RESUMO
With the rise of antibiotic resistance, the drive to discover novel antimicrobial substances and standard testing methods with the aim of controlling transmissive diseases are substantially high. In healthcare sectors and industries, although methods for testing antibiotics and other aqueous-based reagents are well established, methods for testing nanomaterials, non-polar and other particle-based suspensions are still debatable. Hence, utilities of ISO standard validations of such substances have been recalled where corrective actions had to be taken. This paper reports a serial analysis obtained from testing the antimicrobial activities of 10 metallic-based nanomaterials against 10 different pathogens using five different in vitro assays, where the technique, limitation and robustness of each method were evaluated. To confirm antimicrobial activities of metallic-based nanomaterial suspensions, it was found that at least two methods must be used, one being the agar well diffusion method, which was found to be the most reliable method. The agar well diffusion method provided not only information on antimicrobial efficacy through the size of the inhibitory zones, but it also identified antimicrobial ions and synergistic effects released by the test materials. To ascertain the effective inhibitory concentration of nanoparticles, the resazurin broth dilution method is recommended, as MIC can be determined visually without utilising any equipment. This method also overcomes the limit of detection (LoD) and absorbance interference issues, which are often found in the overexpression of cell debris and nanoparticles or quantum dots with optical profiles. In this study, bimetallic AgCu was found to be the most effective antimicrobial nanoparticle tested against across the bacterial (MIC 7 µg/mL) and fungal (MIC 62.5 µg/mL) species.
RESUMO
Hypophosphatemia is well recognized in the intensive care setting, associated with refeeding and continuous forms of renal replacement therapy (CCRT). However, it is unclear as to when and how to administer intravenous phosphate supplementation in the general intensive care setting. There have been recent concerns regarding phosphate administration and development of acute kidney injury. We therefore audited our practice of parenteral phosphate administration. We prospectively audited parenteral phosphate administration (20 mmol) in 58 adult patients in a general intensive care unit in a University tertiary referral center. Fifty-eight patients were audited; mean age 57.2 ± 2.0 years, 70.7% male. The median duration of the infusion was 310 min (228-417), and 50% of the patients were on CRRT. 63.8% of patients were hypophosphatemic (<0.87 mmol/L) prior to the phosphate infusion, and serum phosphate increased from 0.79 ± 0.02 to 1.07 ± 0.03 mmol/L, P < 0.001. Two patients became hyperphosphatemic (>1.45 mmol/L). There was no correlation between the change in serum phosphate and the pre-infusion phosphate. Although there were no significant changes in serum urea, creatinine or other electrolytes, arterial ionized calcium fell from 1.15 ± 0.01 to 1.13 ± 0.01 mmol/L, P < 0.01. Although infusion of 20 mmol phosphate did not appear to adversely affect renal function and corrected hypophosphatemia in 67.7% of cases, we found that around 33% of patients who were given parenteral phosphate were not hypophosphatemic, and that the fall in ionized calcium raises the possibility of the formation of calcium-phosphate complexes and potential for soft tissue calcium deposition.
