Current Issue : January-March Volume : 2026 Issue Number : 1 Articles : 5 Articles
Background: Given the increasing problem of antibiotic resistance in A. baumannii, this study examines in vitro how combinations of colistin, meropenem, and sulbactam influence the expression of genes associated with multiresistance in this pathogen. Methods: Three multidrug-resistant strains, isolated from clinical infections in Panama (2022–2023), were identified using Vitek 2 compact. Susceptibility by broth microdilution, qualitative synergy, time-kill curves, and gene expression analysis by quantitative PCR were performed. Results: Synergistic effects were observed for the colistin–meropenem combination in all three strains, while the sulbactam–colistin combination exhibit synergy only in one of the A. baumannii isolates. Time-kill assays revealed bactericidal effects for the colistin–meropenem and sulbactam–colistin combinations. qPCR analyses indicated that colistin, meropenem, and sulbactam modified the expression of the genes under study. Colistin–meropenem and meropenem–sulbactam combinations decreased the expression of blaADC and blaOXA-51, while sulbactam–colistin did not have a significant effect. carO expression levels were not reduced with any antibiotic combination, while adeB expression was reduced with all the combinations tested. omp33–36 expression varied depending on the antibiotic and strain. Conclusions: Therefore, this study offers a new perspective on how rational combinations of clinically used antibiotics have the potential to modulate gene expression and contribute to the control of MDR strains, indicating that high-dose combination therapy with sulbactam and colistin could offer improved efficacy in treating multidrug resistant Acinetobacter baumannii infections....
Background: Carbapenem-resistant Klebsiella pneumoniae (CRKp) is a critical global health threat due to its multidrug resistance, primarily driven by carbapenemase production. Rapid and accurate detection of carbapenemases is essential for effective treatment and infection control. This study evaluates the validity of the NG-Test CARBA 5, a rapid immunochromatographic assay, for detecting five major carbapenemases (KPC, NDM, VIM, IMP, OXA-48-like) in clinical CRKp isolates. Methods: Clinical isolates of CRKp were collected from various clinical specimens at the Military Medical Academy in Belgrade, Serbia, between January 2023 and October 2024. Detection of carbapenemases was performed using NG-Test CARBA 5, while PCR served as the reference method. Diagnostic performance was assessed by calculating sensitivity, specificity, and Cohen’s kappa coefficient. Results: Among 312 isolates, OXA-48-like was the most prevalent carbapenemase. NG-Test CARBA 5 showed high sensitivity (98.7%) and specificity (100%) overall, with excellent agreement for NDM (κ = 0.947), OXA-48-like (κ = 0.957), and KPC (κ = 0.978). However, it failed to detect VIM in five PCR-positive isolates, suggesting potential limitations. Conclusions: NG-Test CARBA 5 is a rapid and reliable tool for detecting major carbapenemases in CRKp, though its performance for VIM detection requires further investigation. This assay has the potential to improve clinical diagnostics and strengthen infection control in settings with high antimicrobial resistance....
Background: Prosthetic candidiasis remains a significant clinical challenge, particularly due to the ability of Candida species to form resilient biofilms on dental prostheses, which limits the efficacy of conventional antifungal treatments. In this context, developing strategies to prevent or reduce biofilm formation is essential. Objectives This study investigates the antifungal and antibiofilm potential of a hydrogel formulation incorporating aminochalcone AM-35 as a candidate for the prevention and treatment of prosthetic candidiasis. Methods: To achieve this, experiments were conducted to determine the minimum inhibitory concentration (MIC) of aminochalcone AM-35 against Candida albicans and Candida tropicalis strains. AM-35 was incorporated into a hydrogel, which was subsequently tested on biofilms formed by these yeast species, both individually and in combination. The experimental disks were sterilized and incubated with C. albicans, C. tropicalis, and a mixture of both strains for 120 h to allow biofilm maturation. After contamination, the samples were divided into four experimental groups: Group 1: Hydrogel; Group 2: Hydrogel+AM-35; Group 3: Sodium hypochlorite (positive control); and Group 4: No treatment. The samples were then subjected to a sonication process to disaggregate the cells, which were then cultured on plates for colony-forming unit (CFU/mL) counts. The hydrogel’s toxicity was evaluated in vivo using the Galleria mellonella model. Results: The hydrogel formulation demonstrated significant antimicrobial activity, with an MIC of 7.8 μg/mL for C. albicans and 3.9 μg/mL for C. tropicalis. Treatment with the hydrogel at a concentration of 39 μg/mL resulted in a significant reduction in the formation and viability of mixed-species biofilms (p < 0.05). Additionally, the results indicated robust activity against C. albicans and C. tropicalis without presenting toxicity in the Galleria mellonella model. In conclusion, the hydrogel formulation exhibited effective antibiofilm activity, significantly reducing the microbial load. Conclusions: These findings open new possibilities for the development of alternative treatments for prosthetic candidiasis. The research suggests that the use of chalcone-based compounds may represent a promising approach in combating fungal infections in dentistry....
Background: The emergence and spread of the tigecycline resistance gene tet(A)-v1 in carbapenem-resistant Klebsiella pneumoniae (CRKP) poses significant public health challenges. However, the prevalence of tet(A)-v1-positive CRKP, especially in pediatric patients, remains poorly understood. This study aims to address the gap by performing an in-depth analysis of isolates collected from a children’s hospital in China. Methods: A 4-year retrospective study was conducted in the children’s hospital in Suzhou, China. Non-duplicated specimens were obtained from pediatric patients, and antimicrobial susceptibility profiles were assessed. Whole-genome sequencing and bioinformatics analyses were conducted to characterize the genetic background, antimicrobial resistance determinants, hypervirulence-associated genes, diversity of tet(A)-v1-carrying plasmids, the genetic environment of tet(A)-v1, and the potential for clonal transmission. Conjugative transferability of tet(A)-v1-carrying plasmids was also evaluated via conjugation assays. Results: Of the 73 tet(A)-v1-positive CRKP isolates from pediatric patients, 10.96% were non-susceptible to tigecycline. These isolates exhibited high genetic diversity, spanning across 13 STs (sequence types), with ST17 being predominant. Three carbapenemases were identified, with IMP being the most common. Isolates from diverse backgrounds, such as ST17, ST20, ST323, ST792, and ST3157, demonstrated evidence of clonal transmission. The tet(A)-v1 gene was located on 14 distinct plasmids across seven replicon types, with IncFIA/IncHI1 and IncFII being most commonly detected. All tet(A)- v1-carrying plasmids were multidrug-resistant, and 68.49% were conjugatively transferable, indicating a high potential for horizontal transfer. Four genetic contexts bordering tet(A)-v1 were identified, which points to active clonal dissemination. Conclusions: Although limited to a single hospital, this study represents one of the first in-depth investigations of tet(A)- v1-positive CRKP in pediatric patients, providing valuable insights into the prevalence and spread of tet(A)-v1 in this vulnerable group. These findings emphasize the urgent need for enhanced surveillance and infection control measures to curb the spread of tet(A)-v1-positive CRKP in pediatric healthcare environments, offering critical insights to mitigate its public health impact....
Background/Objectives: Extended-spectrum β-lactamase (ESBL)-producing Escherichia coli poses a significant global health challenge, as it leads to antimicrobial treatment failure and is associated with elevated mortality rates. The use of β-lactam/β-lactamase inhibitor combinations offers an alternative approach for combating ESBL-producing bacteria. Ceftriaxone (CRO) and sulbactam have been coadministered in the clinical settings; however, discrepancies in their pharmacokinetics raise concerns regarding the rationality of this combination. Methods: This study was designed to investigate the postβ-lactamase inhibitor effect (PLIE) under both static and dynamic conditions, with the aim of supporting the clinical application of this combination. Results: The minimum inhibitory concentration (MIC) of CRO/SBT (2:1 ratio) against E. coli NCTC 13353 was determined to be 32/16 μg/mL. The PLIEs were determined to be −1.26, −0.57, and 0.37 h at CRO/SBT concentrations ranging from 1/2 MIC to 2 MIC, respectively. The results of CRO concentration, β-lactamase activity, blaCTX-M-15 expression, and cell morphology collectively support that SBT exerts PLIEs and protects against the antibacterial activity of CRO. In the dynamic hollow-fiber infection model, CRO monotherapy showed no inhibitory effect on E. coli, whereas CRO/SBT combination therapy rapidly eliminated SBT, achieved comparable bactericidal effects, prolonged CRO exposure, and maintained low β-lactamase activity levels. Conclusions: In conclusion, CRO/SBT exerts an inhibitory effect on enzyme-producing strains by being able to produce PLIE to maintain the inhibition of β-lactamase....
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