Genotypic and phenotypic characteristics of Candida parapsilosis bloodstream isolates: Health Care Associated Infections in a teaching Hospital in Italy.

BACKGROUND: Candidemia is the most common healthcare associated invasive fungal infection. Over the last few decades, candidemia caused by Candida species other than Candida albicans, particularly the Candida parapsilosis complex, has emerged worldwide. The aims of this study were: to analyze the genotypic and phenotypic characteristics of C. parapsilosis strains isolated from blood cultures and the environment in a hospital in southern Italy, to study the possible source of infection and to correlate the isolated strains. METHODS: From April to October 2022, cases of candidemia due to C. parapsilosis in patients admitted to a hospital in the Apulia region were investigated. However, 119 environmental samples from the intensive care unit were collected for identification of the likely environmental reservoir of infection. Routine antifungal (amphotericin B, anidulafungin, fluconazole) susceptibility was performed on all isolates. Whole genome sequencing was performed to study the genotypic correlation of the isolates. Biofilm biomass and metabolic activity were also quantified for all isolates. RESULTS: A total of 43 C. parapsilosis isolates were cultured from the bloodstream of each patient in different departments, and seven surface samples were positive for C. parapsilosis. Most of the isolated yeasts (41/50; 85 %) were resistant to fluconazole and were genetically related to each other, suggesting an ongoing clonal outbreak of this pathogen. The fluconazole-susceptible isolates produced significantly more biofilm than did the resistant isolates. Metabolic activity was also higher for fluconazole-susceptible than resistant isolates. CONCLUSION: Cross-transmission of the microorganisms is suggested by the phenotypic similarity and genetic correlation between clinical and environmental strains observed in our study.

ER-mitochondria association negatively affects wound healing by regulating NLRP3 activation.

Methicillin-resistant Staphylococcus aureus (MRSA) is the most common causative agent of acute bacterial skin and skin-structure infections (ABSSSI), one of the major challenges to the health system worldwide. Although the use of antibiotics as the first line of intervention for MRSA-infected wounds is recommended, important side effects could occur, including cytotoxicity or immune dysregulation, thus affecting the repair process. Here, we show that the oxazolidinone antibiotic linezolid (LZD) impairs wound healing by aberrantly increasing interleukin 1 ß (IL-1ß) production in keratinocytes. Mechanistically, LZD triggers a reactive oxygen species (ROS)-independent mitochondrial damage that culminates in increased tethering between the endoplasmic reticulum (ER) and mitochondria, which in turn activates the NLR family pyrin domain-containing 3 (NLRP3) inflammasome complex by promoting its assembly to the mitochondrial surface. Downregulation of ER-mitochondria contact formation is sufficient to inhibit the LZD-driven NLRP3 inflammasome activation and IL-1ß production, restoring wound closure. These results identify the ER-mitochondria association as a key factor for NLRP3 activation and reveal a new mechanism in the regulation of the wound healing process that might be clinically relevant.

Side effects of antibiotics and perturbations of mitochondria functions.

Antibiotics are one of the greatest discoveries of medicine of the past century. Despite their invaluable contribution to infectious disease, their administration could lead to side effects that in some cases are serious. The toxicity of some antibiotics is in part due to their interaction with mitochondria: these organelles derive from a bacterial ancestor and possess specific translation machinery that shares similarities with the bacterial counterpart. In other cases, the antibiotics could interfere with mitochondrial functions even if their main bacterial targets are not shared with the eukaryotic cells. The purpose of this review is to summarize the effects of antibiotics administration on mitochondrial homeostasis and the opportunity that some of these molecules could represent in cancer treatment. The importance of antimicrobial therapy is unquestionable, but the identification of interaction with eukaryotic cells and in particular with mitochondria is crucial to reduce the toxicity of these drugs and to explore other useful medical applications.

Detection of an Enterococcus faecium Carrying a Double Copy of the PoxtA Gene from Freshwater River, Italy.

Oxazolidinones are valuable antimicrobials that are used to treat severe infections due to multidrug-resistant (MDR) Gram-positive bacteria. However, in recent years, a significant spread of clinically relevant linezolid-resistant human bacteria that is also present in animal and environmental settings has been detected and is a cause for concern. This study aimed to investigate the presence, genetic environments, and transferability of oxazolidinone resistance genes in enterococci from freshwater samples. A total of 10 samples were collected from a river in Central Italy. Florfenicol-resistant enterococci were screened for the presence of oxazolidinone resistance genes by PCR. Enterococcus faecium M1 was positive for the poxtA gene. The poxtA transfer (filter mating and aquaria microcosm assays), localization (S1-PFGE/hybridization), genetic context, and clonality of the isolate (WGS) were analyzed. Two poxtA copies were located on the 30,877-bp pEfM1, showing high-level identity and synteny to the pEfm-Ef3 from an E. faecium collected from an Italian coastal area. The isolate was able to transfer the poxtA to enterococcal recipients both in filter mating and aquaria microcosm assays. This is-to the best of our knowledge-the first detection of an enterococcus carrying a linezolid resistance gene from freshwater in Italy.

Correction: Morroni et al. Antimicrobial Activity of Aztreonam in Combination with Old and New ß-Lactamase Inhibitors against MBL and ESBL Co-Producing Gram-Negative Clinical Isolates: Possible Options for the Treatment of Complicated Infections. Antibiotics 2021, 10, 1341.

Results have been implemented with additional data, which have been commented in the following paragraphs [...].

Clinical and microbiological features of ceftolozane/tazobactam-resistant Pseudomonas aeruginosa isolates in a university hospital in central Italy.

OBJECTIVES: Ceftolozane/tazobactam (C/T) is a novel cephalosporin and ß-lactamase inhibitor combination with great activity against Pseudomonas aeruginosa. To assess P. aeruginosa susceptibility to C/T, a surveillance study was conducted from October 2018 to March 2019 at the University Hospital 'Ospedali Riuniti' in Ancona, Italy. METHODS: Minimum inhibitory concentrations (MICs) to C/T were determined by Etest strip. Resistant isolates were characterized by phenotypic (broth microdilution antimicrobial susceptibility testing and modified Carbapenem Inactivation Method [mCIM]) and genotypic (Polymerase Chain Reaction [PCR], Pulsed Field Gel Electrophoresis [PFGE], and whole-genome sequencing [WGS]) methods. Clinical variables of patients infected by C/T-resistant P. aeruginosa were collected from medical records. RESULTS: Fifteen of 317 P. aeruginosa collected showed resistance to C/T (4.7%). Ten strains demonstrated carbapenemase activity by mCIM method, and PCR confirmed that eight strains harbored a blaVIM gene while the other two were positive for blaIMP. Additionally, three isolates carried acquired extended spectrum ß-lactamase genes (two isolates carried blaPER and one carried blaGES). Eight strains were strictly related by PFGE and WGS analysis confirmed that they belonged to sequence type (ST)111. The other STs found were ST175 (two isolates), ST235 (two isolates), ST70 (one isolate), ST621 (one isolate), and the new ST3354 (one isolate). Most patients had received previous antibiotic therapies, carried invasive devices, and experienced prolonged hospitalization. CONCLUSION: This study demonstrated the presence of C/T-resistant P. aeruginosa isolates in a regional hospital carrying a number of resistance mechanisms acquired by different high-risk clones.

Antimicrobial Activity of Aztreonam in Combination with Old and New ß-Lactamase Inhibitors against MBL and ESBL Co-Producing Gram-Negative Clinical Isolates: Possible Options for the Treatment of Complicated Infections.

Metallo-ß-lactamases (MBLs) are among the most challenging bacterial enzymes to overcome. Aztreonam (ATM) is the only ß-lactam not hydrolyzed by MBLs but is often inactivated by co-produced extended-spectrum ß-lactamases (ESBL). We assessed the activity of the combination of ATM with old and new ß-lactamases inhibitors (BLIs) against MBL and ESBL co-producing Gram-negative clinical isolates. Six Enterobacterales and three non-fermenting bacilli co-producing MBL and ESBL determinants were selected as difficult-to-treat pathogens. ESBLs and MBLs genes were characterized by PCR and sequencing. The activity of ATM in combination with seven different BLIs (clavulanate, sulbactam, tazobactam, vaborbactam, avibactam, relebactam, zidebactam) was assessed by microdilution assay and time-kill curve. ATM plus avibactam was the most effective combination, able to restore ATM susceptibility in four out of nine tested isolates, reaching in some cases a 128-fold reduction of the MIC of ATM. In addition, relebactam and zidebactam showed to be effective, but with lesser reduction of the MIC of ATM. E. meningoseptica and C. indologenes were not inhibited by any ATM-BLI combination. ATM-BLI combinations demonstrated to be promising against MBL and ESBL co-producers, hence providing multiple options for treatment of related infections. However, no effective combination was found for some non-fermentative bacilli, suggesting the presence of additional resistance mechanisms that complicate the choice of an active therapy.