Evaluation of pH responsive chitosan derivatives for localised "smart" drug release, using novel microfluidic devices.

Background: K. pneumoniae is an opportunistic emerging pathogen responsible for severe hospital-acquired as well as community-acquired infections, often with multidrug resistance and multiple virulence factors, posing a significant clinical challenge due to its ability to cause hard-to-treat infections. Aims: The objective of this study was to identify the phenotypic virulence factors, antibiotic resistance, and molecular identification of dominant virulence genes among K. pneumoniae isolates. Methodology: Twenty clinical isolates were screened. Phenotypic screening included capsule production, biofilm formation, proteinase, gelatinase, hemolysin, and hyaluronidase. Antibiotic susceptibility testing was conducted to determine resistance profiles. Molecular detection targeted virulence genes such as mrkD, T1 fim, magA, and T1fim. Results: Capsule production was detected in 100% isolates, biofilm formation in 75%, proteinase in 80%, gelatinase in 55%, hemolysin in 10%, and hyaluronidase in 15%. Antibiotic susceptibility testing showed high resistance to penicillin (100%), ampicillin (95%), and cephalosporins, while carbapenems demonstrated high effectiveness (imipenem 85% sensitive, meropenem 90% sensitive). Molecular analysis revealed mrkD in 100%, T1 fim in 90%, magA in 65% of isolates, The coexistence of strong virulence determinants and multidrug resistance in K. pneumoniae highlights its elevated pathogenic potential. Conclusion: Molecular characterization of virulence genes provides essential insights for clinical management, therapeutic planning, and infection control strategies.

Peri-implantitis compromises soft and hard tissues around dental implants, often leading to implant failure. Antibacterial nanocoatings offer a promising infection control strategy, but maintaining biocompatibility is essential. This study investigated, through a range of assays and analytical techniques, the biocompatibility of antimicrobial silver and hydroxyapatite (HA) nanocoatings applied to titanium implants with human gingival fibroblasts (HGFs). Silver and hydroxyapatite nanocoatings were applied to the surface of titanium alloy specimens using electroplating, deposition and sintering techniques. The biocompatibility of the nanocoatings with HGFs was assessed by measuring cell metabolic activity (alamarBlue), lactate dehydrogenase (LDH) release, collagen production (Sircol assay), and cell morphology (scanning electron microscopy). Nanocoating stability was tested in ultrapure water, Modified Krebs and artificial saliva. Elevated total Ag+ concentrations were measured in the media released from the silver and HA nanocoatings (1.78 mg/l on day 4 and 1 mg/l by day 7). Electrolytes remained within physiological ranges. The HGFs cultured on the nanocoatings showed normal morphology, intact membranes (LDH < 60 nmol/min/ml), healthy collagen secretion (27.18 - 31.11 µg/ml), and aerobic metabolism at 80% of controls, consistent with biocompatibility. The silver and HA nanocoatings confirmed a sustained Ag+ release, necessary for a strong antimicrobial activity, while maintaining HGFs health and cell functionality. Our previous work has confirmed the strong antimicrobial activity of these nanocoatings when applied to dental implants, and the findings of this study have demonstrated that the implant biocompatibility is not compromised. This suggests that these silver and HA nanocoatings can be safely used to minimise peri-implantitis and prevent implant failure.

Bacterial infections, especially bloodstream infections (BSIs), compromise the overall survival of patients with hematological malignancies undergoing cellular therapies. The interplay between rectal colonization by different types of multidrug-resistant organisms (MDRO) and subsequent BSIs is not fully determined. We aimed to describe the natural history and risk factors for colonization by MDRO, as well as its impact on subsequent BSIs in patients treated with cellular therapies in an environment of antimicrobial resistance. Retrospective, single-center cohort study of consecutive adult hematological malignancies patients treated with allogeneic or autologous hematopoietic cell transplantation (HCT) or chimeric antigen receptor T-cell therapy between 2021 and 2024 in Attikon University Hospital (Greece), with ≥1 available rectal screening test for carbapenem-resistant gram-negative bacilli (CR-GNB) and vancomycin-resistant Enterococcus faecium (VRE). Univariate and multivariate Cox regression were implemented for identifying predictors of CR-GNB and VRE colonization. We also studied the concordance between rectal colonization and subsequent BSIs. One hundred eighty-two patients were included (male: 64%, mean age: 50.2 ± 13 yr, acute myeloid leukemia/myelodysplastic syndrome diagnosis: 55%, relapsing/refractory disease: 58%, allogeneic HCT: 85%). Median duration of hospitalization and neutropenia was 35 and 15 d, respectively. At baseline, 95% of patients were negative on rectal screening for both CR-GNB and VRE, and of those, 8.4% and 23% were colonized with CR-GNB and VRE during follow-up, respectively. Prior colonization with the same pathogen was independently associated with subsequent CR-GNB (HR: 13.0, 95% CI: 2.83 to 59.3) and VRE (HR: 4.83, 95% CI: 2.28 to 10.2) colonization. Seventy-nine patients had ≥1 BSIs (gram-positive: 60%, gram-negative: 38%), with three concordant CR-GNB BSIs among 16 colonized patients (18.7%) and two CR-GNB BSIs among 153 noncolonized patients (1.3%). Regarding VRE, we identified two concordant BSIs among 45 colonized patients (4.4%). Despite the high MDRO prevalence, we observed low rates of CR-GNB colonization in neutropenic patients treated with cellular therapies, with one patient out of five experiencing a concordant CR-GNB BSI. VRE colonization was more frequent, but it rarely resulted in a concordant BSI. These findings highlight the importance of infection control strategies and support de-escalation approaches in empirical antibacterial treatment of febrile neutropenia in this vulnerable population.

Candidozyma (Candida) auris has emerged as a multidrug-resistant pathogen with the capacity to persist in healthcare environments. This study investigated bidirectional interactions between biocidal exposure and antifungal susceptibility, including both minimum inhibitory concentrations (MICs) and minimum fungicidal concentrations (MFCs), in a real-life disinfection scenario, and further evaluated membrane dynamics and efflux pump activity using rhodamine 6G (R6G) uptake/efflux assays. Four clinical isolates and one reference strain were exposed to ethanol (EtOH), chlorine (CHLOR), chlorhexidine (CHX), and triclosan (TRC) for 30s, 5min, and 24h. Post-exposure MIC and MFC values were determined for antifungals-amphotericin B (AMB), voriconazole (VOR), and anidulafungin (ANI)-as well as for the same biocides, following CLSI M27-A3 guidelines. Data were expressed as log₂ fold changes relative to baseline. All experiments were performed in technical triplicates to ensure reproducibility of MIC/MFC measurements. Statistical analyses were conducted using biological comparisons across the five parental isolates and their corresponding post-exposure derivatives. In this exploratory proof-of-concept study, a total of 64 isolate-condition datasets derived from five parental C. auris isolates were evaluated under 12 biocidal exposure conditions, allowing assessment of time-dependent adaptive susceptibility shifts across multiple exposure scenarios. In total, 30 short-term (30s / 5min) and 2 long-term (24h) derivatives were generated from 4 different biocides (EtOH, CHX, TRC, and limited CHLOR data). All 32 biocide-exposed isolates underwent MIC/MFC testing against three antifungals (AMB, VOR, ANI) and three main biocides (EtOH, CHX, TRC), followed by biocide-free serial passaging to assess stability. Baseline MIC distributions were as follows: AMB 0.25-2 µg/mL, VOR 4-16 µg/mL, and ANI 0.01-0.25 µg/mL. After exposure, VOR MICs showed significant reduction to 3.05-4.22 mg/L with TRC exposure being nominally significant before FDR adjustment (raw p=0.043). AMB remained stable (0.47-0.67 mg/L, all p>0.05), while ANI showed non-significant variability in MIC values to 0.04-0.09 mg/L (non-significant, p>0.05). Biocidal MICs also showed changes: EtOH remained heterogeneous (p>0.05), CHX decreased significantly with CHX pre-exposure (p=0.042), and TRC showed non-significant increases. Biocidal exposure produced agent-specific antifungal effects: ANI demonstrated modest non-significant directional shifts in MIC values across all biocides, AMB remained stable with heterogeneous responses, and VOR displayed significant MIC reduction only with TRC exposure. TRC and CHX yielded the most consistent effects in both antifungal and biocidal susceptibility. R6G assays suggested alterations in efflux activity after TRC and CHX exposure, whereas EtOH impaired efflux. Most changes decreased after drug-free passages, indicating adaptive rather than fixed resistance. C. auris demonstrates dynamic and mostly reversible tolerance patterns affecting both antifungals and biocides. R6G assays provided indirect functional observations consistent with altered membrane transport dynamics following biocidal exposure, which may have contributed to the observed adaptive susceptibility shifts. The observed susceptibility shifts highlights the adaptive potential of this pathogen under disinfection stress and underscores the need to consider cross-tolerance when designing infection control strategies in healthcare settings.

Identifying multidrug-resistant (MDR) bacteria in veterinary hospitals is crucial for treatment and public health risk mitigation. This study assessed the hospital prevalence of MDR isolates from canine bacterial skin infections, compared prevalence across services and infection types, and identified the most common MDR organisms. Data from hospital records and aerobic skin cultures from August 2021 to November 2024 were reviewed and analyzed. The dataset included 438 cultures from 416 patients and 647 bacterial isolates, and 196 MDR bacteria yielded from 182 samples. The hospital multidrug resistance prevalence was 42% among cultures and 30% among bacterial isolates. The highest multidrug resistance prevalence by service included Primary Care with 68%, Neurology with 62%, Dermatology with 49%, and Surgery with 44%. The MDR bacteria prevalence for superficial surgical site infections was 34%, pyodermas 33%, wounds 30%, masses 28%, and abscesses 13%. Dermatology cultured 72 of 196 (37%) MDR bacteria, Surgery 48 (24%), Emergency and Critical Care 27 (14%), Urgent Care 18 (9%), Primary Care 14 (7%), Neurology eight (4%), Internal Medicine six (3%), and Oncology three (2%). Staphylococcus pseudintermedius was the most common MDR bacteria. These results underscore the need for ongoing surveillance, antimicrobial stewardship, and targeted infection control strategies specific to each veterinary setting.

Carbapenemase-producing Enterobacterales (CPE) have been designated by the World Health Organization as critical global priority pathogens. Their widespread dissemination and nosocomial outbreaks pose a major public health threat. This study examined the transmission patterns and genetic characteristics of CPE isolated in New Caledonia between 2013 and 2022. A total of 214 CPE isolates were collected, comprising 199 non-duplicate clinical isolates from 164 patients and 15 environmental isolates from hospital surfaces. Isolates were characterized using phenotypic methods and whole-genome sequencing. Among clinical isolates, the most prevalent genera was Enterobacter (n = 68; 34%) and Klebsiella (n = 50; 25%), with 194 isolates (98%) harbouring IMP-type carbapenemases. WGS of 89 selected CPE revealed the predominance of the blaIMP-4 gene (n = 82; 92%). This gene was primarily associated with IncM2-type plasmids carrying a class 1 integron, identified in 65 sequenced isolates. Long-read sequencing resolved these plasmids into seven distinct variants, differentiated by integron structures and a 9305-bp insertion. Genomic, phenotypic, and epidemiological triangulation have identified 12 hospital spread events, with 10 linked to IMP-4 IncM2 plasmids, whose transferability is confirmed by conjugation assays. These results highlighted the pivotal role of plasmid-mediated dissemination in CPE spread and emphasize the urgency of enhanced surveillance to curb silent transmission. The study provided critical insights for targeted infection control strategies in New Caledonia healthcare system, with broader implications for regional antimicrobial resistance containment.

Antimicrobial resistance (AMR) has emerged as a global public health concern, increasing morbidity, mortality, and healthcare costs. Limited surveillance data exist from regional referral hospitals in Tanzania, including Bukoba Regional Referral Hospital (BRRH). Understanding local AMR patterns is essential to guide empirical therapy and inform infection prevention and control strategies. This study aimed to determine the patterns, trends, and factors associated with AMR among bacterial isolates at BRRH between 2019 and 2023. A retrospective cross-sectional study was conducted using laboratory records and patient files from Bukoba Regional Referral Hospital between January 2019 and December 2023. Clinical specimens were cultured, bacterial isolates identified using standard microbiological procedures, and antimicrobial susceptibility testing performed using the Kirby-Bauer disk diffusion method according to CLSI 2024 guidelines. Chi-square test was used to assess associations between bacterial isolates and prescribed antimicrobial agents, with statistical significance considered at P < 0.05. A total of 1,680 specimens were processed during the observation period, the proportion of specimens yielding pathogenic bacterial growth was 297 (17.7%) and 15 (0.9%) of culture samples were discarded due to contamination. The median age of patients was 28 years, with 58% female. Urine 110 (36.9%), pus 99 (33.2%), and stool 76 (25.5%) were the most common samples. Escherichia coli 60 (76.9%), Staphylococcus aureus 32 (86.5%), and Salmonella typhi 63 (100%) were the predominant isolates from urine, pus and stool samples respectively. E. coli showed high resistance to azithromycin (95.0%) and ampicillin (84.4%); S. aureus and coagulase-negative Staphylococci exhibited 100% and 90% resistance to penicillin, respectively. High levels of resistance to commonly used antimicrobial agents on Azithromycin 60 (88.2%), Ceftriaxone 118 (84.3%) and Ampicillin 82 (83.7%) were observed where 17.4% of patients were not prescribed antimicrobial agents despite culture positivity, while mismatches between susceptibility results and prescriptions were common. This study demonstrates a high prevalence of antimicrobial resistance among commonly isolated bacterial pathogens at Bukoba Regional Referral Hospital. Routine development of local antibiograms, strengthening antimicrobial stewardship programs, promoting rational antibiotic prescribing, and enhancing IPC practices are urgently needed to combat AMR at BRRH and similar settings.

Epidermolysis bullosa (EB) is a debilitating genetic disorder characterized by extreme skin fragility and chronic wound formation, often complicated by bacterial infections. Current wound dressings provide limited protection against infection and may induce cytotoxicity or mechanical trauma. Herein, we report a multifunctional nanofibrous dressing based on casein/poly(vinyl alcohol) (PVA) integrated with an aggregation-induced emission (AIE) photosensitiser (PS) for enhanced antibacterial performance. Bilayer nanofibrous mats were fabricated via multi-nozzle electrospinning, combining a mechanically robust PVA support layer with a bioactive casein-rich surface. Post-fabrication, glutaraldehyde crosslinking improved structural stability, while plasma polymerization enabled immobilization of an AIE PS (TPAQ-PF6) onto the fiber surface. The resulting materials exhibited tunable wettability, preserved nanofibrous morphology, and stable AIE fluorescence. Under light irradiation, AIE-functionalised dressings generated reactive oxygen species (ROS), leading to significant antibacterial activity against Staphylococcus aureus and methicillin-resistant S. aureus (MRSA). Fluorescence imaging confirmed enhanced ROS production at the material surface. Importantly, cytocompatibility assays using keratinocytes and fibroblasts demonstrated good cytocompatibility, highlighting suitability for potential wound-contact applications. Overall, this work presents a biocompatible, photodynamically active dressing platform that integrates natural polymers with advanced AIE technology, offering a promising strategy for infection control in fragile skin conditions such as EB.

Prolonged peripherally inserted central catheter (PICC) use in pediatric patients with hematologic disorders is associated with an elevated risk of central line-associated bloodstream infection (CLABSI), which can lead to poor outcomes and a mortality rate approaching 25%. To evaluate the effectiveness of the PICC-Quality Management System (QMS) in reducing CLABSI and PICC-related complications in pediatric hematologic patients. We conducted a single-center, pre-post intervention study including pediatric patients with PICC placement exceeding 48 hours. The 2023 cohort (n = 611) received conventional care, whereas the 2024 cohort (n = 693) received care under the PICC-QMS. Baseline demographics and clinical characteristics were comparable between groups. A total of 1304 patients (mean age ± SD, 9.22 ± 0.11 years; 34.7% female) were analyzed. Compared with conventional care, PICC-QMS implementation was associated with lower CLABSI incidence (22 versus 13 cases; P = .06) and reduced thrombus formation (6 versus 1 case; P = .039). After adjustment for ward type, logistic regression indicated a significantly reduced CLABSI risk in the PICC-QMS group (adjusted odds ratio, 0.46; 95% CI, 0.20-0.90; P = .022). The PICC-QMS effectively reduces CLABSI incidence in pediatric patients with hematologic disorders, underscoring its value as an infection control strategy. Standardization, refinement, and continuous monitoring under the PICC-QMS provide a practical, reproducible framework for integrating high-quality PICC care into routine practice, offering a potential reference model for other high-risk populations.

Global epidemiological survey and genomic analysis of multiple carbapenemases-producing Citrobacter freundii.

Coagulase-negative staphylococci (CoNS) are important opportunistic hospital pathogens. Their ability to acquire antibiotic resistance, especially to methicillin, poses a challenge in clinical management. This study was conducted to determine the prevalence, antibiotic resistance, and genetic profiles of methicillin-resistant (MR) CoNS isolates causing infections in intensive care unit (ICU) patients. A total of 785 hospital-acquired infection samples were investigated, and 113 CoNS strains were identified out of them. Methicillin-resistant isolates were tested for the mecA and mecC genes by using polymerase chain reaction (PCR), followed by DNA sequencing to investigate potential genetic variations. Among the 113 CoNS isolates, 50 (44.2%) were identified as methicillin-resistant. Among these, S. epidermidis exhibited the highest rate of methicillin resistance. Vancomycin and linezolid resistance were each detected in 18% of the isolates. Most of the isolates (45/50, 90%) were multidrug-resistant (MDR), with a multiple-antibiotic resistance (MAR) index ranging from 0.27 to 1. The mecA gene was detected in all of the MR-CoNS isolates, whereas no isolate tested positive for the mecC gene. Nucleotide sequencing of the mecA gene in the selected MR-CoNS revealed high sequence similarity among different species. The widespread presence of mecA and high rates of methicillin and multidrug resistance in CoNS emphasize the need for routine monitoring and infection control strategies in hospital settings.

Photothermal therapy offers a promising alternative for treating infected wounds while mitigating antibiotic overuse. However, the limited near-infrared (NIR) photothermal conversion efficiency of polymeric materials hinders their clinical translation. Herein, we report the synthesis of Mn-chelated mesoporous poly(L-DOPA) nanoparticles (Mn-mDOPA) via polymerization-induced self-assembly, where the surfactant/oil ratio and Mn loading are precisely tuned to optimize mesoporosity and photothermal performance. The resulting Mn-mDOPA nanoparticles exhibit enlarged mesopores (≈28-39nm) and a high specific surface area (up to 75.4 m2·g- 1), enabling superior light absorption and heat generation, as confirmed by COMSOL simulations demonstrating a surface-area-dependent photothermal conversion effect. These structural features endow Mn-mDOPA with efficient NIR-triggered bacterial eradication (99.9% for S. aureus and 99.7% for E. coli) and substantial dark antibacterial activity (>90%), attributed to the synergistic effects of hyperthermia and mesopore-mediated bacterial disruption. Moreover, the abundant catechol groups impart potent ROS scavenging capacity, alleviating oxidative stress and protecting wound-related cells. In a S. aureus-infected wound model, Mn-mDOPA effectively suppresses inflammation, promotes angiogenesis, and accelerates wound closure. Collectively, these results highlight Mn-mDOPA as a multifunctional, antibiotic-free nanoplatform that integrates enhanced photothermal conversion, intrinsic antibacterial activity, and antioxidant protection, providing a highly promising strategy for localized infection control and wound regeneration.

Pseudomonas aeruginosa is a major opportunistic pathogen associated with high morbidity in hospitalized patients due to its intrinsic and acquired resistance mechanisms. Carbapenem resistance, often mediated by the production of carbapenemase, poses a critical therapeutic challenge worldwide. This study investigated the genomic organization, molecular diversity, and plasmid-mediated dissemination of carbapenemase genes in P. aeruginosa isolates from hospitals in Paraná and Santa Catarina, Brazil, and explored their correlation with phenotypic resistance profiles. Eight isolates (80%) were classified as extensively drug-resistant (XDR), showing broad resistance to β-lactams, carbapenems, and β-lactam/β-lactamase inhibitor combinations. Multi-Locus Sequence Typing revealed a heterogeneous clonal structure, with ST1560 being the predominant type (30%). Multiple β-lactamase genes were identified, including chromosomal blaPDC variants, blaOXA-50, and carbapenemase genes blaSPM-1, blaIMP-16, blaIMP-1, blaVIM-2, blaKPC-2, and blaNDM-1. Notably, 40% of isolates carried plasmid-borne carbapenemase genes, indicating a potential for horizontal gene transfer. Isolate 20,783 exhibited high resistance despite lacking additional carbapenemase genes, suggesting alternative mechanisms such as efflux or porin loss. The predominance of XDR P. aeruginosa,which harbors diverse carbapenemases, including plasmid-mediated determinants, underscores the complexity of antimicrobial resistance in Brazilian hospitals. The coexistence of multiple resistance mechanisms, coupled with clonal heterogeneity, highlights the urgent need for integrated genomic surveillance and targeted infection control strategies to mitigate the spread of multidrug-resistant P. aeruginosa in clinical settings.

Rapid detection and accurate classification of carbapenemase-producing Enterobacterales (CPE) are essential for antimicrobial stewardship and infection prevention. We evaluated the performance of the BD Phoenix CPO Detect (BD-CPO) assay and the NG-Test CARBA 5 (NG-C5) using whole-genome sequencing (WGS) as the reference standard in a tertiary pediatric center. A total of 161 non-duplicate WGS-confirmed CPE isolates recovered from clinical and screening specimens were included. NG-C5 demonstrated a sensitivity of 99.4%, correctly identifying and classifying carbapenemase genes in 160 of 161 isolates, including those harboring dual carbapenemase genes. BD-CPO showed a sensitivity of 96.3% (155/161) for CPE detection; however, accurate Ambler class assignment was achieved in only 70.2% (113/161) of isolates. Misclassification occurred in 9.3% (15/161) of isolates, and six false-negative results (3.7%) were observed with the BD-CPO test, particularly among isolates harboring blaOXA genes. Both assays provide rapid detection of carbapenemase production compared to conventional phenotypic methods. However, NG-C5 demonstrated superior performance in carbapenemase gene identification and classification. Implementation of rapid carbapenemase detection assays can support timely therapeutic optimization and infection control interventions, although the results should be interpreted within a comprehensive diagnostic framework that includes molecular confirmation and full antimicrobial susceptibility testing.IMPORTANCEAccurate detection of carbapenemase-producing Enterobacterales (CPE) is critical for guiding targeted antimicrobial therapy and implementing effective infection control strategies. Clinical microbiology laboratories rely on a variety of phenotypic and rapid diagnostic methods; however, their ability to correctly detect and classify carbapenemases remains variable. In this study, we compared the performance of the BD Phoenix CPO Detect and NG-Test CARBA 5 using whole-genome sequencing as the reference standard. Our results demonstrate important differences in diagnostic accuracy, particularly for OXA-type carbapenemases, providing practical evidence to guide laboratories in selecting reliable tools for rapid CPE detection and classification.

Carbapenem-resistant Enterobacterales (CRE) have become a major global public health concern. The production and spread of carbapenemases have rendered carbapenemase-producing Enterobacterales (CPE) a severe clinical threat. Epidemiological data regarding CPE infections remain scarce in secondary hospitals. This study aims to characterize carbapenemase phenotypes and antimicrobial resistance profiles of CRE isolates from a secondary hospital, and explore factors associated with patient clinical outcome. A cohort study was conducted on clinical CRE isolates collected from January 2023 to September 2024. Carbapenemases were identified by immunochromatography. Univariate and multivariate logistic regression models were conducted to identify factors associated with clinical failure of CPE-infected patients. Of 131 strains from enrolled CRE infected patients, the detection rate of carbapenemases was 100% via immunochromatography. Phenotypes distribution revealed 98 (74.8%) Klebsiella pneumoniae carbapenemase (KPC), 25 (19.1%) metallo-β-lactamases (MBL) and 8 (6.1%) double carbapenemases-producer (DCP), with distinct antimicrobial resistance features across groups. Elevated aCCI (aOR 1.4, 95% CI 1.1-1.8, p = 0.007), mechanical ventilation (aOR 7.8, 95% CI 2.2-28.1, p = 0.002) and hospital-onset (aOR 6.7, 95% CI 2.0-23.0, p = 0.002) were independent factors associated with clinical failure. The secondary hospitals face intense carbapenemase prevalence pressure and complex resistance profiles, particularly among DCP strains. Patients with more comorbidities and hospital-acquired infection may develop poor clinical outcomes. These findings underscore the urgent need for enzyme-guided precision therapy and tailored infection control strategies in these high-risk, community-linked medical institutions. Not applicable.

This study presents a pilot whole-genome sequencing analysis of 24 gram-negative bloodstream isolates from a tertiary care hospital in Lebanon. By integrating phenotypic susceptibility testing with genomic, mobilome, and virulence analyses, it reveals marked species- and isolate-level diversity. Resistance and virulence determinants were found within specific genetic contexts rather than being uniformly linked to species or sequence types, underscoring the value of genome-based surveillance to inform antimicrobial stewardship and infection control strategies.

ABSTRACTKlebsiella pneumoniae (K. pneumoniae) is a major cause of urinary tract infections (UTIs) and poses a growing public health concern due to multidrug resistance and virulence potential. This study aimed to characterize antimicrobial resistance, biofilm formation, and virulence gene distribution among urinary K. pneumoniae isolates from North Lebanon and to explore correlations between these factors. A total of 153 non‐duplicate isolates from hospital and community settings were analyzed for antibiotic susceptibility, hypermucoviscosity, biofilm formation, and presence of key virulence (fimH, mrkD, magA, rmpA, entB, iucA, iroN, kfu) and β‐lactamase (blaTEM, blaSHV, blaCTX‐M) genes. Adhesion‐associated genes fimH and mrkD were highly prevalent, particularly in hospital‐acquired and strong biofilm‐producing isolates. Capsular and regulatory genes (magA) was more frequent in putative hypervirulent and community‐acquired strains, while siderophore genes entB and iucA were strongly associated with biofilm formation and hospital‐acquired infections. A significantly higher resistance to cephalosporins, along with an increased frequency of multidrug‐resistant phenotypes, was detected in hospital‐acquired, classical, and strong biofilm‐forming isolates. ESBL production was significantly more common in hospital‐acquired and biofilm‐forming isolates. Strong biofilm formation was largely associated with classical K. pneumoniae and hospital‐acquired infections, whereas putative hypervirulent strains were primarily weak biofilm producers and community‐acquired. These findings highlight the interplay between virulence determinants, biofilm formation, and antibiotic resistance, emphasizing the need for targeted infection control and treatment strategies in North Lebanon.

Real-time reverse transcription polymerase chain reaction (rRT-PCR) is nowadays commonly used to diagnose viral infections. This assay provides cycle threshold (Ct) values, which inversely correlate with viral load but do not directly indicate infectivity. The relationship between Ct values and infectivity remains unclear. As a first step, we assessed this relationship in nasopharyngeal samples from 97 seasonal influenza A (IAV) and 95 influenza B (IBV) virus-rRT-PCR-positive patients. Samples were cultured, viral RNA was quantified using reverse transcriptase digital PCR, and antibody titers against hemagglutinin (HA) were evaluated. We found a robust inverse correlation between sample Ct value and infectious virus titer and virus cultures are consistently positive at Ct < 22 with a 10% positive culture probability near Ct 36, which corresponds to 5.37 × 102 and 1.57 × 103 RNA copies mL-1 for seasonal IAV and IBV, respectively. Nearly all available serum samples showed HA-specific antibodies, with no correlation between HA titer and Ct value or virus titer. In conclusion, these results support the use of Ct values as a semiquantitative proxy for infectious viral load and underscore their value in interpreting molecular diagnostics and informing infection prevention and control strategies.

This study aimed to determine the prevalence of carbapenem-resistant Enterobacterales (CRE), to characterize their molecular resistance mechanisms, and to assess associated clinical outcomes among intensive care unit (ICU) patients in Tunisia. A cross-sectional study was conducted from January to March 2025 in the ICU of Habib Thameur Hospital and included all patients with clinically significant CRE infections. Resistance determinants were identified using multiplex polymerase chain reaction with reverse dot blot hybridization. Among 95 ICU admissions, 17 patients developed CRE infections, corresponding to an incidence density of 21.6 cases per 1,000 patient-days. All infections were hospital-acquired. The most frequent risk factors were the presence of central venous and urinary catheters (16 patients each) and mechanical ventilation (15 patients). Klebsiella pneumoniae predominated, accounting for 26 of 27 isolates, all of which were multidrug-resistant (MDR), with a median antibiotic resistance index of 1.00. The blaNDM and blaOXA-48 genes were detected in 81.5% and 77.8% of isolates, respectively, with 70.4% co-producing both carbapenemases. All K. pneumoniae isolates harbored blaSHV and/or blaCTX-M, while a single Escherichia coli isolate carried blaOXA-48. Cluster analysis revealed strong associations between β-lactamase production and resistance to aminoglycosides and fluoroquinolones, suggesting co-selection of MDR strains. Empirical antimicrobial therapy was appropriate in only 47% of cases, and ICU mortality reached 82.4%. These findings highlight an alarmingly high burden of CRE infections in this ICU, driven mainly by K. pneumoniae co-producing NDM and OXA-48, and underscore the urgent need for strengthened infection control and antimicrobial stewardship strategies.