PURPOSE: The purpose of this in vitro study was to assess the antimicrobial effect of sub 10-nm AgNPs in maxillofacial silicone against Staphylococcus aureus, Candida albicans, and mixed species biofilms containing both and to test the effectiveness of different AgNP concentrations against all 3 biofilms in vitro.
MATERIAL AND METHODS: Silicone disks (M511; Technovent Ltd) containing 0.0% (control), 0.1%, and 0.5% AgNPs were fabricated and treated with S. aureus, C. albicans, and mixed species strains of both in 24-well culture plates containing appropriate media. Each well received a 0.1-mL aliquot of the standardized suspension of microorganisms. The plates were incubated for 21 consecutive days, and colony-forming units per milliliter (CFU/mL) were measured on the first, third, fifth, seventh, fifteenth, and twenty-first day with the Miles and Misra method. Data were analyzed by 2-way ANOVA and the paired t test to evaluate the relationship between AgNP concentration, microbial strain, and time (α=.05). Mean CFU/mL differences for each time and for each biofilm category were assessed by repeated measure ANOVA.
RESULTS: AgNPs decreased the mean CFU/mL in both concentrations compared with the control. The 0.1% concentration showed sustained efficacy throughout the test, while the 0.5% concentration had high efficacy initially with a gradual decrease. However, the results were inconsistent for the mixed biofilm. The paired sample t test at day 3 and 15 and day 3 and 21 showed statistically significantly different results (P
METHODS: This retrospective study was performed on all KTRs ≥18 years of age at our center from January 1, 2006 to December 31, 2015, who were prescribed diltiazem as tacrolimus-sparing agent. Blood tacrolimus trough level (TacC0) and other relevant clinical data for 70 eligible KTRs were reviewed.
RESULTS: The dose of 1 mg tacrolimus resulted in a median TacC0 of 0.83 ± 0.52 ng/mL. With the introduction of a 90-mg/d dose diltiazem, there was a significant TacC0 increase to 1.39 ± 1.31 ng/mL/mg tacrolimus (P < .01). A further 90-mg increase in diltiazem to 180 mg/d resulted in a further increase of TacC0 to 1.66 ± 2.58 ng/mL/mg tacrolimus (P = .01). After this, despite a progressive increment of every 90-mg/d dose diltiazem to 270 mg/d and 360 mg/d, there was no further increment in TacC0 (1.44 ± 1.15 ng/mL/mg tacrolimus and 1.24 ± 0.94 ng/mL/mg tacrolimus, respectively [P < .01]). Addition of 180 mg/d diltiazem reduced the required tacrolimus dose to 4 mg/d, resulting in a cost-savings of USD 2045.92 per year (per patient) at our center. Adverse effects reported within 3 months of diltiazem introduction were bradycardia (1.4%) and postural hypotension (1.4%), which resolved after diltiazem dose reduction.
CONCLUSION: Coadministration of tacrolimus and diltiazem in KTRs appeared to be safe and resulted in a TacC0 increment until reaching a 180-mg/d total diltiazem dose, at which point it began to decrease. This approach will result in a marked savings in immunosuppression costs among KTRs in Malaysia.