By Dr Yu Chin Wing, ICU, NDH
Background: The emerging infection due to multidrug resistant microorganisms has rekindled the usage of colisitn, which was once nearly abolished mainly due to its nephrotoxicity. The prevalence and the safety of colistin therapy in critically ill patients in Hong Kong, however, have not been studied.
Objectives: 1. To review the bacteriology led to colistin therapy in critically ill patients in Hong Kong. 2. To review the dosage and route of colistin, the hospital length of stay, the mortality and the rate of acute kidney injury among these patients.
Method: A retrospective observational study was performed on the patients whom received intravenous or inhalational Colistin during their admission to an adult ICU over a 3-year period from 2010 to 2012. Exclusion criteria included those ICUs with less than 5 relevant cases and where the medical records for data retrieval were not available before predefined time.
Results: 157 cases from 7 adult ICUs were eligible for this study. One out of these 7 ICU contributed 64.3% of the cases. The average age of the patients was 60.7 +/- 15.7. The most common causative organism triggered the usage of colistin was Carbapenem-resistant Acinetobacter species (67.5%, n= 106), followed by Pseudomonas species (13.4%, n = 21). All cases received intravenous colistin, while 4 cases received concomitant inhalational colistin. The total daily dosage of intravenous colistin was of 2.51+/- 1.01mU. The APACHE II score and APACHE IV score were 26.3 +/- 18.0 and 87.9 +/- 35.4 respectively. The ICU mortality, in-hospital mortality and 30-days mortality were 40.1%, 59.2% and 49.0%, respectively. According to the serum creatinine level, with referenced to RIFLE criteria (Risk, Injury, Failure, Loss and End-stage kidney disease) and the need of renal replacement therapy, the rate of acute kidney injury for those received at least 48 hours of colisitn was 36.8% (n = 39). Among them 15.1% (n=16) was at Risk, 12.3% (n=13) was Injury, 9.4% (n = 10) was Failure, while no case had Loss or End-stage kidney disease.
Conclusion: The most common microorganism led to colistin therapy in ICUs of Hong Kong was Carbapenem-resistant Acinetobacter. Mortality and acute kidney injury in critically ill patients treated with colistin was not uncommon, however, these outcomes were also attributed by different confounding factors. Further studies will be valuable to investigate the most optimal dosage of colistin with minimal harmful effects.