B. COLI IN MARKET OYSTERS.* 



S. Henry Ayers. 

 (From the Bacteriological Laboratory, University of Chicago.) 



Since the considerable mass of work on the subject of typhoid 

 fever and oyster infection has been recently reviewed by G. W. Fuller,' 

 there is no need of summarizing it in detail here. One aspect of the 

 subject, which is of importance from the public-health standpoint, 

 seems, however, to have received little attention. Although oysters 

 have been taken from various beds and examined for sewage pollution, 

 I believe no extended examination has been made in this country of 

 oysters obtained from city markets. In England Herdman and 

 Boyce" examined oysters from various shops, and in a very large pro- 

 portion of cases B. coli was isolated. 



It is a matter of considerable importance to know how large a 

 proportion of commercial shell oysters on sale in a given locality are 

 polluted. Knowledge of this sort will aid the health authorities of a 

 city in detecting possibilities of danger and in drying up the source of 

 infection. With this object in view, examination has been made of 

 shell oysters from a number of the principal Chicago markets. 



It has been well established that the presence of B. coli in oysters 

 indicates sewage pollution. C. A. Fuller^ has studied the relation 

 between oysters and sewage in Narragansett Bay, and has shown that 

 bacterial analyses of oysters correspond closely with analyses of river 

 water above the beds and with the opportunities for contamination as 

 determined by inspection. 



Considering B. coli as an index of pollution, the examination was 

 carried on by the following method. 



Each oyster was opened with sterile instruments, carefully removed 

 from its shell, and after being rinsed in sterile water was placed in 

 a Petri dish. The oyster was then finely minced with sterile scissors 

 and mixed with 5 c.c. of sterile water. A dextrose fermentation tube 

 was inoculated with i c.c. of the fluid from the minced oyster. If no 



* Received for publication April 13, 1906. 



'Jour. FranUin Inst., August, 1903, p. 81. ' Thompson-Yates Laboratories Rep., 1899, 2, p. 43. 

 ^ Appendix to 1904 Rep. V. S. Commissioner of Fisheries, pp. 189-238; Science, 1903, 17, p. 371. 



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