Survival of Salmonella typhi and Shigella flexneri in Different Water Samples and at Different Temperatures

Authors: M. HAMİDULLAH UYANIK, HALİL YAZGI, AHMET AYYILDIZ

Abstract: Aim: In this study, we aimed to evaluate the survival of Salmonella typhi and Shigella flexneri, which have significance for public health, in various aqueous media (distilled water, 0.9% NaCl solution, chlorinated water) and at different temperatures. Materials and Methods: The water samples mentioned above were contaminated with approximately 5 x 10^5 bacteria/ml of S. typhi and S. flexneri, and then stored at 37 ºC, room temperature, in refrigerator (4 to 6 ºC) and in deep freezer (-20 ºC). From the water materials prepared accordingly, cultures were done beginning in the first 24 hours and later every other day for viability control of the bacteria until no growth was detected in three consecutive cultures. Results: We observed that S. flexneri in both 0.9% NaCl solution and distilled water survived the longest (87 and 83 days, respectively) when stored in the refrigerator. Similarly, S. typhi was found to be viable as long as 65 days in both 0.9% NaCl solution and distilled water, when stored in the refrigerator. No bacterial growth was determined in the cultures of chlorinated water samples stored at all four temperatures in the first 24 hours. Conclusions: We concluded that S. flexneri generally survived longer than S. typhi in the different water media. Having a prolonged survival of S. flexneri in aqueous media would present more risk than S. typhi for the transmission of waterborne infections.

Keywords: Survival of bacteria, Shigella flexneri, Salmonella typhi, waterborne infections

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