Antimicrobial Resistance Mechanisms in Carbapenem-Resistant Clinical Strains Isolated in Shanghai, China.

Carbapenems, as the preferred treatment for multidrug-resistant , are increasingly facing issues of insufficient therapeutic efficacy. This study aims to investigate the antimicrobial resistance mechanisms of clinical isolates to carbapenems. The whole genome sequencing revealed various β-lactamase genes, including the intrinsic genes and , as well as the acquired (n = 6), and (n = 10) in 40 carbapenem-resistant (CRPA) isolates.

Molecular Characterization of Carbapenemase Genes in Carbapenem-Resistant Klebsiella pneumoniae Isolates.

Carbapenemase genes play important role in the formation and dissemination of carbapenem-resistant Klebsiella pneumoniae (CRKP). The aim of this study was to investigate the distribution of carbapenemase genes in clinical CRKP isolates. Eighty-three clinical CRKPs were collected and antimicrobial susceptibility testing was conducted.

Analysis of the Class 1 Integrons, Carbapenemase Genes and Biofilm Formation Genes Occurrence in Clinical Isolates.

is a non-fermentative Gram-negative bacterium that can cause nosocomial infections in critically ill patients. Carbapenem-resistant (CRAB) has spread rapidly in clinical settings and has become a key concern. The main objective of this study was to identify the distribution of integrons and biofilm-formation-related virulence genes in CRAB isolates.

Screening Key Sites of Class 2 Integron Integrase that Impact Recombination Efficiency.

By capturing and expressing exogenous resistance gene cassettes through site-specific recombination, integrons play important roles in the horizontal transfer of antimicrobial resistant genes among bacteria. The characteristics of integron integrase make it to be a potential gene editing tool enzyme. In this study, a random mutation library using error-prone PCR was constructed, and amino acid residues mutants that impact on attI2 × attC or attC × attC recombination efficiency were screened and analyzed.

Molecular characterization of class 1 integrons in carbapenem-resistant Enterobacterales isolates.

Objective: Carbapenem-resistant Enterobacterales (CRE) infections result in higher treatment costs and mortality rates. Integrons play important roles in emergence and spread of antibiotic resistant genes. To get a better understand on the effects of integron on CRE resistance, distribution of common carbapenemase genes and class 1 integron in clinical CRE isolates were investigated.

Influence of class 2 integron integrase concentration on gene cassette insertion and excision in vivo.

Integron can capture and express antimicrobial resistance gene cassettes and plays important roles in horizontal gene transfer. The establishment of a complete in vitro reaction system will help to reveal integron integrase mediated site-specific recombination process and regulation mechanism. As an enzymatic reaction, the concentration of integrase is assumed to have a great influence on the reaction rate.

Two-dimensional PCR for detecting class 1, 2 and 3 integrons.

Integrons can capture and express foreign gene cassettes through site-specific recombination and are important genetic elements in spreading antibiotic resistance genes among bacteria. We have developed a two-dimensional PCR technology (2D-PCR) based on the base quenching probe technology in detecting three major integrons at the same time. The minimum detection limits were evaluated by detecting three plasmids each harboring different types of integron with different concentrations.

Comparison of Class 2 Integron Integrase Activities.

Integrons play important roles in the dissemination of antimicrobial resistant genes among bacteria. Class 2 integrons usually has an internal stop codon, TAA, in integrase genes (intI2), leading to a truncated integrase, IntI2*. However, a few class 2 integrons with a natural full-length integrase have been reported.

Characterization of Beta-Lactamases in Bloodstream-Infection : Dissemination of bla and bla Among Bacteria via an IncF Plasmid.

Objectives: To describe the molecular characteristics of beta-lactamases in bloodstream-infection isolated from elderly patients, and to determine the genotypic patterns of and .

Methods: A total of 50 bloodstream-infection isolates were obtained from patients aged > 50 years at Shanghai Sixth People's Hospital South Campus during 2015-2018. The isolates were subjected to beta-lactamase detection using phenotypic and molecular methods.

HIF-1α forms regulatory loop with YAP to coordinate hypoxia-induced adriamycin resistance in acute myeloid leukemia cells.

Despite the improvement in acute myeloid leukemia (AML) treatments, most patients had a poor prognosis and suffered from chemoresistance and disease relapse. Therefore, there is an urgent need for elucidation of mechanism(s) underlying drug resistance in AML. In the present study, we found that AML cells showed less susceptibility to adriamycin (ADR) in the presence of hypoxia, while inhibition of hypoxia-inducible factor 1α (HIF-1α) by CdCl can make AML cells re-susceptibile to ADR even under hypoxia.

Polymorphisms of Gene Cassette Promoters of the Class 1 Integron in Clinical Isolates.

Objective: To describe the polymorphisms of gene cassette promoters of the class 1 integron in clinical isolates and their relationship with antibiotic resistance.

Methods: Polymorphisms of the gene cassette promoter in 153 strains of were analyzed by PCR and nucleotide sequencing. Variable regions of atypical class 1 integrons were detected by inverse PCR and nucleotide sequencing.

Pd -Catalyzed Oxidative Tandem aza-Wacker/Heck Cyclization for the Construction of Fused 5,6-Bicyclic N,O-Heterocycles.

A Pd -catalyzed oxidative tandem cyclization was developed for the construction of fused 5,6-bicyclic N, O-heterocycles. This reaction was enabled by the combined use of a 3-methylpyridine ligand and pentafluorobenzoic acid additive. A range of heterocyclic products with different substituents could be prepared in moderate to good yields via this methodology.

Characterization of aminoglycoside resistance and virulence genes among Enterococcus spp. isolated from a hospital in China.

This study investigated the aminoglycoside resistance phenotypes and genotypes, as well as the prevalence of virulence genes, in Enterococcus species isolated from clinical patients in China. A total of 160 enterococcal isolates from various clinical samples collected from September 2013 to July 2014 were identified to the species level using the VITEK-2 COMPACT system. The antimicrobial susceptibilities of the identified Enterococcus strains were determined by the Kirby-Bauer (K-B) disc diffusion method.

A novel functional class 2 integron in clinical Proteus mirabilis isolates.

Objectives: To describe a novel functional class 2 integron that was found in clinical Proteus mirabilis isolates.

Methods: Class 1 and 2 integrons were screened by PCR in 153 clinical Proteus isolates. The variable regions of class 1 and 2 integrons were determined by restriction analysis and sequencing.

Diversity of gene cassette promoter variants of class 1 integrons in uropathogenic Escherichia coli.

Class 1 integrons play important roles in the emergence and horizontal transfer of antibiotic resistance genes among bacteria. The gene cassette promoter variants Pc or Pc-P2 of class 1 integrons not only drive the transcription of downstream gene cassettes, they also correlate with the excision and integration efficiency of the capture exogenous gene cassettes. In this study, the diversity of Pc or Pc-P2 variants of class 1 integrons and their association with antibiotic resistance phenotypes were analyzed in 132 uropathogenic Escherichia coli strains.

Expression and purification of SenX3 from the Mycobacterium tuberculosis strain H37Rv in Escherichia coli.

Infection with the bacterium Mycobacterium tuberculosis (MTB) causes tuberculosis, a pulmonary infection that may be fatal if left untreated. Misuse or mismanagement of tuberculosis drugs may lead to drug-resistant pathogen forms that are difficult to treat and contribute to a global health problem. The MTB SenX3/RegX3 signal transduction system allows bacteria to externally sense the environment and mediate an appropriate internal response; SenX3 is also associated with MTB virulence, suggesting that this protein may provide a potential therapeutic target.

Transcription of integron-harboured gene cassette impacts integration efficiency in class 1 integron.

Class 1 integrons play important roles in the dissemination of antibiotic resistance genes among bacteria. Generally, class 1 integron consists of an integrase gene (intI1), a recombination site (attI1) and a promoter (Pc) that drives the transcription of the downstreamed gene cassettes. Occasionally, there is a second promoter P2 downstream of the Pc promoter.

The pheV phenylalanine tRNA gene Klebsiella pneumoniae clinical isolates is an integration hotspot for possible niche-adaptation genomic islands.

Horizontally acquired genomic islands may allow bacteria to conquer and colonize previously uncharted niches. Four Klebsiella pneumoniae tRNA gene insertion hotspots (arg6, asn34, met56, and pheV) in 101 clinical isolates derived from blood, sputum, wound, bile or urine specimens were screened by long-range PCR for the presence or absence of integrated islands. The pheV phenylalanine tRNA gene was the most frequently occupied site and harbored at least three entirely distinct types of islands: (1) KpGI-1, a 3.

A novel and rapid method for determining integration frequency catalyzed by integron integrase intI1.

We developed a faster and more convenient method to determine integration frequency mediated by integron integrase intI1. This method based on real-time fluorescent quantitative PCR. By using this method, we revealed that the integration frequency of aadA2 gene cassette was 1.