Cryopreservation of Salmonella enterica in porcine fecal samples

Fecal samples are normally tested for Salmonella soon after collection because storage at any temperature, including refrigeration or freezing, can reduce detection. To evaluate several cryopreservation techniques, autoclaved porcine feces with and without additives were inoculated with 103 CFU S. Derby (UW -9)/g with autoclaved feces pnor to freezing. The mixtures and % of the CFU inoculum that was recovered was as follows: Feces only, 11 %; 50% feces plus 50% glycerol, 45%, 25% feces, 50% glycerol, 25% tetrathionate broth, 63%, 25% feces, 50% glycerol, 25% buffered peptone water (BPW), 66%; 50% feces, 50% glycyceroi/Tris buffer, 58%; 50 % feces, 50% BPW, 30%. When fresh (not autoclaved) feces were used, inoculated with a nalidixic acid resistant S Typhimurium (WI-73), 4% of the inoculum was recovered from undiluted frozen feces wh1le the add1tlon of 50% BPW before freezmg mcreased recovery to 27%

Cryopreservation of Salmonella enterica in porcine fecal samples

Fecal samples are normally tested for Salmonella soon after collection because storage at any temperature, including refrigeration or freezing, can reduce detection. To evaluate several cryopreservation techniques, autoclaved porcine feces with and without additives were inoculated with 103 CFU S. Derby (UW -9)/g with autoclaved feces pnor to freezing. The mixtures and % of the CFU inoculum that was recovered was as follows: Feces only, 11 %; 50% feces plus 50% glycerol, 45%, 25% feces, 50% glycerol, 25% tetrathionate broth, 63%, 25% feces, 50% glycerol, 25% buffered peptone water (BPW), 66%; 50% feces, 50% glycyceroi/Tris buffer, 58%; 50 % feces, 50% BPW, 30%. When fresh (not autoclaved) feces were used, inoculated with a nalidixic acid resistant S Typhimurium (WI-73), 4% of the inoculum was recovered from undiluted frozen feces wh1le the add1tlon of 50% BPW before freezmg mcreased recovery to 27%.</p