ntensive spot examination of swimming pool water during heavy bathing loads yielded varying numbers of cocci per sample. Pollution appeared to be pockets of contamination that disappeared as a result of dissemination and destruction by chlorine. The relation to spread of diseases was not studied, but this problem requires investigation. COCC TEST FOR DETECTNG MOUTH AND NOSE POLLUTON OF SWMMNG POOL WATER W. L. Mallmrann, Ph.D., F.A.P.H.A. SNCE 195, it has been routine in our laboratory to test all swimming pool water samples quantitatively for streptococci. From 195 to 194, the lactose broth tubes were examined for streptococci. From 194 to 195 a medium reported by the author,1 dextrose azide buffered tryptose broth, was used. Turbidity in this medium was used as evidence of streptococci, although gram stains of the growth were examined periodically. Since 195, a medium, dextrose azide broth, reported by Mallmann and Seligmann, was used. When this medium was compared with lactose broth and S. F. broth, 45 C much higher counts of streptococci were found. An examination of the streptococci was made by Seligmann3 who found that of the 13 isolants, 43 per cent were Staphylococcus epidermidis, 7 per cent were Streptococcus mitis, 15 per cent Staphylococcus salvarius, 1 per cent Streptococcus faecalis, and 5 per cent unidentified micrococci. Forty-two per cent were buccal streptococci while 1 per cent were fecal streptococci. Because a mixture of cocci was found consisting of the above organisms, it was recommended that the test be called a "coccus test." nasmuch as these organisms emanate from the mouth, nose, and feces, they are indicative of pathogens from these areas, both bacteria and viruses. Fourteen school pools are tested routinely in our laboratory, four senior high schools, four junior high schools, one Y.M.C.A., one Y.W.C.A., and four university pools. The samples are collected by the operators and are delivered to the laboratory by a representative of the county health department, with the exception of the university samples. These are delivered by the operators. Each sample is accompanied by a report of the ph, chlorine residual, and the number of bathers at the time of the collection. Each sample is tested for coliform organisms by planting five 1-ml portions in lauryl tryptose broth and the cocci by five 1-ml portions in dextrose azide broth. Only the coliform most probable number (MPN) is reported to the county health department. The data for the period of September 8, 196, to March 1, 1961, were selected at random for examination. DECEMBER, 1996 1
Station 3.Z, 11'N tation Station a -1 4 5 Figure 1-Cocci in swimming pool Pg expressed as log MPN. The chlorine residual was.75 free, 1. combined ppm, the ph 7.6, and the bathing load boys. --A- During this period, 77 samples were examined. Only two samples showed coliform organisms and then in only one tube per sample. Cocci were found in one or more of the five 1-ml (1+) tubes in 33. per cent of the samples, and in three or more (3+) tubes, 15 per cent. n three junior high school pools of the same size with approximately the same bathing load and chlorine residuals, the percentages for 1+ tubes were pool Pg-39; pool F-47, and pool W- per cent; and for 3 + tubes were pool Pg-, pool F-5.9, and,/ v cl, - %lb, lb - *'4k % Station 3 Station Station 1 5 Figure -Cocci in swimming pool Pg expressed as log MPN. The chlorine residual was 1. (free), 1.4 (combined) ppm, the ph 7.9, and the bathing load boys. VOL. 5. NO. 1. A.J.P.H.
...,.w* EXAMNATON OF SWMMNG POOL WATER., Station 3..*~~~~~~~~~~~~.. ctdlu1 Station Stat ion 1 3 4 5 Figure 3-Cocci in swimming pool Pg expressed as log MPN. The bromine residual was 1.7 ppm, the ph 7., and the bathing load boys. pool W-1. Another pool (pool Y) percentages of 1+ tubes were 5 and 3+ this basis, we may assume that the posi- more resistant than the streptococci. On tubes 6.. tive cocci tests with MPN's of. and Seligmann3 found that when coccus 5.1 represent resistant Staph. epidermidis pollution was high, streptococci were whereas higher incidences may represent mouth and nose contamination. On present in high dilution. n chlorine resistance studies Staph. epidermidis was this assumption, from 6. to per cent StaStation 1 \ Station Station 3 1 3 4 5 Samiipie Numbers Figure 4-Cocci in swimming pool Y ex(pressed as log MPN. The chlorine residual was.35 (free), 1. (combined) ppm. the ph 7.4, and the bathing load 4 boys. DECEMBER. 196 3
/ Statior 3 : \t -,tatior 9 z CL V Station a) r o a a o -- 3 5 Sample Numbers Figure 5-Cocci in swimming pool Y expressed as log MPN. was 1.65 ppni, ph 6.7, and the bathing load 6 boyvs. The bromine residual of samples from the three pools indicate significant pollution. Unfortunately there are no good epidemiological studies on the role of swimming pool water as a source of disease. Typhoid fever has been caused by swimming in sewage polluted waters. What may happen to swimmers who come into contact with fresh gross contamination from adjacent swimmers is not known. Swimming pool bacteriological standards are really standards of attainability and are not based on epidemiological evidence. The permissible coliform organism content of swimming pools is the same as that for drinking water. On the assumption that the absence of coliform organisms is indicative of the absence of intestinal pathogens of comparable resistance, a pool showing no coliforms in five 1-ml portions over a period of testing would be safe for bathing. This standard does not necessarily mean the absence of viruses and bacteria with greater chlorine resistance from mouth and nose and fecal contamination. Bathing thoroughly before entering a pool lessens microbial contamination on the body surfaces, but does nothing to change the microbial populations of the mouth and nose. Unfortunately while swimming. the bather flushes the mouth and nose with pool water and discharges the waste water into his environment. Momentarily this waste water may be a point of high pollution depending upon the kinds and numbers of microorganisms discharged. Conceivably an adjacent bather could take this pollution into his mouth and nose before the organisms could be disseminated and exposed to the action of the chlorine. n the studies presented the samples ranged from 6 to per cent containing cocci with three to five tubes positive. Suppose a detailed examination was 4 VOL. 5, NO. 1, A.J.P.H.
EXAMNATON OF SWMMNG POOL WATER made and each sample was tested to determine maximum population. This was done on pools Pg and Y. Shortly after the bathers (maximum bathing load) * entered the pool, samples were collected on the two sides and shallow end every 3 seconds for.5 minutes, yielding five successive samples from each collection point with a total of 15 samples, plus a sample taken previous to the entry of bathers. Chlorine residuals were determined amperiometrically and ph tests were made with a Wallace-Tiernan colorimeter. All samples were collected in thiosulfate treated glass stopped bottles. n pool Pg with a bathing load of boys (two-thirds maximum bathing, * Maximum bathing load based on one bather per 35 sq ft pool area. The maximum bathing load represents one-third of the bathers on the runways and two-thirds in the water. load) ph 7.6 and a chlorine residual of.75 (free) and 1. (combined) ppm, the cocci MPN's ranged from to 13 with a median of 4.5 (Figure 1). No coliform organisms were detected. n another series of tests, the bathing load was boys, the ph 7.9, and the chlorine residual was 1. ppm (free) and 1.4 ppm (combined). The cocci MPN's ranged from to 14 with a median of 4. (Figure ). No coliform organisms were detected. During the period of testing, three routine samples were received that were for cocci. Later bromination was used in place of chlorination at this pool. n this series, with a comparable load, the amperiometric bromine residual was 1.7 ppm and the ph 7.. The cocci ranged from an MPN of to 45 with a median of 3.7 (Figure 3). Four samples gave MPN. One side of the pool yielded 31 1% % Statior 1 z J -j 1V % / \ s s Station '1 a a vl a m *- a 1 3 4 5 6 7 8 Figure 6-Cocci in swimming pool M expressed as log MPN. The chlorine residual was 1.5 ppm, the ph 6.6, and the bathing load 7 boys. DECEMBER. 196 5
3 z - ) -J j,station Station t Figure 7-Cocci in swimming pool M expressed as log MPN. The chlorine residual was.75 ppm, the ph 6.6, and the bathing load 75 boys. high cocci contents, whereas the other side was on three samples and MPN of two on the other two samples. Routine samples during the months consisted of four samples all cocci. t is interesting to note that no coliforms have been detected from routine samples, however in the series of tests reported, three samples yielded coliform, two samples had MPN's of two and one 16+. n pool Y with a bathing load of 4 (maximum load) ph 7.4 and chlorine residuals of.35 (free) and 1. (combined) ppm the cocci MPN for 15 samples varied from to 4 with a median of 17 (Figure 4). Only one sample was. The coliform organisms were absent in all samples. Routine samples collected before and after this date were negative for both cocci and coliform. At a later date when bromine treatment was in use at pool Y, the bromine residual was 1.6 (free) and.73 (combined) ppm ph 6.7 and a bathing load of 6. The cocci MPN ranged from 6.8 to 9 with a median of 7 (Figure 5). No coliforms were detected. Routine samples collected before and after this date were negative for cocci and coliform organisms. A survey was made of 6, gallon outdoor pool M with a maximum bathing load of 13 based on 35 sq ft of area per bathers. The tests were made with a bathing load in the water of 7, a ph 6.6, and a chlorine OTA residual of 1.6 ppm. Eight samples were col- 6 VOL. 5. NO. 1, A.J.P.H.
EXAMNATON OF SWMMNG POOL WATER lected on each side at 3-second intervals. The cocci index ranged from to greater than 1,6 (Figure 6). Four samples were obtained. No coliforms were detected. n another series with a bathing load in the water of 75, ph 6.6, and OTA chlorine residual of.75, the cocci index ranged from to greater than 1,6 (Figure 7). Assuming one-third of the bathers on the runways, 4 would be a maximum load in the water. Although the bathing loads in the water seldom exceeded 1, the bathers congregated on the periphery of the pool. Only a few bathers at any one time were found in the central area of the pool. Thus the maximum possible pollution would occur at the periphery of the pool. n a series when the bathing load was only 5 bathers in the water, the ph 6.8 and chlorine residual 1 ppm, only two samples yielded cocci with MPN of 5.6 and 1.8. All dextrose azide broth tubes that were positive were checked by transfers made to ethyl violet azide broth to check for the presence of enterococci. Only occasionally was the enterococci demonstrated and then only in low incidence. Discussion The most interesting observation from these studies is the finding of heavy contamination in swimming pool waters, coming probably from the mouth and nose, although Staph. epidermidis is also present. When samples were collected in a series of five to eight samples at the same point, at the edge of the pool, while bathers were actively engaged in swimming, successive samples varied from to greater than 1,6. For example, the MPN's of eight successive samples at the same point at 3-second intervals were 11, 1,6, 3.7,, 14, 1, 1,6, and 9 (Figure 7). n another series the MPN's were 11, 9., 3.6, 11, 1,6, 7, and (Figure 6). n the first series, the chlorine residual was.75 ppm, ph 6.6; in the second, the chlorine residual was 1.5 ppm, ph 6.6. Samples collected before and after the swimming period were for cocci except where chlorine residuals were low Ṫhis variability in the cocci incidence at a given point in the pool is likely due to mouth and nose discharges in the immediate vicinity of the sampling point, followed by short periods where the pollution is disseminated and the cocci are destroyed by the chlorine. f it were possible to color the areas of gross pollution during a period of heavy bathing loads, the pool water would present a mottled appearance, with deeply colored areas of heavy pollution and other rapidly fading and expanding areas as the contamination made contact with germicidal chlorine. The bathers would be constantly creating new areas of pollution as water was discharged from the mouth and nose and they would be moving into areas of varying degree of contamination, taking the contaminated water into the mouth and nose. As one watched, the pool water would yield a kaleidoscopic effect. The writer cannot evaluate the degree of health hazard that exists in swimming pools as represented by the cocci tests which have been reported in this paper. Unfortunately, as previously stated, there have been no epidemiological studies of swimming pools reported in the literature that would offer any answers. Obviously, reducing bathing loads drastically would reduce the areas of pollution and the chances of disease spread. Examination of pool water during light bathing loads has yielded positive cocci samples, but only infrequently. DECEMBER. 196 7
The maintenance of high free chlorine residuals with reduced bathing loads may help. Bromine was tried on the basis that no irritating by-products may be found. Although high bromine residuals (1- ppm) were tried, the degree of cocci pollution remained approximately the same. No studies have been made with free iodine. This study should be done. A second observation of this study pertains to the marked differences obtained by evaluating the degree of contamination of a pool by routine single samples and intensive spot examination. including repeated sampling at various sites in the pool. The individual routine sample generally yields nothing more than the fact that chance determines largely whether a good or bad sample is collected. The routine individual samples would yield significant data only when chlorine residuals are below germicidal levels and indicator organism such as coliform and cocci accumulate so the entire mass of water within the pool is contaminated. f bathing loads are low, most routine samples over a period of months would likely show little if any cocci contamination. The method, time, and place of collection also play an important part in the value of the samples collected. n pool Pg where heavy contamination was always demonstrated with heavy loads, during a period of three months, on routine sampling 7 samples out of 18 yielded cocci. n another pool (pool W) of the same size with similar bathing loads but lower chlorine residuals, only 4 out of 19 samples yielded cocci. The person collecting the sample of water from a junior high school pool generally picks a site away from the bathers to avoid being splashed. This report is presented for provocative reasons with the hope that other workers will study cocci incidence in swimming pool waters and perhaps improvements in pool operation can be made if it can be proved that the presence of cocci is indicative of health hazard by microbial agents. Summary ntensive spot examination of swimming pool water during heavy bathing loads by repeated samplings at various sites in the pool yielded varying numbers of cocci per a sample. varyinr from to MPN of greater than 1,6 cocci. Few of the cocci were enterococci as indicated by checking the positive dextrose azide broth tubes with ethyl violet azide broth. ndividual routine samples failed to yield information concerning bathing load contamination due to method, place and time of collection of the sample besides the factor of chance. Cocci pollution in swimming pools appeared to be pockets of contamination that disappeared by dissemination and destruction by chlorine. The heavier the bathing load, the greater the number of pockets of contamination. REFERENCES 1. Mallmann, W. L. A New Yardstick for Measuring Seswage Polltution. Sew. N'torks J. 1:875, 1(4.. Mallmann, W. L., and Seligmann, E. B. A Comparative Stuidy of NMedia for the Detection of Streptococci. A.J.P.H. 4:86, 195. 3. Seligmann, E. B. A Study of Streptococci and Micrococci as n(licators of Pollution in Swsimming Pool M'saters. Ph.D. thesis, Michigan State Universitv, 1951. Dr. Mallmann is professor of bacteriology, Department of Microbiology and Public Health, Micbigan State University, East Lansing, Mich. This paper was presented before a Joint Session of the Conference of Mtunicipal Public Health Engineers, the Conference of State Sanitary Engineers, the National Association of Sanitarians, and the Engineering and Sanitation Section of the American Public Health Association at the Eighty-Ninth Annuial Meeting in Detroit, Mich.. November 15, 1961. 8 VOL. 5, NO. 1, A.J.P.H.
This article has been cited by: 1. M S Favero. 1985. Microbiologic indicators of health risks associated with swimming. American Journal of Public Health 75:9, 151-154. [Citation] [PDF] [PDF Plus]