Novel Providencia xianensis sp. nov.: A multidrug-resistant species identified in clinical infections.

Providencia genus is known to harbor certain opportunistic pathogens capable of causing human infections. Here, we report two strains of multidrug-resistant bacteria initially identified as Providencia rettgeri by mass spectrometry, but genome analysis revealed their ANI (79.84-84.20%) and dDDH (21.1-25.6%) values to fall below the accepted species threshold for known Providencia species. We therefore propose that these isolates be recognized as a novel species, Providencia xianensis sp. nov. Alarmingly, both strains, isolated from locations far apart, exhibited resistance to last-resort antibiotics, indicating their possible wide distribution, underscoring the urgency for immediate attention and enhanced surveillance for this emerging multidrug-resistant pathogen.

Psoralea corylifolia L. and its active component isobavachalcone demonstrate antibacterial activity against Mycobacterium abscessus.

ETHNOPHARMACOLOGICAL RELEVANCE: Psoralea corylifolia L. (Fabaceae) is a traditional medicinal herb used to treat various diseases, including kidney disease, asthma, psoriasis and vitiligo. AIM OF THE STUDY: To explore the antibacterial activity of Psoralea corylifolia L. and its bioactive components against Mycobacterium abscessus (M. abscessus). MATERIALS AND METHODS: Ultra high performance liquid chromatography was utilized to analyze the bioactive fractions and compounds present in 30%, 60%, and 90% ethanol extracts of Psoralea corylifolia L.. The antibacterial effects of Psoralea corylifolia L. and potential active ingredients were determined by minimum inhibitory concentration (MIC). The bactericidal activity of the active ingredient isobavachalcone was evaluated and then scanning electron microscopy was used to explore the bactericidal mechanism of isobavachalcone. RESULTS: The 90% ethanol extracts of Psoralea corylifolia L. showed significant antibacterial activity against M. abscessus, with an MIC of 156 µg/mL. Isobavachalcone was identified as the bioactive ingredient, and testing of 118 clinical isolates of M. abscessus indicated their MICs ranged from 2 to 16 µg/mL, with an average MIC of 8 µg/mL. Furthermore, the minimum bactericidal concentration/MIC ratio and the time-kill test indicated rapid bactericidal activity of isobavachalcone against M. abscessus. Finally, we found that the bactericidal mechanism of isobavachalcone involved damage to the bacterial cell membrane, causing wrinkled and sunken cell surface and a noticeable reduction in bacterial length. CONCLUSION: Psoralea corylifolia L. ethanol extracts as well as its active component isobavachalcone show promising antimicrobial activity against M. abscessus.

Identification of essential oils with strong activity against stationary phase Mycobacterium abscessus.

Purpose: To identify essential oils (EOs) active against non-growing stationary phase Mycobacterium abscessus and multidrug-resistant M. abscessus strains. Methods: The activity of EOs against both stationary and log phase M. abscessus was evaluated by colony forming unit (CFU) assay and minimum inhibitory concentration (MIC) testing. Results: We assessed the activity of 80 EOs against stationary phase M. abscessus and found 12 EOs (Cinnamon, Satureja montana, Palmarosa, Lemon eucalyptus, Honey myrtle, Combava, Health shield, Mandarin, Thyme, Rosewood, Valerian Root and Basil) at 0.5% concentration to be active against both growing and non-growing stationary phase M. abscessus. Among them, Satureja montana essential oil and Palmarosa essential oil could eliminate all stationary phase M. abscessus at 0.125% and Cinnamon essential oil could eliminate stationary phase bacteria at 0.063% after 1-day treatment. Interestingly, these EOs also exhibited promising activity against multidrug-resistant M. abscessus clinical strains. Conclusions: Our study indicates that some EOs display outstanding effectiveness against both drug susceptible M. abscessus and multidrug-resistant M. abscessus isolates. These findings may be significant for the treatment of persistent M. abscessus infections.

Genomic revisitation and reclassification of the genus Providencia.

Members of Providencia, although typically opportunistic, can cause severe infections in immunocompromised hosts. Recent advances in genome sequencing provide an opportunity for more precise study of this genus. In this study, we first identified and characterized a novel species named Providencia zhijiangensis sp. nov. It has ≤88.23% average nucleotide identity (ANI) and ≤31.8% in silico DNA-DNA hybridization (dDDH) values with all known Providencia species, which fall significantly below the species-defining thresholds. Interestingly, we found that Providencia stuartii and Providencia thailandensis actually fall under the same species, evidenced by an ANI of 98.59% and a dDDH value of 90.4%. By fusing ANI with phylogeny, we have reclassified 545 genomes within this genus into 20 species, including seven unnamed taxa (provisionally titled Taxon 1-7), which can be further subdivided into 23 lineages. Pangenomic analysis identified 1,550 genus-core genes in Providencia, with coenzymes being the predominant category at 10.56%, suggesting significant intermediate metabolism activity. Resistance analysis revealed that most lineages of the genus (82.61%, 19/23) carry a high number of antibiotic-resistance genes (ARGs) and display diverse resistance profiles. Notably, the majority of ARGs are located on plasmids, underscoring the significant role of plasmids in the resistance evolution within this genus. Three species or lineages (P. stuartii, Taxon 3, and Providencia hangzhouensis L12) that possess the highest number of carbapenem-resistance genes suggest their potential influence on clinical treatment. These findings underscore the need for continued surveillance and study of this genus, particularly due to their role in harboring antibiotic-resistance genes. IMPORTANCE: The Providencia genus, known to harbor opportunistic pathogens, has been a subject of interest due to its potential to cause severe infections, particularly in vulnerable individuals. Our research offers groundbreaking insights into this genus, unveiling a novel species, Providencia zhijiangensis sp. nov., and highlighting the need for a re-evaluation of existing classifications. Our comprehensive genomic assessment offers a detailed classification of 545 genomes into distinct species and lineages, revealing the rich biodiversity and intricate species diversity within the genus. The substantial presence of antibiotic-resistance genes in the Providencia genus underscores potential challenges for public health and clinical treatments. Our study highlights the pressing need for increased surveillance and research, enriching our understanding of antibiotic resistance in this realm.

Stenotrophomonas maltophilia: An Urgent Threat with Increasing Antibiotic Resistance.

Stenotrophomonas maltophilia is a Gram-negative opportunistic pathogen that can cause many infections, such as chronic pulmonary infections in patients with cystic fibrosis and infections in immunocompromised patients with hematology-oncology diseases. Because of its remarkable and increasing antimicrobial resistance, the treatment of S. maltophilia infections is quite challenging. Meanwhile, the prevalence of S. maltophilia infections is increasing in recent decades. S. maltophilia is usually considered to be of low virulence but has numerous virulence factors involved in the pathogenesis of infections caused by S. maltophilia. By revealing its pathogenesis associated with virulence factors and molecular mechanisms of antimicrobial resistance, many existing or potential therapeutic strategies have been developed. However, because of the limited treatment options, new strategies are urgently needed. Here, we review the recent progresses in research on S. maltophilia which may help to develop more effective treatments against this increasing threat.

Whole-genome sequencing provides insights into a novel species: Providencia hangzhouensis associated with urinary tract infections.

Providencia rettgeri is a clinically significant opportunistic pathogen that is involved in urinary tract infections. Due to the resolution limitations of identification, distinguishing P. rettgeri from closely related species is challenging by commercial biochemical test systems. Here, we first reported a novel species, Providencia hangzhouensis, which had been misidentified as P. rettgeri. Exhibiting ≤91.97% average nucleotide identity (ANI) and ≤46.10% in silico DNA-DNA hybridization values with all known Providencia species, P. hangzhouensis falls well beneath the established species-defining thresholds. We conducted a population genomics analysis of P. hangzhouensis isolates worldwide. Our study revealed that P. hangzhouensis has emerged in many countries and has formed several transmission clusters. We found that P. hangzhouensis shared the highest ANI values (91.54% and 91.97%) with P. rettgeri and P. huaxiensis, respectively. The pan-genome analysis revealed that these three species possessed a similar component of pan-genomes. Two genes associated with metabolism, folE2 and ccmM, were identified to be specific to P. hangzhouensis. Furthermore, we also observed that carbapenem-resistance genes frequently occur in P. hangzhouensis with the blaIMP-27 being the most prevalent (46.15%; 36/78). The emergence of P. hangzhouensis is often accompanied by extended-spectrum ß-lactamase and carbapenem-resistance genes, and calls for tailored surveillance of this species as a clinically relevant species in the future. IMPORTANCE Our study has identified and characterized a novel species, Providencia hangzhouensis, which is associated with urinary tract infections and was previously misidentified as Providencia rettgeri. Through this study, we have identified specific genes unique to P. hangzhouensis, which could serve as marker genes for rapid PCR identification. Additionally, our findings suggest that the emergence of P. hangzhouensis is often accompanied by extended-spectrum ß-lactamase and carbapenem-resistance genes, emphasizing the need for attention to clinical management and the importance of accurate species identification and proper drug use.

Research progress in laboratory detection of SARS-CoV-2.

BACKGROUND: Nucleic acid testing is a reliable method for diagnosing viral infection in clinical samples. However, when the number of cases is huge and there are individual differences in the virus itself, the probability of false-negative results increases. With the advancement in research on the new coronavirus, new detection technologies that use serum-specific antibodies as detection targets have been developed. These detection technologies have high efficiency and shorter turnaround time, which ultimately shortens the time required for diagnosis. This article summarizes the methods that have been reported to date for the detection of the new coronavirus and discusses their principles and technical characteristics. AIMS: Compare the advantages and disadvantages of various SARS-CoV-2 detection methods and analyze their principles. METHODS: Searched reports on SARS-CoV-2 detection methods published so far, extracted the data and analyzed them. Use the primer blast function of NCBI to analyze the primers used in qRT-PCR detection. RESULTS: The detection sensitivity was the highest when nucleocapsid protein gene was used as the target, reaching 96.6%. The detection efficiency of the remaining targets ranged from 66.7% to 96.0%. Various new detection methods, like Serum specific antibody detection, can speed up the test time. However, due to the complexity of the method and higher testing requirements, it seems that it cannot be used as a complete replacement for qRT-PRC testing. CONCLUSIONS: With the advancement of technology and the improvement of methods, the detection methods of SARSCoV-2 have become more mature. These advances provided great help to the detection of SARS-CoV-2.

Controllable Flowing of a Dielectric Fluid Droplet under the Action of Corona Discharge.

Polymer microfluidic technology is widely used in chemistry, biology, medicine, nanoparticles synthesis, and other fields. In this article, we introduce a novel method for the controllable flowing of dielectric fluid droplets. Under the action of corona discharge, the dielectric fluid droplet can be controllably driven to one or more conductive plate electrodes that are connected to the negative electrode on the substrate. Phenomena of polymerization, migration, and separation and merger are experimentally verified in detail, and the spreading speeds and steady-state time are discussed. The experimental results show that the proposed method is accurate and controllable.

Research progress of circular RNA in digestive tract tumors: a narrative review.

Circular RNA (circRNA) is a newly discovered non-coding RNA with a closed loop structure. The 3' end and the 5' end of circRNA are covalently bonded and not easily degraded by nucleases. Besides, circRNA can exist in eukaryotes widely and conservatively, and it is stably expressed in human liver, brain, lung and other organs. CircRNA can also regulate gene expression by acting on miRNA just like "miRNA sponge". With the deepening of research, growing literature has evidence shows that circRNA is related to tumors closely. For tumors, a large part of malignant ones are gastrointestinal tumors (GIST). In recent years, there are some researches which show that circRNA plays an important role in the occurrence and development, detection and treatment, and prognostic evaluation of malignant tumors of the digestive system. This article summarizes the literature reports on circRNA and GIST since March 2019. From 326 records screened, 79 full text articles were assessed for eligibility and 29 studies met the inclusion criteria. We reviewed the relationship between circRNA and GIST, and its role in the development of tumors. These studies show that in the future, circRNA has the potential to be used as a molecular marker for the detection and treatment of GIST.