Low Percentage of Perforin-Expressing NK Cells during Severe SARS-CoV-2 Infection: Consumption Rather than Primary Deficiency.

Genetic defects in the ability to deliver effective perforin have been reported in patients with hemophagocytic lymphohistiocytosis. We tested the hypothesis that a primary perforin deficiency might also be causal in severe SARS-CoV-2 infection. We recruited 54 volunteers confirmed as being SARS-CoV-2-infected by RT-PCR and admitted to intensive care units or non-intensive care units and age- and sex-matched healthy controls. Compared with healthy controls, the percentage of perforin-expressing CD3-CD56+ NK cells quantified by flow cytometry was low in COVID-19 patients (69.9 ± 17.7 versus 78.6 ± 14.6%, p = 0.026). There was no correlation between the proportions of perforin-positive NK cells and T8 lymphocytes. Moreover, the frequency of NK cells producing perforin was neither linked to disease severity nor predictive of death. Although IL-6 is known to downregulate perforin production in NK cells, we did not find any link between perforin expression and IL-6 plasma level. However, we unveiled a negative correlation between the degranulation marker CD107a and perforin expression in NK cells (r = -0.488, p = 10-4). PRF1 gene expression and the frequency of NK cells harboring perforin were normal in patients 1 y after acute SARS-CoV-2 infection. A primary perforin defect does not seem to be a driver of COVID-19 because NK perforin expression is 1) linked neither to T8 perforin expression nor to disease severity, 2) inversely correlated with NK degranulation, and 3) normalized at distance from acute infection. Thus, the cause of low frequency of perforin-positive NK cells appears, rather, to be consumption.

Anaerobes in diabetic foot infections: pathophysiology, epidemiology, virulence, and management.

SUMMARYDiabetic foot infections (DFI) are a public health problem worldwide. DFI are polymicrobial, biofilm-associated infections involving complex bacterial communities organized in functional equivalent pathogroups, all including anaerobes. Indeed, multiple pathophysiological factors favor the growth of anaerobes in this context. However, the prevalence, role, and contribution of anaerobes in wound evolution remain poorly characterized due to their challenging detection. Studies based on culture reviewed herein showed a weighted average of 17% of patients with anaerobes. Comparatively, the weighted average of patients with anaerobes identified by 16S rRNA gene sequencing was 83.8%. Culture largely underestimated not only the presence but also the diversity of anaerobes compared with cultivation-independent approaches but both methods showed that anaerobic Gram-negative bacilli and Gram-positive cocci were the most commonly identified in DFI. Anaerobes were more present in deeper lesions, and their detection was associated with fever, malodorous lesions, and ulcer depth and duration. More specifically, initial abundance of Peptoniphilus spp. was associated with ulcer-impaired healing, Fusobacterium spp. detection was significantly correlated with the duration of DFI, and the presence of Bacteroides spp. was significantly associated with amputation. Antimicrobial resistance of anaerobes in DFI remains slightly studied and warrants more consideration in the context of increasing resistance of the most frequently identified anaerobes in DFI. The high rate of patients with DFI-involving anaerobes, the increased knowledge on the species identified, their virulence factors, and their potential role in wound evolution support recommendations combining debridement and antibiotic therapy effective on anaerobes in moderate and severe DFI.

The zebrafish embryo model: unveiling its potential for investigating phage therapy against methicillin-resistant Staphylococcus aureus infection.

Staphylococcus aureus is a pathogenic bacterium responsible for a broad spectrum of infections, including cutaneous, respiratory, osteoarticular, and systemic infections. It poses a significant clinical challenge due to its ability to develop antibiotic resistance. This resistance limits therapeutic options, increases the risk of severe complications, and underscores the urgent need for new strategies to address this threat, including the investigation of treatments complementary to antibiotics. The evaluation of novel antimicrobial agents often employs animal models, with the zebrafish embryo model being particularly interesting for studying host-pathogen interactions, establishing itself as a crucial tool in this field. For the first time, this study presents a zebrafish embryo model for the in vivo assessment of bacteriophage efficacy against S. aureus infection. A localized infection was induced by microinjecting either methicillin-resistant S. aureus (MRSA) or methicillin-susceptible S. aureus (MSSA). Subsequent treatments involved administering either bacteriophage, vancomycin (the reference antibiotic for MRSA), or a combination of both via the same route to explore potential synergistic effects. Our findings indicate that the bacteriophage was as effective as vancomycin in enhancing survival rates, whether used alone or in combination. Moreover, bacteriophage treatment appears to be even more effective in reducing the bacterial load in S. aureus-infected embryos post-treatment than the antibiotic. Our study validates the use of the zebrafish embryo model and highlights its potential as a valuable tool in assessing bacteriophage efficacy treatments in vivo.

Direct metagenomics investigation of non-surgical hard-to-heal wounds: a review.

BACKGROUND: Non-surgical chronic wounds, including diabetes-related foot diseases (DRFD), pressure injuries (PIs) and venous leg ulcers (VLU), are common hard-to-heal wounds. Wound evolution partly depends on microbial colonisation or infection, which is often confused by clinicians, thereby hampering proper management. Current routine microbiology investigation of these wounds is based on in vitro culture, focusing only on a limited panel of the most frequently isolated bacteria, leaving a large part of the wound microbiome undocumented. METHODS: A literature search was conducted on original studies published through October 2022 reporting metagenomic next generation sequencing (mNGS) of chronic wound samples. Studies were eligible for inclusion if they applied 16 S rRNA metagenomics or shotgun metagenomics for microbiome analysis or diagnosis. Case reports, prospective, or retrospective studies were included. However, review articles, animal studies, in vitro model optimisation, benchmarking, treatment optimisation studies, and non-clinical studies were excluded. Articles were identified in PubMed, Google Scholar, Web of Science, Microsoft Academic, Crossref and Semantic Scholar databases. RESULTS: Of the 3,202 articles found in the initial search, 2,336 articles were removed after deduplication and 834 articles following title and abstract screening. A further 14 were removed after full text reading, with 18 articles finally included. Data were provided for 3,628 patients, including 1,535 DRFDs, 956 VLUs, and 791 PIs, with 164 microbial genera and 116 species identified using mNGS approaches. A high microbial diversity was observed depending on the geographical location and wound evolution. Clinically infected wounds were the most diverse, possibly due to a widespread colonisation by pathogenic bacteria from body and environmental microbiota. mNGS data identified the presence of virus (EBV) and fungi (Candida and Aspergillus species), as well as Staphylococcus and Pseudomonas bacteriophages. CONCLUSION: This study highlighted the benefit of mNGS for time-effective pathogen genome detection. Despite the majority of the included studies investigating only 16 S rDNA, ignoring a part of viral, fungal and parasite colonisation, mNGS detected a large number of bacteria through the included studies. Such technology could be implemented in routine microbiology for hard-to-heal wound microbiota investigation and post-treatment wound colonisation surveillance.

Immune profiles of pre-frail people living with HIV-1: a prospective longitudinal study.

BACKGROUND: People living with HIV (PLWH) are at risk of frailty, which is predictive for death. As an overactivity of the immune system is thought to fuel frailty, we characterized the immune activation profiles linked to frailty. METHODS: We quantified twenty-seven activation markers in forty-six virological responders (four females and forty-two males; median age, 74 years; median duration of infection, 24 years; median duration of undetectability, 13 years), whose frailty was determined according to the Fried criteria. T cell and NK cell activation was evaluated by flow cytometry, using a panel of cell surface markers. Soluble markers of inflammation, and monocyte activation and endothelial activation were measured by ELISA. The participants' immune activation was profiled by an unsupervised double hierarchical clustering analysis. We used ANOVA p-values to rank immunomarkers most related to Fried score. A Linear Discriminant Analysis (LDA) was performed to link immune activation markers to frailty. RESULTS: 41% of the participants were pre-frail, including 24% with a Fried score of 1, and 17% with a Fried score of 2. ANOVA identified the 14 markers of T cell, monocyte, NK cell, endothelial activation, and inflammation the most linked to Fried 3 classes. The LDA performed with these 14 markers was capable of discriminating volunteers according to their Fried score. Two out of the 5 immune activation profiles revealed by the hierarchical clustering were linked to and predictive of pre-frailty. These two profiles were characterized by a low percentage of CD4 T cells and a high percentage of CD8 T cells, activated CD4 T cells, CD8 T cells, and NK cells, and inflammation. CONCLUSIONS: We identified a particular immune activation profile associated with pre-frailty in PLWH. Profiling participants at risk of developing frailty might help to tailor the screening and prevention of medical complications fueled by loss of robustness. Further studies will indicate whether this frailty signature is specific or not of HIV infection, and whether it also precedes frailty in the general population.

Evolution of the urinary microbiota in spinal cord injury patients with decubitus ulcer: A snapshot study.

Current microbiome investigations of patients with pressure ulcers (PU) are mainly based on wound swabs and/or biopsy sequencing, leaving the colonization scenario unclear. Urinary microbiota has been never studied. As a part of the prospective ESCAFLOR study, we studied urinary microbiota of spinal cord injury (SCI) patients with PU without any urinary tract infection at the inclusion, collected at two times (at admission [D0] and after 28 days [D28]) during the patient's care, investigated by 16S rDNA metagenomics next generation sequencing. Subgroup analyses were carried out between patients with wounds showing improved evolution versus stagnated/worsened wounds at D28. Analysis was done using EPISEQ® 16S and R software. Among the 12 studied patients, the urinary microbiota of patients with improved wound evolution at D28 (n = 6) presented a significant decrease of microbial diversity. This modification was associated with the presence of Proteobacteria phylum and an increase of Escherichia-Shigella (p = 0.005), as well as the presence of probiotic anaerobic bacteria Lactobacillus and Bifidobacterium. In contrast, Proteus abundance was significantly increased in urine of patients with stagnated/worsened wound evolution (n = 6) (p = 0.003). This study proposes urinary microbiota as a complementary factor indirectly associated with the wound evolution and patient cure. It opens new perspectives for further investigations based on multiple body microbiome comparison to describe the complete scenario of the transmission dynamics of wound-colonizing microorganisms.

The ROSA-Like Prophage Colonizing Staphylococcus aureus Promotes Intracellular Survival, Biofilm Formation, and Virulence in a Chronic Wound Environment.

BACKGROUND: The transition from colonization to invasion is critical in diabetic foot ulcer (DFU). Staphylococcus aureus can colonize DFU, or invade the underlying tissues, causing serious infections. The ROSA-like prophage has previously been implicated in strain colonization characteristics of S aureus isolates in uninfected ulcers. METHODS: In this study, we investigated this prophage in the S aureus-colonizing strain using an in vitro chronic wound medium mimicking the chronic wound environment. RESULTS: Chronic wound medium reduced bacterial growth and increased biofilm formation and virulence in a zebrafish model. CONCLUSIONS: The ROSA-like prophage promoted intracellular survival of S aureus-colonizing strain in macrophages, keratinocytes, and osteoblasts.

Antimicrobial activity of antibiotics on biofilm formed by Staphylococcus aureus and Pseudomonas aeruginosa in an open microfluidic model mimicking the diabetic foot environment.

BACKGROUND: Diabetic foot infections (DFIs) represent a public health problem because of their frequency and the severity of their consequences, i.e. amputation and mortality. Polymicrobial biofilms on the skin surface of these ulcers complicate wound healing. Few in vitro models exist to study the antibiotics activity in this context. OBJECTIVES: This study evaluated the in vitro activity of antibiotics against the two main bacteria isolated in DFI, Staphylococcus aureus and Pseudomonas aeruginosa, using a dynamic system (BioFlux™ 200) and a chronic wound-like medium (CWM) that mimic the foot ulcer environment. METHODS: Reference strains and two pairs of clinical S. aureus and P. aeruginosa isolated together from a DFI were cultivated in brain heart infusion and CWM media during 72 h at 37°C, alone and combined in the BioFlux™ 200 system. Antibiotic activity was evaluated after a mechanical debridement. The activities were measured by the reduction of biofilm percentage of bacteria in the microfluidic system using microscopy. RESULTS: Daptomycin for S. aureus and ceftazidime for P. aeruginosa showed excellent activity to reduce biofilm biomass, whereas linezolid action was more mitigated and dalbavancin was ineffective. Ceftazidime + daptomycin presented the most potent in vitro activity on a mixed biofilm. CONCLUSIONS: The combination of CWM and the BioFlux™ microfluidic system represents a valuable tool to screen the potential antimicrobial activity of antibiotics under conditions mimicking those encountered in DFI. It could help clinicians in their management of chronic wounds.

Dalbavancin plasma concentrations in 133 patients: a PK/PD observational study.

OBJECTIVES: Limited pharmacokinetics data support dalbavancin long-term use in off-label indications and the optimal dosing regimen is debated. We aimed to describe dalbavancin concentrations in an observational retrospective multicentre study. METHODS: Patients from 13 French hospitals, treated with 1500 mg doses of dalbavancin and for whom therapeutic drug monitoring was performed from June 2018 to March 2021 were included. Dalbavancin plasma concentrations were described at peak and 1, 2, 3, 4, 6 and 8 weeks after the last 1500 mg dose. Concentrations in patients weighing more or less than 75 kg and with a GFR greater or less than 60 mL/min were compared. Microbiological data were collected and dalbavancin MIC was measured when possible. RESULTS: One hundred and thirty-three patients were included (69% treated for bone and joint infections, 16% for endocarditis). Thirty-five patients received a single dose of dalbavancin and 98 received several administrations. Two, 3 and 4 weeks after the last dose, median plasma concentrations were respectively 25.00, 14.80 and 9.24 mg/L for the first doses and 34.55, 22.60 and 19.20 mg/L for the second or subsequent doses. Weight and renal function had an impact on pharmacokinetics. Infection was documented in 105 patients (Staphylococcus spp. in 68% of cases). Staphylococcus aureus was isolated in 32.5% of cases (median MIC: 0.047 mg/L) and Staphylococcus epidermidis in 27% of cases (median MIC of 0.047 mg/L). CONCLUSIONS: Plasma concentrations of dalbavancin were consistent with those described in clinical trials and those sought during the industrial development of the molecule.

Continuous infusion of meropenem-vaborbactam for a KPC-3-producing Klebsiella pneumoniae bloodstream infection in a critically ill patient with augmented renal clearance.

PURPOSE: To demonstrate the feasibility of continuous infusion of meropenem-vaborbactam to optimize the treatment of carbapenem-resistant Enterobacterales. METHODS: Report of a case of a Klebsiella pneumoniae carbapenemase (KPC)-producing K. pneumoniae bloodstream infection comfirmed by whole genome sequencing and therapeutic drug monitoring (TDM) of meropenem. RESULTS: A patient with augmented renal clearance (ARC) went into septic shock caused by an ST11 KPC-3-producing K. pneumoniae bloodstream infection that was successfully treated with a continuous infusion of meropenem-vaborbactam at a dosage of 1 g/1 g q4h as a 4-h infusion. TDM confirmed sustained concentrations of meropenem ranging from 8 to 16 mg/L throughout the dosing interval. CONCLUSION: Continuous infusion of meropenem-vaborbactam was feasible. It could be appropriate for optimizing the management of critically ill patients with ARC, as it resulted in antibiotic concentrations above the minimum inhibitory concentration for susceptible carbapenem-resistant Enterobacterales (up to 8 mg/L) throughout the dosing interval.

Factors associated with urinary diversion and fatality of hospitalised acute pyelonephritis patients in France: a national cross-sectional study (FUrTIHF-2).

Acute pyelonephritis (AP) epidemiology has been sparsely described. This study aimed to describe the evolution of AP patients hospitalised in France and identify the factors associated with urinary diversion and fatality, in a cross-sectional study over the 2014-2019 period. Adult patients hospitalised for AP were selected by algorithms of ICD-10 codes (PPV 90.1%) and urinary diversion procedure codes (PPV 100%). 527,671 AP patients were included (76.5% female: mean age 66.1, 48.0% Escherichia coli), with 5.9% of hospital deaths. In 2019, the AP incidence was 19.2/10,000, slightly increasing over the period (17.3/10,000 in 2014). 69,313 urinary diversions (13.1%) were performed (fatality rate 6.7%), mainly in males, increasing over the period (11.7% to 14.9%). Urolithiasis (OR [95% CI] =33.1 [32.3-34.0]), sepsis (1.73 [1.69-1.77]) and a Charlson index ≥3 (1.32 [1.29-1.35]) were significantly associated with urinary diversion, whereas E. coli (0.75 [0.74-0.77]) was less likely associated. The same factors were significantly associated with fatality, plus old age and cancer (2.38 [2.32-2.45]). This nationwide study showed an increase in urolithiasis and identified, for the first time, factors associated with urinary diversion in AP along with death risk factors, which may aid urologists in clinical decision-making.

Angiotensin II induces reactive oxygen species, DNA damage, and T-cell apoptosis in severe COVID-19.

BACKGROUND: Lymphopenia is predictive of survival in patients with coronavirus disease 2019 (COVID-19). OBJECTIVE: The aim of this study was to understand the cause of the lymphocyte count drop in severe forms of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection. METHODS: Monocytic production of reactive oxygen species (ROSs) and T-cell apoptosis were measured by flow cytometry, DNA damage in PBMCs was measured by immunofluorescence, and angiotensin II (AngII) was measured by ELISA in patients infected with SARS-CoV-2 at admission to an intensive care unit (ICU) (n = 29) or not admitted to an ICU (n = 29) and in age- and sex-matched healthy controls. RESULTS: We showed that the monocytes of certain patients with COVID-19 spontaneously released ROSs able to induce DNA damage and apoptosis in neighboring cells. Of note, high ROS production was predictive of death in ICU patients. Accordingly, in most patients, we observed the presence of DNA damage in up to 50% of their PBMCs and T-cell apoptosis. Moreover, the intensity of this DNA damage was linked to lymphopenia. SARS-CoV-2 is known to induce the internalization of its receptor, angiotensin-converting enzyme 2, which is a protease capable of catabolizing AngII. Accordingly, in certain patients with COVID-19 we observed high plasma levels of AngII. When looking for the stimulus responsible for their monocytic ROS production, we revealed that AngII triggers ROS production by monocytes via angiotensin receptor I. ROSs released by AngII-activated monocytes induced DNA damage and apoptosis in neighboring lymphocytes. CONCLUSION: We conclude that T-cell apoptosis provoked via DNA damage due to the release of monocytic ROSs could play a major role in COVID-19 pathogenesis.

Taxonomical and functional changes in COVID-19 faecal microbiome could be related to SARS-CoV-2 faecal load.

Since the beginning of the pandemic caused by the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) the gastrointestinal (GI) tract has emerged as an important organ influencing the propensity to and potentially the severity of the related COVID-19 disease. However, the contribution of the SARS-CoV-2 intestinal infection on COVID-19 pathogenesis remains to be clarified. In this exploratory study, we highlighted a possible link between alterations in the composition of the gut microbiota and the levels of SARS-CoV-2 RNA in the gastrointestinal tract, which could be more important than the presence of SARS-CoV-2 in the respiratory tract, COVID-19 severity and GI symptoms. As established by metaproteomics, altered molecular functions in the microbiota profiles of high SARS-CoV-2 RNA level faeces highlight mechanisms such as inflammation-induced enterocyte damage, increased intestinal permeability and activation of immune response that may contribute to vicious cycles. Uncovering the role of this gut microbiota dysbiosis could drive the investigation of alternative therapeutic strategies to favour the clearance of the virus and potentially mitigate the effect of the SARS-CoV-2 infection.

Diagnostic performance of 18 F-FDG-PET/CT in inflammation of unknown origin: A clinical series of 317 patients.

BACKGROUND: Inflammation of unknown origin (IUO) is a challenging situation in internal medicine. OBJECTIVES: To describe the final diagnoses in IUO and assess the helpfulness of 18 F-fluorodesoxyglucose positron emission tomography with computerized tomography (18 F-FDG-PET/CT) in the diagnosis strategy. RESULTS: A total of 317 IUO patients with 18 F-FDG-PET/CT were enrolled. A diagnosis was reached in 228 patients: noninfectious inflammatory diseases (NIID) (37.5%), infectious diseases (18.6%), malignancies (7.9%), and non-systemic-inflammatory miscellaneous diseases (7.9%). The two leading causes of NIID were polymyalgia rheumatica and giant cell arteritis. 18 F-FDG-PET/CT results were classified as true positive in 49.8% of patients and contributory in 75.1% of overall IUO patients (after the complete investigation set and a prolonged follow-up). In multivariate analysis, only C-reactive protein minimum level (≥50 mg/L) was associated with the contributory status of 18 F-FDG-PET/CT. CONCLUSION: Within the wide spectrum of IUO underlying diseases, 18 F-FDG-PET/CT is helpful to make a diagnosis and to eliminate inflammatory diseases. Obese patients constitute a specific group needing further studies.

Predictors of ultrasound abnormalities among women treated for community-onset acute pyelonephritis: a prospective study.

OBJECTIVES: Acute pyelonephritis (AP) is a common but potentially severe infection. It may be complicated by pyelocaliceal dilatation which requires emergency urine drainage. In outpatient care, ultrasound (US) appears to be the easier way to diagnose pyelocaliceal dilatation, though most APs will not be complicated and do not require immediate ultrasound. We aimed to identify predictors of ultrasound abnormalities in an outpatient AP cohort. METHODS: A prospective study was conducted from April 2006 to September 2019 in an outpatient care network. Patients aged 15 and over treated for AP were included. Men, pregnant women, patients with solitary kidney, and patients without data on their management were excluded. A common algorithm ensured the same approach from diagnosis to treatment. Data were collected prospectively in an anonymized database. We described the characteristics of the patients. Univariate and then multivariate analyses were performed to identify predictors of ultrasound abnormalities. RESULTS: 2054 women were treated for AP. Among them, 32.5% (n = 667) had a history of urinary tract infections and 5.8% (n = 120) of uropathy. The most frequent uropathogen was E. coli (n = 1,432; 69.7%); Extended-Spectrum Beta-Lactamases (ESBLs) were found in 39 (1.9%) urine cultures. Ultrasound was abnormal in 7.3% (n = 149). Age over 55 years (OR = 2.23; 95% CI 1.58‒3.15; p < 0.0001) and uropathy (OR = 3.69; 95% CI 2.26‒6.01; p < 0.0001) were independently identified as predictors of ultrasound abnormalities. The risk increased by 1.8% (95% CI 1.0‒2.6) with each additional year of age. CONCLUSIONS: This study identified age and uropathy as independent predictors of abnormal ultrasound in women treated with community-onset AP.

Antibiofilm Properties of Antiseptic Agents Used on Pseudomonas aeruginosa Isolated from Diabetic Foot Ulcers.

In diabetic foot ulcers (DFUs), biofilm formation is a major challenge that promotes wound chronicity and delays healing. Antiseptics have been proposed to combat biofilms in the management of DFUs. However, there is limited evidence on the activity of these agents against biofilms, and there are questions as to which agents have the best efficiency. Here, we evaluated the antibiofilm activity of sodium hypochlorite, polyvinylpyrrolidoneIodine (PVPI), polyhexamethylenebiguanide (PHMB) and octenidine against Pseudomonas aeruginosa strains using static and dynamic systems in a chronic-wound-like medium (CWM) that mimics the chronic wound environment. Using Antibiofilmogram®, a technology assessing the ability of antiseptics to reduce the initial phase of biofilm formation, we observed the significant activity of antiseptics against biofilm formation by P. aeruginosa (at 1:40 to 1:8 dilutions). Moreover, 1:100 to 1:3 dilutions of the different antiseptics reduced mature biofilms formed after 72 h by 10-log, although higher concentrations were needed in CWM (1:40 to 1:2). Finally, in the BioFlux200TM model, after biofilm debridement, sodium hypochlorite and PHMB were the most effective antiseptics. In conclusion, our study showed that among the four antiseptics tested, sodium hypochlorite demonstrated the best antibiofilm activity against P. aeruginosa biofilms and represents an alternative in the management of DFUs.

Polymicrobial Biofilm Organization of Staphylococcus aureus and Pseudomonas aeruginosa in a Chronic Wound Environment.

Biofilm on the skin surface of chronic wounds is an important step that involves difficulties in wound healing. The polymicrobial nature inside this pathogenic biofilm is key to understanding the chronicity of the lesion. Few in vitro models have been developed to study bacterial interactions inside this chronic wound. We evaluated the biofilm formation and the evolution of bacteria released from this biofilm on the two main bacteria isolated in this condition, Staphylococcus aureus and Pseudomonas aeruginosa, using a dynamic system (BioFlux™ 200) and a chronic wound-like medium (CWM) that mimics the chronic wound environment. We observed that all species constituted a faster biofilm in the CWM compared to a traditional culture medium (p < 0.01). The percentages of biofilm formation were significantly higher in the mixed biofilm compared to those determined for the bacterial species alone (p < 0.01). Biofilm organization was a non-random structure where S. aureus aggregates were located close to the wound surface, whereas P. aeruginosa was located deeper in the wound bed. Planktonic biofilm-detached bacteria showed decreased growth, overexpression of genes encoding biofilm formation, and an increase in the mature biofilm biomass formed. Our data confirmed the impact of the chronic wound environment on biofilm formation and on bacterial lifecycle inside the biofilm.

Phenotypic and Genotypic Virulence Characterisation of Staphylococcus pettenkoferi Strains Isolated from Human Bloodstream and Diabetic Foot Infections.

Staphylococcus pettenkoferi is a recently described coagulase-negative Staphylococcus identified in human diseases, especially in infections of foot ulcers in patients living with diabetes mellitus. To date, its pathogenicity remains underexplored. In this study, whole-genome analysis was performed on a collection of 29 S. pettenkoferi clinical strains isolated from bloodstream and diabetic foot infections with regard to their phylogenetic relationships and comprehensive analysis of their resistome and virulome. Their virulence was explored by their ability to form biofilm, their growth kinetics and in an in vivo zebrafish embryo infection model. Our results identified two distinct clades (I and II) and two subclades (I-a and I-b) with notable genomic differences. All strains had a slow bacterial growth. Three profiles of biofilm formation were noted, with 89.7% of isolates able to produce biofilm and harbouring a high content of biofilm-encoding genes. Two virulence profiles were also observed in the zebrafish model irrespective of the strains' origin or biofilm profile. Therefore, this study brings new insights in S. pettenkoferi pathogenicity.

In vitro activity of dalbavancin against Gram-positive bacteria isolated from diabetic foot osteomyelitis.

BACKGROUND: Diabetic foot infections (DFIs) represent a serious threat to public health because of their frequency and the severity of their consequences, i.e. osteomyelitis and amputation. The management of diabetic foot osteomyelitis (DFOM) requires prolonged antibiotic therapy. In Western countries, Gram-positive bacteria are the most commonly encountered pathogens. OBJECTIVES: This study evaluated the in vitro activity of dalbavancin, a novel lipoglycopeptide with extended half-life, recently marketed in Europe for acute bacterial skin and skin structure infections, on a panel of Gram-positive bacteria responsible for DFOM. METHODS: Dalbavancin activity was evaluated against a panel of Gram-positive bacterial strains isolated from bone biopsies performed by a trained surgeon among patients with suspected DFOM. MICs were determined using MIC Test Strips (Liofilchem) and confirmed with the EUCAST broth microdilution method. Three other antimicrobial agents (vancomycin, teicoplanin and ceftobiprole) were used as comparators. RESULTS: Dalbavancin showed excellent activity against all Gram-positive bacterial strains tested, including one teicoplanin-resistant Staphylococcus epidermidis isolate. With MIC50 and MIC90 values of 0.047 and 0.094 mg/L, respectively, dalbavancin showed the most potent in vitro activity among antimicrobial agents tested. CONCLUSIONS: With its efficacy, good tolerability and unique pharmacokinetic properties, dalbavancin appears to be a promising treatment for DFOM involving Gram-positive bacteria.

Epidemiology and risk factors for ureteral stent-associated urinary tract infections in non-transplanted renal patients: a systematic review of the literature.

PURPOSE: Pathophysiology and risk factors for Ureteral Stent-Associated Urinary Tract Infection (USAUTI) have been poorly investigated. This situation results in highly diverse practices regarding USAUTI prevention, diagnosis and treatment. The aim of the present study was to describe the epidemiology and risk factors for USAUTI in non-transplanted patients. METHODS: We conducted a systematic literature review based on a comprehensive PubMed® bibliographic strategy, between October 1998 and March 2020. The methodological quality of the studies included was analyzed according to dedicated grids. The main endpoints were the correlation between different potential risk factors and infection ureteral stent-associated urinary tract infection or colonization rate. Conclusions and their level of evidence were reported on the basis of a critical analysis of the best available scientific evidence. This work has been submitted to a national review, which enabled the potentially divergent opinions of experts to be collected, thereby ensuring adequate quality of data. RESULTS AND CONCLUSION: Twenty-six studies out of the 505 articles identified, were included in the final analysis. Staphylococcus spp, E. coli, Klebsiella spp, Pseudomona aeruginosa, Enterococcus spp. and Candida spp. were the microorganisms most often responsible for asymptomatic bacteriuria (ABU) or USAUTI. Longer indwelling time, diabetes mellitus, female gender, chronic renal failure, diabetic nephropathy and cancer were identified as risk factors for ABU and ureteral stent colonization. No specific risk factor for UTI was identified in the literature studied. A causal relationship between ureteral stent colonization and USAUTI or urosepsis remains to be demonstrated.