<prompt> PID is most commonly caused by -ChlamydiaMycoplasmaTubercular bacillusE.Coli  <response>: Ans. is a i.e., Chlamydia Sexually transmitted diseases are the most common cause of PIP.o Gonococcal Chlamydial infections are the most common,o Mycoplasma hominis genitalumo Tubercular bacilluso Viruseso E. colio Polymicrobial both aerobe anaerobs 