The Effect of Heat upon the Interaction between Aminoglycosides and Semi-synthetic Penicillins in Human Serum: A Consideration for HIV Infectious Serum

Abstract

We conducted 2 experiments to study the effect of heat on the interaction between aminogiycosides and semi-synthetic penicillins in human serum. In one experiment, human serum spiked with either gentamicin or tobramycin at a concentration of 4.7 mg/l plus carbenicillin, ticarcillin, piperacillin, mezlocillin, or azlocillin at concentrations of either 50 mg/l or 150 mg/l was subjected to a 30-min, 56°C waterbath incubation. In the second experiment, randomly selected sera from patients receiving either gentamicin or tobramycin were also heat-treated. Iwo methods, the Abbott TDx and the Syva Emit, were used for each amino-glycoside assay. The difference between pre- and post-heat treatment aminoglycoside concentration was <10% in approximately 92% of the patient sera and in 93% of the spiked sera containing an aminoglycoside plus a semi-synthetic penicillin at 50 mg/l. For sera spiked with an aminoglycoside plus a semi-synthetic penicillin at 150 mg/l, post-heat treatment concentrations were 5–19% lower than pre-heat treatment concentrations. In most instances, heat treatment of sera does not alter aminoglycoside concentrations to any clinically significant degree.