Risk factors for pre- and post-engraftment bloodstream infections after allogeneic hematopoietic stem cell transplantation.

BACKGROUND: Bloodstream infections (BSI) are frequently observed after allogeneic hematopoietic stem cell transplant (HSCT), and could cause morbidity and mortality. METHODS: We retrospectively evaluated the incidence, characteristics of, and risk factors for BSI at both pre- and post-engraftment in 209 adult HSCT patients at our institute between June 2006 and December 2013. The median age at transplantation was 45 years (range, 15-65). A total of 122 patients received bone marrow, 68 received peripheral blood stem cells, and 19 received umbilical cord blood. RESULTS: The cumulative incidences of pre- and post-engraftment BSI were 38.9% and 17.2%, respectively. Nine patients had both pre- and post-engraftment BSI. In the pre- and post-engraftment periods, respectively, 67.4% and 84.1% of isolates were gram-positive bacteria (GPB), 28.3% and 11.4% were gram-negative bacteria (GNB), and 4.3% and 4.5% were fungi. Coagulase-negative staphylococci were the most commonly isolated GPB, while Stenotrophomonas maltophilia and Pseudomonas aeruginosa were the most commonly isolated GNB. Pre-engraftment BSI was associated with an increased risk of death. Overall survival at day 180 for patients with or without pre-engraftment BSI was 70.0% and 82.7%, respectively (P = 0.02). CONCLUSIONS: Risk factors for BSI in the pre-engraftment period were the interval between diagnosis and transplantation (261 days or more), engraftment failure, and high-risk disease status at HSCT in a multivariate analysis. No significant risk factor for BSI in the post-engraftment period was identified by a univariate analysis. These findings may be useful for deciding upon empiric antibacterial treatment for HSCT recipients.

Economic evaluation of a preemptive treatment strategy for invasive fungal infection in neutropenic patients with hematological diseases.

We compared the expected medical costs of empirical and preemptive treatment strategies for invasive fungal infection in neutropenic patients with hematological diseases. Based on the results of two clinical trials with different backgrounds reported by Oshima et al. [J Antimicrob Chemother 60(2):350-355; Oshima study] and Cordonnier et al. [Clin Infect Dis 48(8):1042-1051; PREVERT study], we developed a decision tree model that represented the outcomes of empirical and preemptive treatment strategies, and estimated the expected medical costs of medications and examinations in the two strategies. We assumed that micafungin was started in the empirical group at 5 days after fever had developed, while voriconazole was started in the preemptive group only when certain criteria, such as positive test results of imaging studies and/or serum markers, were fulfilled. When we used an incidence of positive test results of 6.7 % based on the Oshima study, the expected medical costs of the empirical and preemptive groups were 288,198 and 150,280 yen, respectively. Even in the case of the PREVERT study, in which the incidence of positive test results was 32.9 %, the expected medical costs in the empirical and preemptive groups were 291,871 and 284,944 yen, respectively. A sensitivity analysis indicated that the expected medical costs in the preemptive group would exceed those in the empirical group when the incidence of positive test results in the former was over 34.4 %. These results suggest that a preemptive treatment strategy can be expected to reduce medical costs compared with empirical therapy in most clinical settings.

Allotype analysis to determine the origin of cytomegalovirus immunoglobulin-G after allogeneic stem cell transplantation.

BACKGROUND: Cytomegalovirus (CMV) reactivation still remains a major problem following allogeneic hematopoietic stem cell transplantation (HSCT). PATIENTS AND METHODS: In this study, we analyzed an immunoglobulin allotype, IgG1m(f), in CMV-seropositive HSCT recipients and their donors to distinguish donor-derived antibody from recipient-derived antibody. Eight donor-recipient pairs were informative regarding the appearance of donor-derived immunoglobulin-G (IgG), as the recipients were homozygous null for the IgG1m(f) allotype and the donors were IgG1m(f) positive. In these patients, total IgG, IgM, and allotype-specific IgG against CMV were measured by enzyme-linked immunosorbent assay. All subjects were monitored for at least 9 months after HSCT with (n = 5) or without (n = 3) CMV reactivation. RESULTS: Donor-derived CMV IgG tended to be elevated earlier in patients with CMV-seropositive donors than in those with CMV-seronegative donors. In 1 patient with a CMV-negative donor, donor-derived CMV IgG was not detected until late CMV reactivation. In 3 patients without CMV reactivation, donor-derived CMV IgG was also elevated within 1-6 months after HSCT. CONCLUSION: In conclusion, the CMV serostatus of the donor may be related to the timing of the appearance of donor-derived CMV IgG and the reconstitution of humoral immunity against CMV, regardless of the CMV antigenemia level after HSCT.

Persistence of recipient-derived as well as donor-derived clones of cytomegalovirus pp65-specific cytotoxic T cells long after allogeneic hematopoietic stem cell transplantation.

BACKGROUND: Cytomegalovirus (CMV)-specific CD8(+) cytotoxic T lymphocytes (CMV-CTLs) play a crucial role in preventing CMV disease. However, the actual in vivo dynamics of CMV-CTL clones after allogeneic hematopoietic stem cell transplantation (alloHCT) are still unclear. METHODS: Using a single-cell T-cell receptor repertoire analysis, we monitored clones and chimerism of CMV-CTLs in 3 CMV-seropositive alloHCT recipients from CMV-seronegative donors, with or without CMV reactivation. RESULTS: Nearly all of the CMV-CTLs during follow-up were CD45RA(-) CCR7(-) effector memory/CD45RA(+) CCR7(-) effector T cells, and were highly matured. In each case, the use of BV gene families was restricted, especially in BV5, 7, 28, and 29. Although no common predominant CMV-CTL clones were found, several shared motifs of complementarity-determining region-3 were identified among the 3 cases; QGA in all, TGE and TDT in Case 1 and Case 2, and RDRG in Case 2 and Case 3. In all cases, CMV-CTL clones that were detected for the first time after alloHCT persisted as the dominant clones. In Case 1, without CMV reactivation, recipient-derived CMV-CTLs exclusively persisted as a dominant clone, while all CMV-CTLs in the other 2 cases, with CMV reactivation, were donor derived. CONCLUSION: Clone monitoring and chimerism analyses should help to further clarify novel aspects of immuno-reconstitution after alloHCT.

Prediction of infectious complications by the combination of plasma procalcitonin level and localized infection before allogeneic hematopoietic cell transplantation.

We previously reported that the baseline C-reactive protein level did not predict infectious events after hematopoietic cell transplantation (HCT). Procalcitonin (PCT) has recently emerged as a powerful biomarker for the early diagnosis of bacterial infection. We evaluated the ability of the baseline PCT level to predict early infectious events after HCT in 79 recipients who received HCT between 2008 and 2012. The high-PCT group (≥ 0.07 ng/mL, n=27) frequently experienced documented infection (DI) (21.2% vs 44.4% at day 30, P=0.038) and bloodstream infection (BSI) (15.4% vs 37.0% at day 30, P=0.035). In a multivariate analysis, however, the baseline PCT level was not significantly associated with DI (HR 2.01, P=0.089) or BSI (HR 2.28, P=0.084). Localized infection, such as anal canal problems, before the start of conditioning was seen in 26 patients. When we stratified the patients according to the presence of elevated PCT and localized infection, the group with elevated PCT and localized infection (n=17) was significantly associated with increased DI (HR 3.40, P=0.0074) and BSI (HR 3.59 P=0.0078) after HCT. A larger prospective observation is warranted to confirm the impact of the baseline PCT level and clinical features on the outcome of HCT.