Association of halogenated isoxazolylpenicillins with penicillinase-sensitive beta-lactam antibiotics. Microbiological evaluation on beta-lactamase-producing Enterobacteriaceae.

The validity of nonsimultaneous association of penicillinase-sensitive beta-lactam antibiotics with halogenated isoxazolylpenicillins was tested in various Enterobacteriaceae strains. With several bacterial strains, expecially if producers of beta-lactamase type IV, exposure of either the bacterial suspensions of the brothsupernatant to the isoxazolylpenicillins appears both in vivo and in vitro to reduce the extent of subsequent hydrolysis of penicillinase-sensitive beta-lactam antibiotics.