An in vitro evaluation of antimicrobial interaction between glycine and some penicillins using the decimal assay for additivity (DAA) method

The decimal assay for additivity (DAA) method was used to evaluate the in vitro interaction of glycine (Gly) with penicillin G (Pen G); cloxacillin (Clox) and ampicillin (Amp) against a clinical isolate of Staphylococcus aureus . In the interaction between Pen G/glycine with biological equivalent factor (BEF) 5 mg/62 mg, the decimal combination of 4 parts Pen G and 6 parts glycine showed amtagpmos, wjo;e ptjers sjpwed addotive effect In the interaction between Clox/glycine with BEF 1.26 µg/62.5 mg ony 7:3 combination gave a synergistic effect. Others showed antagonism. In Amp/glycine combination with BEF, 1.74 µg/62.5 mg, the decimal combinations of 4:6 gave additive effect; 9:1 gave synergistic effect while 7:3 combinaiton gave indifferent effect. Keywords : glycine, interaction, penicillins, decimal assay for additivity, in vitro Journal of Pharmaceutical and Allied Sciences Vol. 3(1) 2006: 289-293