omparison of Reasoner’۲ Agar and Muller Hinton Agar Media for Microbiological Monitoring of Dialysis Water

Background and Aim : Microbiological culture of dialysis water is a routine safety measure. In, Khorramabad laboratories perform these cultures on Muller Hinton Agar (MHA) at ۳۵–۳۷۸C for ۴۸ h, not on the Reasoner’s ۲A agar (R۲A) at ۱۷–۲۳۸C for ۷ days recommended by international standards, the objective of the present study was the comparison of the efficiency of R۲A and MHA media in the counting of heterotrophic bacteria in the samples of water collected in dialysis centers from ۲ hospitals in Khorramabad, from September to November ۲۰۱۹. Methods : A total of ۱۶۵ samples of treated water in dialysis centers were collected aseptically and then transported in ice packs to the Department of Medical Microbiology of the Lorestan University of Medical Sciences and the pour plate technique was carried out for the enumerating of heterotrophic bacteria. Finally, bacterial colonies were counted after incubation at ۳۴ ± ۲ºC for ۴۸ hours on MHA and ۲۵ ºC for ۱ week on R۲A.Results : Results showed heterotrophic bacterial counts in R۲A were greater than those in MHA in ۸۹% of the samples, so enumeration of heterotrophic bacteria should be carried out in R۲A agar associated with longer incubation times, because of the greater sensitivity. The proportion of water samples yielding colony counts ≥۲۰۰ CFU/mL by R۲A -۷d was significantly different from the proportion by MHA -۴۸h (P<۰.۰۰۱)Conclusion : The results proposed using R۲A agar combined with relative low culture temperature (۲۰-۲۵ °C), and an extended incubation time (۷-۱۰ days) is more efficient. However, as the spectrum of bacterial contamination is not the similar for dialysis centers and countries, many of studies using different media and culture parameters are required in order to confirm this.

کلیدواژه ها:

Dialysis water ، Heterotrophic bacteria ، Pour plate ، Reasoner’۲ Agar