Search PubMed⌕ Search

SEARCH · Search PubMed

Results for “Coliphages”

Search indexed PubMed citations on genomics, clinical trials, systematic reviews and public health. Explore titles, authors and supplied subject terms, then open the PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 1,441 records · Page 80Linked to original sources
PubMed2005

Evaluation of microbiological quality of coastal waters in Greece.

To evaluate the microbiological water quality of bathing sites along the Achaia coastline (south western Greece), a survey was conducted to determine the concentration of faecal bacterial and phage indicators as well as the presence of human viruses. Seawater samples (234) were collected from nine bathing sites on the Achaia coastline and were analysed for the presence of: total coliforms, faecal coliforms, faecal streptococci, Escherichia coli, somatic coliphages, F-RNA bacteriophages, bacteriophages infecting Bacteroides fragilis, enteroviruses, adenoviruses and hepatitis A viruses. Most of the bacteriological analysis results were in accordance with the European Union standards. In all sites, bacteriophages were detected occasionally. Enteroviruses and adenoviruses were detected in 24 samples (10.26%) and 37 samples (15.81%) respectively. No samples were positive for the presence of hepatitis A virus. The overall data indicates that bathing sites are impacted by human faecal material. Both bacterial indicators and phages have low predictive capability for the presence of human viruses in coastal waters. None of the environmental parameters analysed was strongly related to the presence of the indicator organisms and viruses. Appropriate and effective administrative measures that should be taken into account may be considered in order to improve water quality and reduce public health risk.

Bathing Beaches↗
PubMed2006

Bacteroides spp. as reliable marker of sewage contamination in Hawaii's environmental waters using molecular techniques.

Standard PCR (SPCR) and quantitative PCR (QPCR) assays using primers for general and for human-specific Bacteroides 16S rRNA markers were selected as the molecular tests to assess sewage contamination in recreational waters of Hawaii and these same water samples were assayed for culturable concentrations of selected faecal microbial indicators. The results of this study showed that the general primer for Bacteroides was not useful because ambient and polluted water samples were positive for this marker. However, use of human-specific primers reliably detected sewage contamination. The human-specific Bacteroides detection data supported previously reported conclusions that concentrations of alternative faecal indicators (C. perfringens, FRNA coliphages) but not traditional faecal indicators (faecal coliform, E. coli, enterococci) are reliable indicators of faecal contamination in Hawaii's environmental waters. The QPCR assay for the human-specific Bacteroides 16S rRNA marker was faster, more sensitive and more reliable than comparable SPCR assay because OPCR assay provided additional information such as melting temperatures, which confirmed that the right amplicons were being measured and Ct values, which indicated the relative level of faecal contamination.

Bacteroides↗
PubMed2006

Epidemiological surveillance of human enteric viruses by monitoring of different environmental matrices.

In the aim of studying possible relations between viruses detected in clinical specimens and the ones found in different environmental matrices, in the period May 2004 to April 2005, the collection of faecal samples from gastroenteritis cases and the monthly monitoring of raw and treated wastewater, river water, seawater and mussels were carried out. The viruses considered for environmental monitoring were adenovirus, rotavirus, enterovirus, norovirus, hepatitis A virus (HAV) and Torque teno virus (TTV): they were searched for with PCR and RT-PCR and confirmed by gene sequencing. Faecal coliforms and somatic coliphages' counts were also determined. The surveillance of case detected 45 positive faecal samples out of 255 (17.6%) while 35 of 56 environmental samples (62.5%) resulted positive for at least one of the considered viruses. The detection of the same viral strain in the faeces of gastroenteritis cases and in water was possible for adenovirus and rotavirus, which were also predominant in environmental matrices; thus they could be considered as a reference for risk assessment.

Base Sequence↗
PubMed2000

Targeting DNA secondary structures.

DNA secondary structures containing regions of single-stranded DNA have now been identified in the genomic DNA of a number of prokaryotic and eukaryotic species, including humans. Many of these secondary structures are associated with regions of DNA involved in regulation of transcription: promoters or upstream elements. The secondary structures involved appear likely to be hairpin or cruciform structures that may be recognition sites for binding of transcription factors. In the case of the coliphage N4 virion RNA polymerase, a defined hairpin in the polymerase promoter necessary for binding of the polymerase and regulation of transcription has been shown to be extruded under physiological conditions in plasmid DNA. The presence of single-stranded DNA in the promoters of several species suggests that regulatory hairpins may be involved in transcription of a number of genes. In support of this, hairpin- or cruciform-binding proteins have been identified from several species. These results imply that secondary structures in regulatory regions may be targets for drugs that bind and either block or enhance binding of proteins involved in transcription. In this review, we discuss the evidence for DNA secondary structures, particularly hairpins and cruciforms, in genomic DNA and review the studies to date of development of small molecules that can selectively bind these structures.

Animals↗
PubMedDate not supplied

Detection of infectious human adenoviruses in tertiary-treated and ultraviolet-disinfected wastewater.

A pilot-scale study investigating the use of low-pressure, high-intensity UV radiation for disinfection of urban wastewater was conducted. The inactivation of coliform bacteria, wastewater-indigenous enteric viruses, seeded poliovirus, and seeded F-specific coliphage was studied. During the course of the pilot study, infectious human adenoviruses were isolated from 15 of 16 large-volume samples of UV-disinfected secondary- and tertiary-treated wastewater. Half of the tertiary-treated, UV-disinfected effluent samples from which the adenoviruses were isolated had total coliform concentrations that complied with California's Water Recycling Criteria. To determine the relative UV resistance of the adenovirus isolates, purified viruses were seeded into tertiary-treated waste-water and exposed to low-pressure, high-intensity, collimated UV radiation. A dose of approximately 170 mW-s/cm2 was required to achieve 99.99% inactivation. These findings suggest that UV doses effective at meeting certain wastewater regulations for total coliform bacteria may not provide suitable inactivation of the UV-resistant human adenoviruses.

Adenoviruses, Human↗
PubMed2006

Removal of noro- and enteroviruses, Giardia cysts, Cryptosporidium oocysts, and fecal indicators at four secondary wastewater treatment plants in Sweden.

The aim of this study was to investigate variation in the occurrence and removal of enteroviruses, noroviruses, Giardia cysts, Cryptosporidium oocysts, and the most commonly used fecal indicators in four Swedish secondary wastewater treatment plants (WWTPs). Paired samples were taken from the inlet and outlet of each WWTP. (Oo)cysts and indicators were enumerated with standard methods and viruses with a reverse transcriptase polymerase chain reaction. Giardia cysts and enteroviruses were constantly detected (mean numbers were 10(3.31) cysts and 10(4.44) polymerase chain reaction (PCR) units L(-1), respectively). Oocysts were found in 5 out of 19 samples (mean number was 20 L(-1)). Noroviruses were found between November and February, with an average titer of 10(3.29( L(-1). Mean cyst removal was 2.6 log, while noroviruses and enteroviruses were removed by 0.9 and 1.3 log, respectively. There was no correlation between the removals of pathogens and indicators (p > 0.05). Coliphage removal resembled human viral removal better than did F-specific phage.

Animals↗
PubMed1997

Natural protection of spring and well drinking water against surface microbial contamination. II. Indicators and monitoring parameters for parasites.

Recent outbreaks of cryptosporidiosis and reports of other newly described para-sitic diseases associated with drinking water transmission prompted a reevaluation of source water monitoring criteria for public health protection. The field of microbial indicators was reviewed and each candidate sentinel evaluated in terms of its sensitivity, specificity, and technical feasibility. In addition, a clear distinction was made between source water monitoring and monitoring in the distribution system. Of all potential candidate microbial sentinels, Escherichia coli is deemed the most efficacious for public health protection. Based on a conservative estimate of its half-life in groundwater for 8 d, it is recommended that at least two samples be obtained during this half-life. In addition to E. coli, two water quality indicator sentinels, which are not necessarily direct public health threats, should also be monitored at the same frequency. These are the total coliform group and the enterococci. If E. coli is present in any source water sample, the borehole and any directly connected borehole should be embargoed. If either total coliforms or enterococci are detected, only that individual borehole should be taken off line and not used until the situation is remediated and the cause of the fecal contamination eliminated. Clostridium perfringens spores serve as a useful long-lived indicator. However, their perseverance in a sample should not be considered a direct public health threat because spores may far outlive pathogens. As a parasite indicator, C. perfringens should have the same importance as a positive coliform or enterococcus analysis. Coliphages do not yet fulfill enough of the criteria to be routinely employed. Biological monitoring should be coupled with physicochemical monitoring to establish a long-term history of the source. Because all natural waters vary in the amounts of heterotrophic plate count bacteria, test methods should be employed that are refractory to them. A combination of rigorous source protection plus extraordinary source monitoring serve as sufficient multiple barriers for parasite protection.

Animals↗
PubMed2005

Effect of relative humidity on preharvest survival of bacterial and viral pathogens on the surface of cantaloupe, lettuce, and bell peppers.

The purpose of this study was to compare the effects of humidity on the preharvest survival of microbial pathogens on cantaloupe, lettuce, and bell peppers. An additional goal was to evaluate Clostridium perfringens as an indicator of fecal contamination on produce. The microorganisms used in this study included Escherichia coli, E. coli O157:H7, Shigella sonnei, Salmonella enterica subsp. enterica, Clostridium perfringens, hepatitis A virus (HAV), feline calicivirus (FCV), and coliphage PRD1. The study took place in a controlled environment chamber that allowed for the control of temperature (18 to 26 degrees C) and relative humidity. Survival rates under high (mean, 85.7 to 90.3%) and low (mean, 45.1 to 48.4%) relative humidity were compared. The surfaces of the edible portion of each plant were inoculated with the study microorganisms. Samples were collected throughout 2 weeks. More microorganisms survived significantly longer (P < 0.05) on cantaloupe than on lettuce and bell peppers. The type of produce on which each organism experienced the highest inactivation rate tended to change with relative humidity. The survival of microorganisms on produce surfaces was not uniformly affected by relative humidity. Of the studied microorganisms, HAV, PRD1, and C. perfringens were found to have the lowest inactivation rates, whereas FCV and E. coli ATCC 25922 tended to become inactivated most rapidly. C. perfringens generally survived longer than all other bacteria and FCV in all experiments. This trend suggests that C. perfringens may be an acceptable indicator of bacterial contamination and survival in various environments and on different types of crops.

Agriculture↗
PubMed2005

Year-round screening of noncommercial and commercial oysters for the presence of human pathogenic viruses.

Consumption of virus-contaminated shellfish has caused numerous outbreaks of gastroenteritis and hepatitis worldwide. In The Netherlands, oysters are cultured and imported both for consumption and export; therefore, the presence of noroviruses, rotaviruses, astroviruses, hepatitis A viruses, and enteroviruses was determined in 64 commercial and noncommercial oyster samples. Oysters were collected monthly for 13 months from four different harvesting areas in the Oosterschelde Delta. Oyster samples were classified by determining Escherichia coli levels according to the standards set by the Councils Directive (91/ 492/EEC). Two of 36 commercial and 2 of 28 noncommercial oyster samples were B-classified and therefore not ready for consumption. All other oyster samples were A-classified. For the detection of viral RNA, 150 mg of hepatopancreatic tissue was subjected to the Qiagen RNeasy Mini Kit, followed by reverse transcriptase (RT)-PCR and Southern blot hybridization. Enterovirus RNA was detected in 14 of 64 oyster samples, of which 4 were from noncommercial oyster harvesting areas and 10 were from commercial harvesting areas. None of the other human pathogenic viruses were detected. The levels of somatic coliphages and F-specific phages were also determined in all 64 oyster samples, with some samples containing high phage levels (>50 PFU/g of hepatopancreatic tissue), but with most samples containing low phage levels (<50 PFU/g of hepatopancreatic tissue). However, independent of these high or low phage levels, enterovirus RNA could be detected. Thus, commercial oysters can be contaminated with pathogenic viruses, and monitoring only fecal indicators might not sufficiently protect human health.

Animals↗
PubMed1999

Elimination of viruses, phages, bacteria and Cryptosporidium by a new generation Aquaguard point-of-use water treatment unit.

The elimination of human viruses, phages, bacteria and Cryptosporidium oocysts by a new generation commercial Aquaguard purifier for the domestic treatment of drinking water, has been evaluated. The unit basically consists of a candle prefilter, activated carbon filter and ultraviolet irradiation compartment. Drinking water seeded with selected laboratory test strains of resistant micro-organisms was passed through the unit. Similar tests were carried out with sewage-contaminated river water and secondary treated waste water containing naturally occurring organisms. Test procedures were based on internationally accepted principles for the evaluation of point-of-use water treatment units, including a standard test protocol of the United States Environmental Protection Agency. Reduction in numbers of seeded test organisms at several log levels higher than those expected in water for which the unit is intended, was determined by the cultivation of viable organisms. In the case of seeded viruses and Cryptosporidium parvum oocysts the qualitative absence of nucleic acid was determined by the reverse transcriptase polymerase chain reaction (RT-PCR). At the design flow rate of one litre per minute, numbers of polio, hepatitis A, adeno types 2 and 41, rota SA11, human rota and astro viruses, as well as somatic and MS2 coliphages, and Escherichia coli, Streptococcus faecalis, Clostridium perfringens, total coliform bacteria, enterococci, heterotrophic bacteria and C. parvum oocysts, were reduced by more than 99.999% in all waters tested. This efficiency conforms to specifications for such units. The quality of the treated water was well within microbiological limits of international specifications for drinking water.

Animals↗
PubMed1999

Detection of single-stranded cohesive ends in the genome of Bacillus thuringiensis temperate phage KK-88.

Cohesive ends (cos sites) were detected in the genome of temperate KK-88 phage in Bacillus thuringiensis after analysis of the phage DNA generated by the 3'-5' exonuclease activity of Klenow fragment of DNA polymerase I. In addition, unlike the 5'-protruding ends of coliphage lambda genome, the ends of KK-88 phage genome were found to be 3'-protruding. The restriction map of the phage genome was also constructed on the basis of position of the cos fragments.

Bacillus thuringiensis↗
PubMed2001

Secondary wastewater disposal for crop irrigation with minimal risks.

A critical objective for any wastewater reuse program is to close the gap between supply of and demand for water and to minimize health and environmental hazards. Thus, the effects of treated effluent on crops, soils and community health must be considered carefully. When applying wastewater to soil-plant systems, it is to be noted that the passage of water through the soil reduces considerably the number of microorganisms carried out by the reclaimed wastewater. Nevertheless, there is a need to study the real rate of organism decay subject to water quality, soil and vegetable characteristics, and irrigation method. The aim of this work is to determine the fate of the fecal coliforms, coliphages F+ and CN13, and helminth eggs survival during the application of reclaimed wastewater in a vineyard orchard near the City of Arad (Israel) via onsurface and subsurface drip irrigation systems. Wastewater obtained from a stabilization pond, and soil samples were tested and an important decrease of microorganisms was reached in both cases, with the better values obtained with the sub-surface drip irrigation system.

Agriculture↗
PubMed2001

Faecal bacteria and bacteriophage inactivation in a full-scale UV disinfection system used for wastewater reclamation.

A study was carried out to compare the inactivation of faecal bacteria and one type of bacteriophage in a full-scale UV disinfection system. The system is part of a water reclamation facility for effluent reuse in golf course and agricultural irrigation. Influent and effluent samples were taken over two sampling periods (three consecutive days in July and one day in August), with three different UV doses applied each day (ranging from 10 to 40 mW.s/cm2 and 20 to 80 mW.s/cm2 in July and August, respectively). Effluent samples were also taken from a chlorine disinfection channel (5 mg Cl2/L dose) operating in parallel to the UV system. Total coliforms (TC), faecal coliforms (FC), faecal streptoccoci (FS) and somatic coliphages (SC) were measured in each sample. F-specific RNA bacteriophages and bacteriophages of Bacteroides fragilis were also measured one day in July. The decay ratio observed for all the microorganisms was similar when UV doses applied were low (July), ranging from 1.15 to 1.25 log-units. This suggests that bacterial indicators may be suitable for virus inactivation control when low UV doses are applied; however, such low doses are inadequate to achieve effluent quality requirements for unrestricted irrigation. At higher UV doses (August), decay ratios for TC and FC were 3.1 and 2.8 log-units respectively, indicating that they were more susceptible to UV exposure than SC and FS, with decay ratios of 2.6 and 1.0 log-units, respectively. Nevertheless, these higher doses were also inadequate to achieve water quality requirements for unrestricted irrigation. The decay ratio of SC during chlorine disinfection was clearly lower than that of the other microorganisms. Bacteriophages of Bacteroides fragilis were more resistant to UV disinfection than SC and F-specific RNA. In fact, bacteriophages of Bacteroides fragilis were not affected during UV exposure. A UV dose ranging from 40 to 80 mW.s/cm2 marks the borderline beyond which inactivation rates of SC are clearly lower than those of bacterial indicators.

Bacteria↗
PubMed2001

New methods for the detection of viruses: call for review of drinking water quality guidelines.

Drinking water supplies which meet international recommendations for source, treatment and disinfection were analysed. Viruses recovered from 100 L-1,000 L volumes by in-line glass wool filters were inoculated in parallel into four cell culture systems. Cell culture inoculation was used to isolate cytopathogenic viruses, amplify the nucleic acid of non-cytopathogenic viruses and confirm viability of viruses. Over a period of two years, viruses were detected in 23% of 413 drinking water samples and 73% of 224 raw water samples. Cytopathogenic viruses were detected in 6% raw water samples but not in any treated drinking water supplies. Enteroviruses were detected in 17% drinking water samples, adenoviruses in 4% and hepatitis A virus in 3%. In addition to these viruses, astro- and rotaviruses were detected in raw water. All drinking water supplies had heterotrophic plate counts of < 100/mL, total and faecal coliform counts of 0/100 mL and negative results in qualitative presence-absence tests for somatic and F-RNA coliphages (500 mL samples). These results call for a revision of water quality guidelines based on indicator organisms and vague reference to the absence of viruses.

Cell Culture Techniques↗
PubMed2001

Persistence of two model enteric viruses (B40-8 and MS-2 bacteriophages) in water distribution pipe biofilms.

The persistence of two model enteric virions (Bacteroides fragilis phage B40-8 and coliphage MS-2) within pipe biofilms was investigated in situ in an urban distribution system. Biofilms were allowed to develop on uPVC and stainless steel (SS) coupons in a modified Robbins' device for 70 d within a 150 mm uPVC reticulation main. Coupons were then placed in annular reactors and slug dosed with B40-8 and MS-2 phages (10(8) pfu/mL). Pipe water velocity, pH and free chlorine were recorded during the experimental period. Biofilms on uPVC were generally more abundant (based on total bacterial counts, HPCs, total protein and total carbohydrate). Both B40-8 and MS-2 were incorporated into biofilms formed on uPVC and SS coupons (> 10(4) and > 10(3) pfu/microgram protein respectively) and persisted for > 30 d and 6 d respectively, reflecting biofilm biomass on the two pipe surfaces. Virion loss/inactivation from biofilm followed an initial rapid phase, followed by a very slow phase representing approximately 0.01% of the original virion population. Virions, therefore, have the potential to accumulate within distribution biofilm and problems could arise when clusters of biofilm-associated enteric virions become detached from the substrata by hydrodynamic forces or sudden changes in disinfection regime.

Bacteroides fragilis↗
PubMed2001

Removal of Salmonella and microbial indicators in constructed wetlands treating swine wastewater.

Reductions of Salmonella bacteria and enteric microbial indicator organisms were measured in swine wastewater treated by a field-scale surface flow (SF) constructed wetland at a commercial hog nursery in North Carolina and in laboratory-scale SF and subsurface flow (SSF) constructed wetland reactors. Overall reductions of Salmonella, fecal coliforms and E. coli were 96, 98 and 99%, respectively, in the two-cell field-scale wetland. Somatic and F-specific coliphage viral indicators were reduced by 99 and 98%, respectively. Reductions of Salmonella, fecal coliforms and E. coli were similar in the first cell of the field system and in the laboratory-scale SF wetland operated at a TKN loading of 25 kg ha(-1) d(-1) and 30 degrees C (approximately 70, 90 and 90%, respectively). In the SSF wetland reactor, Salmonella and fecal coliform reductions were 80 and 98%, respectively, at a 40 kg TKN ha(-1) d(-1) loading and 99.8 and 99.99%, respectively, at a 10 kg TKN ha(-1) d(-1) loading. These results show that SF constructed wetlands can be effective for reducing enteric pathogens in swine wastewater and that greater removals can be achieved using SSF designs and lower TKN loading rates.

Agriculture↗
PubMed1975

Effects of solar ultraviolet radiations on Bacillus subtilis spores and T7 bacteriophage.

Spores of Bacillus subtilis HA 101 and the DNA polymerase I-defective mutant HA 101 (59) F were exposed to selected wavelengths of solar ultraviolet light and space vacuum during the return of Apollo 16. In addition, coliphage T7 suspensions were exposed to solar ultraviolet radiation as part of the Microbial Response to Space Environment Experiment. Optical filters were employed to provide different energy levels at wavelengths 254 nm and 280 nm. Dose-response curves for lethal and mutagenic effects were compared with ground-based data. A close parallel was observed between the results of solar radiation and ground tests with spores of the two strains. However, significantly greater inactivation of T7 bacteriophage was observed after exposure to solar ultraviolet radiation.

Bacillus subtilis↗
PubMed1967

The survival of micro-organisms in space. Further rocket and balloon-borne exposure experiments.

This report describes the results of survival studies of terrestrial micro-organisms exposed directly to the space environment on two balloons and in two rocket flights. The work is part of a program to develop techniques for the collection of micro-organisms in the size range of micrometeorite particles in space or non-terrestrial atmospheres, and their return to earth in a viable state for further study. Previous survival studies were reported (J. Hotchin, P. Lorenz and C. Hemenway, Nature 206 (1965) 442) in which a few relatively large area samples of micro-organisms were exposed on millipore filter cemented to aluminum plates. In the present series of experiments, newly developed techniques have resulted in a 25-fold miniaturization resulting in a corresponding increase in the number of experiments performed. This has enabled a statistical evaluation of the results to be made. A total of 756 separate exposure units (each approximately 5 x 5 mm in size) were flown in four experiments, and organisms used were coliphage T1, penicillium roqueforti (THOM) mold spores, poliovirus type I (Pfizer attenuated Sabin vaccine strain), and bacillus subtilis spores. The organisms were deposited either by spraying directly upon the vinyl-coated metal units, or by droplet seeding into shallow depressions in the millipore filter membrane-coated units. Groups of units were prepared comprising fully exposed, inverted (screened by 2 mm of Al), and filter-protected organisms. All of these were included in the flight set, the back up set, and a laboratory control set. The altitude of the exposures varied from 35 km in the balloon experiments to 150 km in the rocket experiments. Times of exposures at altitude were approximately 6 hours for the balloon flights and about 3 minutes for the rocket experiments.

Altitude↗