Objective: This study evaluated the usefulness of plasma Cystatin C (pCysC) along with urinary neutrophil gelatinase-associated lipocalin (NGAL), g-glutamyltransferase (GGT), lactate dehydrogenase (LDH), alkaline phosphatase (ALP), aspartate (AST) and alanine (ALT) aminotransferase to monitor colistin nephrotoxicity. Method: Male rats were given intramuscular (i.m.) injections of colistin in doses of 150,000 (G 1 ), 300,000 (G 2 ) and 450,000 IU/kg/day (G 3 ) or normal saline (Control), every 12 h for 7 days. After the 14th injection, animals were placed in metabolic cages and urine samples were collected in the next 12 h. Thereafter, animals were euthanized, blood samples were collected and kidneys were removed for histological assessment. Results: Nephrotoxicity was completely dose-dependent according to pathologic findings. The major insults were acute tubular necrosis in the tubules of G 3 . No significant change in pCr was observed in all treated groups, but pCysC increased in the G 3 compared to the control. In urinary markers, uNGAL level showed a dose dependant increase with significant change in the G2 and G3 groups compared to the control. However, there was no significant change in the AST, ALT, LDH or ALP activities but only GGT increased in the G 3 compared to the control. Conclusion: Based on colistin doses used in our experimental study on rat model, histopathologic assessment remains the most accurate way to diagnose colistin nephrotoxicity. pCysC appears to be more reliable than pCr, and uNGAL seems to be the most sensitive factor of colistin nephrotoxicity.

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Yarrowia lipolytica is ubiquitous in the environment, opportunistic, and might be considered as one of the causative agents of catheter-related candidemia. Our work aimed to study some virulence factors of Y. lipolytica such as hydrolases production and biofilm formation with comparison to the most frequent Candida specie in human disease. In sum, 58 clinical isolates of Y. lipolytica, 16 C. glabrata, and 12 C. albicans were collected from Intensive care unit (ICU). All were tested for enzymatic production and biofilm formation. All tested isolates of C. albicans and C. glabrata were able to degrade casein, and 98.2% of Y. lipolytica showed caseinase activity but no gelatinase activity was detected in all isolates. Y. lipolytica strains showed significantly lower (3.4%) in vitro phospholipase activity than C. albicans and C. glabrata (P < .05). No significant differences of the hemolytic activity were detected between the three species (P > .05). Concerning biofilm formation, and unlike the results obtained on polystyrene plate, the number of adhered and biofilm cultivable cells obtained by Y. lipolytica after 168 hours of catheter subcutaneous implantation is significantly greater and tends to be more compact and structured hyphal layer. Although C. albicans remains the most pathogenic yeast, development of selective ability of Y. lipolytica to adhere, to form a biofilm on catheter medical devices, and to produce phospholipase and hemolytic enzyme is of particular interest, and it is strongly recommended to be vigilant in the use of medical implanted medical devices, particularly in ICU.