Effects of antecedent fermentative and respiratory growth on the detection of chloramine-stressed Escherichia coli and Salmonella typhimurium
In vitro laboratory studies were performed to assess the effects of antecedent growth conditions on the recovery of Escherichia coli ATCC 25922 and Salmonella typhimurium ATCC 14028 following chloramine disinfection. Six- and 18-h cultures of each organism were grown under aerobic, fermentative, and nitrate-reducing conditions prior to disinfection. At predetermined time intervals during a 10-min exposure to chloramine, survivors were surface plated on nonselective recovery media to determine Cnt values. It was observed that nitrate-reducing growth predisposed the test organisms towards an increased sensitivity to chloramine stress over cells grown under fermentation or aerobic conditions (p < 0.01).Key words: Escherichia coli, Salmonella typhimurium, chloramine, survival, antecedent growth conditions.