Localized Leishmania major infection disrupts systemic iron homeostasis that can be controlled by oral iron supplementation.

Leishmania parasites are heavily dependent on efficient iron acquisition from a tightly regulated host iron pool for survival and virulence. Prior studies uncovered multiple strategies adopted by the parasite to hijack the iron-regulatory network of macrophages. Despite these extensive studies with infected macrophages, there is limited knowledge of the effect of Leishmania infection on systemic iron homeostasis. This issue is particularly relevant for Leishmania major, which causes localized skin infection with minimal lymphatic spread. We show for the first time that L. major infection in the mouse footpad induced influx of iron at the site of infection through blood with simultaneous upregulation of transferrin receptor 1 and downregulation of phagolysosomal iron exporter Nramp1 expression in the footpad tissue. Interestingly, localized L. major infection had far-reaching effects beyond the infection site triggering anemia-like symptoms. This was evident from depleted physiological iron stores from the liver and bone marrow as well as reduced hemoglobin levels and deformed erythrocytes. The infected mice also developed splenomegaly with signs of splenic stress erythropoiesis as indicated by upregulation of several erythroid-related genes. These observations prompted us to provide oral iron supplementations to the L. major-infected mice, which resulted in a drastic reduction of the parasite load and restoration of iron homeostasis.

An AI-powered patient triage platform for future viral outbreaks using COVID-19 as a disease model.

Over the last century, outbreaks and pandemics have occurred with disturbing regularity, necessitating advance preparation and large-scale, coordinated response. Here, we developed a machine learning predictive model of disease severity and length of hospitalization for COVID-19, which can be utilized as a platform for future unknown viral outbreaks. We combined untargeted metabolomics on plasma data obtained from COVID-19 patients (n = 111) during hospitalization and healthy controls (n = 342), clinical and comorbidity data (n = 508) to build this patient triage platform, which consists of three parts: (i) the clinical decision tree, which amongst other biomarkers showed that patients with increased eosinophils have worse disease prognosis and can serve as a new potential biomarker with high accuracy (AUC = 0.974), (ii) the estimation of patient hospitalization length with ± 5 days error (R2 = 0.9765) and (iii) the prediction of the disease severity and the need of patient transfer to the intensive care unit. We report a significant decrease in serotonin levels in patients who needed positive airway pressure oxygen and/or were intubated. Furthermore, 5-hydroxy tryptophan, allantoin, and glucuronic acid metabolites were increased in COVID-19 patients and collectively they can serve as biomarkers to predict disease progression. The ability to quickly identify which patients will develop life-threatening illness would allow the efficient allocation of medical resources and implementation of the most effective medical interventions. We would advocate that the same approach could be utilized in future viral outbreaks to help hospitals triage patients more effectively and improve patient outcomes while optimizing healthcare resources.

Antioxidant Polymers with Phenolic Pendants for the Mitigation of Cellular Oxidative Stress.

Overproduction of reactive oxygen species (ROS) in cells is a major health concern as it may lead to various diseases through oxidative damage of biomolecules. Commonly used traditional small molecular antioxidants (polyphenols, carotenoids, vitamins, etc.) have inadequate efficacy in lowering excessive levels of ROS due to their poor aqueous solubility and bioavailability. In response to the widespread occurrence of antioxidant polyphenols in various biorenewable resources, we aimed to develop water-soluble antioxidant polymers with side chain phenolic pendants. Four different types of copolymers (P1-P4) containing phenyl rings with different numbers of hydroxy (-OH) substituents (0: phenylalanine, 1: tyrosyl, 2: catechol, or 3: gallol) were synthesized via reversible addition-fragmentation chain transfer (RAFT) polymerization with a desired molar mass (8500-10000 g/mol) and a narrow dispersity (D ≤ 1.3). After successful characterizations of P1-P4, their in vitro antioxidant properties were analyzed by different methods, including 2,2-diphenyl-1-picrylhydrazyl (DPPH•), 2,2-azino-bis-3-ethylbenzothiazoline-6-sulfonic acid (ABTS•+), 4,4'-diamino-3,3',5,5'-tetramethylbiphenyl (TMB), and ß-carotene (ßC) assays. Our results revealed that the gallol pendant polymers can effectively scavenge ROS. Furthermore, electron paramagnetic resonance (EPR) spectroscopy with DPPH• also confirmed the radical quenching ability of the synthesized polymers. The gallol pendant polymers, at a well-tolerated concentration, could effectively penetrate the macrophage cells and restore the H2O2-induced ROS to the basal level. Overall, the present approach demonstrates the efficacy of water-soluble antioxidant polymers with gallol pendants toward the mitigation of cellular oxidative stress.

A novel leishmanial copper P-type ATPase plays a vital role in parasite infection and intracellular survival.

Copper (Cu) is essential for all life forms; however, in excess, it becomes toxic. Toxic properties of Cu are known to be utilized by host species against various pathogenic invasions. Leishmania, in both free-living and intracellular forms, exhibits appreciable tolerance toward Cu stress. While determining the mechanism of Cu-stress evasion employed by Leishmania, we identified and characterized a hitherto unknown Cu-ATPase in Leishmania major and established its role in parasite survival in host macrophages. This novel L. major Cu-ATPase, LmATP7, exhibits homology with its orthologs at multiple motifs. In promastigotes, LmATP7 primarily localized at the plasma membrane. We also show that LmATP7 exhibits Cu-dependent expression patterns and complements Cu transport in a Cu-ATPase-deficient yeast strain. Promastigotes overexpressing LmATP7 exhibited higher survival upon Cu stress, indicating efficacious Cu export compared with Wt and heterozygous LmATP7 knockout parasites. We further explored macrophage-Leishmania interactions with respect to Cu stress. We found that Leishmania infection triggers upregulation of major mammalian Cu exporter, ATP7A, in macrophages, and trafficking of ATP7A from the trans-Golgi network to endolysosomes in macrophages harboring amastigotes. Simultaneously, in Leishmania, we observed a multifold increase in LmATP7 transcripts as the promastigote becomes established in macrophages and morphs to the amastigote form. Finally, overexpressing LmATP7 in parasites increases amastigote survivability within macrophages, whereas knocking it down reduces survivability drastically. Mice injected in their footpads with an LmATP7-overexpressing strain showed significantly larger lesions and higher amastigote loads as compared with controls and knockouts. These data establish the role of LmATP7 in parasite infectivity and intramacrophagic survivability.

Antibiotic therapy is associated with adverse drug events among older adults with advanced cancer: A cohort study.

BACKGROUND: Older adults with advanced cancer are exposed to antibiotics but estimates of adverse drug events associated with antibiotic therapy are lacking. AIM: Evaluate the association of antibiotic therapy with adverse drug events in older adults with advanced cancer. DESIGN: Cohort study where the exposure was the ratio of days of therapy of an oral or intravenous antibiotic per patient-day and the outcome was an adverse drug event, defined as cardiotoxicity, hepatotoxicity, nephrotoxicity, Clostridioides difficile infection, or new detection of a multidrug-resistant organism. SETTING/PARTICIPANTS: Patients aged ⩾65 years with solid tumors from a tertiary care center who received palliative chemotherapy (n = 914). RESULTS: Mean age was 75 ± 6.6 years, and 52% were female. Common tumors were lung (31%, n = 284) and gastrointestinal (26%, n = 234). Mean time from first course of palliative chemotherapy to index admission was 128 days. Five-hundred thirty (58%) patients were exposed to antibiotics during the index admission; of these, 27% (n = 143) met standardized criteria for infection. Patients were commonly exposed to cephalosporins (33%, n = 298) and vancomycin (30%, n = 276). Among patients exposed to antibiotics, 35% (n = 183/530) developed an adverse drug event. In multivariable testing, antibiotic therapy was associated with development of an adverse drug event (>0 to <1 vs 0 days of therapy/patient-day: adjusted odds ratio [aOR] = 1.9; 95% confidence interval [CI], 1.2-2.8; ⩾1 vs 0 days of therapy/patient-day: aOR = 2.1, 95% CI, 1.4-3.0). CONCLUSION: Antibiotic therapy was independently associated with adverse drug events in hospitalized older adults with advanced cancer. These findings may inform antibiotic decision-making among palliative care providers.

Increased SARS-CoV-2 Testing Capacity with Pooled Saliva Samples.

We analyzed feasibility of pooling saliva samples for severe acute respiratory syndrome coronavirus 2 testing and found that sensitivity decreased according to pool size: 5 samples/pool, 7.4% reduction; 10 samples/pool, 11.1%; and 20 samples/pool, 14.8%. When virus prevalence is >2.6%, pools of 5 require fewer tests; when <0.6%, pools of 20 support screening strategies.

Stability of SARS-CoV-2 RNA in Nonsupplemented Saliva.

The expense of saliva collection devices designed to stabilize severe acute respiratory syndrome coronavirus 2 RNA is prohibitive to mass testing. However, virus RNA in nonsupplemented saliva is stable for extended periods and at elevated temperatures. Simple plastic tubes for saliva collection will make large-scale testing and continued surveillance easier.

Leishmania infection triggers hepcidin-mediated proteasomal degradation of Nramp1 to increase phagolysosomal iron availability.

Natural resistance-associated macrophage protein 1 (Nramp1) was originally discovered as a genetic determinant of resistance against multiple intracellular pathogens, including Leishmania. It encodes a transmembrane protein of the phago-endosomal compartments, where it functions as an iron transporter. But the mechanism by which Nramp1 controls host-pathogen dynamics and determines final outcome of an infection is yet to be fully deciphered. Whether the expression of Nramp1 is altered in response to a pathogen attack is also unknown. To address these, Nramp1 status was examined in Leishmania major-infected murine macrophages. We observed that at 12 hrs post infection, there was drastic lowering of Nramp1 level accompanied by increased phagolysosomal iron content and enhanced intracellular parasite growth. Leishmania infection-induced Nramp1 downregulation was caused by ubiquitin-proteasome degradation pathway, which in turn was found to be mediated by the iron-regulatory peptide hormone hepcidin. Blocking of Nramp1 degradation with proteasome inhibitor or transcriptional agonist of hepcidin resulted in depletion of phagolysosomal iron pool that led to significant reduction of intracellular parasite burden. Interestingly, Nramp1 level was restored to normalcy after 30 hrs of infection with a concomitant drop in phagolysosomal iron, which is suggestive of a host counteractive response to deprive the pathogen of this essential micronutrient. Taken together, our study implicates Nramp1 as a central player in the host-pathogen battle for phagolysosomal iron. We also report Nramp1 as a novel target for hepcidin, and this 'hepcidin-Nramp1' axis may have a broader role in regulating macrophage iron homeostasis.

Education needed to improve antimicrobial use during end-of-life care of older adults with advanced cancer: A cross-sectional survey.

BACKGROUND: Antimicrobial use during end-of-life care of older adults with advanced cancer is prevalent. Factors influencing the decision to prescribe antimicrobials during end-of-life care are not well defined. AIM: To evaluate factors influencing medicine subspecialists to prescribe intravenous and oral antimicrobials during end-of-life care of older adults with advanced cancer to guide an educational intervention. DESIGN: 18-item single-center cross-sectional survey. SETTING/PARTICIPANTS: Inpatient medicine subspecialists in 2018. RESULTS: Of 186 subspecialists surveyed, 67 (36%) responded. Most considered withholding antimicrobials at the time of clinical deterioration during hospitalization (n = 54/67, 81%), viewed the initiation of additional intravenous antimicrobials as escalation of care (n = 44/67, 66%), and believed decision-making should involve patients or surrogates and providers (n = 64/67, 96%). Fifty-one percent (n = 30/59) of respondents who conducted advance care planning did not discuss antimicrobials. Barriers to discussing end-of-life antimicrobials included the potential to overwhelm patients or families, challenges of withdrawing antimicrobials, and insufficient training. CONCLUSIONS: Although the initiation of additional intravenous antimicrobials was viewed as escalation of care, antimicrobials were not routinely discussed during advance care planning. Educational interventions that promote recognition of antimicrobial-associated adverse events, incorporate antimicrobial use into advance care plans, and offer communication simulation training around the role of antimicrobials during end-of-life care are warranted.

Severe respiratory viral infection induces procalcitonin in the absence of bacterial pneumonia.

INTRODUCTION: Procalcitonin expression is thought to be stimulated by bacteria and suppressed by viruses via interferon signalling. Consequently, during respiratory viral illness, clinicians often interpret elevated procalcitonin as evidence of bacterial coinfection, prompting antibiotic administration. We sought to evaluate the validity of this practice and the underlying assumption that viral infection inhibits procalcitonin synthesis. METHODS: We conducted a retrospective cohort study of patients hospitalised with pure viral infection (n=2075) versus bacterial coinfection (n=179). The ability of procalcitonin to distinguish these groups was assessed. In addition, procalcitonin and interferon gene expression were evaluated in murine and cellular models of influenza infection. RESULTS: Patients with bacterial coinfection had higher procalcitonin than those with pure viral infection, but also more severe disease and higher mortality (p<0.001). After matching for severity, the specificity of procalcitonin for bacterial coinfection dropped substantially, from 72% to 61%. In fact, receiver operating characteristic curve analysis showed that procalcitonin was a better indicator of multiple indices of severity (eg, organ failures and mortality) than of coinfection. Accordingly, patients with severe viral infection had elevated procalcitonin. In murine and cellular models of influenza infection, procalcitonin was also elevated despite bacteriologic sterility and correlated with markers of severity. Interferon signalling did not abrogate procalcitonin synthesis. DISCUSSION: These studies reveal that procalcitonin rises during pure viral infection in proportion to disease severity and is not suppressed by interferon signalling, in contrast to prior models of procalcitonin regulation. Applied clinically, our data suggest that procalcitonin represents a better indicator of disease severity than bacterial coinfection during viral respiratory infection.

Interplay between a cytosolic and a cell surface carbonic anhydrase in pH homeostasis and acid tolerance of Leishmania.

Leishmania parasites have evolved to endure the acidic phagolysosomal environment within host macrophages. How Leishmania cells maintain near-neutral intracellular pH and proliferate in such a proton-rich mileu remains poorly understood. We report here that, in order to thrive in acidic conditions, Leishmania major relies on a cytosolic and a cell surface carbonic anhydrase, LmCA1 and LmCA2, respectively. Upon exposure to acidic medium, the intracellular pH of the LmCA1+/-, LmCA2+/- and LmCA1+/-:LmCA2+/- mutant strains dropped by varying extents that led to cell cycle delay, growth retardation and morphological abnormalities. Intracellular acidosis and growth defects of the mutant strains could be reverted by genetic complementation or supplementation with bicarbonate. When J774A.1 macrophages were infected with the mutant strains, they exhibited much lower intracellular parasite burdens than their wild-type counterparts. However, these differences in intracellular parasite burden between the wild-type and mutant strains were abrogated if, before infection, the macrophages were treated with chloroquine to alkalize their phagolysosomes. Taken together, our results demonstrate that haploinsufficiency of LmCA1 and/or LmCA2 renders the parasite acid-susceptible, thereby unravelling a carbonic anhydrase-mediated pH homeostatic circuit in Leishmania cells.

Impact of Hospital Population Case-Mix, Including Poverty, on Hospital All-Cause and Infection-Related 30-Day Readmission Rates.

BACKGROUND: Reducing hospital readmissions, including preventable healthcare-associated infections, is a national priority. The proportion of readmissions due to infections is not well-understood. Better understanding of hospital risk factors for readmissions and infection-related readmissions may help optimize interventions to prevent readmissions. METHODS: Retrospective cohort study of California acute care hospitals and their patient populations discharged between 2009 and 2011. Demographics, comorbidities, and socioeconomic status were entered into a hierarchical generalized linear mixed model predicting all-cause and infection-related readmissions. Crude verses adjusted hospital rankings were compared using Cohen's kappa. RESULTS: We assessed 30-day readmission rates from 323 hospitals, accounting for 213 879 194 post-discharge person-days of follow-up. Infection-related readmissions represented 28% of all readmissions and were associated with discharging a high proportion of patients to skilled nursing facilities. Hospitals serving populations with high proportions of males, comorbidities, prolonged length of stay, and populations living in a federal poverty area, had higher all-cause and infection-related readmission rates. Academic hospitals had higher all-cause and infection-related readmission rates (odds ratio 1.24 and 1.15, respectively). When comparing adjusted vs crude hospital rankings for infection-related readmission rates, adjustment revealed 31% of hospitals changed performance category for infection-related readmissions. CONCLUSIONS: Infection-related readmissions accounted for nearly 30% of all-cause readmissions. High hospital infection-related readmissions were associated with serving a high proportion of patients with comorbidities, long lengths of stay, discharge to skilled nursing facility, and those living in federal poverty areas. Preventability of these infections needs to be assessed.

Identification of metal dithiocarbamates as a novel class of antileishmanial agents.

Dithiocarbamates have emerged as potent carbonic anhydrase (CA) inhibitors in recent years. Given that CAs are important players in cellular metabolism, the objective of this work was to exploit the CA-inhibitory property of dithiocarbamates as a chemotherapeutic weapon against the Leishmania parasite. We report here strong antileishmanial activity of three hitherto unexplored metal dithiocarbamates, maneb, zineb, and propineb. They inhibited CA activity in Leishmania major promastigotes at submicromolar concentrations and resulted in a dose-dependent inhibition of parasite growth. Treatment with maneb, zineb, and propineb caused morphological deformities of the parasite and Leishmania cell death with 50% lethal dose (LD50) values of 0.56 µM, 0.61 µM, and 0.27 µM, respectively. These compounds were even more effective against parasites growing in acidic medium, in which their LD50 values were severalfold lower. Intracellular acidosis leading to apoptotic and necrotic death of L. major promastigotes was found to be the basis of their leishmanicidal activity. Maneb, zineb, and propineb also efficiently reduced the intracellular parasite burden, suggesting that amastigote forms of the parasite are also susceptible to these metal dithiocarbamates. Interestingly, mammalian cells were unaffected by these compounds even at concentrations which are severalfold higher than their antileishmanial LD50s). Our data thus establish maneb, zineb, and propineb as a new class of antileishmanial compounds having broad therapeutic indices.

High nasal burden of methicillin-resistant Staphylococcus aureus increases risk of invasive disease.

In a retrospective cohort study of 1,140 patients harboring methicillin-resistant Staphylococcus aureus, the nasal burden was low in 31%, category 1+ to 2+ in 54%, and category 3+ to 4+ in 15%. There was a significant trend in infection risk with increasing nasal burden (P = 0.007). In multivariate models, high nasal burden remained significantly associated with invasive infection.

Cohort study of patients with advanced cancer: outcomes associated with duration of antibiotic therapy for non-ventilator hospital-acquired pneumonia.

In this single-center observational study of 118 older adults with advanced cancer who developed non-ventilator hospital-acquired pneumonia, prolonged antibiotic durations (8-14 and ≥15 vs ≤7 d) were not associated with reduced adjusted odds of 90-day all-cause readmission or death. These data may inform antimicrobial stewardship efforts in palliative care settings.

Role of Macrophage PIST Protein in Regulating Leishmania major Infection.

PDZ protein interacting specifically with Tc10 or PIST is a mammalian trans-Golgi resident protein that regulates subcellular sorting of plasma membrane receptors. PIST has recently emerged as a key player in regulating viral pathogenesis. Nevertheless, the involvement of PIST in parasitic infections remains unexplored. Leishmania parasites infiltrate their host macrophage cells through phagocytosis, where they subsequently multiply within the parasitophorous vacuole (PV). Host cell autophagy has been found to be important in regulating this parasite infection. Since PIST plays a pivotal role in triggering autophagy through the Beclin 1-PI3KC3 pathway, it becomes interesting to identify the status of PIST during Leishmania infection. We found that while macrophage cells are infected with Leishmania major (L. major), the expression of PIST protein remains unaltered; however, it traffics from the Golgi compartment to PV. Further, we identified that in L. major-infected macrophage cells, PIST associates with the autophagy regulatory protein Beclin 1 within the PVs; however, PIST does not interact with LC3. Reduction in PIST protein through siRNA silencing significantly increased parasite burden, whereas overexpression of PIST in macrophages restricted L. major infectivity. Together, our study reports that the macrophage PIST protein is essential in regulating L. major infectivity.

Clinicians who primarily practice in nursing homes and outcomes among residents with urinary tract infection or pneumonia.

Objective: Assess the association between clinicians who primarily practice in nursing homes (NHs) and 14-day resident outcomes following initial antibiotic dispensing for pneumonia or urinary tract infection (UTI). Design: Retrospective cohort. Setting: U.S. NHs. Participants: NH residents aged ≥65 years who were prescribed antibiotics for pneumonia or UTI between 1 January 2016 and 30 November 2018. Methods: Medicare fee-for-service claims were linked to Minimum Data Set data. Clinicians who primarily practiced in NHs prescribed ≥90% of Part D dispensings to NH residents. Outcomes included death, all-cause and infection-specific hospitalization, and subsequent antibiotic dispensing. Adjusted risk ratios were estimated using inverse-probability-of-treatment-weighted (IPTW) modified Poisson regression models adjusting for 53 covariates. Results: The study population included 28,826 resident-years who were prescribed antibiotics for pneumonia and 106,354 resident-years who were prescribed antibiotics for UTI. Among the pneumonia group, clinicians who primarily practiced in NHs were associated with a greater risk of death (RR 1.3; 95%CLs 1.0, 1.6), lower risks of all-cause (RR 0.9; 95%CLs 0.8, 0.9) and infection-specific hospitalization (RR 0.8; 95%CLs 0.7, 0.9), and similar risk of subsequent antibiotic dispensing (RR 1.0; 95%CLs 1.0, 1.1) after IPTW. No meaningful associations were observed between clinicians who primarily practiced in NHs and outcomes among the UTI group. Conclusions: Clinicians who primarily practiced in NHs were associated with a lower risk of hospitalization but greater risk of mortality for NH residents with pneumonia. Further examination is needed to better understand drivers of differences in infection-related outcomes based on clinicians' training and primary practice setting.

Leishmania major-induced alteration of host cellular and systemic copper homeostasis drives the fate of infection.

Copper plays a key role in host-pathogen interaction. We find that during Leishmania major infection, the parasite-harboring macrophage regulates its copper homeostasis pathway in a way to facilitate copper-mediated neutralization of the pathogen. Copper-ATPase ATP7A transports copper to amastigote-harboring phagolysosomes to induce stress on parasites. Leishmania in order to evade the copper stress, utilizes a variety of manipulative measures to lower the host-induced copper stress. It induces deglycosylation and degradation of host-ATP7A and downregulation of copper importer, CTR1 by cysteine oxidation. Additionally, Leishmania induces CTR1 endocytosis that arrests copper uptake. In mouse model of infection, we report an increase in systemic bioavailable copper in infected animals. Heart acts as the major organ for diverting its copper reserves to systemic circulation to fight-off infection by downregulating its CTR1. Our study explores reciprocal mechanism of manipulation of host copper homeostasis pathway by macrophage and Leishmania to gain respective advantages in host-pathogen interaction.

Diagnostic uncertainty and decision-making in home-based primary care: A qualitative study of antibiotic prescribing.

BACKGROUND: Evaluating infection in home-based primary care is challenging, and these challenges may impact antibiotic prescribing. A refined understanding of antibiotic decision-making in this setting can inform strategies to promote antibiotic stewardship. This study investigated antibiotic decision-making by exploring the perspectives of clinicians in home-based primary care. METHODS: Clinicians from the Department of Veterans Affairs Home-Based Primary Care Program were recruited. Semi-structured interviews were conducted from June 2022 through September 2022 using a discussion guide. Transcripts were analyzed using grounded theory. The constant comparative method was used to develop a coding structure and to identify themes. RESULTS: Theoretical saturation was reached after 22 clinicians (physicians, n = 7; physician assistants, n = 2, advanced practice registered nurses, n = 13) from 19 programs were interviewed. Mean age was 48.5 ± 9.3 years, 91% were female, and 59% had ≥6 years of experience in home-based primary care. Participants reported uncertainty about the diagnosis of infection due to the characteristics of homebound patients (atypical presentations of disease, presence of multiple chronic conditions, presence of cognitive impairment) and the challenges of delivering medical care in the home (limited access to diagnostic testing, suboptimal quality of microbiological specimens, barriers to establishing remote access to the electronic health record). When faced with diagnostic uncertainty about infection, participants described many factors that influenced the decision to prescribe antibiotics, including those that promoted prescribing (desire to avoid hospitalization, pressure from caregivers, unreliable plans for follow-up) and those that inhibited prescribing (perceptions of antibiotic-associated harms, willingness to trial non-pharmacological interventions first, presence of caregivers who were trusted by clinicians to monitor symptoms). CONCLUSIONS: Clinicians face the difficult task of balancing diagnostic uncertainty with many competing considerations during the treatment of infection in home-based primary care. Recognizing these issues provides insight into strategies to promote antibiotic stewardship in home care settings.