Alberto Pagotto

Background/Objectives: Granulicatella adiacens infective endocarditis is conventionally managed with penicillin, ampicillin, or ceftriaxone in combination with gentamicin, although double beta-lactam regiments have been proposed a safer alternative to reduce aminoglycoside-associated nephrotoxicity. To date, the High-Molecular-Mass Penicillin-Binding Proteins (HMM-PBPs) of G. adiacens and their affinities for beta-lactam antibiotics have not been previously characterized. This study investigated the HMM-PBP profile of G. adiacens, with particular interest on sequence alterations and beta-lactam binding properties, both as single agents and in combination. Methods: Beta-lactam activity, synergistic interactions and PBP binding affinities were evaluated in a clinical isolate (IS 48) and compared with those in the reference strain ATCC 49175. Binding of PBPs to ampicillin, ceftriaxone, and ceftobiprole, alone or in combination, was investigated by Bocillin-FL labeling. PBP homology and conserved active-sites motifs were assessed by sequence alignment, and pbp gene mutations were identified by whole-genome sequencing. Results: The clinical isolate was non-susceptible to ampicillin, resistant to ceftriaxone and exhibited higher minimum inhibitory concentrations (MICs) for ceftobiprole relative to the fully susceptible ATCC reference strain. Five HMM PBPs with high enterococcal homology, were identified. In the IS 48 isolate, the class A PBP showed distinct amino acid substitutions in proximity to the catalytic centers. Despite these alterations, PBP1A and PBP2A were strongly inhibited by the tested beta-lactams, whereas PBP2 and PBP2B demonstrated low acylation rates. Combination of ampicillin with either ceftobiprole or ceftriaxone resulted in enhanced acylation of the three bifunctional HMM PBPs compared with monotreatment. IC₅₀ values were consistently higher for the IS 48 clinical isolate, suggesting decreased target availability and/or reduced beta-lactam affinity under clinical conditions. Conclusions: The resistance phenotype of G. adiacens clinical isolate appears to be primarily associated with altered PBP beta-lactam interactions. Nonetheless, beta-lactam combination regimes remain effective by achieving substantial inhibition of key HMM-PBPs involved in peptidoglycan synthesis, thereby supporting the rationale for dual beta-lactam therapy in this setting.

Invasive candidiasis represents a major global health concern, with incidence and mortality rates expected to rise due to medical advancements and unavoidable risk factors. This retrospective, multicentric study was conducted in eight hospitals in a northeastern Italian region, enrolling adult patients diagnosed with candidemia from 1 January 2018 to 31 December 2022. Epidemiological trends and clinical characteristics were analyzed and compared to those from a prior regional study (2009–2011), allowing a fourteen-year comparative evaluation. A shift in species distribution was observed, with a decline in Candida albicans (from 65.7% to 57.8%) and a rise in non-albicans species, particularly the Candida parapsilosis complex (from 16.1% to 18.2%). Guideline adherence was assessed applying the EQUAL Candida score; scores ≥ than 11.5 were independently associated with improved in-hospital survival (HR 3.51, p < 0.001). Among individual score components, empiric echinocandin therapy and central venous catheter removal correlated with better outcomes. Centers with routine infectious disease (ID) consultations showed higher survival and adherence, reinforcing the value of specialist involvement. These findings support local epidemiological and management practice surveillance program adoption to address context-specific gaps, promote the adoption of best practices in Candida BSI management—as expanded ID specialist consultations and education programs—and, ultimately, reduce candidemia-related mortality rates.

(1) Background: Granulicatella adiacens is a former nutritionally variant streptococci (NVS). NVS infective endocarditis (IE) is generally characterized by a higher rate of morbidity and mortality, partially due to difficulties in choosing the most adequate microbiological culture method and the most effective treatment strategy, and partially due to higher rates of complications, such as heart failure, peripheral septic embolism, and peri-valvular abscess, as well as a higher rate of valve replacement. Depending on the affected valve (native valve endocarditisNVE, or prosthetic valve endocarditisPVE), the American Heart Association (AHA) 2015 treatment guidelines (GLs) suggest penicillin G, ampicillin, or ceftriaxone plus gentamicin (2 weeks for NVE and up to 6 weeks for PVE), while vancomycin alone may be a reasonable alternative in patients who are intolerant of β-lactam therapy. The European Society of Cardiology (ESC) 2023 GLs recommend treating NVE with penicillin G, ceftriaxone, or vancomycin for 6 weeks, suggesting combined with an aminoglycoside (AG) for at least the first 2 weeks only for PVE; likewise, the same recommendations for IE due to Enterococcus faecalis. (2) Methods: Starting from the case of a 51-year-old man with G. adiacens aortic bio-prosthesis IE who was successfully treated with aortic valve replacement combined with double beta-lactams, an AG-sparing regimen, we performed microbiology tests in order to validate this potential treatment change. (3) Results: As for E. faecalis IE, we found that the combination of ampicillin plus cephalosporines (like ceftriaxone or ceftobiprole) showed a synergistic effect in vitro, probably due to wider binding to penicillin-binding proteins (PBPs), thus contributing to enhanced bacterial killing and good clinical outcome, as well as avoiding the risk of nephrotoxicity due to AG association therapy. (4) Conclusions: Further studies are required to confirm this hypothesis, but double beta-lactams and an adequate sourcecontrol could be a choice in treating G. adiacens IE.

Enterococcus faecalis is responsible for many serious infections for which combination bactericidal therapy is required¹. A synergism between amoxicillin and cefotaxime against E. faecalis through partial saturation of penicillin-binding proteins (PBPs) 4 and 5 by amoxicillin and total saturation of PBPs 2 and 3 by cefotaxime has been demonstrated². Unlike cefotaxime, ceftobiprole binds with high affinity to PBP2, PBP3, PBP4 and PBP5^3,4,5, thus a potential role in the management of severe E. faecalis infections might be hypothesized. The availability of therapeutic drug monitoring (TDM) for ampicillin and ceftobiprole has been driving the choice of using the combination of ampicillin plus ceftobiprole (ABPR) for the treatment of life-threatening E. faecalis infections. Patient level pathological conditions, clinical and microbiological outcomes and antimicrobial therapy. MIC= minimum inhibitory concentration. The observed Pharmacokinetic/Pharmacodynamic (PK/PD) antimicrobial efficacy index, which is represented by the ratio between the antibiotic plasmatic concentrations at the end of dosing interval (100% T) and the reference MIC (100%T>MIC). A ratio of 1 represents the minimum PK/PD therapeutic target, whereas the ratio of 4 represents a high antimicrobial activity. The reported MICs derive from pathogen isolates. MIC= minimum inhibitory concentration. Time–kill curve of ampicillin and ceftobiprole alone and in combination at different BPR concentrations (1 x MIC, 2 x MIC, 4 x MIC) for one of the 21 studied E. faecalis strains. AMP, ampicillin, BPR, ceftobiprole. MIC AMP: 1 mg/L; MIC BPR: 0.25 mg/L. Ceftobiprole even alone or ABPR might represent a valuable option for the treatment of severe E. faecalis invasive infections. All Authors: No reported disclosures

Background: Meropenem is a carbapenem antibiotic widely employed for serious bacterial infections. Therapeutic drug monitoring (TDM) is a strategy to optimize dosing, especially in critically ill patients. This study aims to show how TDM influences the management of meropenem in a real-life setting, not limited to intensive care units. Methods: From December 2021 to February 2022, we retrospectively analyzed 195 meropenem serum concentrations (Css). We characterized patients according to meropenem exposure, focusing on the renal function impact. Results: A total of 36% (n = 51) of the overall observed patients (n = 144) were in the therapeutic range (8–16 mg/L), whereas 64% (n = 93) required a meropenem dose modification (37 patients (26%) underexposed; 53 (38%) overexposed). We found a strong relationship between renal function and meropenem concentrations (correlation coefficient = −0.7; p-value < 0.001). We observed different dose-normalized meropenem exposure (Css/D) among renal-impaired (severe and moderate), normal, and hyperfiltrating patients, with a median (interquartile range) of 13.1 (10.9–20.2), 7.9 (6.1–9.5), 3.8 (2.6–6.0), and 2.4 (1.6–2.7), respectively (p-value < 0.001). Conclusions: Meropenem TDM in clinical practice allows modification of dosing in patients inadequately exposed to meropenem to maximize antibiotic efficacy and minimize the risk of antibiotic resistance, especially in renal alterations despite standard dose adaptations.

A life-threatening respiratory illness (COVID-19) due to severe acute respiratory syndrome (SARS)-CoV-2 coronavirus was first described in December 2019 in Wuhan (China), rapidly evolving into a pandemic. In the first phase, when the viral replication plays a pivotal pathogenetic role, antiviral drugs could be crucial in limiting viral-induced organ damage. Unfortunately, there are no specific antivirals of proven efficacy for COVID-19, and several drugs have been repurposed to face this dramatic pandemic. In this paper we review the studies evaluating lopinavir/ritonavir association (LPV/r) use in COVID-19, and previously in SARS and Middle East respiratory syndrome (MERS). We searched PubMed to identify all relevant clinical and laboratory studies published up to 15 May 2020; the guidelines on the use of LPV/r in COVID-19 were further directly searched on the website of the main international scientific societies and agencies. Available evidence is currently scarce and of low quality. The recommendations issued for COVID-19 vary from positions clearly against the use of LPV/r to other positions that are more favorable. In our opinion, despite the controversial results of an important randomized clinical trial, and some recommendations, clinicians should not abandon the use of LPV/r for the treatment of COVID-19, possibly using this drug inside a prospective randomized trial, waiting for the results of the numerous ongoing trials evaluating its efficacy.