Use of colistin in adult patients. A cross-sectional study

OBJECTIVES: The objective of this study was to assess the use of colistin in a country endemic for multidrug-resistant Gram-negative bacteria (MDR-GNB). METHODS: Colistin prescription patterns were evaluated in 22 Italian centers. Factors associated with use of colistin in combination with other anti-MDR-GNB agents were also assessed. RESULTS: During the study period, 221 adults receiving colistin were included in the study. Their median age was 64 years (interquartile range 52-73), and 134 were males (61%). Colistin was mostly administered intravenously (203/221, 92%), and mainly for targeted therapy (168/221, 76%). The most frequent indications for colistin therapy were bloodstream infection and lower respiratory tract infection. Intravenous colistin was administered in combination with at least another anti-MDR-GNB agent in 80% of cases (163/203). A loading dose of 9 million units of colistimethate was administered in 79% of patients, and adequate maintenance doses in 85%. In multivariable analysis, empirical therapy (odds ratio [OR] 3.25, 95% confidence intervals [CI] 1.24-8.53, p = 0.017) and targeted therapy of carbapenem-resistant Enterobacterales infections (OR 4.76, 95% CI 1.69-13.43, p = 0.003) were associated with use of colistin in combinations with other agents, while chronic renal failure (OR 0.39, 95% CI 0.17-0.88, p = 0.024) was associated with use of colistin as monotherapy. CONCLUSIONS: Colistin remains an important option for severe MDR-GNB infections when other treatments are not available. Despite inherent difficulties in optimizing its use due to peculiar PK/PD characteristics, colistin was mostly used appropriately in a country endemic for MDR-GNB.