Does metronidazole really helpful for any kind of intestinal infection because it's widely used nowadays for this purpose?best regard.

Not every kind...: Metronidazole is great for many intestinal infections, but isn't appropriate for ALL types. For example, it's good for C.diff infection, intestinal anaerobic infections, amebiasis, and protozoal infection like Giardia. But it doesn't work against Shigella or Salmonella, which would require a different drug. Keep in mind also that most GI infections don't require any antibiotic at all!