Change of Gentamicin Dose in Newborns with Early Onset Sepsis: Audit and Quality Improvement Project

Gentamicin is an aminoglycoside antibiotic, widely used as first line in the treatment of confirmed or suspected neonatal sepsis because of its good cover against gram negative bacteria. Gentamicin is known for its side effects, which include nephrotoxicity (1.6-10%) and ototoxicity (2-2.3%), and for this reason strict monitoring of trough level is mandated.

We suspected that our unit was frequently recording high gentamicin levels when administering the drug at 5mg/kg 24-hourly in more than 32 weeks babies, and 36-hourly in less than 32 weeks (Dosage 1).

We audited 100 babies treated with Dosage 1 and found that 35% of these developed toxic gentamicin levels (>2mg/L pre second dose or >1mg/L pre fifth dose). Overall, toxicity was higher in preterm than term babies (p=0.018). In particular, 54% of preterm babies born between 32 and 38 weeks had a toxic level. We also noticed that only 62.85% of babies with high levels were appropriately referred to audiology for extended hearing test at 6-8 months of life.

As a consequence, we adopted in our Trust new regional antibiotic guidelines, which suggested a different dosing for gentamicin: 5mg/kg 36-hourly for the first 7 days of life irrespective of the gestational age (Dosage 2). We also changed the referral pathway to audiology.

We then re-audited gentamicin levels in 100 newborns treated with Dosage 2. The results show that toxicity levels fell from 35% to 3% (p<0.001) with Dosage 2. 3 patients still showed above reference trough levels: 1 had suffered from a hypoxic insult at birth and the remaining 2 babies had been admitted to NICU for hypoglycaemia and severe sepsis. 100% of babies with high levels were appropriately referred to audiology as per the new pathway.

In conclusion, with Dosage 2 we were able to significantly reduce the number of recorded gentamicin toxic level.