The bacteriological examination of molluscan shellfish

Clegg, L. F. L.; Sherwood, H. P.

doi:10.1017/s0022172400014236

Cited by 35 publications

(19 citation statements)

References 14 publications

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“…If bacteriological survey is to be applied to the problem of beach contamination, and if it is accepted that for the results to be of value, a large number of samples should be examined, a simple test for coliform organisms would be invaluable. The technique suggested by Clegg & Sherwood (1947) for shellfish examination or the membrane filter method (Goetz & Tsuneishi, 1951) are examples of techniques which might prove suitable for this purpose. Whether a simplification of bacteriological technique was practicable would depend to some extent on what degree of contamination it was desired to demonstrate.…”

Section: Discussionmentioning

confidence: 99%

A survey of beach pollution at a seaside resort

Moore

1954

J. Hyg.

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A series of infections with Salmonella paratyphi B which occurred at a seaside resort in North Devon every summer between 1943 and 1946 concentrated local attention on a very unsatisfactory sewage outfall, which discharged into the sea at all stages of the tide and frequently caused fouling of the adjacent beach. The local authority, concerned at the possible association between beach pollution and the enteric infections and also by the prospect of serious economic loss in an area dependent on the summer tourist traffic, planned a new sewage disposal scheme based on the controlled discharge of sewage into the sea from a point which had been shown by float tests to be more suitable than the old outfall site.After discussion with the local sanitary authority and the consulting engineers who drew up the plans for the new scheme, it was agreed that bacteriological surveys of the outfall area should be made both before and after the installation of the new scheme. The main purpose of this paper is to give the results of these surveys, the first of which was carried out in the summer of 1948 and the second in the summer of 1950, 3 months after the new scheme had come into operation. ENGINEERING AND EPIDEMIOLOGICAL ASPECTS OF BEACH POLLUTIONThe problem of sewage pollution of bathing beaches is a complex one. The discharge of sewage into the sea from coastal towns is determined partly by financial considerations and partly by the lack of suitable space for sewage works in most seaside resorts. If the sewage outfall can be pushed far enough out to sea and the sewage liberated at a reasonable depth below the surface, pollution of beaches will not occur, and this method has been successfully used at several seaside towns in this country, e.g. Bournemouth and Brighton. The prolongation of outfalls for long distances under the sea is, however, both difficult and expensive, and in many coastal areas sewer outfalls discharge sewage just below or even above low-water mark. Where this occurs on a beach used for bathing, two quite distinct problems arise. One is the health hazard occasioned by the deliberate discharge of potentially pathogenic material; the other is an aesthetic problem when the amenities of the area are affected by deposition of excreta on the sands, discoloration of the sea water by 'sleek' fields and the formation of slimy deposits on the beach round the outfall. The disfiguration of a popular beach by sewage may discourage summer visitors, and active local authorities are justified even on economic grounds in planning sewage disposal schemes which minimize the pollution of their beaches.If this problem is approached on frankly aesthetic grounds, it should be possible to set a maximum permitted level of sea water contamination on a bathing beach below which a sewage nuisance is very unlikely, and plans for an adequate sewage

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Section: Discussionmentioning

confidence: 99%

A survey of beach pollution at a seaside resort

Moore

1954

J. Hyg.

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“…In early roll-tube experiments, the MacConkey agar used was the modified medium of Clegg & Sherwood (1947) as recommended for the examination of shell-fish. For plate counts, the medium was made as described in Report no.…”

Section: Mediamentioning

confidence: 99%

“…An attempt was made at first to use for sea-water examinations the roll-tube technique described by Clegg & Sherwood (1947) for the examination of shell-fish, i.e. a direct faecal coli count on roll-tubes incubated at 440 C. The development of this test for the examination of shell-fish occurred in two stages.…”

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confidence: 99%

“…In the first, a direct 440 C. test in MacConkey broth was introduced by Dodgson (1938) in order to avoid the misleading results given at 370 C. by organisms of the aerogenescloacae groups that had multiplied within the shell-fish. In the second, a 440 C. count on MacConkey agar was introduced by Clegg & Sherwood (1947) to avoid the big sampling error inherent in the liquid dilution method of counting. It will be shown below that in the grading of bathing beaches the results obtained were not materially altered whether the presumptive or the faecal coli counts were used as a basis for comparison.…”

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confidence: 99%

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Sewage contamination of coastal bathing waters in england and wales A bacteriological and epidemiological study

1959

Epidemiol. Infect.

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1. Bacteriological surveys of more than forty popular bathing beaches around the coasts of England and Wales have been made during the past 5 years. The great majority of the beaches studied were subject to contamination with sewage.2. A rough grading of the beaches studied gave a similar ranking order whether the results of the presumptive coliform test or faecal coli counts were used as the basis of grading.3. Grading of beaches was valid only when surveys were carefully planned to ensure representative sampling from the areas on the beaches concerned where bathing actually took place.4. The coliform test as used in the bacteriological examination of drinking waters was the main test procedure used but had certain limitations. Promising results with plate counts on relatively non-inhibitory media were obtained.5. Various salmonella serotypes, notablySalm. paratyphi B, were isolated in small numbers from a high proportion of sea-water samples. The proportion of positive results for salmonella isolation increased from 13·3% in samples with less than 1000 coliform organisms per 100 ml. to 40·1% in samples with over 10,000 coliforms per 100 ml. Comparison of the numbers of salmonellae isolated with what is known of the minimum infective doses of these organisms suggested that very large volumes of sea water would require to be ingested for infection to occur.6. Poliovirus was not isolated from a small series of sea-water samples examined. Because of the very large dilution factor, special concentration procedures would probably be required to isolate this virus from sea water.7. Four cases of paratyphoid fever probably due to bathing were recorded. Surveys of the two associated beaches had given median presumptive coliform counts of more than 10,000 per 100 ml., and both showed gross macroscopic pollution with sewage.8. A statistically controlled study of the bathing histories of 150 poliomyelitis cases in children living permanently by the seaside gave no evidence that bathing had played any part in causing the disease.

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“…Although the specificity of this faecal bacteria indicator has been questioned (Hood, Ness & Blake, 1983), it has the advantage of being relatively easy to detect. In the United Kingdom E. coli in shellfish are still mainly enumerated using the technique of Clegg & Sherwood (1947). This involves the addition of a dilution of macerated shellfish tissue to molten agar containing bile salts, followed by incubation at 44°C for 18 h, either as a pour plate or roll tube.…”

Section: Introductionmentioning

confidence: 99%