Sepsis poses a significant global health challenge due to immune system dysregulation. This narrative review explores the complex relationship between antibiotics and the immune system, aiming to clarify the involved mechanisms and their clinical impacts. From pre-clinical studies, antibiotics exhibit various immunomodulatory effects, including the regulation of pro-inflammatory cytokine production, interaction with Toll-Like Receptors, modulation of the P38/Pmk-1 Pathway, inhibition of Matrix Metalloproteinases, blockade of nitric oxide synthase, and regulation of caspase-induced apoptosis. Additionally, antibiotic-induced alterations to the microbiome are associated with changes in systemic immunity, affecting cellular and humoral responses. The adjunctive use of antibiotics in sepsis patients, particularly macrolides, has attracted attention due to their immune-regulatory effects. However, there are limited data comparing different types of macrolides. More robust evidence comes from studies on community-acquired pneumonia, especially in severe cases with a hyper-inflammatory response. While studies on septic shock have shown mixed results regarding mortality rates and immune response modulation, conflicting findings are also observed with macrolides in acute respiratory distress syndrome. In conclusion, there is a pressing need to tailor antibiotic therapy based on the patient’s immune profile to optimize outcomes in sepsis management.

Objectives: To assess the hypothesis that an adjunctive therapy with methylprednisolone and unfractionated heparin (UFH) or with methylprednisolone and low molecular weight heparin (LMWH) are more effective in reducing any-cause mortality in critically-ill ventilated patients with pneumonia from SARS-CoV-2 infection compared to LMWH alone. Trial design: The study is designed as a multi-centre, interventional, parallel group, superiority, randomized, investigator sponsored, three arms study. Patients, who satisfy all inclusion criteria and no exclusion criteria, will be randomly assigned to one of the three treatment groups in a ratio 1:1:1. Participants: Inpatients will be recruited from 8 Italian Academic and non-Academic Intensive Care Units Inclusion Criteria (all required): 1. Positive SARS-CoV-2 diagnostic (on pharyngeal swab of deep airways material) 2. Positive pressure ventilation (either non-invasive or invasive) from > 24 hours 3. Invasive mechanical ventilation from < 96 hours 4. PaO₂/FiO₂ ratio lower than 150 mmHg 5. D-dimer level > 6 times the upper limit of normal reference range 6. C-reactive Protein > 6-fold upper the limit of normal reference range Exclusion Criteria: 1. Age < 18 years 2. On-going treatment with anticoagulant drugs 3. Platelet count < 100.000/mm³ 4. History of heparin-induced thrombocytopenia 5. Allergy to sodium enoxaparin or other LMWH, UFH or methylprednisolone 6. Active bleeding or on-going clinical condition deemed at high risk of bleeding contraindicating anticoagulant treatment 7. Recent (in the last 1 month prior to randomization) brain, spinal or ophthalmic surgery 8. Chronic assumption or oral corticosteroids 9. Pregnancy or breastfeeding or positive pregnancy test. In childbearing age women, before inclusion, a pregnancy test will be performed if not available 10. Clinical decision to withhold life-sustaining treatment or “too sick to benefit” 11. Presence of other severe diseases impairing life expectancy (e.g. patients are not expected to survive 28 days given their pre-existing medical condition) 12. Lack or withdrawal of informed consent Intervention and comparator: • LMWH group: patients in this group will be administered enoxaparin at standard prophylactic dosage. • LMWH + steroid group: patients in this group will receive enoxaparin at standard prophylactic dosage and methylprednisolone. • UFH + steroid group: patients in this group will receive UFH at therapeutic dosages and methylprednisolone. UFH will be administered intravenously in UFH + steroid group at therapeutic doses. The infusion will be started at an infusion rate of 18 UI/kg/hour and then modified to obtain aPTT Ratio in between the range of 1.5-2.0. aPTT will be periodically checked at intervals no longer than 12 hours. The treatment with UFH will be administered up to ICU discharge. After ICU discharge anticoagulant therapy may be interrupted or switched to prophylaxis with LMWH in the destination ward up to clinical judgement of the attending physician. Enoxaparin will be administered in both LMWH group and LMWH + steroid group at standard prophylactic dose (i.e., 4000 UI once day, increased to 6000 UI once day for patients weighting more than 90 kg). The treatment will be administered subcutaneously once a day up to ICU discharge. After ICU discharge it may be continued or interrupted in the destination ward up to clinical judgement of the attending physician. Methylprednisolone will be administered in both LMWH + steroid group and UHF + steroid group intravenously with an initial bolus of 0,5 mg/kg followed by administration of 0,5 mg/kg 4 times daily for 7 days, 0,5 mg/kg 3 times daily from day 8 to day 10, 0,5 mg/kg 2 times daily at days 11 and 12 and 0,5 mg/kg once daily at days 13 and 14. Main Outcomes: Primary Efficacy Endpoint: All-cause mortality at day 28 Secondary Efficacy Endpoints: - Ventilation free days (VFDs) at day 28, defined as the total number of days that patient is alive and free of ventilation (either invasive or non-invasive) between randomization and day 28 (censored at hospital discharge). - Need of rescue administration of high-dose steroids or immune-modulatory drugs; - Occurrence of switch from non-invasive to invasive mechanical ventilation during ICU stay; - Delay from start of non-invasive ventilation to switch to invasive ventilation; - All-cause mortality at ICU discharge and hospital discharge; - ICU free days (IFDs) at day 28, defined as the total number of days between ICU discharge and day 28. - Occurrence of new infections from randomization to day 28; including infections by Candida, Aspergillus, Adenovirus, Herpes Virus e Cytomegalovirus - Occurrence of new organ dysfunction and grade of dysfunction during ICU stay. - Objectively confirmed venous thromboembolism, stroke or myocardial infarction; Safety endpoints: - Occurrence of major bleeding, defined as transfusion of 2 or more units of packed red blood cells in a day, bleeding that occurs in at least one of the following critical sites [intracranial, intra-spinal, intraocular (within the corpus of the eye; thus, a conjunctival bleed is not an intraocular bleed), pericardial, intra-articular, intramuscular with compartment syndrome, or retroperitoneal], bleeding that necessitates surgical intervention and bleeding that is fatal (defined as a bleeding event that was the primary cause of death or contributed directly to death); - Occurrence of clinically relevant non-major bleeding, defined ad acute clinically overt bleeding that does not meet the criteria for major and consists of any bleeding compromising hemodynamic; spontaneous hematoma larger than 25 cm², intramuscular hematoma documented by ultrasonography, haematuria that was macroscopic and was spontaneous or lasted for more than 24 hours after invasive procedures; haemoptysis, hematemesis or spontaneous rectal bleeding requiring endoscopy or other medical intervention or any other bleeding requiring temporary cessation of a study drug. Randomization: A block randomisation will be used with variable block sizes (block size 4-6-8), stratified by 3 factors: Centre, BMI (<30/≥30) and Age (<75/≥75). Central randomisation will be performed using a secure, web-based, randomisation system with an allocation ratio of 1:1:1. The allocation sequence will be generated by the study statistician using computer generated random numbers. Blinding (masking): Participants to the study will be blinded to group assignment. Numbers to be randomised (sample size): The target sample size is based on the hypothesis that the combined use of UHF and steroid versus the LMWH group will significantly reduce the risk of death at day 28. The overall sample size in this study is expected to be 210 with a randomization 1:1:1 and seventy patients in each group. Assuming an alpha of 2.5% (two tailed) and mortality rate in LMWH group of 50%, as indicated from initial studies of ICU patients, the study will have an 80% power to detect at least a 25 % absolute reduction in the risk of death between: a) LMHW + steroid group and LMWH group or b) UHF + steroid group and LMWH group. The study has not been sized to assess the difference between LMHW + steroid group and UHF + steroid group, therefore the results obtained from this comparison will need to be interpreted with caution and will need further adequately sized studies confirm the effect. On the basis of a conservative estimation, that 8 participating sites admit an average of 3 eligible patients per month per centre (24 patients/month). Assuming that 80 % of eligible patients are enrolled, recruitment of 210 participants will be completed in approximately 10 months. Trial Status: Protocol version 1.1 of April 26^th, 2020. Recruitment start (expected): September 1^st, 2020 Recruitment finish (expected): June 30^th, 2021 Trial registration: EudraCT number 2020-001921-30, registered on April 15^th, 2020 AIFA approval on May 4^th, 2020 Full protocol: The full protocol is attached as an additional file, accessible from the Trials website (Additional file 1). In the interest in expediting dissemination of this material, the familiar formatting has been eliminated; this Letter serves as a summary of the key elements of the full protocol.

The aim of our study was to evaluate whether the introduction of SDD in a structured protocol for VAP prevention was effective in reducing the occurrence of ventilator-associated pneumonia (VAP) in COVID-19 patients without changes in the microbiological pattern of antibiotic resistance. This observational pre-post study included adult patients requiring invasive mechanical ventilation (IMV) for severe respiratory failure related to SARS-CoV-2 admitted in three COVID-19 intensive care units (ICUs) in an Italian hospital from 22 February 2020 to 8 March 2022. Selective digestive decontamination (SDD) was introduced from the end of April 2021 in the structured protocol for VAP prevention. The SDD consisted of a tobramycin sulfate, colistin sulfate, and amphotericin B suspension applied in the patient’s oropharynx and the stomach via a nasogastric tube. Three-hundred-and-forty-eight patients were included in the study. In the 86 patients (32.9%) who received SDD, the occurrence of VAP decreased by 7.7% (p = 0.192) compared to the patients who did not receive SDD. The onset time of VAP, the occurrence of multidrug-resistant microorganisms AP, the length of invasive mechanical ventilation, and hospital mortality were similar in the patients who received and who did not receive SDD. The multivariate analysis adjusted for confounders showed that the use of SDD reduces the occurrence of VAP (HR 0.536, CI 0.338–0.851; p = 0.017). Our pre-post observational study indicates that the use of SDD in a structured protocol for VAP prevention seems to reduce the occurrence of VAP without changes in the incidence of multidrug-resistant bacteria in COVID-19 patients.

In COVID-19 patients, procalcitonin (PCT) and C-reactive protein (CRP) performance in identifying bacterial infections remains unclear. Our study aimed to evaluate the association of PCT and CRP with secondary infections acquired during ICU stay in critically ill COVID-19 patients. This observational study included adult patients admitted to three COVID-19 intensive care units (ICUs) from February 2020 to May 2022 with respiratory failure caused by SARS-CoV-2 infection and ICU stay ≥ 11 days. The values of PCT and CRP collected on the day of infection diagnosis were compared to those collected on day 11 after ICU admission, the median time for infection occurrence, in patients without secondary infection. The receiver operating characteristic curve (ROC) and multivariate logistic model were used to assess PCT and CRP association with secondary infections. Two hundred and seventy-nine patients were included, of whom 169 (60.6%) developed secondary infection after ICU admission. The PCT and CRP values observed on the day of the infection diagnosis were larger (p < 0.001) than those observed on day 11 after ICU admission in patients without secondary infections. The ROC analysis calculated an AUC of 0.744 (95%CI 0.685–0.803) and 0.754 (95%CI 0.695–0.812) for PCT and CRP, respectively. Multivariate logistic models showed that PCT ≥ 0.16 ng/mL and CRP ≥ 1.35 mg/dL were associated (p < 0.001) with infections acquired during ICU stay. Our results indicated that in COVID-19 patients, PCT and CRP values were associated with infections acquired during the ICU stay and can be used to support, together with clinical signs, rather than predict or rule out, the diagnosis of these infections.

Background: Infections frequently occur after orthotopic liver transplantation (OLT) and are associated with increased mortality. In 2018, we introduced perioperative administration of intravenous immunoglobulin enriched in IgM as an optional therapy in recipients at a high risk of infection. This preliminary study evaluated whether this preparation reduced infections in the early post-transplantation period. Methods: Adult patients with a high risk of postoperative infections who underwent OLT between January 2014 and December 2021 in our center were included in the study. The primary outcome was the occurrence of new postoperative bacterial and fungal infections within the first 30 days after OLT. Results: Ninety recipients at a high risk of postoperative infections who underwent OLT were included, of whom 51 (57%) received IgM preparation. Patients treated and not treated with IgM were similar in terms of demographics, model of end-stage liver disease score, and risk factors for postoperative infections. The occurrence of new infections was lower (absolute risk reduction (ARR) 21.2%; p = 0.038) in patients who received IgM than in those who did not. Multivariate analysis adjusted for confounders (OR 0.348; p = 0.033) and propensity score-based matching analysis (ARR 21.2%, p = 0.067) confirmed an association between IgM preparation and lower occurrence of postoperative infections. The 90-day mortality rate was lower (ARR 13.4%, p = 0.018) in patients who received IgM preparation. Conclusions: In OLT recipients at high risk for infections, perioperative administration of an IgM-enriched preparation seems to reduce the development of new infections within the first 30 days after OLT.