Negatively stained Salmonella typhimurium. Salmonella re a gnus of bacteria belonging to the family enterobacteriaceae. They are gram-negative, usually motile rods. Several of the more than 1400 species are pathogenic, some causing mild gastroenteritis, others producing a severe and often fatal food poisoning. These bacteria are common in poultry and eggs as well as inadequately cooked beef and pork. TEM Magnification =x5,000 at 2.25 film size.