Chemical they have already used. The Wall Street Journal says that in 2014 they used chlorine in battles with the Iraqi army and civilians. And in July 2015 - mustard gas in battles against Iraqi Kurds. At the same time, a group of experts from Conflict Armament Research and Sahan Research, who conducted the investigation, confirmed that the militants were using chemical weapons. On August 22, 2015, IS militants (a banned organization in the Russian Federation) attacked the Syrian city of Mari with shells that could contain toxic substances. The CIA, OPCW and other organizations have repeatedly reported on the use of chemical weapons by militants in Iraq and Syria. About bacteriological is unknown. Perhaps it is not available to them. In principle, such a weapon requires extremely careful handling.
I can assume that it already exists, however, the consequences of using this weapon may cause fear among the owners, it is impossible to say with complete confidence that at the head of ISIS (banned in the Russian Federation) people are so irrational and impulsive.