Salmonella infection, or salmonellosis, is a bacterial disease of the intestinal tract. Salmonella is a group of bacteria that cause typhoid fever, food poisoning, gastroenteritis, enteric fever and other illnesses. People become infected mostly through contaminated water or foods, especially meat, poultry and eggs.yphoid fever treatment. The Salmonella bacteria that causes typhoid can be killed by antibiotics such as ciprofloxacin or ceftriaxone. However, some strains become resistant to antibiotics after long-term use, and antibiotics have known side-effects.