Drug monitoring during ciprofloxacin prophylaxis of allogeneic stem cell transplant patients: associations with bacterial infections through a monocentric observational prospective study.

BACKGROUND: Bacterial infection ranks amongst the most common causes of morbidity and mortality in patients undergoing allogeneic haematopoietic stem cell transplantation (alloHSCT). Although ciprofloxacin (CIP) prophylaxis is recommended, information on serum levels and clinical course is lacking. AIM: To investigate relationships between CIP level and failure of prophylaxis, particularly in terms of whether different pharmacokinetic (PK) indices [area under the concentration-time curve (AUC0-24h) vs single time samples] correlate differently with the outcome. METHODS: This prospective observational monocentric study was conducted at a 1500-bed teaching hospital (March 2018-March 2019), including 63 adult patients with alloHSCT receiving CIP prophylaxis. Blood samples were drawn at three sampling times (1, 6 and 12 h post-administration), twice per week, and measured via high performance liquid chromatography. The onset of febrile episodes (FEBs) indicated suspected failure of CIP prophylaxis. Positive blood cultures [bloodstream infection (BSI)] indicated confirmed failure of prophylaxis. FINDINGS: Seven of 63 patients died without significant differences in their average CIP levels compared with survivors, with patients experiencing FEBs (54/63) displaying a 13% [95% confidence interval (CI) 4-22%] lower probability of survival. In total, 225 sets of three values (triplets) were obtained from 58 primary CIP episodes. Triplets preceding BSI with Gram-negative bacteria (GNB-BSI) showed lower AUC0-24h on average, but similar single time sample indices. An AUC0-24h of ≤21.61 mgh/L resulted in four-fold higher odds of GNB-BSI (adjusted odds ratio 3.96, 95% CI 1.21-13.00). These results were independent of the administration route, patient demographics or sampling protocol deviations, indicating reduced CIP exposure upon GNB-BSI events. CONCLUSION: Monitoring CIP levels, using multiple sampling times, may be useful to reduce alloHSCT-associated bacterial infections. Further analysis is needed to investigate causality.

Effect of gloved hand disinfection on hand hygiene before infection-prone procedures on a stem cell ward.

BACKGROUND: Hand hygiene compliance even before infection-prone procedures (indication 2, 'before aseptic tasks', according to the World Health Organization (WHO)) remains disappointing. AIM: To improve hand hygiene compliance by implementing gloved hand disinfection as a resource-neutral process optimization strategy. METHODS: We performed a three-phase intervention study on a stem cell transplant ward. After baseline evaluation of hand hygiene compliance (phase 1) gloved hand disinfection was allowed (phase 2) and restricted (phase 3) to evaluate and differentiate intervention derived from learning and time effects. The incidence of severe infections as well as of hospital-acquired multidrug-resistant bacteria was recorded by active surveillance. FINDINGS: Hand hygiene compliance improved significantly from 50% to 76% (P < 0.001) when gloved hand disinfection was allowed. The biggest increase was for infection-prone procedures (WHO 2) from 31% to 65%; P < 0.001. Severe infections decreased by trend (from 6.0 to 2.5 per 1000 patient-days) whereas transmission of multidrug-resistant organisms was not affected. CONCLUSION: Gloved hand disinfection significantly improved compliance with the hand hygiene, especially in activities relevant to infections and infection prevention. Thus, this process optimization may be an additional, easy implementable, resource-neutral tool for a highly vulnerable patient cohort.

Self-tolerance of human natural killer cells lacking self-HLA-specific inhibitory receptors.

Natural killer (NK) cells identify cells with altered human leucocyte antigen (HLA) expression as targets through lacking engagement of self-HLA-specific inhibitory receptors (e.g. killer cell immunoglobulin-like receptor, KIR). Thus, they eliminate cells with 'missing self' because of viral or malignant transformation. We performed analysis of HLA, KIR genotypes and KIR receptor expression patterns at single cell level in NK cells in 17 donors. The function of NK cell subsets is determined by degranulation assays using target cells expressing self, cognate, control or no HLA class I. Donors could be grouped into three groups: their NK cells possess potential for alloreactivity, autoreactivity based on the presence of NK cells expressing particular KIR only (mono-KIR) in the absence of its ligand or lack alloreactivity. All donors possess NK cells lacking all detectable inhibitory receptors. Both potential autoreactive subpopulations did not respond to HLA class I-positive target cells. They retain partial reactivity against HLA class I-negative tumour target cells. Mono-KIR NK cells without the corresponding ligands in the individuals and NK cells lacking all inhibitory receptors behave self-tolerant. Our results suggest alternative mechanisms than HLA-specific inhibitory receptors to control NK cell activity. But HLA seems to be involved in shaping effector function of the NK cell repertoire.

Resistance against natural killer cell cytotoxicity: analysis of mechanisms.

Target cell resistance against natural killer (NK) cell-mediated cytotoxicity obstructs NK cell-based immunotherapy of leukaemia. Several mechanisms of resistance have been described. Because of lack of simple assays for analysing these mechanisms, their relative impact on a given effector-target pair is mostly unknown. We here analysed the combination of the Granzyme B (GrB) enzyme-linked immunospot assay (ELISPOT) for the assessment of NK cell reactivity and cytotoxicity assays to estimate target cell escape mechanisms. Target cell recognition failure leads to negative GrB ELISPOT results, whereas target cell resistance shows positive GrB ELISPOT results in the absence of cytotoxicity. We confronted NK cells with the sensitive target cell line K562, and with the resistant cell lines ML2, SupB15 and Raji. ML2 cells sufficiently activated GrB-release whilst being resistant against cytotoxic granules of NK cells. Partial resistance of Raji results from the interaction of HLA class I with inhibitory killer immunglobulin-like receptors (KIR) on the NK cells. Failure of target recognition by HLA class I-KIR interaction, lacking ligands to stimulatory NK cell receptors and partial resistance to cytotoxic granules all contributed to resistance of SupB15. In conclusion, revealing the mechanisms of resistance against NK cell-mediated cytotoxicity may allow improving the results of NK-based immunotherapy.

Reduced-intensity conditioning prior to allogeneic transplantation of hematopoietic stem cells: the need for T cells early after transplantation to induce a graft-versus-lymphoma effect.

In patients with poor-risk relapse of aggressive lymphoma, reduced-intensity conditioning followed by allogeneic PBSCT may have its limitations because of rapid regrowth of the tumor. We tried to address this problem by intermediate-intensity conditioning followed by allogeneic SCT. A total of 21 patients received fludarabine, busulfan and cyclophosphamide prior to allogeneic SCT. In the first 10 patients, GVHD prophylaxis by CD34+ selection of the grafts was employed (group I). The next 11 patients received nonmanipulated grafts and mycophenolat mofetil plus cyclosporinA (group II). In group I, no GVHD was observed. In contrast, patients in group II had a significant risk of acute GVHD (aGVHD) (six patients with grade II-IV acute GVHD). However, in group I, all surviving patients progressed within 9 months. In contrast, eight of nine surviving patients of group II remain in remission after a median observation time of 10.5 months (range 4-22 months). Survival differed significantly between the groups (P=0.004). Multivariate analysis identified intensive GVHD prophylaxis as important risk factor for survival. These results support the existence of a clinically relevant GVL effect in aggressive lymphoma. T-cell depletion (or CD34 selection) of grafts is not recommended in patients with poor-risk aggressive NHL.