Drug-Resistant Salmonella Serotype Typhi. A distinct strain of Salmonella enterica serotype typhimurium, known as definitive type 104 (DT104), is resistant to ampicillin, chloramphenicol, streptomycin, sulfonamides, and tetracycline and has become a major cause of illness in humans and animals in Europe, especially the United Kingdom. According to the Centers for Disease Control and Prevention, more than two million people in the United States get infections that are resistant to antibiotics and at least 23,000 people die as a result. Over-prescription of antibiotics leads to antibiotic-resistant germs.