Search Results (813)

Extraintestinal Pathogenic Escherichia coli (ExPEC) are leading causes of adult bacteremia, neonatal meningitis, pneumonia, and the vast majority of urinary tract infections. ExPEC are present in food, mostly in poultry products. Despite the high burden of ExPEC on human health, their source and impact on food safety are largely unknown. Food-isolated ExPEC carry an abundance of virulence and antibiotic resistance genes and are suggested to have zoonotic potential. Here, ExPEC were characterized for sanitizer tolerance, biofilm formation, antibiotic susceptibility, and adherence to Caco-2 cells (a human intestinal epithelial-derived cell line). The ExPEC used were isolated from poultry meat and from archived collections of poultry and human clinical samples. Overall, low frequency of sanitizer tolerance (2.4%) and biofilm formation (6%) were observed under the test conditions used. The frequency of antibiotic susceptibility was significantly higher (p < 0.05) among human clinical ExPEC (55%) compared to poultry-isolated ExPEC (27.9%). Overall, 62.8% of poultry ExPEC showed adherence to human intestinal epithelia at a level comparable to that of the control enteric pathogen E. coli O157:H7. In summary, the results of this work suggest that the human gastrointestinal tract could serve as a reservoir of high-risk poultry ExPEC if consumed, and, hence, it is a potential source of extraintestinal infections. Full article

Bacteremia is a life-threatening condition contributing significantly to sepsis-related mortality worldwide. With delayed appropriate antibiotic therapy, mortality increases by 20% regardless of antimicrobial resistance. This study evaluated the perceived clinical utility of Artificial Intelligence (AI)-powered Clinical Decision Support Systems (CDSSs) (OneChoice and OneChoice Fusion) among specialist physicians managing bacteremia cases. A cross-sectional survey was conducted with 65 unique specialist physicians from multiple medical specialties who were presented with clinical vignettes describing patients with bacteremia and 90 corresponding AI-CDSS recommendations. Participants assessed the perceived helpfulness of AI decision-making, the impact of AI recommendations on their own clinical judgment, and the concordance between AI recommendations and their own clinical judgment, as well as the validity of changing therapy based on CDSS recommendations. The study encompassed a diverse range of bacterial pathogens, with Escherichia coli representing 38.7% of the isolates and 30% being extended-spectrum β-lactamase (ESBL) producers. Findings show that 97.8% [(95% CI: 92.2–99.7%)] of physicians reported that AI facilitated decision-making and substantial concordance (87.8% [95% CI: 79.2–93.7%; Cohen’s κ = 0.76]) between AI recommendations and physicians’ therapeutic recommendations. Stratification by pathogen revealed the highest concordance for Escherichia coli bacteremia (96.6%, 28/29 cases). Implementation analysis revealed a meaningful clinical impact, with 68.9% [(95% CI: 58.3–78.2%)] of cases resulting in AI-guided treatment modifications. These findings indicate that AI-powered CDSSs effectively bridge critical gaps in infectious disease expertise and antimicrobial stewardship, providing clinicians with evidence-based therapeutic recommendations that can be integrated into routine practice to optimize antibiotic selection, particularly in settings with limited access to infectious disease specialists. For optimal clinical integration, we recommend that clinicians utilize AI-CDSS recommendations as an adjunct to clinical judgment rather than a replacement, particularly in complex cases involving immunocompromised hosts or polymicrobial infections. Future research should prioritize prospective clinical trials that evaluate direct patient outcomes to establish evidence of broader clinical effectiveness and applicability across diverse healthcare settings. Full article

Background/Objectives: The management of asymptomatic bacteriuria (ASB) and candiduria (ASC) in kidney transplant recipients during the early post-transplant period is controversial. This study aimed to evaluate whether treating, versus not treating, ASB and ASC episodes in the first two months after kidney transplantation influences clinical outcomes and the emergence of multidrug-resistant (MDR) infections. Methods: We conducted a single-center retrospective cohort study enrolling patients with ASB or ASC occurring in the first two months after kidney transplantation between January 2019 and July 2024. Patients were classified into treated and untreated groups. The primary endpoint was 30-day mortality. Secondary endpoints included mortality at 90, 180 and 360 days; incidence of sepsis or septic shock; bacteremia/candidemia, hospitalization, graft loss; decline in renal function, urinary tract infections (UTIs), recurrent UTI and rate of MDR colonization/infection. Results: We enrolled 59 kidney transplant recipients and observed 147 episodes of ASB/ASC. Of the 147 episodes, 95 were untreated and 52 were treated. No significant differences were observed between treated and untreated patients in 30-day (2.1% vs. 3.8%) or 90-day mortality (2.1% vs. 1.9%), nor in any of the secondary clinical outcomes. However, patients who received treatment tended to have a higher rate of MDR colonization/infection (63% vs. 46%). MDR pathogen isolation was significantly associated with increased risks of septic shock (OR 4.639, p = 0.04), bacteremia/candidemia (OR 3.734, p = 0.01), hospitalization (OR 2.183, p = 0.03) and renal function deterioration (OR 3.93, p = 0.03). Conclusions: Antimicrobial treatment of ASB and ASC in the early post-transplant period would seem not to confer clinical benefit and may be associated with the risk of MDR colonization/infection. Full article

Background: Escherichia coli (E. coli) bacteremia is a significant cause of mortality, particularly in older adults. Limited data exists on clinical outcomes in octogenarians. This study aims to evaluate the clinical outcomes of E. coli bacteremia in octogenarians and determine whether appropriate empirical therapy leads to improved outcomes in this specific population. Methods: We conducted a retrospective cohort study of hospitalized patients with E. coli bacteremia at Beilinson Hospital from January 2012 to December 2022. Clinical characteristics, bacteremia sources, antibiotic resistance patterns, and patient outcomes were analyzed. The primary outcome was 30-day mortality. Multivariate regression was used to assess the impact of empirical antibiotic appropriateness on mortality. Results: The study included 2717 patients, of which 1042 (38%) were 80 years or older. Older patients had more comorbidities with increased rates of ischemic heart disease (20% vs. 14%, p < 0.01) and congestive heart failure (19% vs. 9%, p < 0.01). Patients with 3rd generation cephalosporin resistant strains were more likely to receive inappropriate empiric antibiotic therapy (54% vs. 23%, p < 0.01). Although appropriate empirical therapy was associated with improved survival in univariate analysis (19% vs. 28%, p < 0.01), it was not an independent predictor of 30-day mortality in multivariate analysis [adjusted OR = 1.10, 95% CI (0.64–1.81), p = 0.7]. A lower SOFA score [adjusted OR = 0.17, CI95% (0.01–0.31), p < 0.01] was associated with decreased 30-day mortality. Hypoalbuminemia was significantly associated with increased 30-day mortality [adjusted OR = 2.49, CI95% (0.1.56–3.97), p < 0.01]. Conclusions: E. coli bacteremia in octogenarians is associated with significant mortality. While timely appropriate antibiotic therapy is crucial, mortality appears to be more influenced by overall health status, comorbidities, and infection severity. Future research should focus on addressing these factors and developing personalized care strategies to improve survival in this high-risk group. Full article

Multidrug-resistant (MDR) bloodstream infections (BSIs) constitute a major challenge in intensive care units, with the COVID-19 pandemic compromising infection control and potentially increasing MDR incidence. Comparative data between COVID and non-COVID ICU populations remain limited. The MARTINI study is a retrospective observational analysis held in a tertiary hospital during the COVID-19 pandemic (2020–2022) encompassing adult patients with MDR BSIs admitted to COVID and non-COVID ICUs. Demographics, comorbidities, severity scores, microbiology, resistance patterns, and outcomes were accessed and compared. A binary logistic regression model and multivariate regression was performed to identify independent predictors of ICU mortality. Among the study’s 156 patients (106 COVID-ICU, 50 non-COVID-ICU), COVID-ICU patients were significantly older with higher comorbidity and severity scores. Gram-negative pathogens predominated in both cohorts, mainly Acinetobacter baumannii and Klebsiella pneumoniae, with comparable resistance mechanisms. Timing of bacteremia onset and initiation of appropriate therapy did not differ between groups. However, ICU mortality was markedly higher in COVID-ICU patients (74.5% vs. 38%, p < 0.001). Age, SOFA score, the presence of systemic inflammation (SIRS) and COVID-19 infection were identified as independent predictors of mortality. Although pathogen distribution and resistance were similar across groups, COVID-ICU patients experienced significantly poorer outcomes. Strengthened infection control and timely and targeted antimicrobial therapy are essential to diminish MDR bacteremia risk in critically ill populations. Full article

Background: Dalbavancin and oritavancin are long-acting lipoglycopeptides increasingly used off-label for a variety of Gram-positive infections. While their efficacy has been described in osteomyelitis, bacteremia, and infective endocarditis, evidence specifically addressing cardiovascular prosthetic infections such as prosthetic valve endocarditis (PVE), cardiac implantable electronic device (CIED) infections, left ventricular assist device infections (LVAD), and prosthetic vascular graft infections (PVGI) remains limited. These conditions are particularly challenging due to biofilm formation, difficulties in achieving surgical source control, and the frequent need for prolonged or suppressive therapy. Objectives: This systematic review aimed to summarize the available literature on the use of dalbavancin and oritavancin in cardiovascular prosthetic infections, with a focus on therapeutic strategies, clinical outcomes, and safety. Methods: We performed a systematic search of PubMed, Embase, Scopus, and Cochrane Library up to 24 June 2025 in accordance with PRISMA guidelines. Eligible studies included adults treated with dalbavancin or oritavancin for cardiovascular prosthetic infections. Data on study characteristics, population demographics, causative pathogens, and microbiological profiles, antibiotic regimens, treatment duration, use of therapeutic drug monitoring (TDM), indication or non-indication for chronic suppressive therapy, adverse events, clinical outcomes, and clinical efficacy were extracted. Results: Twenty studies comprising 113 patients were identified, of whom 111 received dalbavancin and 2 oritavancin. The main infections were PVE, CIED, LVAD, and PVGI. Dalbavancin was most effective as consolidation therapy after surgery or device removal, with high cure rates. Prolonged regimens were used as bridging or in partially treated cases, sometimes supported by TDM or PET/CT. Chronic suppressive therapy, mainly for LVAD and PVGI infections, achieved variable outcomes with relapses in about one fifth of patients. Adverse events were infrequent and generally mild. Conclusions: The included studies were highly diverse, conducted in various settings and with different objectives. Eight of the twenty included studies were single case reports on dalbavancin and oritavancin, highlighting the predominance of individual case descriptions in the available literature. Long-acting lipoglycopeptides may represent a valuable option for cardiovascular prosthetic infections. Their role appears most favorable as consolidation after adequate source control, while chronic suppressive use showed heterogeneous outcomes. This systematic review was registered on Open Science Framework. This work was supported by grants from the Italian Ministry of Health through Ricerca Corrente, Linea 3, Progetto 3. Full article

Background: Some lactobacilli strains have been documented to cause bacteremia and sepsis in immunocompromised or critically ill hospitalized patients, challenging the universally presumed safety of lactobacilli. Therefore, strain-specific risk assessments are required for the use of Lactobacillus as a probiotic. Lactobacillus xujianguonis, a novel Lactobacillus species isolated from Marmota himalayana, has probiotic potential but lacks safety data. Objective: To evaluate the preclinical safety of L. xujianguonis for food-grade use. Methods: Systematic safety assessment includes in vitro studies and oral toxicity studies. In vitro studies encompassed gastrointestinal tolerance, auto-aggregation and pathogen inhibition, antibiotic susceptibility, and hemolysis/gelatinase activity assays. Oral toxicity studies contained acute single-dose and repeated-dose 28-day oral toxicity studies in mice based on the OECD toxicity study guidelines. Results: L. xujianguonis strains HT111-2 and 06-2 demonstrated certain probiotic traits, including high acid/bile tolerance, strong auto-aggregation, and antimicrobial activity against common human gastrointestinal pathogens. In vitro safety assessments showed susceptibility to nine antibiotics and absence of hemolytic/gelatinase activity. Acute oral exposure (1 × 10¹¹ CFU/kg) induced no mortality, clinical abnormalities, or organ toxicity. Subchronic 28-day administration (multiple doses) showed absence of adverse clinical signs with body weight stability and no hematological, biochemical, or histopathological deviations in C57BL/6 mice. Inflammatory and immunological markers remained unaffected. Histological staining results and transcriptional level validation revealed no evidence of intestinal tissue damage. Conclusions: This study provides preliminary evidence of the safety of L. xujianguonis, supporting its advancement to functional research. Full article

Background: Sepsis remains a major cause of morbidity and mortality in both developed and limited-resource countries. Despite over a century of research, accurate biomarkers for reliable diagnosis and prognosis in critically ill patients have yet to be established. Methods: This multicenter retrospective observational study aims to evaluate serum levels of Calprotectin, Azurocidin, cytokines, chemokines, procalcitonin (PCT) and C-Reactive Protein (CRP) in 15 healthy volunteers (controls), 15 non-infectious SIRS patients, 92 alive septic patients (Sepsis_A) and 29 dead septic patients (Sepsis_D). Results: Most biomarkers showed significantly higher serum concentrations in septic patients compared with controls, with IL-4 being increased only in the Sepsis_D group. In addition, several markers, including Calprotectin, Azurocidin, IL-6, IL-8, IL-10, TNF-α, and IL-35, were progressively elevated from SIRS to Sepsis_A and Sepsis_D cohorts, reflecting disease severity. All biomarkers showed good diagnostic performance for predicting Gram-negative bacteremia, although their accuracy in discriminating survivors from non-survivors was relatively low. Conclusions: In conclusion, calprotectin, azurocidin, IL-8, TNF-α, and IL-35 may assist clinicians in identifying Gram-negative bacteremia in septic patients; however, their prognostic value appears to be limited. Full article

Background: Vancomycin-resistant Enterococcus (VRE) has emerged as a major nosocomial pathogen. A recent surveillance of our hospital identified a concerning rise in VRE bacteremia since 2020, despite the stable use of broad-spectrum antibiotics. This trend, coupled with the increased use of daptomycin and linezolid for drug-resistant Gram-positive bacteremia (GPB), prompted an evaluation of their usage beyond approved hospital indications. Methods: A retrospective analysis was carried out from 1 February 2023 to 31 July 2023, during which 100 and 195 patients received linezolid and daptomycin, respectively. Patients’ data were extracted from the hospital’s electronic medical records, and the appropriateness of the antibiotics prescribed was assessed. The amount of daptomycin and linezolid utilization during the study period was also retrieved, as was the incidence of VRE bacteremia. Results: A total of 295 courses of VRE-active agents, linezolid (n = 100) and daptomycin (n = 195), were assessed for appropriateness in this study. Linezolid and daptomycin use were judged as inappropriate 5.0% and 9.2% of the time, respectively. The primary reason for inappropriate linezolid use was overly broad empirical therapy where first-line options like cefazolin and vancomycin could have been prescribed. Daptomycin was often used inappropriately in non-VRE infections, and surgical prophylaxis or use was extended unnecessarily without microbiological justification. Conclusions: Linezolid and daptomycin were prescribed appropriately. Nevertheless, our findings suggest the need to re-evaluate the empirical treatment strategies especially in VRE-colonized patients. Implementation of robust risk-based criteria as well as in-house hospital guidelines or protocols on the initiation of VRE-active agents may help support more judicious prescribing practices of these agents. Full article

Background/Introduction: Carbapenem-resistant Klebsiella pneumoniae (CRKP) bacteremia is a serious public health problem due to its high mortality rate and limited treatment options. This study aimed to identify risk factors associated with ceftazidime–avibactam (CAZ-AVI) resistance in CRKP bacteremia and to evaluate its impact on clinical outcomes. Methods: This retrospective single-center cohort study included adult patients with CRKP bloodstream infections treated at a tertiary hospital in Türkiye between January 2021 and December 2024. Demographic, clinical, and laboratory data were collected, and risk factors for CAZ-AVI resistance and 30-day mortality were analyzed. Results: Among 154 patients, 42.8% had CAZ-AVI-resistant strains. Resistant infections were associated with longer hospital stays and higher Charlson Comorbidity Index (CCI) scores. The resistance rate was lower in patients with intra-abdominal infections, while fluoroquinolone and fosfomycin use was more common in the resistant group. The overall 30-day mortality rate was 57%. Pitt bacteremia score and creatinine levels were identified as independent predictors of mortality. Discussion: CAZ-AVI resistance in CRKP bacteremia appears to develop in patients with prolonged hospitalization and high comorbidity burden. These factors likely increase exposure to resistant microorganisms and antibiotic pressure, complicating treatment outcomes. Conclusions: CAZ-AVI resistance in CRKP bacteremia is associated with specific clinical risk profiles and contributes to high mortality. Identifying high-risk patients and optimizing antimicrobial stewardship are essential to improve prognosis. Full article

Background/Objectives: Bloodstream infections (BSIs) caused by carbapenem-resistant Enterobacterales (CREs) are a growing public health threat due to limited therapeutic options and high mortality. In Turkey, oxacillinase-48 (OXA-48) producers predominate, while OXA-48/New Delhi metallo-β-lactamase (NDM) co-producers are increasingly detected. Although ceftazidime–avibactam (CAZ-AVI) is effective against OXA-48, treating NDM-positive isolates remains challenging. Cefiderocol, a novel siderophore cephalosporin active against both serine- and metallo-β-lactamases, is not yet available in Turkey. Establishing baseline susceptibility rates and identifying clinical predictors of resistance are, therefore, crucial before its introduction. Methods: This retrospective study included adult patients with CRE-BSIs diagnosed at a tertiary university hospital in Istanbul between January and December 2023. Demographic, clinical, and microbiological data were collected from electronic medical records. Susceptibility to cefiderocol, CAZ-AVI, and colistin was determined according to the European Committee on Antimicrobial Susceptibility Testing (EUCAST) 2023 criteria. Risk factors for cefiderocol resistance were analyzed. Results: Among 202 isolates, cefiderocol showed the highest susceptibility (94%, n = 190), followed by CAZ-AVI (82%, n = 166) and colistin (70%, n = 141), with all pairwise differences being statistically significant (p < 0.001). Cefiderocol resistance (6%, n = 12) was significantly associated with hematologic malignancy, hematopoietic stem cell transplantation, prior CAZ-AVI or polymyxin exposure, prolonged hospitalization, and repeated admissions. Conclusions: Cefiderocol demonstrated potent in vitro activity against CRE-BSI isolates, with resistance confined to distinct high-risk clinical settings. This pre-implementation study provides baseline microbiological and epidemiological data from an OXA-48 endemic region with rising NDM prevalence, underscoring the importance of early surveillance and stewardship strategies before cefiderocol becomes clinically available. Full article

Methicillin-resistant Staphylococcus aureus (MRSA) remains a major cause of bloodstream infection worldwide. In Korea, sequence type (ST) 72 has predominated, whereas ST8, including the USA300 lineage, has recently emerged. Comparative data on these genotypes in MRSA bacteremia (MRSAB) are limited. We conducted a retrospective cohort study of adult patients with MRSAB admitted to a 2700-bed tertiary care hospital in Republic of Korea between July 2008 and December 2020. Clinical features and outcomes of patients with ST8 MRSA were compared with those of patients with ST72 MRSA. Among 1975 cases of S. aureus bacteremia, 998 (50.5%) were due to MRSA, including 327 (32.7%) ST72 and 23 (2.3%) ST8 isolates. Demographics and comorbidities were similar, though pneumonia appeared more frequent in ST8 cases without statistical significance. ST8 isolates exhibited greater resistance to ciprofloxacin and erythromycin and more frequent vancomycin E-test MICs ≥1 mg/L, while broth microdilution MICs were comparable. spa type distribution differed, with t324 predominating in ST72 and t008 in ST8. Management practices, persistent bacteremia, recurrence, and 30- and 90-day mortality did not differ significantly. In multivariable analysis, liver cirrhosis and Charlson comorbidity index >4, but not MRSA genotype, independently predicted 30-day mortality. These findings highlight the importance of continued surveillance of emerging ST8 clones. Full article

Background and Clinical Significance: Corynebacterium striatum is an emerging multidrug-resistant pathogen increasingly implicated in infections among immunocompromised patients and patients with indwelling medical devices. Case Presentation: We report the probable first case of pseudomembranous inflammation associated with C. striatum infection in a 53-year-old male with an implanted left ventricular assist device (LVAD) awaiting heart transplantation. The patient experienced recurrent episodes of C. striatum bacteremia despite multiple courses of targeted antibiotic therapy, including vancomycin, linezolid, tedizolid, teicoplanin, and dalbavancin. During urgent heart transplantation, pseudomembranous tissue surrounding the LVAD driveline was observed, and cultures confirmed C. striatum device infection. Histopathological analysis revealed necrotic elements and Gram-positive organisms consistent with pseudomembranous inflammation. Conclusions: The case describes the diagnosis and treatment of this rare infection, highlighting the pathogenic potential of C. striatum, its role in device-related infections, and the histopathological evidence of pseudomembrane formation. Full article

Background: Carbapenem-resistant Klebsiella pneumoniae (CRKP) poses a significant therapeutic challenge, particularly when multiple resistance mechanisms, such as metallo-β-lactamases (MBLs) and Klebsiella pneumoniae carbapenemase (KPC), coexist. Case description: We describe a case of a 51-year-old male with a post-sternotomy surgical site infection and concurrent bacteremia caused by a CRKP. Sternal swab and mediastinal liquid culture results highlighted CRKP harboring bla_NDM and bla_KPC genes, while the blood isolate showed bla_CTX and bla_KPC, indicating phenotypic resistance to ceftazidime-avibactam. All the strains exhibited phenotypic susceptibility to meropenem-vaborbactam (MEV), despite having a high minimum inhibitory concentration. Following clinical failure of MEV-based therapy, combination treatment with aztreonam (ATM) and imipenem/cilastatin/relebactam (IMI/REL), plus gentamicin, was initiated. Therapy was well tolerated and resulted in microbiological eradication and full clinical recovery. The patient completed 49 days of ATM and IMI/REL without relapse over a 3-month follow-up period. This is, to the best of our knowledge, the first reported case of IMI/REL being used in combination with ATM. Full article

(1) Background: Methylobacterium radiotolerans (M. radiotolerans) is a fastidious, aerobic, Gram-negative bacillus primarily found in environmental sources such as soil and sewage, with rare clinical isolation. Its identification remains challenging due to poor growth with conventional culture methods. (2) Case presentation: A 42-year-old male patient with early T-cell precursor acute lymphoblastic leukemia (ETP-ALL) presented with M. radiotolerans bacteremia during hospitalization. The organism was successfully isolated from peripheral blood using the Myco/F Lytic culture vial (Becton, Dickinson and Company, Lincoln, MT, USA). Comparative analysis demonstrated markedly superior growth of M. radiotolerans in Myco/F Lytic culture vials compared with Plus Aerobic/F Lytic and Lytic/10 Anaerobic/F culture vials (Becton, Dickinson and Company, Lincoln, MT, USA). Antimicrobial susceptibility testing, performed with the epsilometer test (E-test) and Bauer–Kirby disk diffusion (BK) method, guided the selection of an appropriate therapeutic regimen. The patient’s infection was ultimately controlled following targeted antimicrobial therapy. (3) Conclusions: M. radiotolerans demonstrates a distinct growth preference for the Myco/F Lytic culture medium. This observation highlights the importance of considering alternative culture media in cases of rare or fastidious bacterial infections that cannot be reliably detected using conventional Plus Aerobic/F Lytic or Lytic/10 Anaerobic/F culture vials, which are typically employed for clinical isolation of aerobic and anaerobic bacteria. Full article