Enterococcus species are known for their ability to form biofilms, which contributes to their survival in extreme environments and involvement in persistent bacterial infections, especially in the case of multi-drug-resistant strains. This review aims to provide a comprehensive understanding of the mechanisms underlying biofilm formation in clinically important species such as Enterococcus faecalis and the less studied but increasingly multi-drug-resistant Enterococcus faecium, and explores potential strategies for their eradication. Biofilm formation in Enterococcus involves a complex interplay of genes and virulence factors, including gelatinase, cytolysin, Secreted antigen A, pili, microbial surface components that recognize adhesive matrix molecules (MSCRAMMs), and DNA release. Quorum sensing, a process of intercellular communication, mediated by peptide pheromones such as Cob, Ccf, and Cpd, plays a crucial role in coordinating biofilm development by targeting gene expression and regulation. Additionally, the regulation of extracellular DNA (eDNA) release has emerged as a fundamental component in biofilm formation. In E. faecalis, the autolysin N-acetylglucosaminidase and proteases such as gelatinase and serin protease are key players in this process, influencing biofilm development and virulence. Targeting eDNA may offer a promising avenue for intervention in biofilm-producing E. faecalis infections. Overall, gaining insights into the intricate mechanisms of biofilm formation in Enterococcus may provide directions for anti-biofilm therapeutic research, with the purpose of reducing the burden of Enterococcus-associated infections.

Background. Pulmonary superinfections increase the mortality risk among COVID-19 patients, highlighting the need for enhanced understanding to enable early and accurate diagnosis. Methods. We present the case of a patient, a 76-year-old man, hospitalized for a severe form of COVID-19, with a ground-glass pneumonia, involving 40–45% of lung surfaces. Results. In evolution, the clinical condition worsened, presenting leukocytosis with neutrophilia, imaging towards resorption, and computer tomography images showing the appearance of pulmonary condensations in the right lower lobe, the posterior portion of the left lower lobe and pleural collections. Carbapenemase-producing Klebsiella pneumoniae was isolated from the tracheal aspirate, and the real-time polymerase chain reaction test was positive for Klebsiella pneumoniae and Legionella pneumophila. The investigations that were carried out allowed us to establish the coinfections as a probable case of Legionnaire’s disease and a ventilator-associated pneumonia with Klebsiella pneumoniae. Conclusions. The case analysis revealed that rare pneumonias may remain undiagnosed, and coinfections may be conditioned by pathophysiological factors or components of COVID-19 critical form treatment. Enhanced understanding of these aspects in clinical practice may contribute to reducing mortality risk in COVID-19 patients.

Actinomyces odontolyticus is a strictly anaerobic species, a member of the Actinomyces genus and of the commensal flora, especially oral flora, which can trigger severe infections through breaches in healthy tissue or necrotic tissue that are often hard to diagnose clinically and microbiologically. Most infections with this species are pulmonary or pleural, which might hint at a connection with poor dental hygiene, but other locations have been documented. We present a case of a tubo-ovarian abscess with a difficult identification of the etiological agent in a woman with multiple admissions, no significant comorbidities, and a longstanding use of an IUD (intrauterine device). To our knowledge, no previous case of tubo-ovarian abscess with an accurate A. odontolyticus microbiological species identification has been reported so far. This case also highlights the importance of considering an anaerobic species as an etiologic agent in an infectious process concerning a previously damaged tissue and the importance of appropriate harvesting and culturing in the accurate diagnosis of such species.

This study examines the prevalence and the mechanisms of antibiotic resistance in Pseudomonas aeruginosa isolates collected from healthcare units in Northwestern Transylvania, Romania, between 2022 and 2023. Given the alarming rise in antibiotic resistance, the study screened 34 isolates for resistance to 10 antibiotics, 46 ARGs, and integrase genes using PCR analysis. The results reveal a concerning increase in multidrug-resistant (MDR) and extensively drug-resistant (XDR) isolates over the two-year period. Notably, the prevalence of ARGs encoding resistance to sulfonamides and beta-lactams, particularly sul1 and bla_OXA-50, has shown a significant rise. Furthermore, the study detected the emergence of new resistance mechanisms in the same time interval. These include target protection and even more specific mechanisms, such as metallo-beta-lactamases or enzymes involved in the methylation of 23S rRNA. Statistical analysis further confirmed the correlation between Class I integrons and several ARGs, underscoring the role of horizontal gene transfer in the dissemination of resistance. These findings emphasize the urgent need for updated treatment strategies and monitoring programs to effectively combat the spread of ARGs in clinical settings.