Rapid Determination of Bacteria in Pools.Abstract If a method for rapid determination of bacterial levels in swimming pools and whirlpools were available, bacterial health risks could be avoided before exposure occurred. Such a method would enable public-health authorities to make timely decisions about closing or reopening pools and to adjust disinfectant doses. The purpose of this study was to determine if a rapid adenosine adenosine /aden·o·sine/ (ah-den´o-sen) a purine nucleoside consisting of adenine and ribose; a component of RNA. It is also a cardiac depressant and vasodilator used as an antiarrhythmic and as an adjunct in myocardial perfusion imaging triphosphate triphosphate /tri·phos·phate/ (tri-fos´fat) a salt containing three phosphate radicals. tri·phos·phate n. A salt or ester containing three phosphate groups. (ATP ATP: see adenosine triphosphate. ATP in full adenosine triphosphate Organic compound, substrate in many enzyme-catalyzed reactions (see catalysis) in the cells of animals, plants, and microorganisms. ) bioluminescence bioluminescence (bī'ōl  'mĭnĕs`əns), production of light by living organisms. method would serve this purpose. Bacteriological bac·te·ri·ol·o·gy n. The study of bacteria, especially in relation to medicine and agriculture. bac·te analyses were completed on samples from swimming pools and whirlpools in Washtenaw County, Michigan Washtenaw County is a county in the U.S. state of Michigan. As of the 2000 census, the population was 322,895. Its county seat is Ann Arbor.6 The United States Office of Management and Budget defines the county as part of the Detroit–Warren–Flint Combined . The results from the ATP assay were compared with those from the conventional plate count method and were found to be highly correlated (r = .92). To assess whether a prefiltration step was necessary to delete nonbacterial ATP--which might originate from bathers' skin cells or other debris--two procedures were tested: one with prefiltration and one without prefiltration. The results for prefiltered samples were not statistically different from the result s for non-prefiltered samples (p [greater than] .05), for both the heterotrophic heterotrophic /het·ero·tro·phic/ (-tro´fik) not self-sustaining; said of microorganisms requiring a reduced form of carbon for energy and synthesis. plate counts and the ATP bioluminescence method. This study indicates that the ATP assay can estimate bacterial levels in pools within minutes and without preffitration. Introduction The sanitary quality of swimming pools and whirlpools is a concern for swimmers, because unintentional ingestion ingestion /in·ges·tion/ (-chun) the taking of food, drugs, etc., into the body by mouth. in·ges·tion n. 1. The act of taking food and drink into the body by the mouth. 2. of the water, inhalation, and contact while swimming make it possible to acquire gastrointestinal illness, and skin, ear, eye, and upper-respiratory-tract infections. Many local and state health departments require microbiological monitoring of recreational waters on a regular basis. There has been debate, however, about what indicators are best for estimating the safety of pool water. Coliform bacteria coliform bacteria Rod-shaped bacteria usually found in the intestinal tracts of animals, including humans. Coliform bacteria do not require but can use oxygen, and they do not form spores. They produce acid and gas from the fermentation of lactose sugar. continue to be recommended because they can indicate fecal contamination (American Public Health Association The American Public Health Association (APHA) is Washington, D.C.-based professional organization for public health professionals in the United States. Founded in 1872 by Dr. Stephen Smith, APHA has more than 30,000 members worldwide. [APHA], American Water Works Association American Water Works Association (AWWA) is an international nonprofit professional organization dedicated to the improvement of drinking water quality and supply. It was founded in 1881 and, as of 2007, there are approximately 60,000 AWWA members world-wide. [AWWA AWWA American Water Works Association AWWA Army Wives Welfare Association (India) AWWA Australian Water and Wastewater Association ], & Water Environment Federation [WEF WEF World Economic Forum WEF Water Environment Federation WEF Winter Equestrian Festival (Wellington, FL) WEF With Effect From (aviation) WEF World Environment Fund WEF Weight Enumerating Function ], 1998), while Staphylococcus aureus Staphylococcus au·re·us n. A bacterium that causes furunculosis, pyemia, osteomyelitis, suppuration of wounds, and food poisoning. Staphylococcus aureus Staphylococcus pyogenes , Candida albicans Candida albicans, n a pathogenic yeast, which is the causal agent of thrush, vaginal infections, and systemic candidiasis. Candida albicans , and Pseudomonas aeruginosa Pseudomonas aeruginosa A normal soil inhabitant and human saprophyte that may contaminate various solutions in a hospital, causing opportunistic infection in weakened Pts Clinical Infective endocarditis in IVDAs, RTIs, UTIs, bacteremia, meningitis, 'malignant' have been suggested for the assessment of microorganisms shed by swimmers (Klapes & Vesley, 1986; Rivera & Adera, 1991; Sato, Sanchez, Alves, Stoppe, & Martins, 1995; Seyfried & Fraser, 1980). For whirlpool-associated infection , Pseudomonas aeruginosa and Legionella pneumophila Legionella pneumophila is a thin, pleomorphic, flagellated Gram-negative bacterium of the genus Legionella.[1] L. pneumophila is the primary human pathogen in this group and is the causative agent of legionellosis or Legionnaires' disease. also have been suggested (Geldreich, Highsmith, & Martone, 1985). The most common microbiological tests for assessing the sanitary quality of recreational waters are, however, heterotrophic counts and total- and fecal-coliform tests (APHA et al., 1998). The problem is that these tests take 18 to 48 hours, so the analyses cannot provide timely results for public-health decisions. A pool may be closed too late, or the opening of a pool may be delayed until a test result is known. Thus, a rapid detection method that gives real-time results and is easy to use for routine analysis would be desirable. The adenosine triphospate (ATP) bioluminescence method meets these criteria. The overall objective of the research reported here was to determine whether the ATP bioluminescence assay is applicable for rapid determination of total bacteria levels in swimming pools and whirlpools. The testing focused on heterotrophic bacteria because total-bacteria count provides information on the efficacy of disinfection disinfection, n the process of destroying pathogenic organisms or rendering them inert. disinfection, full oral cavity, n a procedure used to reduce active periodontal disease, usually completed within a certain short time frame. , sanitary conditions, and maintenance. Furthermore, studies have shown that numbers of heterotrophic bacteria correlated well with bather loads (Martins et al., 1995) and that many swimming-associated diseases (e.g., ear, skin, eye, and upper-respiratory-tract infections) are not necessarily of fecal origin (Favero, 1985; Mossel, 1986). An ATP bioluminescence method based on the ATP content of the bacteria in the water has been developed. The principle of this assay is the quantification of adenosine triphosphate, which is an energy-rich molecule found in all living cells. The bioluminescence is associated with the reaction between luciferase luciferase (loosif´  rās´),n an enzyme present in certain luminous organisms that act to bring about the oxidation of luciferins; energy produced in the (enzyme), luciferin luciferin (loosif´ rin),n a chemical substance present in certain luminous organisms that, when acted upon by the enzyme luciferase, produces a glow called (substrate), and ATP (Qureshi & Patel, 1976). The light emitted during the reaction can be measured quantitatively and correlated with the ATP quantity extracted from bacteria. Luciferase reactions are rapid, requiring only minutes to complete. There is no need to isolate and incubate incubate /in·cu·bate/ (in´ku-bat) 1. to subject to or to undergo incubation. 2. material that has undergone incubation. in·cu·bate v. 1. bacteria before analyses. Thus, this method can rapidly enumerate To count or list one by one. For example, an enumerated data type defines a list of all possible values for a variable, and no other value can then be placed into it. See device enumeration and ENUM. total numbers of viable bacterial cells (Lee & Deininger, 1999). The study reported here also examined whether a prefiltration step is necessary to delete any nonbacterial ATP that might derive from bathers' skin cells and other debris. Materials and Methods Pool Samples During the summer (June-August) of 2000, a total of 39 samples were randomly obtained according to according to prep. 1. As stated or indicated by; on the authority of: according to historians. 2. In keeping with: according to instructions. 3. the regular sampling plans of the Washtenaw County Division of Environmental Health (WCDEH) in Ann Arbor, Michigan  “Ann Arbor” redirects here. For other uses, see Ann Arbor (disambiguation). Ann Arbor is a city in the U.S. state of Michigan and the county seat of Washtenaw County. . Samples were collected from disinfected Disinfected Decreased the number of microorganisms on or in an object. Mentioned in: Isolation swimming pools and whirlpools in compliance with APHA Standard Methods. A sufficient amount of sodium thiosulfate sodium thiosulfate, Na2S2O3, colorless crystalline compound that is more familiar as the pentahydrate, Na2S2O3·5H2 was present in the sampling bottles to neutralize the chlorine residual in the samples. All samples were processed immediately upon arrival, and duplicate samples were processed by a WCDEH contract laboratory. Sample Analyses The WCDEH samples were analyzed for coliform bacteria, E. coli E. coli: see Escherichia coli. E. coli in full Escherichia coli Species of bacterium that inhabits the stomach and intestines. E. coli can be transmitted by water, milk, food, or flies and other insects. bacteria, and heterotrophic bacteria. The coliforms and E. coli were simultaneously tested with Colilert (IDEXX, Westbrook, Maine Westbrook is a city in Cumberland County, Maine, United States. The population was 16,142 at the 2000 census. Originally part of Falmouth, the settlement once known as Saccarappa was incorporated as Stroudwater in 1814, but soon changed its name to Westbrook, after an early ) according to the manufacturer's instructions. After incubation at 35[degrees]C for 24 hours Adv. 1. for 24 hours - without stopping; "she worked around the clock" around the clock, round the clock , each sample was checked for the presence of coliform bacteria. If the test was positive, the presence of E. coli was confirmed by a fluorescence check. The heterotrophic bacteria were counted by the standard plate count (SPC 1. (business) SPC - Statistical Process Control. Something to do with quality management. 2. (body) SPC - Software Productivity Centre. 3. (company) SPC - Software Publishing Corporation. 4. ) method after incubation at 35[degrees]C for 24 hours (APHA, AWWA, & WEF, 1998). These tests were carried out by an independent laboratory that contracted with WCDEH. Duplicate samples were analyzed at the University of Michigan (body, education) University of Michigan - A large cosmopolitan university in the Midwest USA. Over 50000 students are enrolled at the University of Michigan's three campuses. The students come from 50 states and over 100 foreign countries. to determine the bacterial ATP level by the bioluminescence method and to produce a seven-day R2A agar plate count, both in triplicate. ATP Bioluminescence Concentrating Water Samples Details of the ATP bioluminescence method and of the procedure for concentrating water samples are described by Lee and Deininger (1999). Briefly, a Filtravette[TM] (New Horizons Diagnostics, Columbia, Maryland), which is a combination of a filter and a cuvette cuvette /cu·vette/ (ku-vet´) [Fr.] a glass container generally having well-defined characteristics (dimensions, optical properties), to contain solutions or suspensions for study. cu·vette n. with pore size of 0.45 micrometers ([micro]m), was used to filter water samples. The volumes of water used for testing were between 0.1 and 20 milliliters (mL), based on the expected number of bacteria in the sample. When the filtration volume was more than 0.5 mL, a sterile syringe was used for drawing the water samples. In this case, the Filtravette was placed into a 13-millimeter Swinex filter holder (Millipore Corporation, Bedford, Massachusetts), the filter holder was screwed onto the syringe, and the water sample was pushed through. The Filtravette then was removed from the filter holder and placed onto sterile blotting paper. The remaining water inside the filtravette was removed with a specially converted 3-mL syringe through application of gen tle air pressure. Prefiltration To assess whether a prefiltration step would be needed to remove nonbacterial ATP-containing cells that might derive from human skin or other sources, the authors used a prefilter with a pore size of 5[micro]m (New Horizons Diagnostics, Columbia, Maryland). Results from the ATP assay and the R2A count were compared for the two sets of procedures--one with prefiltration and the other without. Light Emission A somatic somatic /so·mat·ic/ (so-mat´ik) 1. pertaining to or characteristic of the soma or body. 2. pertaining to the body wall in contrast to the viscera. so·mat·ic adj. cell-releasing agent (New Horizons Diagnostic Corporation, Columbia, MD) was used according to the manufacturer's instructions to lyse lyse (liz) 1. to cause or produce disintegration of a compound, substance, or cell. 2. to undergo lysis. lyse or lyze v. To undergo or cause to undergo lysis. all nonbacterial cells. Air pressure was used to expel the released nonbacterial ATP through the filter. At this stage, the Filtravette retains only bacteria on its surface. The Filtravette was then inserted into the microluminometer (Model 3550, NHD NHD National History Day NHD National Hydrography Dataset NHD Natural Heritage Division NHD Non-Homogeneity Detector NHD National Heritage Database NHD Netscape Hypertext Document , Columbia, Maryland), and the bacterial cell-releasing agent was added according to the manufacturer's instructions to lyse the bacterial cells retained on the surface of the filter. The released bacterial ATP was mixed with 50 microliters ([micro]L) of luciferin-luciferase (NHD, Columbia, Maryland), and the light emission was recorded after 10-second integration of the light impulses. The unit of measure was relative light unit (RLU RLU Relative Light Unit RLU Relative Luminescence Units RLU Report Layout Utility (IBM) RLU Remote Line Unit RLU Registered Linux User RLU Raised Leg Urination (wolves) RLU Rack Location Unit ). The result was expressed as RLUs/mL, indicating division of the RLU values by the filtered-sample volume. The activity of the luciferin-luciferase was checked with an ATP standard (NHD, Co lumbia, Maryland) according to the manufacturer's instructions. The RLUs are proportional to the amount of ATP, and the amount of ATP is proportional to the number of viable bacteria (Lee & Deininger, 1999). Results and Discussion Out of a total of 39 samples, the R2A count found 12 showing high bacteria counts--defined as over 200 colony-forming units per milliliter milliliter /mil·li·li·ter/ (mL) (-le?ter) one thousandth (10-3) of a liter. mil·li·li·ter n. Abbr. (CFUs/mL) (Table 1). The other 27 samples had acceptable bacteria levels. By contrast, the SPC method found four samples with over 200 CFUs/mL. The R2A method produced more colony counts than the SPC because R2A is a low-concentration medium, has a greater variety of nutrients than SPC and maximizes bacterial recoveries in water that has been treated with a disinfectant (Reasoner & Geldreich, 1985). In some cases, high bacterial counts were obtained by R2A while SPC produced no colonies at all. This discrepancy might be attributable to the presence of slow-growing bacteria that cannot be detected within the SPC incubation time of 24 hours but can grow during the longer period of time used by the R2A method. The chlorine residual varied from 0.1 to 5.0 mg/L, and the pH was in the range of 7.0 to 8.0. E. coli bacteria were not detected during the study period, but coliforms were present in six samples. The results obtained from the ATP bioluminescence method were compared with the results from the traditional plate count method. Good correlation (r = .92) was found between the two methods (Figure 1). The ATP assays were conducted before the HPC (Handheld PC) A palmtop computer that weighs less than one pound and runs specialized versions of popular applications. Microsoft coined the term for its Windows CE operating system, which is an abbreviated version of Windows. See Pocket PC. assays. On the basis of the RLUs/mL value found by the ATP method, the approximate HPC could be predicted. In other words Adv. 1. in other words - otherwise stated; "in other words, we are broke" put differently , the ATP results enabled the analyst to choose the optimum sample volume for inoculation inoculation, in medicine, introduction of a preparation into the tissues or fluids of the body for the purpose of preventing or curing certain diseases. The preparation is usually a weakened culture of the agent causing the disease, as in vaccination against and the dilution rate for the HPC method. Thus, impossible plate count readings--too numerous to count (TNTC TNTC Too numerous to count Lab medicine A popular abbreviation for a 'lawn' of bacteria on a culture plate that may be seen in UTIs–confluent growth is equal to ±105 colonies Medtalk An abbreviation facetiously used for a hypochondriac Pt's list of complaints ) and [greater than]5,700 CFUs/mL, for instance--were avoided. Another advantage was the wide range of filtration volume of the ATP assay For this study the filtration volume was between 0.1 and 20 mL. The ATP method allows researchers to work with volumes down to 0.01 mL and also up to 50 mL. This latitude means that the time and effort involved in performing a dilution step can be saved. The microluminometer is about the size of a handheld calculator, and all the other necessary equipment fits onto a clipboard (see photos on page 11). Thus instead of delivering pool samples to a laboratory, one can perform the ATP assay on site. For bacteria in a swimming pool, the level of concern is [greater than]200 CFUs/mL (APHA, AWWA, & WEF, 1998). With the microluminometer used in this study the detection limit for ATP bioluminescence was 0.2 picogram picogram /pi·co·gram/ (pg) (pi´ko-gram) one-trillionth (10-12) of a gram. pi·co·gram n. Abbr. pg One-trillionth (10-12) of a gram. of ATP, which corresponds to approximately 4 CFUs (Lee & Deininger, 1999). Thus, bacteria at the level of concern can surely be detected by the ATP bioluminescence method. Since the authors also wished to know whether a prefiltration step was needed to remove nonbacterial ATP that, if present, might give a false positive, the HPC measurements with prefiltration and without prefiltration were compared by paired t-test ([H.sub.o]: [[micro].sub.d] = 0) (Table 2). No significant difference was observed in the determination of HPC from swimming pools and whirlpools (p [greater than] .05). The ATP results for prefiltered and non-prefiltered samples also were compared by paired t-test (Table 3). This comparison also found no statistically significant difference in ATP measurement for prefiltration and non-prefiltration. These results indicate that use of the somatic cell--releasing agent to lyse nonbacterial cells is effective enough on its own to remove nonbacterial ATP in pool samples and that a prefiltration step is not necessary. Conclusions The results from the ATP assay correlated well with those from conventional procedures. For removal of possible nonbacterial ATP from pool water, the treatment with a somatic cell--releasing agent was good enough, and prefiltration was not necessary. Use of a miniaturized handheld luminometer made it possible to perform the test on site. With this method, only minutes pass from the time a sample is collected until the bacteria level in a pool is known. Decisions about the closing and reopening of a pool can be made promptly with real-time bacteriological data. This method also could increase pool safety, because disinfectant doses can be adjusted in a timely manner. Thus, ATP bioluminescence can be used as an alternative tool to assess the bacteriological quality of swimming pools and whirlpools. Acknowledgements: This study was partially supported by a grant from the Office of Vice President for Research, the University of Michigan, Ann Arbor, Michigan. The authors thank Richard Badics at the Washtenaw County Division of Environmental Health for providing pool samples. Corresponding Author: JiYoung Lee, Postdoctoral Research Fellow, Department of Environmental Health Sciences, University of Michigan 109 S. Observatory, Ann Arbor, MI 48109. REFERENCES American Public Health Association, American Water Works Association, Water Environment Federation, (1998). Standard methods for the examination of water and wastewater. (20th ed.). Washington, DC: American Public Health Association. Favero, M.S. (1985). Microbiologic indicators of health risks associated with swimming. American Journal of Public Health The American Journal of Public Health (AJPH) is a peer reviewed monthly journal of the American Public Health Association (APHA). The Journal also regularly publishes authoritative editorials and commentaries and serves as a forum for the analysis of health policy. , 75(9), 1051-1054, Geldreich, E.E., Highsmith, A.K., & Martone, W.J. (1985). Public whirlpools--The epidemiology and microbiology of disease. Infection Control, 6(10), 392-393. Klapes, N., & Vesley, D. (1986). Rapid assay for in situ In place. When something is "in situ," it is in its original location. identification of coagulase-positive staphylococci staph·y·lo·coc·cus n. pl. staph·y·lo·coc·ci A spherical gram-positive parasitic bacterium of the genus Staphylococcus, usually occurring in grapelike clusters and causing boils, septicemia, and other infections. recovered by membrane filtration from swimming pool water. Applied and Environmental Microbiology Applied and Environmental Microbiology is an academic journal published by the American Society for Microbiology. The title is commonly abbreviated AEM and the ISSN is 0099-2240 for the print version, and 1098-5336 for the electronic version. 52(3), 589-590. Lee, J., & Deininger, R.A. (1999). A rapid method for detecting bacteria in drinking water drinking water supply of water available to animals for drinking supplied via nipples, in troughs, dams, ponds and larger natural water sources; an insufficient supply leads to dehydration; it can be the source of infection, e.g. leptospirosis, salmonellosis, or of poisoning, e.g. . Journal of Rapid Methods and Automation in Microbiology 7(2), 135-145. Martins, M.T., Sato, M.I.Z., Alves, M.N., Stoppe, N.C., Prado, V.M. & Sanchez, P.S. (1995). Assessment of microbiological quality for swimming pools in South America. Water Research. 29(10), 2417-2420. Mossel, D.A.A. (1986). Microbiological markers for swimming-associated infectious health hazards. American Journal of Public Health, 76(3), 297. Qureshi, A.A., & Patel, J. (1976). ATP levels in microbial microbial pertaining to or emanating from a microbe. microbial digestion the breakdown of organic material, especially feedstuffs, by microbial organisms. cultures and a review of the ATP biomass estimation technique (Scientific Series No. 63). Burlington, Ontario: Canada Center for Inland Waters Canals, lakes, rivers, water courses, inlets, and bays that are nearest to the shores of a nation and subject to its complete sovereignty. Inland waters, also known as internal waters, are subject to the total sovereignty of the country as much as if they were an actual part . Reasoner, D.J., & Geldreich, E.E. (1985). A new medium for the enumeration 1. (mathematics) enumeration - A bijection with the natural numbers; a counted set. Compare well-ordered. 2. (programming) enumeration - enumerated type. and subculture of bacteria from potable potable /pot·a·ble/ (po´tah-b'l) fit to drink. po·ta·ble adj. Fit to drink; drinkable. potable fit to drink. water. Applied and Environmental Microbiology, 49(1), 1-7. Rivera, J.B., & Adera, T. (1991). Assessing water quality-- Staphylococci as microbial indicators in swimming pools. Journal of Environmental Health, 53(6), 29-32. Sato, M.I.Z., Sanchez, P.S., Alves, M.L., Stoppe, N.C., & Martins, M.T. (1995). Evaluation of culture media for Candida albicans and Staphylococcus aureus recovery in swimming pools. Water Research, 29(10), 2412-2416. Seyfried, P.L., & Fraser, D.J. (1980). Persistence of Pseudomonas aeruginosa in chlorinated chlorinated /chlo·ri·nat·ed/ (klor´i-nat?ed) treated or charged with chlorine. chlorinated charged with chlorine. chlorinated acids some, e.g. swimming pools. Canadian Journal of Microbiology, 26(3), 350-355.
TABLE 1
Bacteria Levels in Swimming Pools and Whirlpools--Comparison of Results
from Different Assays
WCDEH a UM b
Sample Number E. coli Coliforms SPC R2A
(CFUs/mL) (CFUs/mL)
1S e 0 present 68 480
2W f 0 present [greater than]5,700 360,000
3S 0 0 5
4S 0 present 0 20
5S 0 present 29 500
6S 0 0 3,000
7S 0 0 0
8S 0 0 2300
9S 0 0 0
10S 0 0 26,000
11S 0 800 45,000
12S 0 13 5
13S 0 90 290
14S 0 17 11
15S 0 present [greater than]5,700 1,300,000
16W 0 0 0
17S 0 0 2
18S 0 0 9,200
19S 0 0 3
20S 0 0 0
21S 0 0 0
22S 0 0 1
23S 0 0 150
24S 0 0 16
25S 0 0 36
26S 0 0 2
27S 0 0 10
28S 0 0 3
29S 0 0 1
30S 0 0 2
31S 0 0 1
32S 0 0 34
33S 0 0 15,000
34S 0 present 2,600 1,600
35W 0 32 77
36W 0 0 24
37W 0 0 2
38W 0 0 4
39W 0 0 1
Chemical Parameters c
Sample Number pH Chlorine d
(mg/L)
1S e 7.6 1.5
2W f 8.0 0.5
3S 7.6 2.0
4S 7.6 1.0
5S 8.0 0.5
6S 7.6 2.0
7S 7.6 0.5
8S 7.2 3.0
9S 7.2 5.0
10S 7.6 3.0
11S 7.0 0.1
12S 7.4 2.0
13S 7.2 0.1
14S 7.2 5.0
15S 8.0 0.1
16W 7.0 5.0
17S 7.2 5.0
18S 7.6 1.5
19S 7.2 1.0
20S 7.6 3.0
21S 8.0 5.0
22S 7.0 5.0
23S 8.0 1.0
24S 7.8 2.0
25S 7.8 5.0
26S 7.8 5.0
27S 7.0 2.0
28S 7.0 1.0
29S 7.0 2.0
30S 7.0 2.0
31S 7.4 3.0
32S 7.2 3.0
33S 7.4 2.0
34S 7.6 3.0
35W 7.4 1.5
36W 7.8 1.5
37W 7.8 5.0
38W 7.2 5.0
39W 7.0 5.0
(a)Washtenaw County Division of Environmental Health.
(b)University of Michigan
(c)WCDEH data.
(d)Total chlorine residual.
(e)S = swimming pool.
(f)W = whirlpool.
TABLE 2
HPC Results With and Without Prefiltration
Sample With Without
Number Prefiltration Prefiltration
(CFUs/mL) (CFUs/mL)
1 1,502 477
2 145,107 355,828
3 1 5
4 5 20
5 730 500
6 1,000 3,000
7 0 0
8 924 2,324
9 1 0
10 18,762 26,153
11 32,680 45,464
12 8 5
13 191 290
14 21 11
15 1,007,727 1,339,312
16 0 0
17 3 2
18 1,414 9,165
19 2 3
20 0 0
21 0 0
22 1 1
23 340 152
24 5 16
25 6 36
26 2 2
27 2 10
28 2 3
29 1 1
30 2 2
31 3 1
32 21 34
33 10,954 15,485
34 387 1,600
35 50 77
36 18 24
37 6 2
38 3 4
39 10 1
TABLE 3
ATP Results with and Without Prefiltration
Sample With Without
Number Prefiltration Prefiltration
(RLUs/mL) (RLUs/mL)
1 143 173
2 17,110 18,424
3 0 2
4 0 0
5 18 36
6 228 1,226
7 0 0
8 20 66
9 0 0
10 183 136
11 134 398
12 0 0
13 2 15
14 0 0
15 5,470 4,673
16 0 0
17 0 0
18 171 478
19 0 0
20 0 0
21 0 0
22 0 0
23 15 37
24 0 0
25 0 3
26 0 0
27 0 0
28 0 0
29 0 0
30 0 0
31 0 0
32 0 0
33 136 245
34 78 464
35 0 16
36 1 0
37 0 0
38 3 0
39 0 0
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