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The morphological dynamics of microbial cell proliferation on an antimicrobial surface at an early growth stage was studied with Escherichia coli on the surface of a gel supplied with AgNbO3 antimicrobial particles. We demonstrated an inhibitory surface concentration, analogous to minimum inhibitory concentration, beyond which the growth of colonies and formation of biofilm are inhibited. In contrast, at lower concentrations of particles, after a lag time the cells circumvent the antimicrobial activity of the particles and grow with a rate similar to the case in the absence of particles. The lag time depends on the surface concentration of the particles and amounts to 2 h at a concentration of ½ minimum inhibitory concentration. The applicability of these findings, in terms of estimating inhibitory surface concentration, was tested in the case of antimicrobial polymethyl methacrylate (PMMA) bone cement. [ABSTRACT FROM AUTHOR]

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This study was conducted to find the etiology of acute diarrhea in Iranian children and determine the antimicrobial resistance patterns. The pathogenic bacteria were recovered from 110/269 (40.9%) diarrheal fecal samples with the following profiles: the most predominant pathogen was diarrheagenic Escherichia coli (DEC) (43.6%), comprising enteroaggregative E. coli (23.6%), enteropathogenic E. coli (10.9%), enteroinvasive E. coli (5.5%), and enterotoxigenic E. coli (3.6%); Shigella spp. (37.3%), Salmonella spp. (12.7%) and Campylobacter jejuni (6.4%) were ranked second and fourth in terms of prevalence, respectively. The rates of extended-spectrum beta-lactamase (ESBL) production were 66.7% and 53.7% in DEC and Shigella, respectively. Resistance to ampicillin (AMP) (95.1%), trimethoprim/sulfamethoxazole (SXT) (73.2%), azithromycin (ATH) (21.9%), and ciprofloxacin (CIP) (14.6%) was observed among Shigella isolates. Multidrug resistance phenotype was observed in 24.4% (10/41) of Shigella isolates, with the most common pattern of resistance to cefotaxime, ceftriaxone, ceftazidime, AMP, SXT, and ATH. This study indicates an alarming increase in the ESBL production of DEC and Shigella spp. and identifies them as the two most prevalent diarrhea-causing enteropathogens in the region. The results show that CIP could be an alternative to third-generation cephalosporins against these two pathogens. Therefore, it is proposed that further investigation be done in the pursuit of alternative antibiotics that are effective against the resistant cases. For instance, one study could look into the comparative clinical effectiveness of third-generation cephalosporins versus CIP, the latter not being presently the drug of choice for the treatment of acute diarrhea in children in Iran. [ABSTRACT FROM AUTHOR]

Although silver is known for its antibacterial activity, its exact mode of action remains unclear. In our previous work, we described AgNbO 3 nanoparticles (AgNbO 3 NPs) prepared using a ceramic method, followed by high-energy and low-energy ball-milling processes, which exhibited antimicrobial activity with negligible release of Ag + in deionized water. Here, we investigated thoroughly the mode of action of these AgNbO 3 NPs against Escherichia coli . Drastic morphological changes in E. coli were observed after their exposure to AgNbO 3 NPs. In addition to cellular damage, AgNbO 3 NPs induced the production of reactive oxygen species and lipid peroxidation, likely following the release of small amounts of Ag + . This was concluded from the characterization of mutants resistant to AgNbO 3 NPs that showed cross-resistance to AgNO 3 , impaired reactive oxygen species production and lipid peroxidation, and harbored a key mutation in a two-component regulatory system regulating an Ag + efflux pump. We calculated, however, that the quantity of Ag + released from AgNbO 3 NPs is not sufficient by itself to lead to bacterial death. We propose that bacterial contact with the AgNbO 3 NPs in combination with Ag + release is necessary for the mode of action of AgNbO 3 NPs.IMPORTANCESilver is known for its antibacterial activity, but its exact mode of action remains unclear. Here, we investigated thoroughly the mode of action of AgNbO 3 nanoparticles against Escherichia coli . Our data suggest that AgNbO 3 nanoparticles have dual effects on the cell and that both are required for its lethal action., Competing Interests: The authors declare no conflict of interest.

The morphological dynamics of microbial cell proliferation on an antimicrobial surface at an early growth stage was studied with Escherichia coli on the surface of a gel supplied with AgNbO3 antimicrobial particles. We demonstrated an inhibitory surface concentration, analogous to minimum inhibitory concentration, beyond which the growth of colonies and formation of biofilm are inhibited. In contrast, at lower concentrations of particles, after a lag time the cells circumvent the antimicrobial activity of the particles and grow with a rate similar to the case in the absence of particles. The lag time depends on the surface concentration of the particles and amounts to 2 h at a concentration of ½ minimum inhibitory concentration. The applicability of these findings, in terms of estimating inhibitory surface concentration, was tested in the case of antimicrobial polymethyl methacrylate (PMMA) bone cement., Competing Interests: The authors have declared that no competing interests exist., (Copyright: © 2024 Talebpour et al. This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.)

We investigated the possibility of loading PMMA bone cement with antimicrobial nanostructured AgNbO 3 particles to counter biofilm formation at the cement-tissue interface. We found that a formulation containing (1-4)% AgNbO 3 showed high antibacterial activity against Gram-positive Staphylococcus aureus and Gram-negative Pseudomonas aeruginosa while not showing any toxicity against THP1 human cell lines. In addition, loading the particles did not impact the mechanical properties of the cement. The results thus obtained illustrate the potential of the approach to replace the current technique of mixing cement with conventional antibiotics, which is associated with shortcomings such as efficacy loss from antibiotic depletion.

Background: Autoimmune type 1 diabetes mellitus is caused by the T-cell mediated immune destruction of the insulin-producing beta-cell in pancreatic islets of Langerhans. The specificity of the auto-antibodies and of the auto-reactive T cells has been investigated, in which several auto-antigens were proposed., Objective: The purpose of this study was to determine whether glutamic acid decarboxylase (GAD) feeding would induce oral tolerance of either the T cell or B cell compartment in streptozotocin (STZ) diabetic rats., Methods: Experimental rats were fed 2 mg/kg of GAD (extracted from Escherichia coli) 14 days before being given intra-peritoneal injections of streptozotocin (STZ, 30 mg/kg body weight for 5 consecutive days). Of the two control groups, one was the diabetic control, which underwent STZ injections without being given the GAD; and the second was the normal control group. Systemic responses were compared between the three groups. T cell responses were assessed by a proliferation assay of spleen cells, and those of the B cell, by enzyme-linked immunosorbent assay ELISA for anti-GAD specific Abs in serum., Results: Compared with the diabetic control group, a significant reduction was observed only in the proliferative response of spleen cells, but not in the level of anti-GAD antibody., Conclusion: We concluded that GAD feeding induces systemic T cell tolerance in STZ-induced diabetes.