Objective: Recent changes to therapeutic drug monitoring (TDM) of gentamicin have been advocated in Australia. It remains uncertain whether these will have an effect on hard clinical endpoints. The aim of this study was to determine clinical outcomes in patients with gram-negative infections treated with gentamicin.
Methods: Microbiology results of patients with confirmed gram-negative cultures were retrospectively reviewed and those treated with gentamicin included. Medical records were reviewed and patient demographics, diagnosis, renal function, comorbidities, gentamicin doses, duration, monitoring, concomitant antibiotics, antimicrobial sensitivity and clinical and microbiological outcomes recorded.
Results: A total of 100 patients were included in the study: 52% were male, median age 64 years (17-97). Total body weight was recorded in 56% (median 74.5 kg, range 35-134 kg). Most patients had two or more important comorbidities. A total of 72% received empiric and 28% directed treatment. The organism was identified on blood culture in 45%, urine culture in 43% and aspiration of liver abscess in 12%; 95% of organisms were sensitive to gentamicin. Baseline renal function was normal in 62%. Mean gentamicin dose was 3.9 ± 0.9 mg/kg and mean duration 2.9 ± 2.5 days. Only 21% had optimal TDM. Clinical outcome was favourable in 90%. There were no cases of preventable serious toxicity.
Conclusions: Despite the modest doses of gentamicin used in an elderly population with comorbidities, as well as the absence of optimal TDM, outcomes were favourable without preventable serious toxicity.
Keywords: gentamicin; outcomes; therapeutic drug monitoring.