Salmonella typhi, bacterium, SEM

Scanning electron micrograph (SEM) of Salmonella typhi is a Gram-negative, enteric, rod prokaryote (family Enterobacteriaceae) that causes typhoid fever. Salmonella typhi is a serovar of Salmonella enterica typhi (known now as Salmonella typhi). This bacterium is a facultative anaerobic, obligate parasite that has no known natural reservoir outside of humans. Infection by S. typhi leads to the development of typhoid, or enteric fever. This disease is characterized by the sudden onset of a sustained and systemic fever, severe headache, nausea, and loss of appetite. Other symptoms include constipation or diarrhoea, enlargement of the spleen, possible development of meningitis, and/or general malaise. Typhoid fever affects roughly 17 million people annually, causing nearly 600,000 deaths. Magnification: x5,255 when shortest axis printed at 25 millimetres.