Adults with Philadelphia Chromosome–Like Acute Lymphoblastic Leukemia: Considerations for Allogeneic Hematopoietic Cell Transplantation in First Complete Remission

Philadelphia chromosome–like (Ph-like) acute lymphoblastic leukemia (ALL) is a subset of high-risk B cell ALLs. A large proportion of Ph-like ALL cases carry activating kinase mutations that could potentially allow them to be targeted by tyrosine kinase inhibitors. Ph-like ALL is not an uncommon entity, especially among adults, with a frequency exceeding 20%, including in older patients (>60 years old) with ALL. Ph-like ALL is associated with inferior outcomes across all ages, and studies have consistently shown a higher incidence of persistent postinduction minimal residual disease in patients carrying Ph-like ALL compared with other subgroups of ALL, and this translates into inferior leukemia-related outcomes. The inferior outcome of conventional chemotherapy for Ph-like ALL in adults raises the fundamental question of whether all adults with Ph-like ALL require an allogeneic hematopoietic cell transplantation (HCT) in first complete remission (CR1) regardless of other presenting features and treatment response parameters. Here we present and discuss several scenarios in which adults with Ph-like ALL underwent or were considered for HCT in CR1 for various reasons. Although the decision to proceed with HCT was clear and indisputable in some of these situations, in others we struggled with the decision to transplant in CR1 because of the lack of published data regarding the efficacy of allogeneic HCT as consolidation for Ph-like ALL. We emphasize the urgent need for developing well-designed studies to address this important question.     

CAPN5 genetic inactivation phenotype supports therapeutic inhibition trials

Small molecule pharmacological inhibition of dominant human genetic disease is a feasible treatment that does not rely on the development of individual, patient‐specific gene therapy vectors. However, the consequences of protein inhibition as a clinical therapeutic are not well‐studied. In advance of human therapeutic trials for CAPN5 vitreoretinopathy, genetic inactivation can be used to infer the effect of protein inhibition in vivo. We created a photoreceptor‐specific knockout (KO) mouse for Capn5 and compared the retinal phenotype to both wild‐type and an existing Capn5 KO mouse model. In humans, CAPN5 loss‐of‐function (LOF) gene variants were ascertained in large exome databases from 60,706 unrelated subjects without severe disease phenotypes. Ocular examination of the retina of Capn5 KO mice by histology and electroretinography showed no significant abnormalities. In humans, there were 22 LOF CAPN5 variants located throughout the gene and in all major protein domains. Structural modeling of coding variants showed these LOF variants were nearby known disease‐causing variants within the proteolytic core and in regions of high homology between human CAPN5 and 150 homologs, yet the LOF of CAPN5 was tolerated as opposed to gain‐of‐function disease‐causing variants. These results indicate that localized inhibition of CAPN5 is a viable strategy for hyperactivating disease alleles.     

In vitro expression of vital virulent genes of clinical and environmental isolates of Cryptococcus neoformans/gattii in endothelial cells of human blood-brain barrier

BackgroundEvaluation of the pathogenesis of clinical and environmental cryptococcal isolates to the central nervous system is necessary for understanding the risk. This study was designed to determine the in vitro expression of six important virulent genes of Cryptococcus neoformans/gattii in Human Brain Microvascular Endothelial cells (hBMEC).MethodsThe hBMEC were infected with Cryptococcus to determine invasion and survival rate at 3, 12 and 24 hours by subsequent colony count of internalized yeasts. The whole RNA of the intracellular Cryptococcus was extracted to quantify the expression of CAP10, PLB1, ENA1, URE1, LAC1, and MATα genes by real-time quantitative PCR for 3 and 12 hours of infection.ResultsInvasion and survival rates were higher in clinical and standard strains of C. neoformans. A significant difference was observed among the clinical and environmental isolates for the expression of CAP10, ENA1, LAC1, MATα and URE1 at 3 hours, and ENA1, LAC1, MATα, PLB1 and URE1 at 12 hours. Clinical isolates showed significant upregulation of all the genes except PLB1, which was higher in environmental isolates. Relative expressions at the two time-points showed statistically significant (P = 0.043) changes for the clinical isolates and no significance (P = 0.063) for environmental isolates.ConclusionThe C. gattii (VGI) isolates showed significantly lower invasion and survival than C. neoformans (VNI, and VNII) irrespective of their sources. Clinical isolates exhibited higher expression for the majority of the virulent genes until 12 hours of infection, probably due to their better adaptation in the host system and enhanced pathogenicity than the environmental counterparts.     

Combining VITEK® 2 with colistin agar dilution screening assist timely reporting of colistin susceptibility

ObjectivesThe rise in carbapenem resistance among Gram-negative bacteria has renewed interest in colistin. Recently, the EUCAST-CLSI Polymyxin Breakpoints Working Group declared that broth microdilution (BMD) is the only valid method for colistin susceptibility testing. BMD is not easily incorporated into the routine work of clinical laboratories, and usually this test is incorporated serially, resulting in delayed susceptibility reporting. We tested a strategy of combining VITEK^® 2 with a 2 μg/mL colistin agar dilution (VITEK^® 2/AD) screening plate to improve performance and time to reporting of colistin susceptibility.MethodsColistin susceptibility for 364 clinical isolates was determined by VITEK^® 2/AD and compared with the reference standard BMD according to the ISO 20776-1:2007 and CLSI guidelines. The EUCAST colistin susceptibility breakpoint of ≤2 μg/mL was used. Escherichia coli NCTC 13846 served as quality control strain. Agreement, very major error (VME) and major error rates were determined using ISO 20776-2:2007.ResultsThe VME rate for VITEK^® 2 alone was 30.6% (15/49, 95% CI 18.3–45.4%), and was reduced to 10.2% (5/49, 95% CI 3.4–22.2%) using the VITEK^® 2/AD combined testing. The combined testing had categorical agreement with BMD of 97% (354/364, 95% CI 95.0–98.7%), and a major error (ME) rate of 1.6% (5/315, 95% CI 0.5–3.7%). Using the combined testing, even against challenging strains, 349 (95.8%, 95% CI 93.3–97.7%) colistin susceptibility results could be reported, and only 15 isolates required further analysis by BMD.DiscussionOur method is simple to apply and allows rapid reporting of colistin susceptibility.     

Fluoroquinolones versus trimethoprim-sulfamethoxazole for the treatment of Stenotrophomonas maltophilia infections: a systematic review and meta-analysis

BackgroundFluoroquinolones are a popular alternative to trimethoprim-sulfamethoxazole for Stenotrophomonas maltophilia infections.ObjectivesTo compare the effects of fluoroquinolones and trimethoprim-sulfamethoxazole on mortality of S. maltophilia infections.Data sourcesPubMed and EMBASE.Study eligibility criteriaClinical studies reporting mortality outcomes of S. maltophilia infections.ParticipantsPatients with clinical infections caused by S. maltophilia.InterventionsFluoroquinolone monotherapy in comparison with trimethoprim-sulfamethoxazole monotherapy.MethodsSystematic review with meta-analysis technique.ResultsSeven retrospective cohort and seven case–control studies were included. Three cohort studies were designed to compare the two drugs, whereas others had other purposes. A total of 663 patients were identified, 332 of which were treated with trimethoprim-sulfamethoxazole (50.1%) and 331 with fluoroquinolones (49.9%). Three cohort studies were designed to compare the effect of the two drugs, whereas the others had other purposes. Levofloxacin was most frequently used among fluoroquinolones (187/331, 56.5%), followed by ciprofloxacin (114/331, 34.4%). The overall mortality rate was 29.6%. Using pooled ORs for the mortality of each study, fluoroquinolone treatment (OR 0.62, 95% CI 0.39–0.99) was associated with survival benefit over trimethoprim-sulfamethoxazole treatment, with low heterogeneity (I² = 18%). Specific fluoroquinolones such as ciprofloxacin (OR 0.44, 95% CI 0.17–1.12) and levofloxacin (OR 0.78, 95% CI 0.48–1.26) did not show a significant difference in comparison with trimethoprim-sulfamethoxazole. In the sub-group analyses of adult and bacteraemic patients, significant differences in mortality were not observed between fluoroquinolones and trimethoprim-sulfamethoxazole.ConclusionsBased on a meta-analysis of non-randomized studies, fluoroquinolones demonstrated comparable effects on mortality of S. maltophilia infection to trimethoprim-sulfamethoxazole, supporting the use of fluoroquinolones in clinical S. maltophilia infections. Although the pooled analysis of overall studies favoured fluoroquinolones over trimethoprim-sulfamethoxazole, the studies included were observational, and sub-group analyses of certain fluoroquinolone agents did not show statistical differences with trimethoprim-sulfamethoxazole. Randomized clinical studies are needed to address these issues.     

Transmission events and antimicrobial susceptibilities of methicillin-resistant Staphylococcus argenteus in Stockholm

ObjectivesStaphylococcus argenteus has been increasingly reported since the species was defined as a novel staphylococcal species in 2015. This study aims to investigate genetic epidemiological links and antimicrobial susceptibilities of methicillin-resistant S. argenteus isolates recovered in Stockholm.MethodsSixteen methicillin-resistant S. argenteus isolates were identified from a collection of methicillin-resistant Staphylococcus aureus in Stockholm 2007–2018, by using whole-genome sequencing and matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS). The genomes of the isolates were investigated by pulsed-field gel electrophoresis, single-nucleotide polymorphism (SNP)-based phylogeny, k-mer analysis, core-genome multi-locus sequence typing (cgMLST), resistance traits and virulence factors. The MICs of 19 antimicrobial agents for each isolate were determined by using the broth microdilution method.ResultsOf the 16 isolates, seven, seven and two isolates were assigned to ST1223, ST2250 and ST2793, respectively, with the S. aureus MLST-scheme. Analyses based on SNPs and cgMLST revealed a likely clonal spread of methicillin-resistant S. argenteus in 2007. Four isolates were found to be resistant to non-β-lactams in antimicrobial susceptibility testing.ConclusionsA transmission event of methicillin-resistant S. argenteus in family was identified by this study. Among our limited number of isolates, non-β-lactam resistance was detected, which highlights the necessity of a continued surveillance on this emerging pathogen. S. argenteus could be correctly identified by MALDI-TOF MS with the updated database, enabling its detection also in clinical laboratories.