Cefdinir, sold under the brand name Omnicef among others, is an antibiotic used to treat pneumonia, otitis media, strep throat, and cellulitis.

[4][5] Therapeutic uses of cefdinir include otitis media, soft tissue infections, and respiratory tract infections, including sinusitis, strep throat (note: no documented resistance of Group A Streptococcus to penicillin has ever been reported, and penicillin or amoxicillin is preferred except in penicillin-allergic patients), community-acquired pneumonia, and acute exacerbations of bronchitis.

Cefdinir is a broad-spectrum antibiotic and has been used to treat infections of the respiratory tract including pneumonia, sinusitis, and bronchitis.

[8] The pediatric version of cefdinir can bind to iron in the digestive tract; in rare cases, this causes rust or red discoloration of the stool.

If the reddish stool is accompanied by abdominal pain, weight loss, diarrhea, etc., a Clostridioides difficile infection caused by the antibiotic could be signified.

The active methylene group in that compound is then nitrosated with sodium nitrite; the initial product spontaneously tautomerizes to afford the oxime (4).