Aminoglycoside antibiotics and lysosomal enzymes of human tears

T. Shiono and S. Hayasaka

We examined biochemically the effect of six aminoglycoside antibiotics on the activity of lysozyme, acid phosphatase, and N-acetyl-beta-D-glucosaminidase in human tears. All six antibiotics strongly inhibited lysozyme activity, the degree of inhibition depending on the dose administered. Except for bekanamycin, antibiotics had little effect on the activity of acid phosphatase or N-acetyl-beta-D-glucosaminidase. The nature of the inhibition was competitive. Other kinds of antibiotics, such as sulbenicillin or erythromycin, had no inhibitory effect on lysozyme, acid phosphatase, or N-acetyl-beta-D-glucosaminidase. These results suggested that the inhibition of lysozyme by aminoglycosides is specific and that the decreased effectiveness of a protective system against bacterial infection in the eye is highly possible when aminoglycoside antibiotics are used without prior sensitivity testing.