Explore the vast range of titles available.

Susceptibility testing for colistin remains challenging primarily due to its inherent properties. We evaluated colistin stability in agar and reproducibility of colistin MICs obtained by agar dilution, broth macro- and micro-dilution and MIC gradient strips on 3–7 iterations of each method using clinical Klebsiella pneumoniae (susceptible-CS, and resistant-CR, n = 2 each), mcr-harboring Escherichia coli (n = 2), and reference strains E. coli ATCC25922 and Pseudomonas aeruginosa ATCC27853. MICs for reference strains were not in the given range using Etest and broth microdilution (ATCC25922, 0.125 and 4 μg/ml, respectively). MICs of CR-1 and CR-2, and of the mcr-harboring E. coli showed high concordance between agar and broth dilution varying up to one 2-fold dilution. However, remarkable variations were observed on broth dilution with CS-1 and CS-2 (MIC range 0.25–32 and 0.5–64 μg/ml, respectively); whereas for agar dilution the MIC for both CS strains was 0.5 μg/ml in all the runs. MICs obtained by MIC gradient strips were lower than those obtained by dilution methods (1–2 dilutions for CS and mcr strains, and up to five dilutions for CR strains). To confirm uniform distribution of colistin in agar, a single strain was spotted in five different regions of the same plate. All spots showed concordant growth with maximum one dilution difference. No effect on MIC was found due to storage of colistin-containing agar plates for 7 days at 4 °C. In our hands, agar dilution was superior in terms of reproducibility and robustness, compared to broth dilution methods, for colistin MIC determination.

Antimicrobial resistance remains a significant global challenge across various fields. To solve this problem, researchers are working on developing antimicrobial agents, antiseptics, and disinfectants with different formulations. In this study, methanol (MeOH) extracts of Phytolacca americana L. fruits and leaves, were evaluated for their both antimicrobial and antibiofilm activities using microdilution method and antibiofilm assay against bacteria and fungi including Staphylococcus aureus, Streptococcus mutans, Bacillus subtilis, Escherichia coli, Pseudomonas aeruginosa, Klebsiella pneumoniae, Acinetobacter baumannii, Candida albicans, C. parapsilosis, C. krusei, Trichophyton rubrum, Epidermophyton floccosum, and Microsporum gypseum.. According to the activity studies, extracts displayed 32-128 µg/mL MICs against tested bacteria and fungi. In the microduliton method; inhibition curves of IC50 obtained by the resazurin microplate assay for the extracts showed results in the range of 12-41 μg/mL.

[This corrects the article DOI: 10.3389/fcimb.2023.1141115.].[This corrects the article DOI: 10.3389/fcimb.2023.1141115.].

While the inhalation of Thymus vulgaris L. essential oil (EO) is commonly approved for the treatment of mild respiratory infections, there is still a lack of data regarding the antimicrobial activity and chemical composition of its vapours. The antibacterial activity of the three T. vulgaris EOs against respiratory pathogens, including Haemophilus influenzae, Staphylococcus aureus, and Streptococcus pyogenes, was assessed in both liquid and vapour phases using the broth microdilution volatilisation (BMV) method. With the aim of optimising a protocol for the characterisation of EO vapours, their chemical profiles were determined using two headspace sampling techniques coupled with GC/MS: solid-phase microextraction (HS-SPME) and syringe headspace sampling technique (HS-GTS). All EO sample vapours exhibited antibacterial activity with minimum inhibitory concentrations (MIC) ranging from 512 to 1024 μg/mL. According to the sampling technique used, results showed a different distribution of volatile compounds. Notably, thymol was found in lower amounts in the headspace—peak percentage areas below 5.27% (HS-SPME) and 0.60% (HS-GTS)—than in EOs (max. 48.65%), suggesting that its antimicrobial effect is higher in vapour. Furthermore, both headspace sampling techniques were proved to be complementary for the analysis of EO vapours, whereas HS-SPME yielded more accurate qualitative results and HS-GTS proved a better technique for quantitative analysis.

A total of 44 samples of salmon, pangasius (shark catfish), shrimps, and oysters were tested for the presence of Escherichia coli, enterococci, Pseudomonas aeruginosa, and Staphylococcus aureus, which are indicator organisms commonly used in programs to monitor antibiotic resistance. The isolated bacterial strains, confirmed by matrix-assisted laser desorption ionization time-of-flight mass spectroscopy, were tested against a panel of 29 antimicrobial agents to obtain MICs. Across the four sample types, Enterococcus faecalis (59%) was most common, followed by E. coli (55%), P. aeruginosa (27%), and S. aureus (9%). All bacterial species were resistant to some antibiotics. The highest rates of resistance were in E. faecalis to tetracycline (16%), in E. coli to ciprofloxacin (22%), and in S. aureus to penicillin (56%). Antibiotic resistance was found among all sample types, but salmon and oysters were less burdened than were shrimps and pangasius. Multidrug-resistant (MDR) strains were exclusively found in shrimps and pangasius: 17% of pangasius samples (MDR E. coli and S. aureus) and 64% of shrimps (MDR E. coli, E. faecalis, and S. aureus). Two of these MDR E. coli isolates from shrimps (one from an organic sample) were resistant to seven antimicrobial agents. Based on these findings, E. coli in pangasius, shrimps, and oysters, E. faecalis in pangasius, shrimps, and salmon, and P. aeruginosa in pangasius and shrimps are potential candidates for programs monitoring antimicrobial resistance. Enrichment methods for the detection of MDR bacteria of special public health concern, such as methicillin-resistant S. aureus and E. coli producing extended-spectrum β-lactamases and carbapenemases, should be implemented.

Dental caries is a major lifestyle concern as dental components affect the face of an individual. The issue of tooth decay occurs in every age group throughout the globe. Researchers are probing incipient implements and techniques to develop filling agents for decayed teeth. Zinc oxide (ZnO) powder is utilized mostly as a filling agent. Nanotechnology enhanced the efficiency of compounds of metal oxides utilized for dental caries. The present study aims to investigate the properties of ZnO nanoparticles (NPs) synthesized chemically (using ZnCl2 and NaOH) as well as biologically (using aqueous leaf extract of Murraya paniculata). The XRD patterns confirm that ZnO NPs have a hexagonal crystalline structure with particle sizes of 47 nm and 55 nm for chemically and biologically synthesized NPs, respectively. The FE-SEM data confirm the nanorod and spherical/cubical shape morphologies for the chemically and biologically synthesized ZnO NPs, respectively. FTIR data show the peaks between 4000 and 450 cm−1 of the functional groups of –OH, C-O, –C-H-, and Zn-O bonds. The UV–Vis absorption study indicates a peak around 370 nm and a hump around 360 nm corresponding to the chemically and biologically synthesized ZnO NPs, respectively. An antibacterial bioassay was performed and compared with commercially available ZnO bulk powder against tooth decaying pathogens, viz., Streptococcus mutans, Staphylococcus aureus, E. coli, and Lactobacillus fermentum, and found that both ZnO NPs had results closer to those of the standard drug (rifampicin). Thus, the synthesized ZnO NPs may be utilized as nano-drugs for the application of tooth decaying filling agents. Even biologically synthesized ZnO NPs may be considered more environmentally friendly and less toxic to human health concerns.

Antimicrobial resistance (AMR) is a well-recognized global threat. The World Health Organization (WHO) issued a report ranking the critical types of bacterial resistance that need to be monitored. Several studies from individual institutions in Saudi Arabia have reported rates of antimicrobial resistance using automated methods. However, no national surveillance study has been conducted to date using gold standard methods for antimicrobial susceptibility testing. This review summarizes AMR rates for major bacterial pathogens in Saudi Arabia and provides a justification for the need for a national surveillance project. In Saudi Arabia, AMR rates for both Gram-positive and Gram-negative bacteria are on the rise. Surveillance studies help identify AMR trends and emergence of outbreaks. The WHO has started a program, the Global Antimicrobial Resistance Surveillance System (GLASS), encouraging its member states, including Saudi Arabia, to conduct antimicrobial surveillance studies to estimate AMR rates worldwide. Of the microbiological methods used to test antimicrobial susceptibility, only broth microdilution (BMD) is considered the “gold standard.” As AMR studies in Saudi Arabia are sparse, mostly limited to single centers and were conducted using automated methods, a national AMR surveillance project is needed to evaluate the current status and to inform stewardship decisions.

Background Candidozyma auris is a multidrug resistant fungal pathogen classified by the World Health Organization (WHO) as a critical priority species. Broth microdilution (BMD) is the recommended reference method for antifungal susceptibility testing (AFST), with interpretation based on tentative breakpoints proposed by the Centers for Disease Control and Prevention (CDC) and, more recently, EUCAST clinical breakpoints published in 2025. However, automated systems such as VITEK 2 currently lack validated susceptibility interpretations for C. auris . This study aimed to evaluate the performance of the VITEK 2 system for AFST of C. auris isolates by comparison with the BMD method and to assess the impact of applying CDC and EUCAST breakpoints on susceptibility interpretation. Methods Antibiotic susceptibility testing (AFST) was performed simultaneously on 88 C. auris isolates using the VITEK 2 system and the BMD method. Susceptibility results were interpreted according to both CDC and EUCAST clinical breakpoints. The clade distribution of the isolates was determined by multiplex PCR. Results All isolates were identified as clade I. Categorical agreement (CA) between VITEK 2 and BMD was 31.8% for amphotericin B, 76.1% for fluconazole, and 92.0% for both caspofungin and micafungin. Based on CDC breakpoints, no very major errors (VME) were observed for amphotericin B, caspofungin, or micafungin using VITEK 2, whereas a VME rate of 15.0% was detected for fluconazole. Major error (ME) rates for VITEK 2 were 93.7% for amphotericin B, 68.7% for fluconazole, and 7.9% for caspofungin and micafungin, all exceeding the acceptable performance threshold (ME ≤ 3%). Concordance between CDC- and EUCAST-based interpretations was high for micafungin (VITEK 2: 93.1%; BMD: 96.5%) but markedly lower for amphotericin B (VITEK 2: 59.0%; BMD: 27.2%). Conclusion In conclusion, VITEK 2 showed a high level of agreement with the BMD method in the echinocandin susceptibility test of C. auris , while very high ME and VME ratios were observed for amphotericin B and fluconazole. These findings indicate that VITEK 2 amphotericin B and fluconazole AFST results should be interpreted carefully and validated using reference methods. Furthermore, the differences between CDC and EUCAST breakpoint interpretations, particularly for amphotericin B, highlight the significant impact of breakpoint selection on antifungal susceptibility categorization in C. auris .

Chen D, Lan H, Yang W, et al. Infect Drug Resist. 2026;19:1-13. https://doi.org/10.2147/IDR.S583973 There is an unintentional textual error in Figure 1 on page 4 of the published paper, the text \"(n=4: CRAB, n=3; CRKP, n=1)\" should read \"(n=20: CRAB, n=15; CRKP, n=5)\". The authors apologize for the error and advise that it was purely a labelling oversight and does not alter the statistical analysis, results, or the scientific conclusions of the paper. The correct Figure 1 is shown below. Figure 1 Experimental Workflow.

Background Ceftazidime-avibactam was approved in China in 2019 for treating complicated intra-abdominal infections, hospital-acquired pneumonia, ventilator-associated pneumonia, and infections caused by Enterobacterales and Pseudomonas aeruginosa for which treatment options are limited. However, no currently available commercial systems have been approved for antimicrobial susceptibility testing of ceftazidime-avibactam in China. Here, we evaluated the Etest and disk diffusion method for detecting the activity of ceftazidime-avibactam against Enterobacterales and P. aeruginosa in China. Results In total, 194 Enterobacterales and 77 P. aeruginosa isolates, which were divided into a random selection group (140 Enterobacterales and 46 P. aeruginosa isolates) and stock group (54 Enterobacterales and 31 P. aeruginosa isolates), were assessed by the Etest, disk diffusion and broth microdilution methods. Minimum inhibitory concentrations and zone diameters were interpreted according to the CLSI supplement M100 30th edition. For all 271 tested isolates, no very major errors were found by using Etest, whereas the overall major error rate was 2.0% (4/203). The overall categorical agreement rates of Etest for Enterobacterales and P. aeruginosa were 99.5% (193/194) and 96.1% (74/77), respectively, and the essential agreement rates were 95.9% (186/194) and 94.8% (73/77), respectively. The disk diffusion method showed that the very major error and major error rates were 1.5% (3/204) and 2.5% (5/203), respectively. Overall categorical agreement rates values of the disk diffusion method for Enterobacterales and P. aeruginosa were 98.5% (191/194) and 93.5% (72/77) compared with broth microdilution, respectively. Conclusions For Enterobacterales and P. aeruginosa , both the Etest and disk diffusion method showed acceptable performance as alternatives to the standard broth microdilution method for clinical treatment interpretation. Application of the disk diffusion method in Enterobacterales was slightly better than that in P. aeruginosa .