Colistin Therapy, Survival and Renal Replacement Therapy in Burn Patients: A 10-Year Single-Center Cohort Study

Colistin is still a therapeutic cornerstone against multidrug-resistant gram-negative bacteria (MDRGN), mostly when other antibiotics do not gain adequate activity on these strains. In the present study, we evaluated in a cohort of burn patients the relationship between colistin therapy, survival and requirement of renal replacement therapy (CRRT).

Retrospective study of 133 burn patients treated with iv colistimethate sodium (loading dose 9.0 × 10⁶ IU, maintenance dose 4.5 × 10⁶ IU BID) and 35 treated with other antibiotics for MDRGN infection including Acinetobacter baumannii, Pseudomonas aeruginosa, and Klebsiella pneumoniae between January 2008 and December 2017. Multivariate analysis with logistic regression was used to determine the effect of the predictors such as age, total body surface area (TBSA), third-degree burn areas, Revised Baux score, Charlson comorbidity score, length of stay, colistin dose and duration of treatment, mechanical ventilation, and need of CRRT on in-hospital mortality. To investigate the relationship between colistin and renal function, we focused on survivor patients as the completion of the therapeutic course of colistin represented the basic requirement to analyze its impact on the kidney.

Out of 133 colistin- and 35 other antibiotics-treated patients, 83 (62.4%) and 31 (88.6%) survived, and 53 (39.8%) and 3 (9.7%) required CRRT, respectively. The severity of burns, as well as CRRT requirement and mortality, was significantly higher in colistin-treated patients than in other antibiotics-treated patients. Age and TBSA% were the significant predictors of mortality. Out of 83 colistin-treated survivors, 19 (22.9%) required CRRT (9 before and 10 after the start of colistin), and 64 (77.1%) had a normal renal function. No difference about the colistin dose and baseline characteristics, but the revised Baux score was found between the 9 patients requiring CRRT before the colistin course and the 10 patients after. Similarly, among the 64 patients not undergoing CRRT, no difference was found between the patients treated with the cumulative dose of colistin <99.0 × 10⁶ IU (n = 33, median daily dose of 4.0 × 10⁶ IU) and >99.0 × 10⁶ IU (n = 31, median daily dose of 9.0 × 10⁶ IU) about the baseline characteristics and the daily median plasma creatinine over 24 days of therapy.

Colistin therapy was associated with more severe burns, mortality, and CRRT requirement. A short course therapy, at appropriate cumulative dosage, can lead to clinical success without a significant association with severe renal impairment.