A chemical formula that indicates the simplest numerical ratio of the elements within a molecule, without demonstrating the molecule's chemical bonds or structure. For example, the empirical formula for water is H2O. Synonym: molecular formula.
Pelvic inflammatory disease (PID) is an infection caused by bacteria. When bacteria from the vagina or cervix travel to your womb, fallopian tubes, or ovaries they can cause an infection. Most of the time, PID is caused by bacteria from chlamydia and gonorrhea. These are sexually transmitted infections (STIs). Having unprotected sex with someone who has an STI can cause PID.
Several different types of bacteria can cause PID, including the same bacteria that cause the sexually transmitted infections (STIs) gonorrhea and chlamydia. What commonly occurs is that bacteria first enter the vagina and cause an infection. As time passes, this infection can move into the pelvic organs.