Background Dried blood spots (DBSs) could allow patients to prepare their own samples at home and send them to the laboratory for therapeutic drug monitoring (TDM) of immunosuppressants. The purpose of this review is to provide an overview of the current knowledge about the impact of DBS-related preanalytical factors on TDM of tacrolimus, sirolimus and everolimus. Content Blood spot volume, blood spot inhomogeneity, stability of analytes in DBS and hematocrit (Hct) effects are considered important DBS-related preanalytical factors. In addition, the influence of drying time has recently been identified as a noteworthy preanalytical factor. Tacrolimus is not significantly influenced by these factors. Sirolimus and everolimus are more prone to heat degradation and exhibited variations in recovery which were dependent on Hct and drying time. Summary and outlook DBS-related preanalytical factors can have a significant impact on TDM for immunosuppressants. Tacrolimus is not significantly influenced by the studied preanalytical factors and is a viable candidate for DBS sampling. For sirolimus and everolimus more validation of preanalytical factors is needed. In particular, drying conditions need to be examined further, as current protocols may mask Hct-dependent effects on recovery. Further validation is also necessary for home-based self-sampling of immunosuppressants as the sampling quality is variable.

Our study shows a successful prolonged human colonization by a colistin-resistant Klebsiella pneumoniae isolate harboring mcr-1.2. An intense antibiotic therapy contributed to the maintenance of this microorganism through the acquisition of new resistance genes. The isolates carrying mcr-1.2 showed fewer fitness costs than isogenic isolates with a pmrB mutation in the chromosome. Coselection and reduced fitness costs may explain the replacement of isolates with the pmrB mutation by other isolates and the ability of the microorganism to persist despite antibiotic treatment.

Performance and potential clinical impact of Alfred60(AST) (Alifax®) for direct antimicrobial susceptibility testing on positive blood culture bottles