Comparison of preservation media for storage of stool samples.

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RESUMO

Transportation of clinical samples and long-term recoverability of pathogens are critical to epidemiological studies, particularly when conditions do not permit immediate processing. This study confirms that Cary-Blair medium (CB) is suitable for the preservation of Salmonella and Shigella isolates for more than 2 weeks at 25, 4, or -70 degrees C. Campylobacter jejuni was not recovered after 2 days of storage in CB at 25 degrees C when an inoculum of 12 x 10(8) cells per ml was used. Lower temperatures supported the recovery of this organism for 6 days. When individual pathogens were preserved with stools in CB and incubated at 25, 4, or -70 degrees C, the Salmonella and Shigella concentrations dropped from 12 x 10(8) cells to 1 x 10(3) or 1 x 10(4) cells per ml within 2 days and then remained stable for the rest of the observation period (15 days). C. jejuni survived preservation with stools for 5 to 9 days. The addition of blood and glycerol to CB improved the recoverability of all enteropathogens, particularly C. jejuni, which was consistently detected for 7 to 9 days at the different preservation temperatures used. When trypticase soy broth-glycerol (freezing medium), with or without blood, was used, there was little or no decrease in the Salmonella and Shigella concentrations during 2 weeks of preservation with stools at -70 degrees C. C. jejuni demonstrated a relatively sustained high concentration in Trypticase soy broth-glycerol with 5% blood.(ABSTRACT TRUNCATED AT 250 WORDS)

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