs and bore wells (with values of 2,311 and 1,500 cfu/100 ml, respectively). The pH ranged from 3.4–6.5, which is lower than the guidelines for drinking water. Groundwater samples from background upstream inland natural areas W1 and W2 had low electrical conductivity (54.2 and 74.8 μs/cm, respectively) and major ions, which increased downstream in the valleys, peaking in the more densely settled areas. An acceptable concentration of solutes was observed for the bore wells except for a single sample from B4. The bore-well sample B4 registered the highest microbial content (2,130 cfu/100 ml) and nitrate level(26 mg/l), which could be due to the bottom of this well lying just at or close to the zone of mixing between sewage and groundwater. The absence of a direct correlation between nitrate and fecal matter suggests multiple sources of contamination. The shallow alluvial aquifer consists of unconsolidated deposits of gravel, sand, silt and clay. The springs, therefore, receive direct recharge from the ground surface with limited contaminant attenuation, which leads to water quality deterioration, especially during the rainy season. This shows the urgent need to put basic service infrastructures in place. The local population should be sensitized to the importance of chlorinating and boiling drinking water to prevent health hazards.

Tandem use of immunofluorescent and DNA staining assays to validate nested PCR detection of mycoplasma

Mycoplasma contamination in cell culture is a serious setback to cell culturists across the world with a very high rate of reported occurrence particularly because of difficult early detection. Out of a variety of detection methods known, the double-step nested polymerase chain reaction (PCR)-based detection of mycoplasma in cell culture has been critically viewed upon because of chances of producing reliable results. A nested PCR technique, described to detect a large range of cell-culture-contaminating mycoplasma species, with greater sensitivity to detect as low a contamination as a few organisms, was compared with the results from two cytological techniques employed in tandem. These are DNA staining using Hoechst, the gold standard, and an immunofluorescent assay using a highly specific monoclonal antibody. The study undertaken on randomly collected cell cultures revealed a false-negative and several false-positive results in comparison to the cytological methods employed. The observations were particularly more unambiguous with the immunofluorescent assay employed in the study while simultaneously employed Hoechst staining serving as an indicator of bacterial contamination. There is a general apprehension that genus-specific PCR approaches could be associated with inaccurate outcome and only species-specific PCRs may be satisfactory in routine screening for mycoplasma contamination in cell cultures. At this juncture, it may be suggested that caution must be exercised while adopting the two-step nested PCR-based detection approaches, and the simultaneous employment of cytological methods used in this investigation could prove to be practicable in the proper interpretation of results.

Calibration of a Continuous Simulation Fecal Coliform Model Based on Historical Data Analysis

Since 1984, the major water reclamation plants discharging to the Chicago Waterway System (CWS) have not disinfected their effluents. The possible addition of disinfection at these plants is the subject of an ongoing use attainability analysis (UAA). For the UAA, Escherichia coli (E. coli) is used as the indicator of bacterial contamination. However, only a few years of E. coli data are available for the CWS and the treatment plants discharging to the CWS. Thus, it was decided to develop a model based on fecal coliforms for which more data are available and to develop a relation between fecal coliform and E. coli counts for the CWS. A 1:1 relation was found between fecal coliform and E. coli counts in the CWS by Limnotech (2004, written communication) as part of the UAA. In order to evaluate the effects of possible disinfection measures on fecal coliform and related E. coli counts in the CWS, a simple first-order fecal coliform decay model was added to the continuous-simulation flow-water quality model DU...

Study the incidence of bacterial and fungal contaminants in imported chicken femurs

Incidence of bacterial and fungal contaminants in imported chicken femurs wasdetermined and compared with standard microbiological limits. A total of (12) Kgof imported chicken femurs were randomly collected at two batches from (6) areasin Baghdad city. Total aerobic bacterial count, coli form count and Staphylococcusaureus count were used as an indicator for bacterial contamination, in addition toyeast and mould count as an indicator for fungal contamination.Data revealed that skins of imported chicken femurs produced high level ofcontamination, in which most of the bacterial counts were near the maximumstandard limit as well as contamination with fungi, whereas the level ofcontamination in the meat of these femurs were low in comparison with standardlimits.

Dynamics and interaction of organic carbon, turbidity and bacteria in a karst aquifer system

The dynamics of organic carbon (OC), turbidity, faecal indicator bacteria and physicochemical parameters was studied in a karst system near Yverdon, Switzerland. Online measurements and sampling were done at a swallow hole draining an agricultural surface (the input), and two groups of springs (the outputs) that often show bacterial contamination. A fluorescent tracer that was injected into the swallow hole during low-flow conditions first arrived at the springs 10–12 days after injection; the total recovery rate was 29%. Previous tracer tests during high-flow conditions gave shorter travel times. After a major rainfall event, a primary turbidity peak was observed at the springs. It coincides with the rising limb of the hydrograph, indicating remobilisation of autochthonous particles from the aquifer. A secondary turbidity peak occurs several days later, suggesting the arrival of allochthonous particles from the swallow hole. Wider peaks of OC and bacteria were observed simultaneously. Applying methods from molecular microbiology (PCR-DGGE) allowed characterisation of the bacterial communities at the swallow hole and the springs. The results demonstrate that the swallow hole is an important source of groundwater contamination, while its contribution to aquifer recharge is insignificant. OC appears to be a better indicator for bacterial contamination than turbidity.

Determination of L- and D-amino acids in foodstuffs by coupling of high-performance liquid chromatography with enzyme reactors.

A technique is described for the enantiomeric determination of L- and D-amino acids. It works on the principle that the separation efficiency of high-performance liquid chromatography is coupled with the specificity of enzymes and the sensitivity of electrochemical detection. After separation on a lithium cation-exchange column the amino acids are converted into keto acids and hydrogen peroxide under catalyzation of L- or D-amino acid oxidase. Hydrogen peroxide is detected amperometrically. The method has been tested by the analysis of beer, port, sherry, wine and fruit juice. A main emphasis was put onto the determination of D-alanine which can serve as an indicator for bacterial contamination. It is shown that a coupling of HPLC with enzyme reactors is a suitable technique for the rapid detection of this marker.

Assessment of the suitability of food colouring materials as indicators of bacterial contamination of enteral feeds

The suitability of using food colouring materials in enteral feeds as indicators of bacterial contamination was examined. Experiments using Triosorbon, Clinifeed ISO or Vivonex Standard plus amaranth, carmoisine, ponceau 4R, sunset yellow FCF, tartrazine or erythrosine demonstrated that although the change in appearance of coloured feed could be linked with the presence of high numbers of bacteria in the feed, the converse was not always true.

Evaluation of Rapid Tests for Monitoring Alterations in Meat Quality During Storage

Seven rapid analytical tests (color value, thiobarbituric acid number, extract release volume, pH, “tyrosine” value, pHt, and redox potential) were evaluated as possible indicators of bacterial contamination in intact meat. Color value is a reflectance value related to hedonic acceptance of the meat. Comparisons of results from these seven tests with determination of bacterial load (plate count) and with time of storage were analyzed statistically to determine the relative contributions of bacterial action and of intrinsic reactions. The color values and “tyrosine” values were the most effect monitors of bacterial contamination. Although the thiobarbituric acid test effectively monitored changes in meat quality, it was not specific for those produced by bacteria. The remaining tests were ineffective under conditions employed.

Comparative Evaluation on the Determination of Coliforms and Enterococci in Frozen Seafood Products

Fifty samples of commercial frozen raw and prepared seafood products were tested for total bacterial counts, coliforms, enterococci and Escherichia coli. For the determination of coliforms desoxycholate agar plate method and lactose broth-BGLB Most Probable Number (MPN) method were used, while Azide Esculin (AE) agar plate method and ACAC MPN method according to Horie, et al. were used for enterococcus counts.The values obtained with the plate method and the MPN method were fairly related both in the coliform and the enterococcus test. Relationships between total bacterial counts, coliform counts obtained by desoxycholate agar and enterococcus counts by AE agar were investigated. Enterococcus counts were more closely related to total counts than to coliform counts, while coliform counts were not so related to both the other two counts. On the other hand, E. coli was not detected except in only 3 samples.Bacterial suspensions of coliforms and enterococci in 10% skim milk were frozen and storaged at -21°C for long period. Viable cell counts of coliforms decreased significantly during freezing and freezing strorage, furthermore, majorities of the survived population had lost the ability of colony-formation in desoxycholate agar. Conversely, enterococcus counts determined by AE agar remained relatively constant during the same storage period. In general, lower values of coliform counts of frozen food samples, as compared with enterococcus counts, may be considered to be caused by not only rapid death but also loss of the growth ability of coliform organisms in desoxycholate agar during freezing storage.The result suggests that entrococci can be used advantageously in preferrence to coliforms as indicator of bacterial contamination before freezing of frozen seafood products.