The immunocompromised host is usually vulnerable to infectious diseases due to broad-spectrum treatments and immunological dysregulation. The Enterococcus genus consists of normal gut commensals, which acquire a leading role in infective processes among individuals with compromised immune systems. These microorganisms may express a potential virulence and resistance spectrum, enabling their function as severe pathogens. The Enterococcus spp. infections in immunocompromised hosts appear to be difficult to resolve due to the immunological response impairment and the possibility of facing antimicrobial-resistant strains. As regards the related risk factors, several data demonstrated that prior antibiotic exposure, medical device insertion, prolonged hospitalization and surgical interventions may lead to Enterococcus overgrowth, antibiotic resistance and spread among critical healthcare settings. Herein, we present a comprehensive review of Enterococcus spp. in the immunocompromised host, summarizing the available knowledge about virulence factors, antimicrobial-resistance mechanisms and host-pathogen interaction. The review ultimately yearns for more substantial support to further investigations about enterococcal infections and immunocompromised host response.

Carbapenem-resistant gram-negative bacteria represent a challenging healthcare threat, accounting for metallo-β-lactamases (MBL) production increase across the world. MBL-producing Enterobacterales and Pseudomonas aeruginosa represent the main target for ultimate antibiotics combinations due to the difficulty to include carbapenems within the antimicrobial treatment. To provide a comprehensive review of the current knowledge about the aztreonam/avibactam (ATM-AVI) combination, which has emerged as a promising option for treating MBL-producing bacteria. Relevant in vitro and in vivo studies on ATM-AVI effectiveness. The review summarizes ATM-AVI characteristics and targets, examining how AVI restores ATM effectiveness against MBLs while protecting it from other β-lactamases. Key in vitro and in vivo studies on ATM-AVI efficacy are presented. This review provides insights into the potential clinical management implications of ATM-AVI for treating carbapenem-resistant gram-negative infections, particularly those caused by MBL-producing organisms.

Intensive care units constitute a critical setting for the management of infections. The patients’ fragilities and spread of multidrug-resistant microorganisms lead to relevant difficulties in the patients’ care. Recent epidemiological surveys documented the Gram-negative bacteria supremacy among intensive care unit (ICU) infection aetiologies, accounting for numerous multidrug-resistant isolates. Regarding this specific setting, clinical microbiology support holds a crucial role in the definition of diagnostic algorithms. Eventually, the complete patient evaluation requires integrating local epidemiological knowledge into the best practice and the standardization of antimicrobial stewardship programs. Clinical laboratories usually receive respiratory tract and blood samples from ICU patients, which express a significant predisposition to severe infections. Therefore, conventional or rapid diagnostic workflows should be modified depending on patients’ urgency and preliminary colonization data. Additionally, it is essential to complete each microbiological report with rapid phenotypic minimum inhibitory concentration (MIC) values and information about resistance markers. Microbiologists also help in the eventual integration of ultimate genome analysis techniques into complicated diagnostic workflows. Herein, we want to emphasize the role of the microbiologist in the decisional process of critical patient management.

Diabetes is characterized by an increased rate of serum glucose due to defects in insulin secretion, insulin action or both conditions. Glucose excesses can lead to extended cellular damage, with the consequence of several infectious and non-infectious skin disorders. The aim of the present study was to evaluate the toenail onychomycosis incidence in diabetic patients and healthy ones. The non-interventional, retrospective study was performed at the mycology laboratory of the University hospital “Policlinico-San Marco” in Catania, Italy, for over one year. Nail clippings were collected to perform microscopic and cultural exams, which allowed for the identification of fungal aetiological agents. A total of 715 patients (47 diabetic and 668 non-diabetic patients) were enrolled. In diabetic patients, dermatophytes were the most common cultural isolates (50%), followed by yeasts and moulds in 30.8% and 19.2%, respectively. In non-diabetic patients, the distribution of dermatophytes, yeasts and non-dermatophytic moulds was 67.4%, 5.3% and 27.3%, respectively. According to our results, diabetic patients are more predisposed to nail fungal infection. Our data suggest that dermatological follow-ups should always be performed for diabetic patients. All skin and nail disorders should be carefully monitored to perform a diagnostic confirmation and correct management of diabetic patients.

This comprehensive review examines the unique attributes, distinctions, and clinical implications of ceftazidime–avibactam (CAZ-AVI) and meropenem–vaborbactam (MEM-VAB) against difficult-to-treat Enterobacterales infections. Our manuscript explores these antibiotics’ pharmacokinetic and pharmacodynamic properties, antimicrobial activities, in vitro susceptibility testing, and clinical data. Moreover, it includes a meticulous examination of comparative clinical and microbiological studies, assessed and presented to provide clarity in making informed treatment choices for clinicians. Finally, we propose an expert opinion from a microbiological and a clinical point of view about their use in appropriate clinical settings. This is the first review aiming to provide healthcare professionals with valuable insights for making informed treatment decisions when combating carbapenem-resistant pathogens.

Background: The rise of multi-drug-resistant Gram-negative bacteria necessitates the development of new antimicrobial agents. Cefiderocol shows promising activity by exploiting bacterial iron transport systems to penetrate the outer membranes of resistant pathogens. Objectives: This study evaluates the efficacy of cefiderocol testing methods and trailing effect impact using a ComASP^® Cefiderocol panel, disk diffusion (DD), and MIC test strips (MTS) compared to iron-depleted broth microdilution (ID-BMD). Methods: A total of 131 Gram-negative strains from clinical samples was tested by commercial methods and the gold standard. Results were interpreted as per 2024 and 2023 EUCAST guidelines. Results: ID-BMD revealed high cefiderocol susceptibility among Enterobacterales and Pseudomonas aeruginosa, with one Klebsiella pneumoniae isolate being resistant. Acinetobacter baumannii exhibited higher MIC values, particularly considering trailing effects that complicated MIC readings. ComASP^® showed 97% categorical agreement (CA) and 66% essential agreement (EA) with ID-BMD for Enterobacterales but failed to detect the resistant K. pneumoniae. DD tests demonstrated variable CA (72% or 93%), and 38% or 34% of strains within the ATU according to EUCAST Breakpoint Tables v13.0 and 14.0, respectively, with major errors only. MTS for P. aeruginosa had 100% CA but 44% EA, and often underestimated MIC values. Conclusions: The study emphasizes the need for standardized criteria to address trailing effects and ATU and highlights the discrepancies between testing methods. While cefiderocol resistance remains rare, accurate susceptibility testing is crucial for its effective clinical use. The findings suggest that current commercial tests have limitations, necessitating careful interpretation and potential supplementary testing to guide appropriate antibiotic therapy.