Steam quality and effective sterilization.
Faced with using steam from a commercial utility having boilers greater than 5 miles distant and being the last user on the system resulted in ineffective sterilization. A three phase testing program was established utilizing: Direct physical measurements - an Ellison model 915A portable steam calorimeter. Direct microbiology - Autoclaved feed pellets were aseptically placed in fluid thioglycolate medium and incubated at 37 degrees C. Indirect microbiology - Feces from "defined flora" mice fed the autoclaved pelleted feed were tested. Colorimetric measurements verified that the steam sometimes contained greater than 5% entrained water. During periods of wet steam it was impossible to maintain consistent sterility of the mouse pellets even using a cycle of 126 degrees C for 60 minutes. One spore-forming Gram positive rod, Clostridium perfringens type D was the predominant bacterium isolated. Lactating mice, or mice stressed experimentally came down with diarrhea within days of eating pellets treated with wet steam (calorimetric measurements) and a subsequent positive culture. These mice voided stools predominantly showing Clostridium perfringens type D.
Sedlacek
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RS
Rose
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EF
D000818:Animals; D001407:Bacillus / Q000302:isolation & purification; D003016:Clostridium perfringens / Q000302:isolation & purification; D003967:Diarrhea / Q000382:microbiology; D005243:Feces / Q000382:microbiology; D005260:Female; D007774:Lactation; D051379:Mice; D011247:Pregnancy; D013242:Sterilization / Q000379:methods* / Q000592:standards; D014867:Water
D014867:Water