Background. Colistin is an antibiotic in the polymyxin group and is especially important in the elimination of multi-drug resistant gram negative bacteria. To date, there are many studies investigating colistin related side effects, especially nephrotoxicity. However, there are few studies involving premature neonates, and this study aimed to investigate the side effects of colistin in this particular patient group.

Methods. Between January 2016 and May 2019, the medical records of premature neonates treated with colistin were retrospectively reviewed. The diagnosis of acute kidney injury (AKI) was performed according to the modified neonatal KDIGO criteria. Serum electrolyte levels were recorded at the initiation of colistin treatment and 4-7 days after.

Results. A total of 47 premature neonates; with a median gestational age of 27 weeks and median weight of 970 g at birth were included in the study. The median postnatal day of colistin initiation was 24 days and mean duration of colistin therapy was 15.95 ± 3.70 days. Colistin was combined with aminoglycosides in 44.6% of the patients. Acute kidney injury was documented in 17.0% of premature neonates. (n = 6 for stage 1, n = 2 for stage 2, none of the patients had stage 3). In univariate analysis, gestational age and concomitant aminoglycoside use were associated with AKI development (OR, 0.446; 95% CI 0.238-0.832; p = 0.011 and OR, 1.324; 95% CI 1.023- 7.584; p = 0.024). Mean magnesium level significantly decreased after colistin treatment (1.70 ± 0.84 vs. 1.57 ± 0.29, p = 0.017) and the frequency of hypomagnesemia increased after colistin use (78.7% vs. 91.5%, p = 0.031). Frequency of elevated AST increased from 23.4% to 44.7% following colistin use (p = 0.031).

Conclusions. Colistin-related side effects observed in premature neonates are not as common as in pediatric patients. Electrolyte imbalance is observed more frequently in this age group following colistin use. We suggest strict serum electrolyte level monitoring, especially magnesium, in premature neonates that are receiving colistin.

Keywords: acute kidney injury, colistin, hypocalcemia, hypomagnesemia, premature neonates, side effect