Preparation of Modified Selective Medium for Isolation of Enterococcus faecalis in Pure Culture from Heavy Sources (Rapid Diagnosis)

Abstract

Subject: This research focuses on the preparation of a new modified selective medium for the primary isolation of Enterococcus faecalis in pure culture from heavy and clinical sources. Materials and Methods: The modified selective medium was prepared and named as Enterococcus Jawad (EJ)–Medium. The new medium was prepared by adding 0.4 g of sodium azide, 2 mL of 0.1% crystal violet (CV), and 60 g of sodium chloride in a liter of Brain-Heart Infusion Agar (BHIA), and the pH of the medium was adjusted to 8.6. The primary isolation of E. faecalis from heavy bacterial sources and clinical infections was performed by culturing all collected samples on EJ-medium and comparing them with other approved selective media, such as Azide-BHIA, CV-blood agar, and Enterococcus selective agar (ESA), to estimate the ability of these media in isolating E. faecalis (during primary isolation) in pure culture. Results: The results showed that the EJ-medium had a high rate of isolation, 100%, of E. faecalis in pure culture from heavy sources (human feces and sewage water) and from clinical sources (urine, bedsore, and blood) when compared with other culture media that were already used for isolation of this organism. The Azide-BHIA and CV-blood agar showed no high purity in an initial isolation of the organism. Conclusions: From these results, we concluded that the EJ-medium is highly efficient in the primary isolation of E. faecalis in pure culture by one step from different environmental and clinical sources; thus, it does not need to be diagnosed by classical methods that are expensive and consume a long time. Since Azide-BHIA, CV-blood agar, and ESA were not exactly selective media for the isolation of E. faecalis in pure cultures from heavy sources, their use was limited in clinical cases.