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GUIDELINES FOR SUBMITTING WATER SAMPLES FOR BACTERIOLOGICAL TESTING

Drinking water and non-potable water are routinely tested for indicator organisms including Escherichia coli and other members of the "coliform group", and Enterococci. These bacteriological screens are usually performed for regulatory purposes. For bona fide public health concerns (as determined by a local or State health authority) the laboratory has the capacity to isolate other organisms from water samples including Salmonella, Shigella, Pseudomonas, Legionella, Staphylococcus aureus, fecal streptococci and Klebsiella. Pathogen isolation is not performed on routine compliance samples. A. Drinking water samples, routine compliance for coliform/ E. coli screening: 1. Samples are collected in EPA approved containers only--no exceptions! Use products such as Thiobags or Corning water sampling bottles, or any other container which meets all of these criteria: a) container must be borosilicate glass or food grade plastic resin with non-toxic closure, b) minimum capacity of 120 ml., c) have marked or embossed 100 ml. Fill-line, and d) contain the proper amount of sterile sodium thiosulfate solution to neutralize any chlorine in the water. Before collecting sample remove any aerators or other devices from the faucet or hose bib. Clean the threads of the faucet with bleach or rubbing alcohol. Run the water several minutes. Before collecting the sample be aware that you are not to rinse the sample container or closure. If collecting the sample in bottles, remove the plastic seal or other tamper proofing, uncap the bottle (do not touch the rim or inside of the bottle or cap) and fill the bottle to at least the 100 ml. Fill-line. Do not overfill the bottle or pour out any water, as this will also cause part of the thiosulfate to spill out. If using a sample bag tear off the scored line at the top of the bag. Pull-tabs (if provided) to open the bag and fill bag to the fill-line. Pull wires on the bag to close it. Whirl the bag 3 revolutions to seal it. Rolling the tapes down on the bag will not seal it! There should be a small amount of air in the bag with the water. Turn the taped wires at the top of thee bag inward on opposite face of fold. If the bag is over-filled by accident, collect another sample instead of pouring out part of the sample. Label the sample with your name, collection number, and point of collection with a felt-tip marker, which contains waterproof, permanent ink. Complete the proper submittal form and proofread the completed form to check for omissions or errors. Ship or deliver the samples (refrigeration is not necessary) in an insulated cooler to the laboratory so that the samples are received within 30 hours after collection. Placing the submittal form in a plastic bag in the cooler will prevent the paper from getting wet in transit. Do not store samples in a hot vehicle or in sunlight.

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B. Collection of water samples for pathogen isolation from drinking water or surface waters should be performed by DOH county public health units due to the risk of possible infection to the sample collector. Gloves, aprons, and respiratory protection should be used when handling potentially infectious materials. 1. Whenever possible, a collection of 1 liter of water is preferred. Larger volumes of water sample (1 to 10 liters) are occasionally needed to detect legionellae and other pathogens in water that has a very low concentration of these bacteria such as municipal water supplies. If a liter can not be collected from a sample source, a smaller volume is acceptable. Water sample should be collected in sterile 1-liter wide-mouth screw capped plastic bottles. If the water source has recently been treated with chlorine, add 0.5 ml of 0.1 N sodium thiosulfate to each 1-liter sample to neutralize the disinfectant. Swabs of faucet aerators and showerheads should be taken before water samples from these sites. The sample should be taken with the aerator or showerhead removed if possible. Polyester swabs with wooden shafts work well for this purpose. Cotton swabs do not work as well. The swabs should be submerged in 3 ­ 5 ml. of water taken at the same time to prevent drying during transport.

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All samples should be transported to the laboratory in insulated coolers as protection against extreme heat or cold. Samples that will not reach the laboratory within 24 hours should be refrigerated before shipping.

C. Collection of non-potable water samples for coliform/enteroccci screens 1. Single use sampling containers should be of food grade plastic resin with non-toxic closures and have a capacity of at least 120-ml. Chlorinated effluents must container sufficient sodium thiosulfate to neutralize any chlorine residual. If the collection bottles do not already contain a neutralizing tablet, add 0.1 ml. of a 10% solution of sodium thiosulfate to a 120 ml. bottle to neutralize up to 15 mg/L chlorine residual. Take care to not pour out this solution during sample collection. Keep sampling bottle closed until ready to fill. Do not rinse the container. To collect the sample take the bottle by its base with lid open and plunge it neck downward below the water surface. Turn the bottle until the neck points slightly upward and the mouth is directed toward the current. If the water is not moving, push the bottle horizontally away from the hand. Close the lid on the bottle. The sample volume should be at least 100 ml. Label the sample with a marker containing waterproof ink. Submit to the laboratory in a cooler to prevent exposure to extremes of temperature and sunlight.

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D. Disinfecting your private well 1. If you suspect microbial contamination of your private well, you may wish to disinfect the well and your home plumbing. Typically you will have a four-inch diameter well with a submersed pump. (If you have an aboveground jet pump with a closed system, you will need to contact a well driller of your choice to disinfect the system.) Shut off the pump; drain the water from the pressure tank and all water lines including those inside your home. Obtain 2 ­ 3 pounds of calcium hypochlorite from a distributor of swimming pool supplies. Mix this in a bucket with 5 gallons of water. You can use instead, 4 gallons of liquid pool chlorine (about 10% sodium hypochlorite). Remove the ½" access plug from the top of the casing and pour the chlorine solution into the well. Follow this with 2 gallons of plain water. Replace the plug. Turn the power on. Start the pump and fill the pressure tank. Open all faucets, one at a time and shut them off when you smell the odor of chlorine at the faucet. Do not use any water from the system for 10 ­ 12 hours. Maintain pressure in the pressure tank. After 10 ­ 12 hours, thoroughly drain all lines and pressure tank, allowing water to run from each faucet until no chlorine odor remains. DO NOT RUN ANY OF THE CHLORINATED WATER INTO YOUR SEPTIC TANK! You can use a bucket to collect water from faucets that drain into your septic tank. After another 8 hours, you should collect and submit a sample to the laboratory for testing. Follow the instructions above for collecting routine drinking water samples for coliform screening.

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GUIDELINES FOR SUBMITTING FOOD SAMPLES AS PART OF THE INVESTIGATION OF A FOOD-BORNE DISEASE OUTBREAK

County health departments and other government agencies under the supervision of epidemiologists collect food samples. Food samples are not accepted from individuals. The samples can be analyzed for Staphylococcal enterotoxins A, B, C, and D; Bacillus cereus diarrhea toxin; Staphylococcus aureus; Bacillus cereus; Clostridium perfringens; Listeria monocytogenes; Salmonella species; Shigella; Campylobacter; and Vibrio species. 1. Food samples should be collected in sterile containers of food grade plastic resin. The guidelines for optimal sample collection differ for each desired isolate. Meaningful laboratory test results arise from sampling procedures that produce portions of food representative of the whole lot of food material. The collector should receive training and be familiar with the sampling techniques Chapter 2 the American Public Health Association's Compendium of Methods for the Microbiological Examination of Foods, and Chapter 1 of AOAC International's Bacteriological Analytical Manual. General considerations should center on keeping food samples under refrigeration and submitting them as promptly as possible to the laboratory. Samples should not be touched with the hands. Sampling instruments must be sterile and their use should follow a plan that prevents cross-contamination. Samples should be properly labeled. A copy of the currently used submittal form is given below. The laboratory should be notified as soon as possible concerning the proposed shipment of food samples by telephone so that the appropriate isolation media can be prepared. This minimizes any delay in beginning the analyses of samples.

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GUIDELINES FOR SUBMITTING WATER SAMPLES FOR BACTERIOLOGICAL TESTING

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