Audit of prescription and assay of aminoglycosides in a UK teaching hospital

Despite potential nephrotoxicity and ototoxicity, aminoglycosides are widely used in the treatment of severe sepsis but monitoring of serum levels is necessary. The use and assay of aminoglycosides, together with microbiologists' and pharmacists' advice on dosage and potential toxicity were examined in a teaching hospital group during an eight week period. A total of 480 courses of aminoglycoside was recorded in 4.40 hospital in-patients and of these, 306 (64%) were for prophylaxis. For 79 (45%) of 174 therapeutic courses, bacteriological results were available at the start and the choice of antibiotic was appropriate in 69 cases. Serum aminoglycoside assays were performed in 86% (149/174) of therapeutic courses. Correct assay request forms were used in 79% of 473 assay requests, and the clinical diagnosis was given on 73% of forms. In so-called peak samples with a documented time of collection, this ranged from 5 mm to over 9 h post dose. Potentially toxic concentra tions were present in 56(12%) serum samples from 50 courses, in ten of which there was a serum creatinine rise of > 40 μM. However, there were confounding factors in five cases. Probable nephrotoxicity was rare, although assays were not performed in 14% of therapeutic courses. There were no symptomatic cases of ototoxicity but audiometry and vestibular studies were not performed. Closer liaison between the microbiologists, pharmacists and clinical staff is essential to improve clinical practice. Computer notification of inadequately monitored courses would be helpful. The routine therapeutic use of aminoglycosides needs to be reviewed in the light of the rising costs of assay litigation and the increasing number of alternative antibiotics available.