Clostridioides difficile infection (CDI) is the leading cause of antibiotic-associated diarrhea, especially in hospitalized elderly patients, representing a global public health concern. Clinical presentations vary from mild diarrhea to severe pseudomembranous colitis that may progress to toxic megacolon or intestinal perforation. Antibiotic therapy is recognized as a risk factor and exacerbates dysbiosis of the intestinal microbiota, whose role in CDI is increasingly acknowledged. A clinically challenging complication is the development of recurrent disease (rCDI). In this study, using amplicon metagenomics, we compared the fecal microbiota of CDI and rCDI patients (sampled at initial and recurrent episode) and of non-infected controls. We also investigated whether CDI severity relates to specific microbiota compositions. rCDI patients showed a significantly decreased bacterial diversity as compared to controls (p < 0.01). The taxonomic composition presented significant shifts: both CDI and rCDI patients displayed significantly increased frequencies of Firmicutes, Peptostreptococcaceae, Clostridium XI, Clostridium XVIII, and Enterococcaceae. Porphyromonadaceae and, within it, Parabacteroides displayed opposite behaviors in CDI and rCDI, appearing discriminant between the two. Finally, the second episode of rCDI was characterized by significant shifts of unclassified Clostridiales, Escherichia/Shigella and Veillonella. No peculiar taxa composition correlated with the severity of infection, likely reflecting the role of host-related factors in determining severity.

Coagulase-negative staphylococci (CoNS) are commensal on human body surfaces and, for years, they were not considered a cause of bloodstream infection and were often regarded as contamination. However, the involvement of CoNS in nosocomial infection is increasingly being recognized. The insertion of cannulas and intravascular catheters represents the primary source of CoNS entry into the bloodstream, causing bacteremia and sepsis. They owe their pathogenic role to their ability to produce biofilms on surfaces, such as medical devices. In this study, we evaluate the adhesive capacity of CoNS isolated from blood cultures by comparing a spectrophotometric phenotypic assay with genotypic analysis based on the evidence of the ica operon. We retrospectively reviewed the database of CoNS isolated from blood cultures from January to December 2021 that were considered responsible for 361 bloodstream infections. Eighty-nine CoNS were selected among these. Our data show that Staphylococcus epidermidis was the predominant species isolated, expressing greater adhesive capacities, especially those with the complete operon. Knowledge of the adhesive capabilities of a microorganism responsible for sepsis can be useful in implementing appropriate corrective and preventive measures, since conventional antibiotic therapy cannot effectively eradicate biofilms.

New Delhi metallo-beta-lactamase (NDM)-producing Klebsiella pneumoniae (Kp) ST147 caused a large multi-hospital outbreak in Italy from 2018 to 2021. We describe a new ST6668 NDM-producing Kp clone, belonging to CC147, which rapidly spread across hospitals in the Pavia province (Northern Italy) from February to August 2023. Genomic analyses revealed that ST6668 is different from ST147 and fast evolving. As shown here, genomic surveillance programmes are useful for tracking the spread of new clones with reduced susceptibility to most antibiotics.

Patients with solid tumors present a higher risk of infectious diseases with worse outcomes compared with immunocompetent patients. Prolonged treatment of prophylactic and empirically chosen antibiotics and health care–acquired infections can predispose patients with cancer to infections with antimicrobial-resistant (AMR) organisms. AMR is a global health priority and can affect patients with cancer. The outcome of patients with cancer worsens dramatically if multidrug-resistant (MDR) microorganisms cause infections. Moreover, the emergence of MDR organisms increases health care costs. Antimicrobial stewardship programs can be useful to monitor and improve the use of antibiotics in all oncological settings, including the palliative setting. Awareness of the magnitude of these issues is still low, so it is important to inform and educate oncologists. This narrative review aims to illustrate the main evidence on infections caused by AMR organisms in patients with cancer and the tools that oncologists should have to enhance their multidisciplinary management.

The guidelines on ventilator-associated pneumonia (VAP) recommend an empiric therapy against methicillin-resistant Staphylococcus aureus (MRSA) according to its prevalence rate. Considering the MRSA and MSSA VAP prevalence over the last 9 years in our tertiary care hospital, we assessed the clinical value of the MRSA nasal-swab screening in either predicting or ruling out MRSA VAP. We extracted the data of 1461 patients with positive bronchoalveolar lavage (BAL). Regarding the MRSA nasal-swab screening, 170 patients were positive for MRSA or MSSA. Overall, MRSA had a high prevalence in our ICU. Despite the COVID-19 pandemic, there was a significant downward trend in MRSA prevalence, while MSSA remained steady over time. Having VAP due to MRSA did not have any impact on LOS and mortality. Finally, the MRSA nasal-swab testing demonstrated a very high negative predictive value for MRSA VAP. Our results suggested the potential value of a patient-centered approach to improve antibiotic stewardship.

Several studies have strengthened the link between the gut microbiota (GM) and the response to immunotherapy in patients with tumors, highlighting the potential role of GM as a biomarker of response. Targeted therapies including B-cell receptor (BCR) inhibitors (BCRi) represent the newest approach to the treatment of chronic lymphocytic leukemia (CLL); however, not all patients achieve a satisfactory response, and immune-related adverse events (irAEs) can also impact the efficacy. The aim of the study was to compare GM biodiversity in patients with CLL, treated with BCRi for at least 12 months. Twelve patients were enrolled: 10 patients in the responder group (R) and 2 patients in the non-responder group (NR). We identified seven patients (58.3%) who experienced adverse reactions (AE). Although we did not observe a significant difference across the study population in terms of relative abundance and alpha and beta diversity, we found a differing distribution of bacterial taxa between the analyzed groups. We noted a higher level of the class Bacteroidia and the order Bacteroidales in the R group, and an inversion in the Firmicutes and Bacteroidetes ratio in the AE group. No prior studies have focused on linking GM and response to BCRi in these patients. Although the analyses are preliminary, they provide suggestions to guide future research.