Impact of peri-transplant vancomycin and fluoroquinolone administration on rates of bacteremia in allogeneic hematopoietic stem cell transplant (HSCT) recipients: a 12-year single institution study

Global impact of antibacterial resistance in patients with hematologic malignancies and hematopoietic cell transplant recipients

Patients with hematologic malignancies and hematopoietic cell transplant (HCT) recipients are at high risk of developing bacterial infections. These patients may suffer severe consequences from these infections if they do not receive immediate effective therapies, and thus are uniquely threatened by antimicrobial-resistant bacteria. Here, we outline how the emergence of specific resistant bacteria threatens the effectiveness of established approaches to prevent and treat infections in this population. The emergence of fluoroquinolone resistance among Enterobacterales and viridans group streptococci may decrease the effectiveness of fluoroquinolone prophylaxis during neutropenia. The emergence of Enterobacterales that produce extended-spectrum β-lactamases or carbapenemases and of increasingly resistant Pseudomonas aeruginosa may result in neutropenic patients experiencing delayed time to active antibacterial therapy, and consequently worse clinical outcomes. The ability to select targeted antibacterial therapies after the availability of susceptibility data may be limited in patients infected with metallo-β-lactamase-producing Enterobacterales and difficult-to-treat P. aeruginosa. Vancomycin-resistant enterococci and Stenotrophomonas maltophilia can cause breakthrough infections in patients already being treated with broad-spectrum β-lactam antibiotics. Resistance can also limit the ability to provide oral stepdown antibacterial therapy for patients who could otherwise be discharged from hospitalization. We also outline strategies that have the potential to mitigate the negative impact of antimicrobial resistance, including interventions based on active screening for colonization with resistant bacteria and the use of novel rapid diagnostic assays. Additional research is needed to better understand how these strategies can be leveraged to combat the emerging crisis of antimicrobial resistance in patients with hematologic malignancies and HCT recipients.

Anti-Pseudomonas aeruginosa Vaccines and Therapies: An Assessment of Clinical Trials

Pseudomonas aeruginosa is a Gram-negative opportunistic pathogen that causes high morbidity and mortality in cystic fibrosis (CF) and immunocompromised patients, including patients with ventilator-associated pneumonia (VAP), severely burned patients, and patients with surgical wounds. Due to the intrinsic and extrinsic antibiotic resistance mechanisms, the ability to produce several cell-associated and extracellular virulence factors, and the capacity to adapt to several environmental conditions, eradicating P. aeruginosa within infected patients is difficult. Pseudomonas aeruginosa is one of the six multi-drug-resistant pathogens (ESKAPE) considered by the World Health Organization (WHO) as an entire group for which the development of novel antibiotics is urgently needed. In the United States (US) and within the last several years, P. aeruginosa caused 27% of deaths and approximately USD 767 million annually in health-care costs. Several P. aeruginosa therapies, including new antimicrobial agents, derivatives of existing antibiotics, novel antimicrobial agents such as bacteriophages and their chelators, potential vaccines targeting specific virulence factors, and immunotherapies have been developed. Within the last 2-3 decades, the efficacy of these different treatments was tested in clinical and preclinical trials. Despite these trials, no P. aeruginosa treatment is currently approved or available. In this review, we examined several of these clinicals, specifically those designed to combat P. aeruginosa infections in CF patients, patients with P. aeruginosa VAP, and P. aeruginosa-infected burn patients.

A compilation of fecal microbiome shotgun metagenomics from hematopoietic cell transplantation patients

Hospitalized patients receiving hematopoietic cell transplants provide a unique opportunity to study the human gut microbiome. We previously compiled a large-scale longitudinal dataset of fecal microbiota and associated metadata, but we had limited that analysis to taxonomic composition of bacteria from 16S rRNA gene sequencing. Here we augment those data with shotgun metagenomics. The compilation amounts to a nested subset of 395 samples compiled from different studies at Memorial Sloan Kettering. Shotgun metagenomics describes the microbiome at the functional level, particularly in antimicrobial resistances and virulence factors. We provide accession numbers that link each sample to the paired-end sequencing files deposited in a public repository, which can be directly accessed by the online services of PATRIC to be analyzed without the users having to download or transfer the files. Then, we show how shotgun sequencing enables the assembly of genomes from metagenomic data. The new data, combined with the metadata published previously, enables new functional studies of the microbiomes of patients with cancer receiving bone marrow transplantation.

Impact of Letermovir Primary Cytomegalovirus Prophylaxis on 1-Year Mortality After Allogeneic Hematopoietic Cell Transplantation: A Retrospective Cohort Study

BACKGROUND

Cytomegalovirus (CMV)-seropositive (R+) hematopoietic cell transplant (HCT) recipients have a survival disparity compared with CMV-seronegative recipient/donor (R-D-) pairs. We hypothesized that primary letermovir prophylaxis (LET) may abrogate this disparity. We investigated the relationship between LET and mortality at 1 year post-HCT.

METHODS

In this retrospective cohort study, we included adult R-D- or R+ patients who received HCT pre-LET (between 1 January 2013 through 15 December 2017) and post-LET (between 16 December 2017 through December 2019). R+ were categorized by LET receipt as R+/LET or R+/no-LET. Cox proportional hazard models were used to estimate the association of LET with all-cause mortality at 1 year after transplantation.

RESULTS

Of 848 patients analyzed, 305 were R-D-, 364 R+/no-LET, and 160 R+/LET. Because of similar mortality (adjusted hazard ratio [aHR], 1.29 [95% confidence interval {CI}, .76-2.18]; P = .353]) between pre-LET/R-D- and post-LET/R-D-, R-D- were combined into 1 group. Compared with R-D-, the aHR for mortality was 1.40 (95% CI, 1.01-1.93) for R+/no-LET and 0.89 (95% CI, .57-1.41) for R+/LET. Among R+, LET was associated with decreased risk of death (aHR, 0.62 [95% CI, .40-.98]); when conventional HCT and T-cell depleted HCT were analyzed separately, the aHR was 0.86 (95% CI, .51-1.43) and 0.21 (95% CI, .07-.65), respectively.

CONCLUSIONS

At 1 year post-HCT, LET was associated with closing the mortality disparity between R-D- and R+. Among all R+, LET was associated with decreased mortality, driven by 79% reduced incidence of death in T-cell depleted HCT.

Efficacy and safety of isavuconazole compared with voriconazole as primary antifungal prophylaxis in allogeneic hematopoietic cell transplant recipients

Voriconazole is frequently discontinued prematurely as primary antifungal prophylaxis (AFP) in allogeneic hematopoietic cell transplant (HCT) recipients due to adverse events. Limited data exists for isavuconazole as AFP. We analyzed adult HCT recipients who received voriconazole or isavuconazole AFP to estimate rate of premature AFP discontinuation, identify risk factors for premature AFP discontinuation, and compare incidence of invasive fungal infection (IFI) and survival at day + 180 post-HCT between patients who received voriconazole/isavuconazole-AFP. This was a propensity score matched cohort analysis of 210 HCT-recipients who received voriconazole-AFP (9/1/2014-12/31/2016; voriconazole-cohort), and 95 HCT-recipients who received isavuconazole-AFP (5/1/2017-10/31/2018; isavuconazole-cohort). AFP discontinuation for any reason prior to completion was defined as "premature". Median (interquartile range, IQR) duration of AFP was longer in the isavuconazole-cohort (94 days, 87-100) vs. the voriconazole-cohort (76 days, 23-94; P-value < 0.0001). Premature AFP discontinuation was more frequent in the voriconazole-cohort (92/210, 43.8%) vs. the isavuconazole-cohort (14/95, 14.7%; P-value < 0.0001). The most common reason for premature discontinuation was biochemical hepatotoxicity (voriconazole-cohort: 48/210, 22.8% vs. isavuconazole-cohort: 5/95, 5.26%; P-value = 0.0002). Transaminase values between baseline and end-of-treatment (EOT) and up to 14 days post-EOT significantly increased in the voriconazole-cohort, but remained unchanged in the isavuconazole-cohort. The incidence of IFI at day + 180 was 2.9% (6/210) and 3.2% (3/95) in the voriconazole-cohort and isavuconazole-cohort, respectively (P-value = 0.881). All-cause mortality at day + 180 was 2.4% (5/210) and 6.3% (6/95) in the voriconazole-cohort and isavuconazole-cohort, respectively (P-value = 0.089). When compared to voriconazole, isavuconazole was a safer and as effective primary AFP during the first 3 months after HCT.

LAY SUMMARY

When compared to voriconazole, isavuconazole is a safer and as effective primary antifungal prophylaxis during the first 3 months after allogeneic hematopoietic cell transplant, with lower rates of hepatotoxicity, and similar rates of fungal infections and all-cause mortality.

Human herpes virus 6 DNAemia is associated with worse survival after ex vivo T-cell depleted hematopoietic cell transplant

BACKGROUND

We examined the correlation between persistent HHV-6 DNAemia (p-HHV-6) and absolute lymphocyte counts (ALC), platelet counts (PLT) and all-cause mortality the 1-year after ex vivo T-cell depleted (TCD) hematopoietic cell transplant (HCT).

METHODS

We analyzed a cohort of adult TCD HCT recipients 2012-2016 prospectively monitored for plasma HHV-6 by qPCR from day +14 post-HCT (D+14) through D+100. P-HHV-6 was defined as ≥2 consecutive values of ≥500 copies/mL by D+100. PLT and ALC were compared between patients with and without p-HHV-6 using mixed model analysis of variance. Multivariable Cox proportional hazard models were used to identify the impact of p-HHV-6 on 1-year mortality.

RESULTS

Of 312 patients, 83 (27%) had p-HHV-6 by D+100. P-HHV-6 was associated with lower ALC and PLT in the first year post-HCT. In multivariable models, p-HHV-6 was associated with higher mortality by 1-year post-HCT (adjusted hazard ratio 2.97, 95% confidence intervals: 1.62-5.47, P=0.0005), after adjusting for age, antiviral treatment, and ALC at D+100.

CONCLUSIONS

P-HHV-6 was associated with lower ALC and PLT in the first year post-HCT. P-HHV-6 was an independent predictor of mortality in the first year after TCD HCT.

CMV viral load kinetics predict CMV end-organ disease and mortality after hematopoietic cell transplant (HCT)

BACKGROUND

We investigated the association between time-averaged area under the curve (AAUC) of CMV viral load (VL) by D100 and overall survival (OS) at one-year post-hematopoietic cell transplantation (HCT).

METHODS

A retrospective cohort study, including patients receiving HCT between 2010.6 and 2017.12 from Memorial Sloan Kettering Cancer Center. AAUC was calculated for patients with detected VL. Patients were categorized into "non-controllers" (Q4) and "controllers" (Q1-3) using the highest AAUC quartile as cutoff. Kaplan-Meier analyses and Cox models were used to estimate the association between AAUC and OS. Patients with non-detected CMV VL were categorized into "elite-controllers" (R+ or R-/D+) and "R-/D-".

RESULTS

The study (N=952) included 282 controllers, 93 non-controllers, 275 elite-controllers, and 302 R-/D-. OS was 80.1% and 58.1% for controllers and non-controllers, respectively. In multivariable models, non-controllers had worse OS versus controllers (adjusted hazard ratio [HR] 2.65, 95% CI 1.71-4.12). In landmark analyses, CMV controllers had similar OS as elite-controllers (HR 1.26, 95% CI 0.83-1.91) or R-/D- (HR 0.98, 95% CI 0.64-1.5).

CONCLUSION

CMV non-controllers had worse OS at one-year post-HCT. CMV controllers had similar OS as elite-controllers or R-/D-. Future studies are needed to validate our AAUC cutoff across different cohorts and CMV management strategies.

Compilation of longitudinal microbiota data and hospitalome from hematopoietic cell transplantation patients

The impact of the gut microbiota in human health is affected by several factors including its composition, drug administrations, therapeutic interventions and underlying diseases. Unfortunately, many human microbiota datasets available publicly were collected to study the impact of single variables, and typically consist of outpatients in cross-sectional studies, have small sample numbers and/or lack metadata to account for confounders. These limitations can complicate reusing the data for questions outside their original focus. Here, we provide comprehensive longitudinal patient dataset that overcomes those limitations: a collection of fecal microbiota compositions (>10,000 microbiota samples from >1,000 patients) and a rich description of the "hospitalome" experienced by the hosts, i.e., their drug exposures and other metadata from patients with cancer, hospitalized to receive allogeneic hematopoietic cell transplantation (allo-HCT) at a large cancer center in the United States. We present five examples of how to apply these data to address clinical and scientific questions on host-associated microbial communities.

American Society of Transplantation and Cellular Therapy Series, 1: Enterobacterales Infection Prevention and Management after Hematopoietic Cell Transplantation

The Practice Guidelines Committee of the American Society of Transplantation and Cellular Therapy partnered with its Transplant Infectious Disease Special Interest Group to update its 2009 compendium-style infectious diseases guidelines for hematopoietic cell transplantation (HCT). A completely fresh approach was taken, with the goal of better serving clinical providers by publishing each stand-alone topic in the infectious diseases series in a concise format of frequently asked questions (FAQs), tables, and figures [1]. Adult and pediatric infectious diseases and HCT content experts developed and then answered FAQs, and then finalized topics with harmonized recommendations that were made by assigning a strength of recommendation ranging from A to E paired with a level of supporting evidence graded I to III. The first topic in the series focuses on potentially life-threatening infections in HCT caused by Enterobacterales, relevant infection risk factors, and practical considerations regarding prevention and treatment of these infections in the setting of emerging multidrug resistance.

Bloodstream Infection Due to Vancomycin-resistant Enterococcus Is Associated With Increased Mortality After Hematopoietic Cell Transplantation for Acute Leukemia and Myelodysplastic Syndrome: A Multicenter, Retrospective Cohort Study

BACKGROUND

We examined the impact of vancomycin-resistant Enterococcus (VRE) bloodstream infection (BSI) on outcomes of allogeneic hematopoietic cell transplantation (HCT) utilizing the Center for International Blood and Marrow Transplant Research database.

METHODS

Adult and pediatric patients (N = 7128) who underwent first HCT for acute leukemia or myelodysplastic syndrome from 2008 through 2012 were analyzed as 3 groups-VRE BSI, non-VRE BSI, without BSI-according to BSI status at 100 days (D100) after allogeneic HCT. Multivariable models examined the effect of VRE BSI for overall survival (OS) and nonrelapse mortality (NRM) at 1 year.

RESULTS

Of 7128 patients, 258 (3.2%) had VRE BSI, 2398 (33.6%) had non-VRE BSI, and 4472 (63%) had no BSI. The median time to VRE BSI and non-VRE BSI were D11 and D15, respectively. Compared with non-VRE BSI patients, VRE BSI patients were older, had advanced-stage acute leukemia, and received umbilical cord blood (UCB) allografts. In multivariable models, VRE BSI was associated with lower OS (relative risk [RR], 2.9;(99% confidence interval [CI], 2.2-3.7) and increased NRM (RR, 4.7; 99% CI, 3.6-6.2) (P < .0001) for both. Other predictors for worse OS and increased NRM were non-VRE BSI, older age, advanced disease stage, UCB allograft, - mismatch, comorbidity index ≥3, and cytomegalovirus seropositivity (P < .001 for all variables).

CONCLUSIONS

VRE BSI is associated with lowest OS and highest NRM compared with patients without BSI or non-VRE BSI. Novel interventions that address the pathophysiology of VRE BSI have the potential of improving survival after HCT.

Impact of Preemptive Therapy for Cytomegalovirus on Hospitalizations and Cost after Hematopoietic Stem Cell Transplantation

Cytomegalovirus (CMV) viremia occurs in 40% to 80% of CMV-seropositive (R+) recipients of allogeneic hematopoietic cell transplantation (HCT). The preemptive therapy (PET) strategy has reduced the risk of CMV end-organ disease (EOD) and associated mortality but may lead to substantial healthcare resource utilization (HCRU) and costs. Real-world data on the economic impact of PET is relevant for the evaluation of alternative strategies for CMV management. We examined the impact of clinically significant CMV treated with PET on inpatient length of stay (LOS), number of readmissions, and associated costs from day 0 through day 180 post-HCT. This was a retrospective study of R+ adults who underwent peripheral blood or marrow allogeneic HCT at Memorial Sloan Kettering Cancer Center between March 2013 and December 2017. Patients were routinely screened for CMV by qPCR and received PET according to institutional standards of care. Data were extracted from electronic medical records and hospital databases. Itemized cost data per patient were obtained from the Vizient database, adjusted to 2017 dollars using inflation indices. Study outcomes included HCRU evaluated by inpatient LOS and inpatient cost in patients who received PET for clinically significant CMV (PET group) compared with those who did not receive PET (no PET group) and the frequency and cost of CMV-related readmissions compared with non CMV-related readmissions. We used generalized linear models to examine the incremental HCRU and costs associated with PET controlling for other potential factors. Of 357 patients, PET was initiated in 208 (58.3%), at a median of 35 days after HCT. By day 180, 23 patients (6.4%) had developed CMV EOD and 3 (.8%) had died of CMV. Compared with the no PET group, the PET group had a longer LOS for HCT admission (P = .0276), longer total LOS by day 180 (P = .0001), a higher number of readmissions (P = .0001), a higher mean inpatient cost for HCT admission ($189,389 versus $151,646; P = .0133), and a higher total inpatient cost ($297,563 versus $205,815; P < .0001). Among PET recipients, CMV-related readmissions were associated with higher mean cost per episode compared with non CMV-related readmissions ($165,455 versus $89,419; P = .005). CMV-related readmissions comprised 40.6% of total all-cause readmissions and incurred 55.9% of total all-cause readmission costs in PET recipients. Our data show that patients treated with currently available PET had greater inpatient HCRU and cost, by day 180 compared with patients who did not receive PET. The cost of CMV-related readmissions accounted for 56% of total readmission cost among PET recipients. Future studies are needed to examine the cost-effectiveness of alternative strategies for CMV management.

Impact of Preemptive Therapy for Cytomegalovirus on Toxicities after Allogeneic Hematopoietic Cell Transplantation in Clinical Practice: A Retrospective Single-Center Cohort Study

(Val)ganciclovir (vGCV) or foscarnet (FCN) as preemptive therapy (PET) for cytomegalovirus (CMV) after allogeneic hematopoietic cell transplantation (HCT) is associated with myelosuppression and nephrotoxicity, respectively. We analyzed a cohort of CMV-seropositive (R⁺) HCT recipients managed preemptively at a single center. The objectives of our study were to (1) quantify the frequencies of neutropenia and acute kidney injury (AKI) through day +100 (D100) post-HCT and at PET discontinuation and (2) assess the impact of PET on neutropenia and AKI in multivariate models. This was a retrospective cohort study of adult CMV R⁺ recipients who underwent allo-HCT at Memorial Sloan Kettering Cancer Center from March 18, 2013, through December 31, 2017, and were managed with PET. Patients were grouped by receipt of PET (PET and no PET). Neutropenia and AKI were defined by Common Terminology Criteria for Adverse Events version 4. Frequencies of toxicities by D100 were compared between relevant groups. The impact of PET on toxicities was examined in univariate and multivariate Poisson/negative binomial regression models. Of 368 CMV R⁺ HCT recipients, 208 (56.5%) received PET. Neutropenia by D100 occurred in 41.8% and 28.6% patients in PET and no PET, respectively (P = .0009). PET increased the risk of neutropenia (adjusted relative risk = 1.81; 95% confidence interval [CI], 1.48 to 2.21; P < .0001) in multivariate analyses. AKI by D100 occurred in 12.0% and 7.8% patients in PET and no PET, respectively (P = .19). PET increased the risk of AKI by 2.75-fold (95% CI, 1.71 to 4.42; P < .0001). When PET recipients were grouped by first antiviral, neutropenia by D100 occurred in 34.8% and 48.9% of vGCV and FCN recipients, respectively, (P = .08), and AKI occurred in 13.0% and 34.0% of vGCV and FCN recipients, respectively (P = .001). At discontinuation of vGCV or FCN, neutropenia was present in 11.2% versus 2.1% patients, respectively (P = .08), and AKI was present in 1.9% of versus 12.8% patients respectively (P = .005). Preemptive therapy for CMV increased the risk of neutropenia and AKI in the first 100 days post-HCT by 1.8-fold and 2.8-fold, respectively. Our results underscore the need for safer antivirals for CMV management in HCT recipients.

Febrile Neutropenia in Transplant Recipients

Febrile neutropenic patients are at increased risk of developing infections. During the initial stages of neutropenia, most of these infections are bacterial. The spectrum of bacterial infections depends to some extent on whether or not patients receive antimicrobial prophylaxis when neutropenic. Since most transplant recipients do, Gram-positive organisms predominate, due to the fact prophylaxis is directed primarily against Gram-negative organisms. Staphylococcus species (often methicillin-resistant), Streptococcus species (viridans group streptococci, beta-hemolytic streptococci), and Enterococcus species (including vancomycin-resistant strains) are isolated most often. Therefore, potent empiric Gram-positive coverage is recommended by many in this setting. Escherichia coli, Pseudomonas aeruginosa, and Klebsiella species are the most common Gram-negative pathogens isolated. Non-fermentative Gram-negative bacilli (Stenotrophomonas maltophilia, Acinetobacter species) are emerging as important pathogens. Many of these organisms acquire multiple mechanisms of resistance that render them multidrug resistant. The administration of prompt, broad-spectrum, empiric, antimicrobial therapy is essential and is generally based on local epidemiology and susceptibility/resistance patterns. Response rate to the initial regimen is generally in the range of 75–85%. Fungal infections develop in patients with prolonged neutropenia (greater than 7–10 days). Candida species and Aspergillus species are the predominant fungal pathogens, although many other fungi are opportunistic pathogens in this setting. Fungal infections are seldom documented microbiologically or on histopathology, and the administration of empiric antifungal therapy, when such infections are suspected, is the norm. Therapy is often prolonged, and outcomes are still suboptimal. The importance of infection control and antimicrobial stewardship cannot be overemphasized.

Impact of Empiric Treatment for Vancomycin-Resistant Enterococcus in Colonized Patients Early after Allogeneic Hematopoietic Stem Cell Transplantation

In recent years, vancomycin-resistant Enterococcus (VRE) colonization is being increasingly encountered in transplant recipients, and VRE has become one of the leading causes of bacteremia early after allogeneic hematopoietic stem cell transplantation (allo-HSCT). Data are sparse on the effect of empiric VRE therapy for febrile, neutropenic allo-HSCT recipients colonized with VRE. All allo-HSCT recipients aged ≥18years who developed VRE bacteremia (VREB) between 2005 and 2014 were identified and categorized as to whether they received empiric or directed VRE therapy. There were 434 (33%) VRE-colonized and 872 (67%) non-VRE-colonized patients during the study period, and 172 of the 434 (40%) VRE-colonized patients received empiric therapy. There was no significant difference in incidence of VREB among colonized patients who did or did not receive empiric therapy (28 of 172 [16%] vs 55 of 262 [21%]; P = .22). There were 95 patients with VREB, of which the majority (83 of 95; 87%) was known to be VRE-colonized. Of the 95 VREB episodes, 29 (31%) were treated with empiric VRE therapy, whereas 66 (69%) were treated with directed therapy. No significant differences in clinical outcomes, including median duration of bacteremia (2 days vs 2 days; P = .39), recurrent VREB (3 of 29 [10%] vs 5 of 66 [8%]; P = .65), 30-day all-cause mortality (1 of 29 [3%] vs 4 of 66 [6%]; P = .62), or VRE-attributable mortality (1 of 29 [3%] vs 1 of 66 [2%]; P = .55), were observed between the empiric therapy and directed therapy groups. Kaplan-Meier curve analysis showed no significant difference in survival at 30days in allo-HSCT recipients with VREB who received empiric therapy and those who received directed therapy (97% vs 94%; P = .62). Based on our data, we recommend against empiric use of VRE-active agents for fever and neutropenia in VRE-colonized patients undergoing allo-HSCT.

Risk Factors for Viridans Group Streptococcal Bacteremia in Neutropenic and Non-neutropenic Patients: A Single Center Case-Case-Control Study

Background

Viridans group streptococcal (VGS) bacteremia is common among neutropenic patients. Although VGS bacteremia occurs in non-neutropenic patients, risk factors are not well established. We conducted a case-case-control study to identify risk factors for VGS among neutropenic and non-neutropenic patients.

Methods

Patients with VGS bacteremia between January 2009 and December 2014 in our 200-bed clinical research hospital were identified using microbiology records. Neutropenic and non-neutropenic patients at the time of positive culture were matched 1:1 to controls on the basis of neutrophil count (ANC), ward, and length of stay. We extracted demographic, laboratory, medication, and other clinical data from chart reviews. Data were analyzed using McNemar's test, Wilcoxon signed-rank test, and conditional logistic regression modeling.

Results

Among 101 patients, 63 were neutropenic and 38 non-neutropenic at the time of VGS bacteremia. In multivariable analysis of neutropenic patients, only lower ANC predicted VGS bacteremia (odds ratio [OR], 0.16; 95% confidence interval [CI], 0.05-0.59; P = 0.006). Recent use of vancomycin was protective (OR, 0.23; 95% CI, 0.07-0.73; P = 0.013). No clinical factors were associated with VGS in the non-neutropenic cases.

Conclusions

Only lower ANC nadir increased the risk for VGS bacteremia in the neutropenic group, and vancomycin was protective. Other previously described factors (chemotherapy, radiation, oral conditions) related to neutropenia were not independently associated with VGS bacteremia. No tested clinical factors predicted infection in the non-neutropenic group. Our results suggest that VGS bacteremia should be anticipated when making antimicrobial choices in profoundly neutropenic patients, and merit further exploration in non-neutropenic patients.

Multidrug-resistant Enterobacteriaceae, Pseudomonas aeruginosa, and vancomycin-resistant Enterococcus: Three major threats to hematopoietic stem cell transplant recipients

Hematopoietic stem cell transplant (HSCT) recipients are uniquely threatened by the emergence of multidrug-resistant (MDR) bacteria because these patients rely on immediate active antimicrobial therapy to combat bacterial infections. This review describes the epidemiology and treatment considerations for three challenging MDR bacterial pathogens in HSCT recipients: MDR Enterobacteriaceae, including extended-spectrum β-lactamase (ESBL)-producing and carbapenem-resistant Enterobacteriaceae (CRE), Pseudomonas aeruginosa, and vancomycin-resistant Enterococcus (VRE). These bacteria are common causes of infection in this population and bacteremias caused by these organisms are associated with high mortality rates. Carbapenems remain the treatments of choice for serious infections due to ESBL-producing Enterobacteriaceae in HSCT recipients. Administration of β-lactam agents as an extended infusion is associated with improved outcomes in patients with severe infections caused by P. aeruginosa. Older agents used for the treatment of CRE and MDR P. aeruginosa infections, such as polymyxins and aminoglycosides, have major limitations. Newer agents, such as ceftazidime-avibactam and ceftolozane-tazobactam have great potential for the treatment of Klebsiella pneumoniae carbapemenase-producing CRE and MDR P. aeruginosa, respectively, but more pre-clinical and clinical data are needed to better evaluate their efficacy. Daptomycin dosages ≥8 mg/kg/day are recommended to treat VRE infections in this population, particularly in the setting of increasing daptomycin resistance. Strategies to prevent these infections include strict adherence to recommended infection control practices and multidisciplinary antimicrobial stewardship. Last, gastrointestinal screening to guide empirical therapy and the use of polymerase chain reaction-based rapid diagnostics may decrease the time to administration of appropriate therapy for these infections, thereby leading to improved outcomes.

Bacterial bloodstream infections in the allogeneic hematopoietic cell transplant patient: new considerations for a persistent nemesis

Bacterial bloodstream infections (BSI) cause significant transplant-related morbidity and mortality following allogeneic hematopoietic cell transplantation (allo-HCT). This manuscript reviews the risk factors for and the bacterial pathogens causing BSIs in allo-HCT recipients in the contemporary transplant period. In addition, it offers insight into emerging resistant pathogens and reviews clinical management considerations to treat and strategies to prevent BSIs in allo-HCT patients.

The growing threat of multidrug-resistant Gram-negative infections in patients with hematologic malignancies

Prolonged neutropenia and chemotherapy-induced mucositis render patients with hematologic malignancies highly vulnerable to Gram-negative bacteremia. Unfortunately, multidrug-resistant (MDR) Gram-negative bacteria are increasingly encountered globally, and current guidelines for empirical antibiotic coverage in these patients may not adequately treat these bacteria. This expansion of resistance, coupled with traditional culturing techniques requiring 2-4 days for bacterial identification and antimicrobial susceptibility results, have grave implications for these immunocompromised hosts. This review characterizes the epidemiology, risk factors, resistance mechanisms, recommended treatments, and outcomes of the MDR Gram-negative bacteria that commonly cause infections in patients with hematologic malignancies. We also examine the infection prevention strategies in hematology patients, such as infection control practices, antimicrobial stewardship, and targeted decolonization. Finally, we assess the strategies to improve outcomes of the infected patients, including gastrointestinal screening to guide empirical antibiotic therapy, new rapid diagnostic tools for expeditious identification of MDR pathogens, and use of two new antimicrobial agents, ceftolozane/tazobactam and ceftazidime/avibactam.

Breakthrough viridans streptococcal bacteremia in allogeneic hematopoietic stem cell transplant recipients receiving levofloxacin prophylaxis in a Japanese hospital

Background

Breakthrough viridans streptococcal bacteremia (VSB) in patients with hematological malignancy receiving levofloxacin prophylaxis is a major blood stream infection (BSI) occurring during febrile neutropenia. However, clinical data focused on VSB in allogeneic hematopoietic stem cell transplant (allo-HSCT) recipients are lacking.

Methods

The medical records of allo-HSCT recipients who received oral levofloxacin prophylaxis between January 2011 and August 2013 at Toranomon Hospital were reviewed to evaluate breakthrough VSB. Stored viridans streptococcal (VGS) species were identified by using sodA gene sequencing, and were assessed for drug susceptibility.

Results

Among the 184 allo-HSCT recipients on levofloxacin prophylaxis, 28 (15.2 %) experienced breakthrough VSB. All of the 28 recipients with VSB were treated with a cefepime-based or piperacillin/tazobactam-based regimen. The susceptibility rates of the VGS strains for levofloxacin, cefepime, piperacillin/tazobactam, meropenem, and vancomycin were 0 %, 95 %, 100 %, 100 %, and 100 %, respectively. Both the MIC₅₀ (minimum inhibitory concentration) and the MIC₉₀ of ceftazidim (0.5 μg/mL and 2 μg/mL, respectively) were higher than the MIC₉₀ of all the other anti-pseudomonal beta-lactams (APBLs). Only 1 VGS strain had a penicillin MIC ≥ 2 μg/mL by the Etest (3.6 %). There were no cases with acute respiratory distress syndrome (ARDS) that was associated with VSB, although the rate of viridans group streptococcal shock syndrome was high (26 %). The crude 30-day mortality rate in the VSB group (10.7 %) did not differ significantly from that in the BSI without VSB group (9.3 %) or non-BSI group (7.0 %) (P = 0.77). Also, VSB was not a risk factor for all-cause mortality up to 60 days following allo-HSCT (P = 0.43).

Conclusions

APBL with increased anti-VGS activity (APBL-VA) monotherapy would typically be optimal for treating the VGS strains in this setting. Indication of adding an empiric anti-gram-positive agent to APBL-VA for treating VSB should depend on local factors, such as the susceptibility results. In addition, breakthrough VSB is probably not a major cause of death in allo-HSCT settings, where beta-lactam non-susceptible VGS and the ARDS are rare.

Electronic supplementary material

The online version of this article (doi:10.1186/s12879-016-1692-y) contains supplementary material, which is available to authorized users.

Increased GVHD-related mortality with broad-spectrum antibiotic use after allogeneic hematopoietic stem cell transplantation in human patients and mice

Intestinal bacteria may modulate the risk of infection and graft-versus-host disease (GVHD) after allogeneic hematopoietic stem cell transplantation (allo-HSCT). Allo-HSCT recipients often develop neutropenic fever, which is treated with antibiotics that may target anaerobic bacteria in the gut. We retrospectively examined 857 allo-HSCT recipients and found that treatment of neutropenic fever with imipenem-cilastatin and piperacillin-tazobactam antibiotics was associated with increased GVHD-related mortality at 5 years (21.5% for imipenem-cilastatin-treated patients versus 13.1% for untreated patients, P = 0.025; 19.8% for piperacillin-tazobactam-treated patients versus 11.9% for untreated patients, P = 0.007). However, two other antibiotics also used to treat neutropenic fever, aztreonam and cefepime, were not associated with GVHD-related mortality (P = 0.78 and P = 0.98, respectively). Analysis of stool specimens from allo-HSCT recipients showed that piperacillin-tazobactam administration was associated with perturbation of gut microbial composition. Studies in mice demonstrated aggravated GVHD mortality with imipenem-cilastatin or piperacillin-tazobactam compared to aztreonam (P < 0.01 and P < 0.05, respectively). We found pathological evidence for increased GVHD in the colon of imipenem-cilastatin-treated mice (P < 0.05), but no difference in the concentration of short-chain fatty acids or numbers of regulatory T cells. Notably, imipenem-cilastatin treatment of mice with GVHD led to loss of the protective mucus lining of the colon (P < 0.01) and the compromising of intestinal barrier function (P < 0.05). Sequencing of mouse stool specimens showed an increase in Akkermansia muciniphila (P < 0.001), a commensal bacterium with mucus-degrading capabilities, raising the possibility that mucus degradation may contribute to murine GVHD. We demonstrate an underappreciated risk for the treatment of allo-HSCT recipients with antibiotics that may exacerbate GVHD in the colon.

Cytomegalovirus Infection after CD34(+)-Selected Hematopoietic Cell Transplantation

The effectiveness of preemptive treatment (PET) for cytomegalovirus (CMV) in recipients of ex vivo T cell-depleted (TCD) hematopoietic cell transplantation (HCT) by CD34(+) selection is not well defined. We analyzed 213 adults who received TCD-HCT at our institution from June 2010 through May 2014. Patients were monitored by a CMV quantitative PCR assay if recipient (R) or donor (D) were CMV seropositive. CMV viremia occurred early (median, 27 days after HCT) in 91 of 213 (42.7%) patients for a 180-day cumulative incidence of 84.5%, 61.8%, and 0 for R+/D+, R+/D-, and R-/D+ patients, respectively. CMV disease occurred in 5% of patients. In Cox regression analysis, R+/D+ status was associated with increased risk for CMV viremia compared with R+/D- (hazard ratio [HR], 1.79, 95% confidence interval [CI], 1.16 to 2.76, P = .01), whereas matched unrelated donor allograft was associated with decreased risk (HR, .62; 95% CI, .39 to .97, P = .04). Of 91 patients with CMV viremia, 52 (57%) had persistent viremia (>28 days duration). Time lag from detection of CMV viremia to PET was associated with incremental risk for persistent viremia (HR, 1.09; 95% CI, 1.01 to 1.18; P = .03). Overall, 166 of 213 (77.9%) patients were alive 1 year after HCT, with no difference between patients with and without CMV viremia or among the different CMV serostatus pairs (P = not significant). CMV viremia occurred in 70% of R + TCD-HCT. Delay in PET initiation was associated with persistent viremia. With PET, CMV R/D serostatus did not adversely impact survival in TCD-HCT on 1-year survival in the present cohort.

Bloodstream infections in neutropenic cancer patients: A practical update

Bloodstream infections (BSI) are among the most frequent complications in neutropenic cancer patients and, if caused by Gram-negative rods, are associated with high mortality. Thus, fever during neutropenia warrants prompt empirical antibiotic therapy which should be active against the most frequent Gram-negatives. In the last decade, there has been a worldwide increase in multidrug resistant (MDR) strains. In these cases, the traditional choices such as oral therapy, ceftazidime, cefepime, piperacillin-tazobactam, or even carbapenems, might be ineffective. Therefore novel de-escalation approach has been proposed for patients who are at high risk for infections due to MDR bacteria. It consists of starting antibiotics which cover the most probable resistant strain but it is narrowed down after 72 hours if no MDR pathogen is isolated. With increasing bacterial resistance, the benefit of fluoroquinolone prophylaxis during prolonged neutropenia remains to be confirmed. Antibiotic stewardship and infection control programs are mandatory in every cancer center.

Effect of application of a PVP-iodine solution before and during subgingival ultrasonic instrumentation on post-treatment bacteraemia: a randomized single-centre placebo-controlled clinical trial

BACKGROUND

To assess the effect of concomitant subgingival rinsing with 10% PVP-iodine during subgingival instrumentation on the prevalence and magnitude of bacteraemia of oral origin.

MATERIALS AND METHODS

Subgingival instrumentation was performed with water or PVP-iodine rinse in patients with periodontitis. Prior to instrumentation, subjects gargled for 1 min with the allocated liquid. Pockets were then rinsed for 1 min and subgingivally instrumented with liquid-cooled (water/PVP-iodine) ultrasonic scalers (1 min). Two minutes later, a blood sample from the arm vein was drawn using a lysis centrifugation blood culture system for quantitative microbiological analysis. Non-parametric statistical tests were performed to assess differences in the prevalence and extent of bacteraemia between groups.

RESULTS

Of the 19 samples in each group, oral-borne bacteraemia was detected in 10 of the control and 2 of the test samples. With an average of 3.0 [1; 5] colony forming units, significantly less bacteria and bacteraemia were found in the test group compared to the controls (12.2 [1; 46]) (p = 0.003). Anaerobic bacteria were not found in the test group.

CONCLUSIONS

Bacteraemia after subgingival instrumentation with concomitant PVP-iodine rinsing is reduced but not eliminated. Therefore, it might be recommended for patients at a high risk of endocarditis or infection of endoprostheses. However, preventive antibiotic treatment should not be omitted.

Role of antimicrobial prophylaxis during treatment of adults with acute leukemia

Patients with acute leukemia (AL) are at high risk for developing bacterial, viral and fungal infections during chemotherapy. Because these infections cause considerable morbidity and mortality, prevention is attractive. In recent decades, several trials have established the benefit of prophylactic antimicrobials in patients with AL. Administration of prophylactic fluoroquinolone, acyclovir and triazole is recommended in neutropenic patients with AL by both the USA and European national guidelines. The potential for antimicrobial resistance as a long-term consequence of prophylaxis, however, is a concern. The recent development of nonculture-based diagnostic tests for invasive fungal infections has made early diagnosis and targeted treatment a promising future strategy as an alternative to mold-active prophylaxis.