Possible beta-lactamase activities detectable in infective clinical specimens.

Biological beta-lactam antibiotic-inactivating activities were detected in bacteriuria and suppurating pleural fluids. Clinical specimens were sterilized with membrane filters and the amounts of ampicillin and/or cephalothin which were being inactivated by 1 ml of each filtrate were determined. In general, filtrates which originally yielded Klebsiella sp. tended to show activity against ampicillin; whereas those yielding Enterobacter sp. and Pseudomonas aeruginosa showed activity against cephalothin.