A latent effervescent body comprising a selective agent is disclosed. A method of using the latent effervescent body in a method to selectively enrich a target microorganism is also disclosed. The method comprises providing a sample, a culture medium, and the latent effervescent body. The method further comprises contacting the sample, the culture medium, and the latent effervescent body under conditions to facilitate growth of the target microorganism. The method further comprises releasing the selective agent from the latent effervescent body. Optionally, the method includes detecting a microorganism.