Inactivation of fosfomycin by crude extracts of P. aeruginosa CU252 and CU358 with and without ATP. ●, heated crude extract (CU252); ■, crude extract (CU252) in the presence of ATP; ▴, crude extract (CU252) without ATP; ○, heated crude extract (CU358); □, crude extract (CU358) in the presence of ATP; ▵, crude extract (CU358) without ATP.