scholarly journals A Simple Methodological Approach for Counting and Identifying Culturable Viruses Adsorbed to Cellulose Nitrate Membrane Filters

2000 ◽  
Vol 66 (1) ◽  
pp. 194-198 ◽  
Author(s):  
Georgios T. Papageorgiou ◽  
Laura Mocé-Llivina ◽  
Christina G. Christodoulou ◽  
Francisco Lucena ◽  
Dina Akkelidou ◽  
...  
Keyword(s):  
Tap Water ◽  
Membrane Filter ◽  
Methodological Approach ◽  
Plaque Assay ◽  
Cellulose Nitrate ◽  
Assay Method ◽  
Most Probable Number ◽  
Cellulose Membrane ◽  
Probable Number ◽  
Membrane Filters

ABSTRACT We identified conditions under which Buffalo green monkey cells grew on the surfaces of cellulose nitrate membrane filters in such a way that they covered the entire surface of each filter and penetrated through the pores. When such conditions were used, poliovirus that had previously been adsorbed on the membranes infected the cells and replicated. A plaque assay method and a quantal method (most probable number of cytopathic units) were used to detect and count the viruses adsorbed on the membrane filters. Polioviruses in aqueous suspensions were then concentrated by adsorption to cellulose membrane filters and were subsequently counted without elution, a step which is necessary when the commonly used methods are employed. The pore size of the membrane filter, the sample contents, and the sample volume were optimized for tap water, seawater, and a 0.25 M glycine buffer solution. The numbers of viruses recovered under the optimized conditions were more than 50% greater than the numbers counted by the standard plaque assay. When ceftazidime was added to the assay medium in addition to the antibiotics which are typically used, the method could be used to study natural samples with low and intermediate levels of microbial pollution without decontamination of the samples. This methodological approach also allowed plaque hybridization either directly on cellulose nitrate membranes or on Hybond N+ membranes after the preparations were transferred.

Application of an Automated Hydrophobic Grid Membrane Filter Interpreter System at a Poultry Abattoir

1991 ◽  
Vol 54 (8) ◽  
pp. 619-622 ◽  
Author(s):  
W. BRUCE MCNAB ◽  
CHRISTINE M. FORSBERG ◽  
ROBERT C. CLARKE
Keyword(s):  
Membrane Filter ◽  
Geometric Mean ◽  
Aerobic Bacteria ◽  
Most Probable Number ◽  
Probable Number ◽  
Membrane Filters ◽  
Government Inspection ◽  
Data Files ◽  
Good Repeatability ◽  
Set Up

The performance of a system to measure broiler carcass hygiene was investigated in the abattoir environment. The system involved: whole carcass rinses aided by a mechanical carcass shaker; filtration of rinse solutions though hydrophobic grid membrane filters (HGMF) (ISO-GRIDR, QA Laboratories Ltd.); and use of an automated HGMF interpreter. The interpreter recorded culture results in units of most probable number (MPN) of aerobic bacteria, in electronic data files (MI-100 HGMF Interpreter System, Richard Brancker Research Ltd.). Set-up and operation of the system by government inspection staff at an abattoir ran relatively smoothly with minimal interference to normal plant operation. The system demonstrated good repeatability in measuring log10 most probable number per gram of carcass (LgMPN/g), between repeat readings of the same filters (r=0.993 p<0.001), and good repeatability between repeat filters within the same carcass rinses (r=0.970 p<0.001). Overall, the LgMPN/g ranged from 0.258 to 3.955 with a mean of 2.276 and a variance of 0.324. These corresponded to MPN/g counts in the range of 2 to 9000 and a geometric mean of 188.8 MPN/g. A regression model was developed to investigate poultry supplier and abattoir effects on the variability of counts. A significant supplier effect was observed. The addition of two more carcass showers located just after the venting machine along the evisceration line was not associated with a change in carcass hygiene.

scholarly journals Double-Layer Plaque Assay for Quantification of Enteroviruses

2004 ◽  
Vol 70 (5) ◽  
pp. 2801-2805 ◽  
Author(s):  
Laura Mocé-Llivina ◽  
Francisco Lucena ◽  
Juan Jofre
Keyword(s):  
Double Layer ◽  
Carcinoma Cell ◽  
Plaque Assay ◽  
Most Probable Number ◽  
Suspended Cell ◽  
Probable Number ◽  
Membrane Filters ◽  
Naturally Occurring ◽  
Order Of Magnitude ◽  
Virus Quantification

ABSTRACT We describe here a double-layer plaque assay for the quantification of enteroviruses, combining a monolayer plaque assay and a suspended-cell plaque assay. The double-layer assay provides significantly greater counts than other methods of virus quantification of both suspensions of pure culture viruses and naturally occurring viruses. The counts obtained by this method are approximately one order of magnitude greater than those obtained with the more commonly used method, the monolayer plaque assay. We conclude that the methods available for quantifying viruses rank in efficiency as follows: double-layer plaque assay ≥ suspended-cell plaque assay > counting cytopathogenic virus adsorbed to cellulose nitrate membrane filters ≥ most probable number of cytopathogenic units > monolayer plaque assay. Moreover, the double-layer plaque assay allows the use of two different cell lines in the two layers. Using the human colonic carcinoma cell line CaCo2 facilitates the recovery of a greater number and diversity of naturally occurring enteroviruses in water than the monolayer agar method. In addition, the pretreatment of cells with 5-iodo-2′-deoxyuridine (IDU) prior to the quantification of enteroviruses by the double-layer plaque assay provides significantly higher recoveries than the use of IDU does with the other methods of quantification.

Comparative study of membrane filtration and enrichment media for the isolation and enumeration of Pseudomonas aeruginosa from sewage, surface water, and swimming pools

1985 ◽  
Vol 31 (8) ◽  
pp. 686-692 ◽  
Author(s):  
A. H. Havelaar ◽  
M. During ◽  
E. H. M. Delfgou-Van Asch
Keyword(s):  
Pseudomonas Aeruginosa ◽  
Membrane Filtration ◽  
Culture Media ◽  
Polluted Water ◽  
Most Probable Number ◽  
Cellulose Ester ◽  
Swimming Pools ◽  
Probable Number ◽  
Membrane Filters ◽  
Swimming Water

The recovery of Pseudomonas aeruginosa on several selective culture media was tested using raw sewage and secondary sewage effluent samples as well as spiked chlorinated imitation swimming water and samples from whirlpools. mPA-medium B gave good recovery of both vital and chlorine-injured P. aeruginosa and selectivity was greater than 90% when analysing whirlpool samples. It is therefore the medium recommended for examination of chlorinated swimming pools. When analysing sewage polluted water with the mPA-B medium, reduced selectivity was noted from low verification rates and from overgrowth by competitive flora. A modified medium (mPA-D; addition of cetrimide, omission of sulphapyridine and actidione) was more selective and sufficiently recovered noninjured cells. Chlorine-injured cells were completely inhibited, however. C-390 (9-chloro-9-(4-diethylaminophenyl)-10-phenylacridan) was confirmed to be highly selective for P. aeruginosa when used in spread plates at a concentration of 30 μg/mL; P. aeruginosa was slightly inhibited. However, the medium could not be used with conventional membrane filtration techniques, because cellulose ester filters interfered with the selective action of C-390. Selectivity could be improved by using Gelman Tuffryn (polysulphone) filters and increasing the C-390 concentration to 120 μg/mL. At this concentration, however, the medium was strongly inhibitory to P. aeruginosa; resuscitation only partially improved recovery. Two other membrane filtration media were tested. Both cetrimide – nalidixic acid agar and Drake's medium No. 19 were inhibitory to chlorine-injured cells. Several types of membrane filters were tested and there was little difference between them. In the most-probable-number technique, recovery of P. aeruginosa was shown to be excellent when using asparagine broth. Malachite green broth was strongly inhibitory to chlorine-injured P. aeruginosa.

Detection of Coliform, faecal Coliform And Total Bacterial Count From Drinking Water Of Varanasi (U.P.) India

2021 ◽  
Vol 27 (2) ◽  
Author(s):  
Alok Kumar Singh ◽  
Anand Prakash Singh ◽  
Sanjay Srivastava
Keyword(s):  
Drinking Water ◽  
Water Samples ◽  
Tap Water ◽  
Bacterial Count ◽  
Most Probable Number ◽  
Total Bacterial Count ◽  
Indicator Organisms ◽  
Cross Sectional ◽  
Probable Number ◽  
Hand Pump

In India source of drinking water at Varanasi city for common people are tap water, well, hand pump, Ganga river and stored tank water collected from bore well. All water samples were studied to assess their bacteriological characteristics and suitability for potable purposes. A cross-sectional epidemiological method was adopted to investigate the drinking water of six different sites of Varanasi city. The bacteriological examination of water samples included the most probable number of presumptive coliforms, faecal coliforms, and total bacterial count. The results showed that the total coliform count was detected in all the site. In all the methods coliforms presence was indicated. Maximum number of coliform observed in all the seasons, were from river and well water followed by hand pump, tap water and stored tank. The most common group of indicator organisms used in water quality monitoring are coliforms. These organisms are representative of bacteria normally present in the intestinal tract of mammals including human. Contamination of water may occur through different way like sewage disposal in the river, seepage of bathing near sites, fecal excreta of human, bird and other animals. Improving and expanding the existing water treatment and sanitation systems are more likely to provide good, safe and sustainable sources of water in the long term.

Acceptability of Individual Water Supplies as Judged by a Single Test for Total Coliform Bacteria

1980 ◽  
Vol 43 (7) ◽  
pp. 563-563
Author(s):  
E. P. MERRILL
Keyword(s):  
Membrane Filter ◽  
Total Coliform ◽  
Coliform Bacteria ◽  
Most Probable Number ◽  
Filter Method ◽  
Single Test ◽  
Water Supplies ◽  
Probable Number ◽  
Dug Wells ◽  
Membrane Filter Method

Of 658 individual water supplies tested over an 8-year period, 69% of drilled wells, 62% of driven wells, 27% of dug wells and 32% of springs were judged acceptable on the basis of a single test for total coliforms. The acceptability standard consisted of 0 to 1 coliforms/100 ml of sample by the membrane filter method or a Most Probable Number index of less than 2.2 (presumptive and confirmed tests).

24-Hour Presumptive Enumeration of Escherichia coli O157:H7 in Foods by Using the ISO-GRID® Method with SD-39 Agar

1997 ◽  
Vol 60 (8) ◽  
pp. 883-890 ◽  
Author(s):  
PHYLLIS ENTIS ◽  
IRINA LERNER
Keyword(s):  
Escherichia Coli ◽  
Membrane Filter ◽  
Storage Conditions ◽  
Food Storage ◽  
Most Probable Number ◽  
Escherichia Coli O157 ◽  
Filtration Method ◽  
Probable Number ◽  
Direct Filtration ◽  
The Comparative Study

Two 24-hour presumptive enumeration methods for Escherichia coli O157:H7 organisms based on the hydrophobic grid membrane filter (ISO-GRID) and using SD-39 agar, a new selective and differential culture medium, were developed and compared to a 3-tube MPN (most probable number) method using modified tryptone soy broth enrichment. The comparative study comprised 22 combinations of storage conditions and food products, including a variety of raw and cooked meats and several dairy products. The ISO-GRID direct filtration method produced counts which were equivalent to or significantly higher than the 3-tube MPN method for all food-storage combinations except for frozen pasteurized whole egg. The ISO-GRID resuscitation method produced counts equivalent to the 3-tube MPN method for the frozen egg.

scholarly journals VIDAS Salmonella (SLM) Assay Method EasySLM with ChromID Salmonella (SM2) Agar

2009 ◽  
Vol 92 (6) ◽  
pp. 1861-1864 ◽  
Author(s):  
Ronald Johnson ◽  
John Mills ◽  
Judith Coln-Reveles ◽  
Thomas Hammack
Keyword(s):  
Peanut Butter ◽  
Reference Method ◽  
Black Pepper ◽  
Assay Method ◽  
Most Probable Number ◽  
Chicken Breast ◽  
Probable Number ◽  
Pork Sausage ◽  
Selective Enrichment ◽  
Matrix Extension

Abstract A method modification study was conducted for the VIDAS Salmonella (SLM) assay (AOAC Performance Tested MethodSM 020901) using the EasySLM method to validate a matrix extension for peanut butter. The VIDAS EasySLM method is a simple enrichment procedure compared to traditional Salmonella methods, requiring only pre-enrichment and a single selective enrichment media, Salmonella Xpress 2 (SX2) broth. SX2 replaces the two selective broths in traditional methods and eliminates the M broth transfer, incubation, and subsequent pooling of M broths prior to VIDAS assay. The validation study was conducted under the AOAC Research Institute Emergency Response Validation program. VIDAS SLM was compared to the U.S. Food and Drug Administration's Bacteriological Analytical Manual (FDA-BAM) method for detection of S. enterica ser. Typhimurium in peanut butter. All peanut butter samples were prepared, blind-coded, and shipped to the method developers' laboratory by Q Laboratories. In addition, Q Laboratories performed most probable number and reference method analyses on peanut butter samples. The VIDAS EasySLM ChromID Salmonella (SM2) Agar was previously validated in the Performance Tested Methods program for the detection of Salmonella in roast beef, raw ground pork, turkey, pork sausage, raw chicken breast, dry pet food, whole milk, ice cream, bagged spinach, shrimp (raw, peeled), raw cod, spent irrigation water, pecans, peanut butter, dry pasta, cake mix, ground black pepper, nonfat dry milk, liquid eggs, cantaloupe, and orange juice. In the matrix extension study for peanut butter, the VIDAS EasySLM method was shown to be equivalent to the appropriate reference culture procedure using both buffered peptone water pre-enrichment and the FDA-BAM lactose pre-enrichment in the two-step enrichment method with SX2 media. The current study extends the validation to include peanut butter.

scholarly journals Simulation of Cross-Contamination and Decontamination of Campylobacter jejuni during Handling of Contaminated Raw Vegetables in a Domestic Kitchen

2008 ◽  
Vol 71 (12) ◽  
pp. 2448-2452 ◽  
Author(s):  
LAY-CHING CHAI ◽  
HAI-YEN LEE ◽  
FARINAZLEEN MOHD GHAZALI ◽  
FATIMAH ABU BAKAR ◽  
PRADEEP KUMAR MALAKAR ◽  
...  
Keyword(s):  
Campylobacter Jejuni ◽  
Tap Water ◽  
Hot Water ◽  
Wash Water ◽  
Most Probable Number ◽  
Cross Contamination ◽  
Probable Number ◽  
Transfer Rates ◽  
Log Reduction ◽  
Potential Risk Factors

Campylobacter jejuni was found to occur at high prevalence in the raw salad vegetables examined. Previous reports describe cross-contamination involving meat; here we investigated the occurrence of cross-contamination and decontamination events in the domestic kitchen via C. jejuni–contaminated vegetables during salad preparation. This is the first report concerning quantitative cross-contamination and decontamination involving naturally contaminated produce. The study was designed to simulate the real preparation of salad in a household kitchen, starting with washing the vegetables in tap water, then cutting the vegetables on a cutting board, followed by slicing cucumber and blanching (heating in hot water) the vegetables in 85° water. Vegetables naturally contaminated with C. jejuni were used throughout the simulation to attain realistic quantitative data. The mean of the percent transfer rates for C. jejuni from vegetable to wash water was 30.1 to 38.2%; from wash water to cucumber, it was 26.3 to 47.2%; from vegetables to cutting board, it was 1.6 to 10.3%; and from cutting board to cucumber, it was 22.6 to 73.3%. The data suggest the wash water and plastic cutting board as potential risk factors in C. jejuni transmission to consumers. Washing of the vegetables with tap water caused a 0.4-log reduction of C. jejuni attached to the vegetables (most probable number/gram), while rapid blanching reduced the number of C. jejuni organisms to an undetectable level.

Bacterial quality of drinking water sources and antimicrobial resistance profile of Enterobacteriaceae in Bahir Dar city, Ethiopia

2014 ◽  
Vol 4 (3) ◽  
pp. 384-390 ◽  
Author(s):  
Bayeh Abera ◽  
Mulugeta Kibret ◽  
Goraw Goshu ◽  
Mulat Yimer
Keyword(s):  
Drinking Water ◽  
Antimicrobial Resistance ◽  
Water Samples ◽  
Multiple Drug Resistance ◽  
Tap Water ◽  
World Health ◽  
Most Probable Number ◽  
Bahir Dar ◽  
Probable Number

A cross-sectional study was conducted to determine the bacterial quality and antimicrobial susceptibility profiles of Enterobacteriaceae from drinking water in Bahir Dar city. A total of 140 water samples were collected in the wet and dry periods from springs (n = 4), reservoirs (n = 10) and private tap water at households (n = 126). Bacteriological analysis of water was conducted using multiple tube method. Overall, 21.4%, 18.6% and 17.8% of drinking water samples had total coliforms (TC), faecal coliforms (FC) and Escherichia coli, respectively. All spring water samples and 29.2% of private tap water had the highest TC load (18 most probable number/100 mL, 95% CI: 100). For FC, 81.4% of the drinking water supplies tested complied with both World Health Organization and Ethiopian Standards. High levels of resistance (98–100%) were observed for ampicillin by Enterobacteriaceae and Pseudomonas aeruginosa. All P. aeruginosa isolates and 20 (66.7%) of E. coli revealed multiple drug resistance. Enterobacteriaceae and P. aeruginosa isolates exhibited high levels of antimicrobial resistance. The bacterial quality of drinking water in Bahir Dar city was poor. Microbial surveillance and monitoring with periodic assessment on physical integrity of the water pipelines need to be undertaken.

scholarly journals Drinking Water and Diarrheal Characteristic Cases in Darbendikhan City

2020 ◽  
Author(s):  
Sabah Shareef Mohammed ◽  
Yadgar Hussien Hama-karim ◽  
Mohammed Ibrahim Mohialdeen Gubari
Keyword(s):  
Drinking Water ◽  
Tap Water ◽  
Water Source ◽  
Water Sources ◽  
Coliform Bacteria ◽  
Most Probable Number ◽  
Probable Number ◽  
Pipe System ◽  
Software Application ◽  
Drinking Water Sources

Water pollution in Iraq has been extended disaster edge; this pollution is caused by wastes and sewages into soil and rivers, pollutant water sources influence the outbreak and serious epidemic status among the population.. The aim of this study is to determine the bacteriological quality of drinking water sources and characteristics of water-borne diseases especially diarrheal cases in Darbandikhan city. 166 water samples, collected from the different sources and areas, were tested for the presences of coliform bacteria as an indicator for pathogen contamination. Most probable number index was used for coliform enumeration. 161 diarrheal cases were taken as a sample from the patients were admitted to the general hospital in Darbandikhan district.. The questionnaire form was planned to view characteristics of diarrheal cases and patients were interviewed directly, the data was analyzed by STATA software application. 46% of the diarrheal cases used tap water for drinking. On the other hand, the reminder (54%) used other sources for the same purpose. All the risk factor such as type of water source, sufficiency of the water, duration of water storage and chlorination were associated with diarrhea. Almost half of the cases were children and three quarters were single. The data was analyzed by STATA version 13.1.This study indicated that the majority of drinking water sources in Darbandikhan city are not suitable for drinking, although net pipe system supplied chlorine significantly it has been proven that the tap water from the homes is not suitable for consumption.

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