BACKGROUND AND OBJECTIVE

The human nasal passages host major human pathogens. Recent research suggests that the microbial communities inhabiting the epithelial surfaces of the nasal passages play a key factor in maintaining a healthy microenvironment by affecting both resistance to pathogens and immunological responses. Colonization of the nasal cavity by different pathogens such as Staphylococcus aureus and Klebsiella aerogenes, is associated with a higher postoperative infection morbidity. Povidone-iodine (PVP-I) as an antiseptic has been proven to display high antibacterial, antiviral, and antifungal properties even at low concentrations, and was shown to be effective in the control of infections to limit their impact and spread. It can be used as a topical antiseptic for skin decontamination and wound management, as a nasal spray, or as a gargle. There are different methods in testing the efficacy of potential antimicrobial suspensions. This study aimed to determine the concentration of PVP-I that is most effective in nasal decolonization using microsuspension test and colorimetric minimum inhibitory concentration (MIC) determination assays, resazurin microtiter assay (REMA), and Dey-Engley (D/E) neutralizer assay. The findings of this study will contribute to knowledge regarding the intended use of PVP-I in microbial control, particularly in bacterial infections.

Several dilutions (2.0%, 1.0%, 0.5%, 0.25%, 0.1% and 0.09%) of commercially bought 10% (10 mg per 100 ml) povidone-iodine were prepared and tested against a standardized inoculum (1x105) of Staphylococcus aureus and Klebsiella aerogenes at different contacttimes (5 seconds, 10 seconds, 30 seconds, 1 minute, and 5 minutes). Microdilution suspension test was performed to determine the log reduction per variable, while REMA and D/E neutralizer assay were used to determine the MIC. A value of greater than or equal to 5 log reduction was considered effective for microdilution suspension test. Estimates of agreement statistics were used to interpret the results of the assay in which the overall percent agreement (OPA), positive percent agreement (PPA), negative percent agreement (NPA), and Cohen’s kappa statistics were calculated.

Povidone-iodine concentration of 0.25% exhibited ?5 log reduction against K. aerogenes at the minimum contact time of 5 seconds. On the other hand,  a slightly higher PVP-I concentration was required to achieve ?5 log reduction for S. aureus at 0.5% concentration and a minimum contact time of 1 minute. There was an observed concordance of the results of REMA and D/E neutralizer as MIC colorimetric indicators, which yielded an overall test percent agreement of 90.30% (95% CI: 84.73–94.36), and a strong level of agreement (? = 0.8, pCONCLUSION

Low povidone-iodine concentrations (i.e., 0.5% against S. aureus and 0.25% against K. aerogenes) were observed to have bactericidal activity of at least 5 log reduction as rapid as the minimum contact time of 5 seconds. Furthermore, D/E and REMA, as colorimetric indicators, had comparable performance (OPA = 90.30%; ? = 0.8, p
Human ; Bacteria ; Povidone-iodine ; Microbial Sensitivity Tests ; Anti-infective Agents, Local ; Enterobacter Aerogenes ; Staphylococcus Aureus

Artemisia argyi (A. argyi), a plant with a longstanding history as a raw material for traditional medicine and functional diets in Asia, has been used traditionally to bathe and soak feet for its disinfectant and itch-relieving properties. Despite its widespread use, scientific evidence validating the antifungal efficacy of A. argyi water extract (AAWE) against dermatophytes, particularly Trichophyton rubrum, Trichophyton mentagrophytes, and Microsporum gypseum, remains limited. This study aimed to substantiate the scientific basis of the folkloric use of A. argyi by evaluating the antifungal effects and the underlying molecular mechanisms of its active subfraction against dermatophytes. The results indicated that AAWE exhibited excellent antifungal effects against the three aforementioned dermatophyte species. The subfraction AAWE6, isolated using D101 macroporous resin, emerged as the most potent subfraction. The minimum inhibitory concentrations (MICs) of AAWE6 against T. rubrum, M. gypseum, and T. mentagrophytes were 312.5, 312.5, and 625 μg·mL^-1, respectively. Transmission electron microscopy (TEM) results and assays of enzymes linked to cell wall integrity and cell membrane function indicated that AAWE6 could penetrate the external protective barrier of T. rubrum, creating breaches ("small holes"), and disrupt the internal mitochondrial structure ("granary"). Furthermore, transcriptome data, quantitative real-time PCR (RT-qPCR), and biochemical assays corroborated the severe disruption of mitochondrial function, evidenced by inhibited tricarboxylic acid (TCA) cycle and energy metabolism. Additionally, chemical characterization and molecular docking analyses identified flavonoids, primarily eupatilin (131.16 ± 4.52 mg·g^-1) and jaceosidin (4.17 ± 0.18 mg·g^-1), as the active components of AAWE6. In conclusion, the subfraction AAWE6 from A. argyi exerts antifungal effects against dermatophytes by disrupting mitochondrial morphology and function. This research validates the traditional use of A. argyi and provides scientific support for its anti-dermatophytic applications, as recognized in the Chinese patent (No. ZL202111161301.9).
Antifungal Agents/chemistry* ; Arthrodermataceae ; Artemisia/chemistry* ; Molecular Docking Simulation ; Mitochondria ; Microbial Sensitivity Tests

The widespread of tigecycline resistance gene tet(X4) has a serious impact on the clinical efficacy of tigecycline. The development of effective antibiotic adjuvants to combat the looming tigecycline resistance is needed. The synergistic activity between the natural compound β-thujaplicin and tigecycline in vitro was determined by the checkerboard broth microdilution assay and time-dependent killing curve. The mechanism underlining the synergistic effect between β-thujaplicin and tigecycline against tet(X4)-positive Escherichia coli was investigated by determining cell membrane permeability, bacterial intracellular reactive oxygen species (ROS) content, iron content, and tigecycline content. β-thujaplicin exhibited potentiation effect on tigecycline against tet(X4)-positive E. coli in vitro, and presented no significant hemolysis and cytotoxicity within the range of antibacterial concentrations. Mechanistic studies demonstrated that β-thujaplicin significantly increased the permeability of bacterial cell membranes, chelated bacterial intracellular iron, disrupted the iron homeostasis and significantly increased intracellular ROS level. The synergistic effect of β-thujaplicin and tigecycline was identified to be related to interfere with bacterial iron metabolism and facilitate bacterial cell membrane permeability. Our studies provided theoretical and practical data for the application of combined β-thujaplicin with tigecycline in the treatment of tet(X4)-positive E. coli infection.
Humans ; Tigecycline/pharmacology* ; Escherichia coli/metabolism* ; Reactive Oxygen Species/therapeutic use* ; Plasmids ; Anti-Bacterial Agents/metabolism* ; Escherichia coli Infections/microbiology* ; Bacteria/genetics* ; Microbial Sensitivity Tests

Objective: To investigate the antimicrobial resistance of food-borne diarrheagenic Escherichia coli (DEC) and the prevalence of mcr genes that mediates mobile colistin resistance in parts of China, 2020. Methods: For 91 DEC isolates recovered from food sources collected from Fujian province, Hebei province, Inner Mongolia Autonomous Region and Shanghai city in 2020, Vitek2 Compact biochemical identification and antimicrobial susceptibility testing platform was used for the detection of antimicrobial susceptibility testing (AST) against to 18 kinds of antimicrobial compounds belonging to 9 categories, and multi-polymerase chain reaction (mPCR) was used to detect the mcr-1-mcr-9 genes, then a further AST, whole genome sequencing (WGS) and bioinformatics analysis were platformed for these DEC isolates which were PCR positive for mcr genes. Results: Seventy in 91 isolates showed different antimicrobial resistance levels to the drugs tested with a resistance rate of 76.92%. The isolates showed the highest antimicrobial resistance rates to ampicillin (69.23%, 63/91) and trimethoprim-sulfamethoxazole (59.34%, 54/91), respectively. The multiple drug-resistant rate was 47.25% (43/91). Two mcr-1 gene and ESBL (extended-spectrum beta-lactamase) positive EAEC (enteroaggregative Escherichia coli) strains were detected. One of them was identified as serotype of O11:H6, which showed a resistance profile to 25 tested drugs referring to 10 classes, and 38 drug resistance genes were predicted by genome analysis. The other one was O16:H48 serotype, which was resistant to 21 tested drugs belonging to 7 classes and carried a new variant of mcr-1 gene (mcr-1.35). Conclusion: An overall high-level antimicrobial resistance was found among foodborne DEC isolates recovered from parts of China in 2020, and so was the MDR (multi-drug resistance) condition. MDR strains carrying multiple resistance genes such as mcr-1 gene were detected, and a new variant of mcr-1 gene was also found. It is necessary to continue with a dynamic monitoring on DEC contamination and an ongoing research into antimicrobial resistance mechanisms.
Humans ; Colistin/pharmacology* ; Anti-Bacterial Agents/pharmacology* ; Escherichia coli Infections/epidemiology* ; Escherichia coli Proteins/genetics* ; Drug Resistance, Bacterial/genetics* ; China/epidemiology* ; Escherichia coli ; Plasmids/genetics* ; Microbial Sensitivity Tests

Objective: Analysis and investigation of pathogenic characteristics of polymyxin-and carbapenem-resistant Klebsiella pneumoniae (PR-CRKP). Methods: A total of 23 PR-CRKP strains isolated from clinical specimens from the General Hospital of Southern Theater Command from March 2019 to July 2021 were retrospectively collected, Whole-genome sequencing was performed on 23 PR-CRKP strains, resistance genes were identified by comparison of the CARD and the ResFinder database, high-resolution typing of PR-CRKP strains was analyzed by core genomic multilocus sequencing (cgMLST) and single nucleotide polymorphism (SNP); polymyxin resistance genes were determined by PCR and sequencing. Results: All PR-CRKP strains were KPC-2 producing ST11 types. cgMLST results showed that the evolutionary distance between the PR-CRKP strains and Klebsiella pneumoniae in mainland China was 66.44 on average, which is more closely related than foreign strains; the 23 PR-CRKP strains were divided into 3 main subclusters based on SNP phylogenetic trees, with some aggregation among Clade 2-1 in the isolation department and date. The two-component negative regulatory gene mgrB has seven mutation types including point mutations, different insertion fragments and different insertion positions. Conclusion: The close affinity of PR-CRKP strains indicate the possibility of nosocomial clonal transmission and the need to strengthen surveillance of PR-CRKP strains to prevent epidemic transmission of PR-CRKP.
Humans ; Carbapenems/pharmacology* ; Anti-Bacterial Agents/therapeutic use* ; Klebsiella pneumoniae/genetics* ; Polymyxins/pharmacology* ; beta-Lactamases ; Phylogeny ; Retrospective Studies ; Multilocus Sequence Typing ; Microbial Sensitivity Tests

To explore the clinical distribution and drug resistance characteristics of carbapenem-resistant Klebsiella pneumoniae (CRKP), in order to provide reference for the prevention and treatment of CRKP infection. Retrospective analysis was performed on 510 clinical isolates of CRKP from January 2017 to December 2021, and strain identification and drug sensitivity tests were conducted by MALDI-TOF mass spectrometer and VITEK-2 Compact microbial drug sensitivity analyzer. The carbapenemase phenotype of CRKP strain was detected by carbapenemase inhibitor enhancement test. The CRKP strain was further categorized by immunochromogenic method and polymerase chain reaction (PCR) was used for gene detection. The results showed that 302 strains (59.2%) were derived from sputum, 127 strains (24.9%) from urine and 47 strains (9.2%) from blood. 231 (45.3%) were mainly distributed in intensive care, followed by 108 (21.2%) in respiratory medicine and 79 (15.5%) in neurosurgery. Drug susceptibility test result shows that the resistant rate of tigecycline increased from 1.0% in 2017 to 10.1% in 2021, the difference was statistically significant (χ²=14.444,P<0.05). The results of carbapenemase inhibitor enhancement test showed that 461 carbapenemase strains (90.4%) of 510 CRKP strains, including 450 serinase strains (88.2%), 9 metalloenzyme strains (1.8%), and 2 strains (0.4%) produced both serine and metalloenzyme. 49 strains (9.6%) did not produce enzymes. Further typing by immunochromogenic assay showed that 461 CRKP strains were KPC 450 (97.6%) and IMP 2 (0.4%). 7 NDM (1.5%); 2 strains of KPC+NDM (0.4%); PCR results were as follows: 450 strains of blaKPC (97.6%), 2 strains of blaIMP (0.4%), 7 strains of blaNDM (1.5%), and 2 strains of blaKPC+NDM (0.4%). In conclusion, CRKP strains mainly originated from sputum specimens and distributed in intensive care department, and the drug resistance characteristics were mainly KPC type in carbapenemase production. Clinical microbiology laboratory should strengthen the monitoring of CRKP strains, so as to provide reference for preventing CRKP infection and reducing the production of bacterial drug resistance.
Anti-Bacterial Agents/pharmacology* ; Carbapenems/pharmacology* ; Klebsiella pneumoniae/genetics* ; Hospital Distribution Systems ; Retrospective Studies ; Microbial Sensitivity Tests ; beta-Lactamases/genetics* ; Bacterial Proteins/genetics* ; Drug Resistance, Bacterial/genetics*

OBJECTIVE: To investigate the inhibitory effects of levofloxacin (LEV) combined with cellulase against bacille CalmetteGuerin (BCG) biofilms in vitro. METHODS: The mature growth cycle of BCG biofilms was determined using the XTT method and crystal violet staining. BCG planktonic bacteria and BCG biofilms were treated with different concentrations of LEV and cellulose alone or jointly, and the changes in biofilm biomass were quantified with crystal violet staining. The mature BCG biofilm was then treated with cellulase alone for 24 h, and after staining with SYTO 9 and Calcofluor White Stain, the number of viable bacteria and the change in cellulose content in the biofilm were observed with confocal laser scanning microscopy. The structural changes of the treated biofilm were observed under scanning electron microscopy. RESULTS: The MIC, MBC and MBEC values of LEV determined by broth microdilution method were 4 μg/mL, 8 μg/mL and 1024 μg/mL, respectively. The combined treatment with 1/4×MIC LEV and 2.56, 5.12 or 10.24 U/mL cellulase resulted in a significant reduction in biofilm biomass (P < 0.001). Cellulase treatments at the concentrations of 10.24, 5.12 and 2.56 U/mL all produced significant dispersion effects on mature BCG biofilms (P < 0.001). CONCLUSION LEV combined with cellulose can effectively eradicate BCG biofilm infections, suggesting the potential of glycoside hydrolase therapy for improving the efficacy of antibiotics against biofilmassociated infections caused by Mycobacterium tuberculosis.
Levofloxacin/pharmacology* ; Gentian Violet/pharmacology* ; BCG Vaccine/pharmacology* ; Anti-Bacterial Agents/pharmacology* ; Biofilms ; Cellulases/pharmacology* ; Microbial Sensitivity Tests

Humans ; Mycobacterium tuberculosis/genetics* ; Microspheres ; Antitubercular Agents/pharmacology* ; Mutation ; Microbial Sensitivity Tests ; Fluoroquinolones ; Drug Resistance, Bacterial/genetics* ; Tuberculosis, Multidrug-Resistant/microbiology*

OBJECTIVE: To explore the genotyping characteristics of human fecal Escherichia coli( E. coli) and the relationships between antibiotic resistance genes (ARGs) and multidrug resistance (MDR) of E. coli in Miyun District, Beijing, an area with high incidence of infectious diarrheal cases but no related data. METHODS: Over a period of 3 years, 94 E. coli strains were isolated from fecal samples collected from Miyun District Hospital, a surveillance hospital of the National Pathogen Identification Network. The antibiotic susceptibility of the isolates was determined by the broth microdilution method. ARGs, multilocus sequence typing (MLST), and polymorphism trees were analyzed using whole-genome sequencing data (WGS). RESULTS: This study revealed that 68.09% of the isolates had MDR, prevalent and distributed in different clades, with a relatively high rate and low pathogenicity. There was no difference in MDR between the diarrheal (49/70) and healthy groups (15/24). CONCLUSION We developed a random forest (RF) prediction model of TEM.1 + baeR + mphA + mphB + QnrS1 + AAC.3-IId to identify MDR status, highlighting its potential for early resistance identification. The causes of MDR are likely mobile units transmitting the ARGs. In the future, we will continue to strengthen the monitoring of ARGs and MDR, and increase the number of strains to further verify the accuracy of the MDR markers.
Humans ; Escherichia coli/genetics* ; Escherichia coli Infections/epidemiology* ; Multilocus Sequence Typing ; Genotype ; Beijing ; Drug Resistance, Multiple, Bacterial/genetics* ; Anti-Bacterial Agents/pharmacology* ; Diarrhea ; Microbial Sensitivity Tests

Stenotrophomonas species are non-fermentative Gram-negative bacteria that are widely distributed in environment and are highly resistant to numerous antibiotics. Thus, Stenotrophomonas serves as a reservoir of genes encoding antimicrobial resistance (AMR). The detection rate of Stenotrophomonas is rapidly increasing alongside their strengthening intrinsic ability to tolerate a variety of clinical antibiotics. This review illustrated the current genomics advances of antibiotic resistant Stenotrophomonas, highlighting the importance of precise identification and sequence editing. In addition, AMR diversity and transferability have been assessed by the developed bioinformatics tools. However, the working models of AMR in Stenotrophomonas are cryptic and urgently required to be determined. Comparative genomics is envisioned to facilitate the prevention and control of AMR, as well as to gain insights into bacterial adaptability and drug development.
Stenotrophomonas/genetics* ; Drug Resistance, Bacterial/genetics* ; Anti-Bacterial Agents/pharmacology* ; Gram-Negative Bacteria ; Genomics ; Microbial Sensitivity Tests