A rare case of necrotizing fasciitis of the leg in an intravenous drug user caused by Prevotella denticola.

Background: Intravenous drug users (IDUs) have a high risk of developing skin and soft tissue infections such as erysipelas, abscesses, and less frequently necrotizing fasciitis (NF) or gas gangrene. Rarely, the cause of the infection is microorganisms residing in the oral cavity and can lead to life-threatening infections. Methods: We describe the case of a 43-year-old man intravenous drug user (IDU) who was admitted for intense leg pain following an injection of cocaine at that site. Results: A clinical and radiological diagnosis of NF was made, so the patient was started on empirical antibiotic therapy and underwent surgical fasciotomy (after 8 hours from admission). Prevotella denticola was isolated from multiple intraoperative specimens and was resistant to initial antimicrobial therapy. The man, suffering from periodontal disease, reported sucking the syringe several times to unblock it. Both fasciotomy surgery and adjustment of antimicrobial therapy enabled therapeutic success. Conclusions: In IDUs the risk of deep skin and soft tissue infections is high and may be aggravated by contamination with oral microorganisms. The choice of empirical antibiotic treatment should include agents active against oral cavity anaerobes, such as P. denticola.

Development and validation of a prediction score for failure to casirivimab/imdevimab in hospitalized patients with COVID-19 pneumonia.

Introduction: Casirivimab and imdevimab (CAS/IMV) are two non-competing, high-affinity human IgG1 anti-SARS-CoV-2 monoclonal antibodies, that showed a survival benefit in seronegative hospitalized patients with COVID-19. This study aimed to estimate the day-28 risk of mechanical ventilation (MV) and death in individuals hospitalized for severe COVID-19 pneumonia and receiving CAS/IMV. Additionally, it aimed to identify variables measured at the time of hospital admission that could predict these outcomes and derive a prediction algorithm. Methods: This is a retrospective, observational cohort study conducted in 12 hospitals in Italy. Adult patients who were consecutively hospitalized from November 2021 to February 2022 receiving CAS/IMV were included. A multivariable logistic regression model was used to identify predictors of MV or death by day 28 from treatment initiation, and ß-coefficients from the model were used to develop a risk score that was derived by means of leave-one-out internal cross-validation (CV), external CV, and calibration. Secondary outcome was mortality. Results: A total of 480 hospitalized patients in the training set and 157 patients in the test set were included. By day 28, 36 participants (8%) underwent MV and 28 died (6%) for a total of 58 participants (12%) experiencing the composite primary endpoint. In multivariable analysis, four factors [age, PaO2/FiO2 ratio, lactate dehydrogenase (LDH), and platelets] were independently associated with the risk of MV/death and were used to generate the proposed risk score. The accuracy of the score in the area under the curve (AUC) was 0.80 and 0.77 in internal validation and test for the composite endpoint and 0.87 and 0.86 for death, respectively. The model also appeared to be well calibrated with the raw data. Conclusion: The mortality risk reported in our study was lower than that previously reported. Although CAS/IMV is no longer used, our score might help in identifying which patients are not likely to benefit from monoclonal antibodies and may require alternative interventions.

Intravenous fosfomycin in combination regimens as a treatment option for difficult-to-treat infections due to multi-drug-resistant Gram-negative organisms: A real-life experience.

AIM: To investigate the efficacy of intravenous (IV) fosfomycin as combination therapy for treatment of difficult-to-treat (DTT) acute and subacute infections with multi-drug-resistant (MDR) Gram-negative bacteria (GNB), and risk factors associated with 90-day mortality. METHODS: A retrospective, observational, monocentric study enrolled patients treated with IV fosfomycin in combination regimens (≥72 h) for proven DTT-MDR-GNB infection. Multi-variate regression analysis identified independent risk factors for 90-day mortality. A propensity score for receiving fosfomycin was performed to control for confounding factors. RESULTS: In total, 70 patients were included in this study: 54.3% had carbapenem-resistant isolates, 31.4% had ceftazidime/avibactam-resistant isolates and 28.6% had ceftolozane/tazobactam-resistant isolates. The main pathogens were Pseudomonas aeruginosa (57.1%) and Klebsiella pneumoniae (22.9%). The most prevalent infections were nosocomial pneumonia (42.9%), osteomyelitis (17.1%) and intra-abdominal infections. All-cause 30- and 90-day mortality were 15.7% and 31.4%, respectively (18.9% and 50% considering acute DTT-MDR-GNB infections alone). Relapse at 30 days occurred in 22.9% of cases (29% with emergence of fosfomycin resistance). Mortality at 90 days was independently associated with septic shock and ceftolozane/tazobactam resistance. The relationship between resistance to ceftolozane/tazobactam and 90-day mortality was confirmed to be significant after adjustment by propensity score analysis (hazard ratio 5.84, 95% confidence interval 1.65-20.68; P=0.006). CONCLUSIONS: Fosfomycin seems to be a promising salvage, combination treatment in DTT-MDR-GNB infections. Resistance to ceftolozane/tazobactam seems to be independently associated with treatment failure. Randomized clinical trials focusing on pathogen and infection sites are needed urgently to demonstrate the superiority of fosfomycin in combination with other agents for the resolution of DTT-MDR-GNB infections.

Advances and Challenges in Sepsis Management: Modern Tools and Future Directions.

Sepsis, a critical condition marked by systemic inflammation, profoundly impacts both innate and adaptive immunity, often resulting in lymphopenia. This immune alteration can spare regulatory T cells (Tregs) but significantly affects other lymphocyte subsets, leading to diminished effector functions, altered cytokine profiles, and metabolic changes. The complexity of sepsis stems not only from its pathophysiology but also from the heterogeneity of patient responses, posing significant challenges in developing universally effective therapies. This review emphasizes the importance of phenotyping in sepsis to enhance patient-specific diagnostic and therapeutic strategies. Phenotyping immune cells, which categorizes patients based on clinical and immunological characteristics, is pivotal for tailoring treatment approaches. Flow cytometry emerges as a crucial tool in this endeavor, offering rapid, low cost and detailed analysis of immune cell populations and their functional states. Indeed, this technology facilitates the understanding of immune dysfunctions in sepsis and contributes to the identification of novel biomarkers. Our review underscores the potential of integrating flow cytometry with omics data, machine learning and clinical observations to refine sepsis management, highlighting the shift towards personalized medicine in critical care. This approach could lead to more precise interventions, improving outcomes in this heterogeneously affected patient population.

Low-molecular-weight heparin for the prevention of clinical worsening in severe non-critically ill COVID-19 patients: a joint analysis of two randomized controlled trials.

Coronavirus disease 2019 (COVID-19) carries a high risk of vascular thrombosis. However, whether a specific anticoagulation intensity strategy may prevent clinical worsening in severe COVID-19 patients is still debated. We conducted a joint analysis of two randomized controlled trials, COVID-19 HD (NCT044082359) and EMOS-COVID (NCT04646655), to assess the efficacy and safety of two anticoagulant regimens in hospitalized severe COVID-19 patients. Subjects with COVID-19-associated respiratory compromise and/or coagulopathy were randomly assigned to low (4000 IU qd) or high (70 IU Kg-1 every 12 h) enoxaparin dose. The primary efficacy endpoint was clinical worsening within 30 days, defined as the occurrence of at least one of the following events, whichever came first: in-hospital death, evidence of arterial or venous thromboembolism, acute myocardial infarction, need for either continuous positive airway pressure (CPAP) or non-invasive ventilation (NIV) in patients receiving standard oxygen therapy or none at randomization, and need for mechanical ventilation in any patient. The safety endpoint was major bleeding. We estimated the relative risk (RR) and its 95% confidence interval (CI) for the outcomes. Among 283 patients included in the study (144 in the low-dose and 139 in the high-dose group), 118 (41.7%) were on NIV or CPAP at randomization. 23/139 (16.5%) patients in the high-dose group reached the primary endpoint compared to 33/144 (22.9%) in the low-dose group (RR 0.72, 95% CI 0.45-1.17). No major bleeding was observed. No significant differences were found in the clinical worsening of hospitalized COVID-19 patients treated with high versus low doses of enoxaparin.

Vancomycin resistant enterococcus risk factors for hospital colonization in hematological patients: a matched case-control study.

BACKGROUND: Vancomycin-resistant enterococcus (VRE) was the fastest growing pathogen in Europe in 2022 (+ 21%) but its clinical relevance is still unclear. We aim to identify risk factors for acquired VRE rectal colonization in hematological patients and evaluate the clinical impact of VRE colonization on subsequent infection, and 30- and 90-day overall mortality rates, compared to a matched control group. METHODS: A retrospective, single center, case-control matched study (ratio 1:1) was conducted in a hematological department from January 2017 to December 2020. Case patients with nosocomial isolation of VRE from rectal swab screening (≥ 48 h) were matched to controls by age, sex, ethnicity, and hematologic disease. Univariate and multivariate logistic regression compared risk factors for colonization. RESULTS: A total of 83 cases were matched with 83 controls. Risk factors for VRE colonization were febrile neutropenia, bone marrow transplant, central venous catheter, bedsores, reduced mobility, altered bowel habits, cachexia, previous hospitalization and antibiotic treatments before and during hospitalization. VRE bacteraemia and Clostridioides difficile infection (CDI) occurred more frequently among cases without any impact on 30 and 90-days overall mortality. Vancomycin administration and altered bowel habits were the only independent risk factors for VRE colonization at multivariate analysis (OR: 3.53 and 3.1; respectively). CONCLUSIONS: Antimicrobial stewardship strategies to reduce inappropriate Gram-positive coverage in hematological patients is urgently required, as independent risk factors for VRE nosocomial colonization identified in this study include any use of vancomycin and altered bowel habits. VRE colonization and infection did not influence 30- and 90-day mortality. There was a strong correlation between CDI and VRE, which deserves further investigation to target new therapeutic approaches.

Long-Term Suppressive Therapeutic-Drug-Monitoring-Guided Dalbavancin Therapy for Cardiovascular Prosthetic Infections.

Dalbavancin represents a promising treatment for cardiovascular prosthetic infections due to its prolonged half-life, bactericidal activity, large spectrum of activity, and excellent biofilm penetration. However, the use of dalbavancin in this setting is limited, and only a few cases have performed therapeutic drug monitoring (TDM) analysis to optimize dosage in suppressive treatments longer than 4 weeks. Our retrospective case series reports the use of dalbavancin in a small cohort of patients with cardiovascular prosthetic infections (cardiac implantable electronic device infections (CEDIs), prosthetic valve endocarditis (PVE), prosthetic vascular graft infections (PVGIs)) treated with dalbavancin as sequential therapy. From May 2019 to May 2023, 14 patients were included: eight cases of PVE (57.1%), seven cases of PVGI (50%), three cases of CEDI (21.4%), and four cases with overlap of infection sites (28.6%). The main pathogen was Staphylococcus aureus (35.7%). Prosthesis replacement was obtained in four patients (28.6%). The median time between symptom onset and the end of treatment was 15 weeks (IQR 7-53), with a median duration of dalbavancin therapy of 8 weeks (IQR 1 to 45 weeks) and 3.5 doses per patient. Among patients managed with TDM-guided strategy, dalbavancin infusion intervals ranged from 4 to 9 weeks. The median length of follow-up was 65 weeks (IQR 23 to 144 weeks). Clinical success was achieved in 10 cases (76.9%); all clinical failures occurred in patients with the implant retained. Among patients monitored by TDM, clinical success was 87.5% vs. 60% in patients treated without TDM. Because of pharmacokinetic individual variability, dalbavancin TDM-guided administration could improve clinical outcomes by individualizing dosing and selecting dosing intervals. This case series seems to suggest a promising role of long-term suppressive dalbavancin treatment for difficult-to-treat cardiovascular prosthesis infection, also with limited surgical indications.

Association between Pulmonary Aspergillosis and Cytomegalovirus Reactivation in Critically Ill COVID-19 Patients: A Prospective Observational Cohort Study.

COVID-19-associated invasive pulmonary aspergillosis (CAPA) is common and is associated with poor outcomes in critically ill patients. This prospective observational study aimed to explore the association between CAPA development and the incidence and prognosis of cytomegalovirus (CMV) reactivation in critically ill COVID-19 patients. We included all consecutive critically ill adult patients with confirmed COVID-19 infection who were admitted to three COVID-19 intensive care units (ICUs) in an Italian hospital from 25 February 2020 to 8 May 2022. A standardized procedure was employed for early detection of CAPA. Risk factors associated with CAPA and CMV reactivation and the association between CMV recurrence and mortality were estimated using adjusted Cox proportional hazard regression models. CAPA occurred in 96 patients (16.6%) of the 579 patients analyzed. Among the CAPA population, 40 (41.7%) patients developed CMV blood reactivation with a median time of 18 days (IQR 7-27). The CAPA+CMV group did not exhibit a significantly higher 90-day mortality rate (62.5% vs. 48.2%) than the CAPA alone group (p = 0.166). The CAPA+CMV group had a longer ICU stay, fewer ventilation-free days, and a higher rate of secondary bacterial infections than the control group of CAPA alone. In the CAPA population, prior immunosuppression was the only independent risk factor for CMV reactivation (HR 2.33, 95% C.I. 1.21-4.48, p = 0.011). In critically ill COVID-19 patients, CMV reactivation is common in those with a previous CAPA diagnosis. Basal immunosuppression before COVID-19 appeared to be the primary independent variable affecting CMV reactivation in patients with CAPA. Furthermore, the association of CAPA+CMV versus CAPA alone appears to impact ICU length of stay and secondary bacterial infections but not mortality.

COVID-19 omicron variant outbreak in a hematopoietic stem cell transplant unit.

Recommendations and guidelines for management of SARS-COV-2 infection in hematologic patients were developed in the very difficult context of dealing with novel viral variants from one pandemic wave to another, with different susceptibility to available drugs and vaccines. Moreover, the largest SARS-COV-2 case series in patients treated for hematologic malignancies, including stem cell transplant recipients, was published before the Omicron surge, and refers mainly to Alpha and Delta viral variants. These infections had very high mortality, in a period when antivirals and monoclonal antibodies were mostly unavailable. Here, we report for the first time a SARS-COV-2 Omicron variant outbreak inside a Bone Marrow Transplant (BMT) Unit, describing the characteristics, clinical course, and infection outcomes shortly before and shortly after myeloablative transplantation. We detail how infections were treated off-label and managed inside the BMT ward, to guarantee the best possible outcomes while avoiding risks for non-infected inpatients. The positive outcomes observed suggest that it may not be absolutely necessary to obtain SARS-CoV-2 PCR negativity before BMT in hematologic patients after treated infection, in cases with long-term PCR positivity and high-risk hematologic disease.

Epidemiology and Prevention of Early Infections by Multi-Drug-Resistant Organisms in Adults Undergoing Liver Transplant: A Narrative Review.

Invasive bacterial infections are a leading cause of morbidity and mortality after liver transplant (LT), especially during the first months after LT, and infections due to multi-drug-resistant organisms (MDRO) are increasing in this setting. Most of the infections in patients in intensive care unit arise from the endogenous microflora and, for this reason, pre-LT MDRO rectal colonization is a risk factor for developing MDRO infections in the post-LT. Moreover, the transplanted liver may carry an increased risk of MDRO infections due to organ transportation and preservation, to donor intensive care unit stay and previous antibiotic exposure. To date, little evidence is available about how MDRO pre-LT colonization in donors and recipients should address LT preventive and antibiotic prophylactic strategies, in order to reduce MDRO infections in the post-LT period. The present review provided an extensive overview of the recent literature on these topics, with the aim to offer a comprehensive insight about the epidemiology of MDRO colonization and infections in adult LT recipients, donor-derived MDRO infections, possible surveillance, and prophylactic strategies to reduce post-LT MDRO infections.

A Fatal Case of Pseudomonas aeruginosa Community-Acquired Pneumonia in an Immunocompetent Patient: Clinical and Molecular Characterization and Literature Review.

Rare cases of Pseudomonas aeruginosa community-acquired pneumonia (PA-CAP) were reported in non-immunocompromised patients. We describe a case of Pseudomonas aeruginosa (PA) necrotizing cavitary CAP with a fatal outcome in a 53-year-old man previously infected with SARS-CoV-2, who was admitted for dyspnea, fever, cough, hemoptysis, acute respiratory failure and a right upper lobe opacification. Six hours after admission, despite effective antibiotic therapy, he experienced multi-organ failure and died. Autopsy confirmed necrotizing pneumonia with alveolar hemorrhage. Blood and bronchoalveolar lavage cultures were positive for PA serotype O:9 belonging to ST1184. The strain shares the same virulence factor profile with reference genome PA01. With the aim to better investigate the clinical and molecular characteristics of PA-CAP, we considered the literature of the last 13 years concerning this topic. The prevalence of hospitalized PA-CAP is about 4% and has a mortality rate of 33-66%. Smoking, alcohol abuse and contaminated fluid exposure were the recognized risk factors; most cases presented the same symptoms described above and needed intensive care. Co-infection of PA-influenza A is described, which is possibly caused by influenza-inducing respiratory epithelial cell dysfunction: the same pathophysiological mechanism could be assumed with SARS-CoV-2 infection. Considering the high rate of fatal outcomes, additional studies are needed to identify sources of infections and new risk factors, along with genetic and immunological features. Current CAP guidelines should be revised in light of these results.

Efficacy of bezlotoxumab in preventing the recurrence of Clostridioides difficile infection: an Italian multicenter cohort study.

OBJECTIVES: Bezlotoxumab (BEZ) is a promising tool for preventing the recurrence of Clostridioides difficile infection (rCDI). The aim of the study was to emulate, in a real-world setting, the MODIFY trials in a cohort of participants with multiple risk factors for rCDI treated with BEZ in addition to the standard of care (SoC) versus SoC alone. METHODS: A multicenter cohort study was conducted including 442 patients with Clostridioides difficile infection from 2018 to 2022, collected from 18 Italian centers. The main outcome was the 30-day occurrence of rCDI. The secondary outcomes were (i) all-cause mortality at 30 days (ii) and the composite outcome (30-day recurrence and/or all-cause death). RESULTS: rCDI at day 30 occurred in 54 (12%): 11 in the BEZ + SoC group and 43 treated with SoC alone (8% vs 14%, odds ratio [OR] = 0.58, 95% confidence interval [CI]: 0.31-1.09, P = 0.09). The difference between BEZ + SoC versus SoC was statistically significant after controlling for confounding factors (adjusted OR = 0.40, 95% CI: 018-0.88, P = 0.02) and even more using the composite outcome (adjusted OR = 0.35, 95% CI: 0.17-0.73, P = 0.005). CONCLUSION: Our study confirms the efficacy of BEZ + SoC for the prevention of rCDI and death in a real-world setting. BEZ should be routinely considered among participants at high risk of rCDI regardless of age, type of Clostridioides difficile infection therapy (vancomycin vs fidaxomicin), and number of risk factors.

Persistent SARS-CoV-2 infection with multiple clinical relapses in two patients with follicular lymphoma treated with bendamustine and obinutuzumab or rituximab.

PURPOSE: People with hematologic malignancies have a significantly higher risk of developing severe and protracted forms of SARS-CoV-2 infection compared to immunocompetent patients, regardless of vaccination status. RESULTS: We describe two cases of prolonged SARS-CoV-2 infection with multiple relapses of COVID-19 pneumonia in patients with follicular lymphoma treated with bendamustine and obinutuzumab or rituximab. The aim is to highlight the complexity of SARS-CoV-2 infection in this fragile group of patients and the necessity of evidence-based strategies to treat them properly. CONCLUSIONS: Patients with hematological malignancies treated with bendamustine and anti-CD20 antibodies had a significant risk of prolonged and relapsing course of COVID-19. Specific preventive and therapeutic strategies should be developed for this group of patients.

The WEST Study: A Retrospective and Multicentric Study on the Impact of Steroid Therapy in West Nile Encephalitis.

Background: The use of steroid therapy in potentially life-threatening neuroinvasive forms of West Nile infection (WNND) is controversial. The aim of this study is to assess the efficacy of steroid therapy in reducing intrahospital mortality, length of stay, and neurological sequelae at discharge. Methods: This was a multicenter, retrospective, observational study conducted in 5 hospitals in Northern Italy, headed by the Fondazione IRCSS Policlinico San Matteo (Pavia). We extracted all patient data with WNND diagnoses, comparing patients who received steroid treatment with patients who did not receive steroid treatment between January 2014 and January 2022. Comparisons between the 2 groups were performed using chi-square tests for categorical variables and Mann-Whitney tests for non-normal continuous data, and a generalized linear model for the binomial family was carried out. Results: Data from 65 WNND patients were extracted. Among these patients, 33 (50.7%) received steroid therapy at any point during their hospitalization. Receiving steroid therapy did not significantly reduce intrahospital mortality (odds ratio [OR], 1.70; 95% CI, 0.3-13.8; P = .89) or neurological sequelae at discharge (OR, 0.53; 95% CI, 0.16-1.76; P = .47). Conclusions: Steroid treatment is currently used on a single-case basis in severe WNND. More prospective data are needed to demonstrate a protective effect on mortality and neurological sequelae.

Blackwater Fever Treated with Steroids in Nonimmune Patient, Italy.

Causes of blackwater fever, a complication of malaria treatment, are not completely clear, and immune mechanisms might be involved. Clinical management is not standardized. We describe an episode of blackwater fever in a nonimmune 12-year-old girl in Italy who was treated with steroids, resulting in a rapid clinical resolution.

Do All Critically Ill Patients with COVID-19 Disease Benefit from Adding Tocilizumab to Glucocorticoids? A Retrospective Cohort Study.

BACKGROUND: Treatment guidelines recommend the tocilizumab use in patients with a CRP of >7.5 mg/dL. We aimed to estimate the causal effect of glucocorticoids + tocilizumab on mortality overall and after stratification for PaO2/FiO2 ratio and CRP levels. METHODS: This was an observational cohort study of patients with severe COVID-19 pneumonia. The primary endpoint was day 28 mortality. Survival analysis was conducted to estimate the conditional and average causal effect of glucocorticoids + tocilizumab vs. glucocorticoids alone using Kaplan-Meier curves and Cox regression models with a time-varying variable for the intervention. The hypothesis of the existence of effect measure modification by CRP and PaO2/FiO2 ratio was tested by including an interaction term in the model. RESULTS: In total, 992 patients, median age 69 years, 72.9% males, 597 (60.2%) treated with monotherapy, and 395 (31.8%), adding tocilizumab upon respiratory deterioration, were included. At BL, the two groups differed for median values of CRP (6 vs. 7 mg/dL; p < 0.001) and PaO2/FiO2 ratio (276 vs. 235 mmHg; p < 0.001). In the unadjusted analysis, the mortality was similar in the two groups, but after adjustment for key confounders, a significant effect of glucocorticoids + tocilizumab was observed (adjusted hazard ratio (aHR) = 0.59, 95% CI: 0.38-0.90). Although the study was not powered to detect interactions (p = 0.41), there was a signal for glucocorticoids + tocilizumab to have a larger effect in subsets, especially participants with high levels of CRP at intensification. CONCLUSIONS: Our data confirm that glucocorticoids + tocilizumab vs. glucocorticoids alone confers a survival benefit only in patients with a CRP > 7.5 mg/dL prior to treatment initiation and the largest effect for a CRP > 15 mg/dL. Large randomized studies are needed to establish an exact cut-off for clinical use.

Pneumocystis jirovecii pneumonia in patients with decompensated cirrhosis: a case series.

OBJECTIVES: Pneumocystis jirovecii pneumonia (PCP) incidence is increasing in people without HIV. Decompensated liver cirrhosis is not currently considered a risk factor for PCP. The aim of this paper is to describe a case series of patients with decompensated liver cirrhosis and PCP. METHODS: All consecutive patients hospitalized with decompensated cirrhosis and microbiology-confirmed PCP at Policlinico Modena University Hospital from January 1, 2016 to December 31, 2021 were included in our series. RESULTS: Eight patients were included. All patients had advanced-stage liver disease with a model for end-stage liver disease score above 15 (6/8 above 20). Four were on an active orthotopic liver transplant waiting list at the time of PCP diagnosis. Five patients did not have any traditional risk factor for PCP, whereas the other three were on glucocorticoid treatment for acute-on-chronic liver failure. All patients were treated with cotrimoxazole, except two who died before the diagnosis. Five patients died (62.5%), four of them within 30 days from PCP diagnosis. Of the remaining three, one patient underwent liver transplantation. CONCLUSION: Although further studies are needed, liver cirrhosis can be an independent risk factor for PCP in patients with decompensated cirrhosis that is mainly due to severe alcoholic hepatitis and who are on corticosteroids therapy, and primary prophylaxis for PCP should be considered.

External Validity of a Randomized Controlled Trial on Duration of Antibiotics for the Treatment of Gram-Negative Bacteremia.

INTRODUCTION: Reports regarding the external validity of randomized controlled trials (RCTs) are scarce. We aimed to assess the population external validity of an investigator-initiated RCT on the duration of antibiotics for the treatment of Gram-negative bacteremia by comparing patients included in the RCT to patients that were not included in the trial. METHODS: Hospitalized patients with Gram-negative bacteremia were recruited into an RCT and randomized to receive 7 or 14 days of covering antibiotic therapy in Israel and Italy from 2013 to 2017. In a concomitant observational study, RCT participants were compared with patients who fulfilled the inclusion criteria but were not included in the trial due to participation in other trials, discharge before approached by researchers, refusal to participate, or unwillingness of the treating physician to allow participants' recruitment. RESULTS: Six hundred and four RCT patients were compared with 613 nonincluded patients. Almost 50% of nonincluded patients (288/613) were dependent on others for activities of daily living at baseline compared to 37.7% of RCT participants (228/604). Dementia was nearly 2-fold more frequent in nonincluded patients than those included (5.9% [36/613] versus 3.6% [22/604], p = 0.07). Patients who were not included in the RCT were more likely to acquire their infection in the hospital (53.3% [327/613] versus 29.1% [176/604], p < 0.001). The primary composite outcome of mortality, clinical failure, readmissions, or extended hospitalization at 90 days occurred in 353 of 613 nonincluded patients (57.6%) compared to 299 of 604 RCT participants (49.6%), p = 0.005. However, on multivariate analysis noninclusion in the RCT was not an independent risk factor for clinical failure and mortality. CONCLUSIONS: RCTs, even with broad eligibility criteria, do not represent the whole spectrum of patients and leave out a population with more severe illness for whom the evidence is lacking.

Duration of antibiotic treatment for Gram-negative bacteremia - Systematic review and individual participant data (IPD) meta-analysis.

Background: We aim to compare the effect of short versus long treatment duration in Gram-negative bacteremia on all-cause mortality in pre-specified sub-groups. Methods: Individual participant data meta-analysis of randomized controlled trials (RCTs) comparing short (≤7) versus longer (>7 days) antibiotic treatment for Gram-negative bacteremia. Participants were adults (≥18 years), with Gram-negative bacteremia during hospital stay. We searched PubMed, Cochrane Central Register of Controlled Trials, and Web of Science to identify trials conducted up to May 2022. Primary outcome was 90-day all-cause mortality. Secondary outcomes were 30-day mortality, relapse of bacteremia, length of hospital stay, readmission, local or distant infection complications, adverse events, and resistance emergence.Outcomes were assessed in pre-specified subgroups: women vs men; non-urinary vs urinary source; presence vs absence of hypotension on initial presentation; immunocompromised patients versus non-immunocompromised patients, and age (above/below 65). Fixed-effect meta-analysis model was used to estimate pooled odds ratio (OR) and 95% confidence interval (CI). All three trials had low risk of bias for allocation generation and concealment. Findings: Three RCTs (1186 patients) were included; 1121 with enterobacterales bacteremia. No significant difference in mortality was demonstrated between 7- and 14-days treatment (90-day mortality: OR 1.08, 95% CI 0.73-1.58; 30-day mortality: 1.08, 0.62-1.91). Relapse (1.00, 0.50-1.97); length of hospital stay (P = 0.78); readmission (0.96, 0.80-1.22); and infection complications (local: 1.62 0.76-3.47; distant: 2.00, 0.18-22.08), were without significant difference, and so were adverse events or resistance emergence.No significant difference in clinical outcomes between 7 and 14 days of antibiotics was demonstrated in the subgroups of gender, age, hemodynamic status, immune status, and source of infection. Interpretation: For patients hemodynamically stable and afebrile at 48 h prior to discontinuation, seven days of antibiotic therapy for enterobacterales bacteremia result in similar outcomes as 14 days, in terms of mortality, relapse, length of hospital stay, complications of infection, resistance emergence, and adverse events. These results apply for any adult age group, gender, source of infection, immune status, and hemodynamic status on presentation. Funding: There was no funding source for this study.

A proof-of-concept study on the genomic evolution of Sars-Cov-2 in molnupiravir-treated, paxlovid-treated and drug-naïve patients.

Little is known about SARS-CoV-2 evolution under Molnupiravir and Paxlovid, the only antivirals approved for COVID-19 treatment. By investigating SARS-CoV-2 variability in 8 Molnupiravir-treated, 7 Paxlovid-treated and 5 drug-naïve individuals at 4 time-points (Days 0-2-5-7), a higher genetic distance is found under Molnupiravir pressure compared to Paxlovid and no-drug pressure (nucleotide-substitutions/site mean±Standard error: 18.7 × 10-4 ± 2.1 × 10-4 vs. 3.3 × 10-4 ± 0.8 × 10-4 vs. 3.1 × 10-4 ± 0.8 × 10-4, P = 0.0003), peaking between Day 2 and 5. Molnupiravir drives the emergence of more G-A and C-T transitions than other mutations (P = 0.031). SARS-CoV-2 selective evolution under Molnupiravir pressure does not differ from that under Paxlovid or no-drug pressure, except for orf8 (dN > dS, P = 0.001); few amino acid mutations are enriched at specific sites. No RNA-dependent RNA polymerase (RdRp) or main proteases (Mpro) mutations conferring resistance to Molnupiravir or Paxlovid are found. This proof-of-concept study defines the SARS-CoV-2 within-host evolution during antiviral treatment, confirming higher in vivo variability induced by Molnupiravir compared to Paxlovid and drug-naive, albeit not resulting in apparent mutation selection.