Intravenous Colistimethate Sodium in Neonatal Sepsis

To the Editor: Colistin is a re-emerging antibiotic in the last few years owing to increase in Gram negative multi drug resistant (MDR) nosocomial infections. Effect of the drug on the immature renal system of neonates has not been studied extensively yet. In this retrospective descriptive study, we have tried to evaluate the safety and efficacy of colistimethate sodium (CMS) in MDR neonatal infections. Medical records of all the neonates treated with intravenous CMS for MDR sepsis in neonatal care units between September 2013 and February 2015 were retrieved and analyzed. Twenty eight neonates with mean gestational age of 35.57 wk (range 28–43 wk), and mean birth weight of 2048 g (range 990–3780 g) received CMS during the study period. Mean postnatal age at initiation of CMS therapy was 8.46 d (range 5–12 d), and mean duration of CMS therapy was 16.1 d (range 14–24 d) in surviving cases. CMS was used in the doses of 50,000–75,000 IU/ kg/d. Empirical antimicrobials were continued despite known resistance to them owing to lack of data on efficacy of colistin. Following CMS therapy, 22 neonates (78.6 %) survived. Death in the remaining 6 neonates (21.4 %) was unrelated to adverse effects of CMS. There were no significant statistical differences between baseline and post CMS values of blood urea, serum creatinine, and estimated creatinine clearance (Table 1). Nephrotoxicity was noted in 3 neonates (10.7 %) on 4– 6 d of therapy. However, those neonates were on netilmicin therapy in addition to CMS; and renal functions returned to normal after discontinuation of netilmicin. Moreover, urine examination of the study population revealed no significant abnormality. In some related studies, the efficacy of CMS was 72.2 % to 81 % and nephrotoxicity was noted among 5.1 % to 19 % neonates [1–3]. CMS was used in dose of 50,000–1,20,000 IU/kg/d or 2–5 mg/kg/d in their study subjects. Although electrolyte imbalance was observed in some studies [2, 4], we did not find such changes in our cohort.