Although enteropathogenic strains of Esckerickia coli are a frequent cause of disease in human infants, it has proven difficult to establish experimental infections in animals with these organisms. The most successful results so far have been obtained by feeding cultures to mice treated with antibacterial drugs prior to the test in order to suppress their indigenous intestinal flora (1). Useful as it is, this method is obviously artificial and fails to reproduce the conditions under which the disease is commonly observed in man. The availability at The Rockefeller University of a colony of mice (NCS) maintained under so called "specific pathogen-free" conditions, and especially free of E. coli, prompted us to investigate whether these animals would prove more receptive to human strains of E. coli than mice raised under usual conditions.The experiments reported in the present paper were carried out with a culture of E. coli, serotype 026: K60 (026: B6). This type has been found to be associated with infantile diarrhea and is also occasionally recovered from animals (2); the strain used here was isolated from an infant. While the ultimate purpose of our study was to determine whether NCS mice can be used to differentiate virulent enteropathogenic strains of E. coli from ordinary strains, it seems worthwhile reporting at this time a finding of more general importance. It was found namely that the age of the animal host has a profound effect on the ability of the bacteria to colonize the intestine and on their persistence in this organ. Colonization uniformly took place when very young mice received E. coli per os, whereas adult animals usually failed to become infected under the same conditions. Indeed the population of E. coli in the gastrointestinal tract abruptly fell to very low levels around the time of weaning.
1. The presence of a new thermolabile an named β antigen has been demonstrated in motile and non-motile coliform, paracolon andProteusstrains, and inShigellabacilli (Sh. flexneri Sh. flexneriV1 and D19). This antigen can be frequently found in the above types.2. The characteristics of the β antigen have been described, and its dissimilarity to H, O, Vi, 2, A, B and α antigens has been established.3. A high incidence of β antibodies was demonstrated in normal human and rabbit sera.4. β strains of paracolon and coliform b injected intraperitoneally into mice were shown to be more virulent to mice than β minus forms of the same strains.5. It is suggested that unrecognized presence of β antigen in cultures and β antibody in human and rabbit sera may cause errors in bacteriological and serological diagnoses of enteric infections.
1. An outbreak ofSalmonella derby, involving sixty-eight patients, is described.2. The organism was isolated from clinical cases, from carriers and also from dust in the wards, from a mouse and from a hand towel used by nurses.3. The value of tetrathionate broth with subsequent cultivation on ‘SS’ agar as an aid to isolation ofSalmonellabacilli was confirmed.4. Cultural and biochemical characters ofSalm. derbywere recorded.5. The antigenic structure of the isolated strains ofSalm. derbywas demonstrated, showing the presence of factorland the absence of a minor flagellar antigen.6. A serological response toSalm. derbyinfection was shown in patients, their sera containing H antibodies of a titre 1/20 to 1/320, whereas O agglutinins were absent at the time the tests were made.7. Pathogenicity tests were performed on mice indicating the possibility of infectionper osor by intraperitoneal injections. Mice were found to be potential faecal and urinary carriers.
SUMMARYThe high incidence (8041 %) of Pseudomonas aeruginosa pyocine type 1 in bovine mastitis in Israel suggested some degree of selectivity under local conditions. Contrary to other reports, cattle and calves showed a high rate of faecal carriage of this organism. The water supply on farms was often contaminated. The presence of certain pyocine types in the udder, gut or water occasionally led to their transmission from one reservoir to another; however, many types did not seem to spread.P. aeruginosa was found in association with infections in various animals and was present in many locations such as a mouse breeding house and a chick hatchery.
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