Salmonella typhi is a rod-shaped, gram-negative bacterium that causes Typhoid fever. Typhoid is transmitted through the ingestion of water or water contaminated by the urine or feces of an infected person. Symptoms include fever, sweating, malaise, gastroenteritis, diarrhea or constipation and a rash. The disease can be treated with oral rehydration therapy and antibiotics. Leifson stain. Magnification: 600x.