A method for the recovery of Vibrio parahaemolyticus from seafoods is described. By this procedure, a total of 56 biochemically positive cultures of V. parahaemolyticus were recovered from market samples of Chesapeake Bay processed blue crab (cooked, picked, packed, and refrigerated meat). All of the isolates were tested serologically, and 22 strains were serotyped according to the schema of Sakazaki as follows: K3, K5, K28, K31, K36, K37, K39, K43, and K44. These results indicate the broad distribution of these specific serotypes in a seafood harvested from the Chesapeake Bay. Vibrio parahaemolyticus is the cause of a considerable number of food poisoning cases in Japan. In 1965 and 1966, it was responsible for more than 45 % of all the cases of bacterial food poisonings occurring in that country (9). Sakazaki et al. (6) list 41 specific K serotypes of this organism which have been isolated from humans ill with this disease. Of this entire group, 13 serotypes, or 32%, have not been recovered from Japanese seafoods or marine environments. Epidemiological studies suggest that marine habitats are the most probable sources of this
Surveillance for dysentery-related invasive potential in bacteria using the Sereny keratoconjunctivitis test is restricted by expense, time factor, and necessity for confirmation. Primary screening of isolates in a standardized mammalian cell culture system is recommended. Bacteria are grown 20 hr in veal infusion, washed, and resuspended in 20% heat-inactivated fetal bovine serum (FBS) supplemented with 0.12% brain heart infusion and 0.1% bile salts. The HeLa culture is grown 20 hr as a monolayer in chamber slides with 90% minimal essential medium (MEM)-10% FBS. The host culture is infected at a ratio of 10 bacteria/ mammalian cell for 3 hr at 35°C. The infection medium is replaced with MEM-FBS supplemented with 300 μg lysozyme and 5 μg gentamycin/ml. The infected monolayer is incubated 5 hr at 35°C to permit intracellular multiplication. Specimens arc washed, fixed with methanol, and stained successively with May-Grunwald and Giemsa dyes. Bacteria occur within the cytoplasm if invasion has occurred. The criterion for a positive test is that 1% of the host cells possesses at least 5 bacteria in 2 of 3 trials. Invasiveness is correlated with and possibly pre-conditioned by cytotoxic principle(s). Infectivity rates vary from 0 to 30%. The cytopathic effect is noted in 5–50% of HeLa cells. Positive results must be confirmed by the Sereny test.
The aerogenic response of Escherichia coli and strains of Aerobacter in EC broth and selected sugar broths at elevated temperatures. Appl. Microbiol. 10:79-85. 1962.-Gas formation by 116 strainis of Escherichia coli and 104 strains of Aerobacter was determined in a specially constructed and accurately controlled water bath employing EC, lactose, maltose, sucrose, glucose, levulose, and galactose broths at temperatures ranging from 44.5 to 46.5 C. Greatest gas activity occurred in EC broth. In the range 44.9 to 45.5 C over 92 % of the E. coli cultures formed gas, but the Aerobacter strains dropped from 68 to 2 %. A natural point of separation of the two groups occurred at 45.5 C. Inhibition of the gas-forming mechanism rather than death is the universal response of the Escherichia organisms to these temperatures. The inhibition increases with rising temperatures and is readily reversible. At 46.5 C, 64.5 % of all the Escherichia cultures were inhibited and 69.1 % of all the cultures were actually viable. In EC broth it was found that as a group atypical E. coli (-+-) were the most resistant gas-positive types. Least resistant in EC broth was a group of known typical fecal isolates of E. coli (++-). Of intermediate resistance between the two groups was the large body of typical E. coli (+ +-) organisms. Certain individual strains of E. coli excelled in the production of gas in the variety of sugar broths tested at elevated temperatures. The Aerobacter strains did not exhibit this property.
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