Restoring colistin sensitivity in colistin-resistant and : combinatorial use of berberine and EDTA with colistin.

Unlabelled: The appearance and prevalence of multidrug-resistance (MDR) Gram-negative bacteria (GNB) have limited our antibiotic capacity to control bacterial infections. The clinical efficacy of colistin (COL), considered as the "last resort" for treating GNB infections, has been severely hindered by its increased use as well as the emergence and prevalence of mobile colistin resistance (MCR)-mediated acquired drug resistance. Identifying promising compounds to restore antibiotic activity is becoming an effective strategy to alleviate the crisis of increasing MDR.

Upregulation of outer membrane porin gene contributed to enhancement of azithromycin susceptibility in multidrug-resistant .

The outer membrane (OM) in gram-negative bacteria contains proteins that regulate the passive or active uptake of small molecules for growth and cell function, as well as mediate the emergence of antibiotic resistance. This study aims to explore the potential mechanisms for restoring bacteria to azithromycin susceptibility based on transcriptome analysis of bacterial membrane-related genes. Transcriptome sequencing was performed by treating multidrug-resistant T28R with azithromycin or in combination with colistin and confirmed by reverse transcription-quantitative PCR (RT-qPCR).

Synergistic antibacterial activity of baicalin and EDTA in combination with colistin against colistin-resistant Salmonella.

The emergence and rapid spread of multidrug resistant (MDR) Gram-negative bacteria have posed a serious threat to global health and security. Because of the time-consuming, high cost and high risk of developing new antibiotics, a significant method is to use antibiotic adjuvants to revitalize the existing antibiotics. The purpose of the study is to research the traditional Chinese medicine baicalin with the function of inhibiting the efflux pump and EDTA whether their single or combination can increase the activity of colistin against colistin-resistant Salmonella in vitro and in vivo, and to explore its molecular mechanisms.

Characterization of IncI1/ST71 and IncF18:A-:B1 multidrug-resistance plasmids from an avian Escherichia coli isolate.

To characterize IncI1 and IncF18:A-:B1 multidrug-resistance plasmids from an avian Escherichia coli isolate, antibiotic susceptibility testing, conjugation assays, transformation assays, S1-PFGE, and WGS analysis were performed. The 119,457-bp plasmid pEC014-1 with a multidrug-resistance region (MRR) containing four different segments interspersed with six IS26 elements, belonged to incompatibility group I1 and sequence type 71. The 154,516-bp plasmid pEC014-2 with two replicons, typed as FII-18 and FIB-1, carried 14 resistance determinants including bla, bla, oqxAB, dfrA17, aac(6')-Ib-cr, sul1, sul2, tet(A), floR, catB3, hph(aph(4)-Ia), aacC4(aac(3)-IV), aadA5, arr-3, and a merEDACPTR loci in MRR, and additionally encoded three virulence loci: iroNEDCB, sitABCD, and iucABCD-iutA.

Double deletion of cpxR and tolC significantly increases the susceptibility of Salmonella enterica serovar Typhimurium to colistin.

Background: The increasing use of colistin causes a serious breach in our last line of defence against MDR Gram-negative pathogens. Our previous study showed that CpxR overexpression increases the susceptibility of acrB and cpxR double-deleted Salmonella enterica serovar Typhimurium to colistin.

Objectives: To identify the mechanism of CpxAR and efflux pumps that synergistically enhance the susceptibility of S.

The Formation of Two Hybrid Plasmids Mediated by IS and Tn in Serotype .

To characterize the formation mechanism and characteristics of two cointegrate plasmids in serotype strain S13, plasmids from strain S13 and three corresponding transconjugants were subjected to whole genome sequencing and analyzed using bioinformatics tools. The traits of two fusion plasmids in transconjugants were characterized by stability and conjugation experiments. Sequence analysis indicated that strain S13 contained four plasmids, including -bearing pS13-1, -carrying pS13-2, (M)-bearing pS13-3, and -carrying pS13-4.

Characterization of bla-carrying IncC and rmtB-carrying IncI1/ST136 plasmids in an avian Escherichia coli ST224 strain.

To analyze characteristics and underlying evolutionary processes of IncC and IncI1 plasmids in a multidrug-resistant avian E. coli strain, antibiotic susceptibility testing, PCR, conjugation assays, and next-generation sequencing were performed. The type 1 IncC plasmid pEC009.

Molecular Characterization of a Novel Integrative Conjugative Element ICE in .

ICE was identified in the genome of a serovar 8 ST288 isolate YHP170504 from a case of swine lower respiratory tract infection. The aim of the present study was to characterize the integrative conjugative element ICE and its multiresistance region. Susceptibility testing was determined by broth microdilution and the complete ICE was identified by WGS analysis.

Characterization of pTS14, an IncF2:A1:B1 Plasmid Carrying (M) in a Isolate.

The objective of this study was to explore the genetic and biological features of the (M)-harboring plasmid pTS14 in strain S14 isolated from a chicken fecal sample. Plasmid pTS14 was identified by conjugation, S1-pulsed-field gel electrophoresis (PFGE), Southern hybridization, and plasmid sequencing. The biological characteristics of pTS14 were assessed via stability, growth kinetics, and starvation survival experiments.

CpxR regulates the colistin susceptibility of Salmonella Typhimurium by a multitarget mechanism.

Background: The two-component signalling systems PmrAB and PhoPQ of Salmonella have been extensively studied with regard to colistin resistance. We previously showed that overexpressed CpxR could significantly increase the colistin susceptibility (16-fold compared with the WT strain) of Salmonella enterica serovar Typhimurium (Salmonella Typhimurium) through PmrAB and PhoPQ.

Objectives: To identify the potential target genes of CpxR in PmrAB- and PhoPQ-related signalling pathways.

Antimicrobial resistance-encoding plasmid clusters with heterogeneous MDR regions driven by IS26 in a single Escherichia coli isolate.

Background: IS26-flanked transposons played an increasingly important part in the mobilization and development of resistance determinants. Heterogeneous resistance-encoding plasmid clusters with polymorphic MDR regions (MRRs) conferred by IS26 in an individual Escherichia coli isolate have not yet been detected.

Objectives: To characterize the complete sequence of a novel blaCTX-M-65- and fosA3-carrying IncZ-7 plasmid with dynamic MRRs from an E.

IS26-Flanked Composite Transposon Tn6539 Carrying the (M) Gene in IncHI2-Type Conjugative Plasmids From Isolated From Ducks in China.

Tet(M)-type proteins confer resistance to tetracycline and related antibiotics by interacting with the ribosome. Genes encoding Tet(M) have been found in a range of bacteria, including . In the current study, conjugation experiments were performed between seven different tetracycline-resistant, azide-susceptible strains isolated from ducks and tetracycline-sensitive, azide-resistant J53.

CpxR overexpression increases the susceptibility of acrB and cpxR double-deleted Salmonella enterica serovar Typhimurium to colistin.

Background: Colistin has been used as the last therapeutic resort for treatment of MDR Gram-negative bacteria infections in humans. The two-component system CpxAR has been reported to contribute to the MDR of bacteria. There may be a more complex network mediated by CpxAR contributing to colistin susceptibility than previously understood.

Identification and prevalence of RND family multidrug efflux pump oqxAB genes in Enterococci isolates from swine manure in China.

Purpose: The resistance/nodulation/cell division (RND) family multidrug efflux pump, OqxAB, has been identified as one of the leading mechanisms of plasmid-mediated quinolone resistance and has become increasingly prevalent among Enterobacteriaceae in recent years. However, oqxAB genes have not yet been reported in Enterococcus isolates. The aim of the present study was to identify the oqxAB genes and investigate their prevalence among Enterococcus from swine manure in China.

Comparative genomics of rmtB-carrying IncI1 ST136 plasmids in avian escherichia coli isolates from chickens in China.

Eight rmtB-carrying avian Escherichia coli strains from a farm in China were characterised in our previous study, but little is known about the backbones and entire multiresistance regions (MRRs) of these plasmids. Here, three rmtB-carrying IncI1 ST136 plasmids were analysed by whole-plasmid sequencing and were compared. These plasmids were composed of an 83 470-bp IncI1 backbone carrying genes responsible for plasmid replication, transfer, maintenance and stability functions, as well as a 17 330-bp MRR for pEC006 and pEC007, and a 34 626-bp MRR for pEC008.

Novel lnu(G) gene conferring resistance to lincomycin by nucleotidylation, located on Tn6260 from Enterococcus faecalis E531.

Objectives: To identify a novel putative lincosamide resistance gene determinant in a swine Enterococcus faecalis E531 exhibiting a lincosamide resistance/macrolide susceptibility (L R M S ) phenotype and to determine its location and genetic environment.

Methods: The whole genomic DNA of E. faecalis E531, which tested negative for the known lincosamide nucleotidyltransferase genes, was sequenced.

Complete Sequence of pEC012, a Multidrug-Resistant IncI1 ST71 Plasmid Carrying bla CTX-M-65, rmtB, fosA3, floR, and oqxAB in an Avian Escherichia coli ST117 Strain.

A 139,622-bp IncI1 ST71 conjugative plasmid pEC012 from an avian Escherichia coli D-ST117 strain was sequenced, which carried five IS26-bracketed resistance modules: IS26-fosA3-orf1-orf2-Δorf3-IS26, IS26-fip-ΔISEcp1-bla CTX-M-65-IS903D-iroN-IS26, IS26-ΔtnpR-bla TEM-1-rmtB-IS26, IS26-oqxAB-IS26, and IS26-floR-aac(3)-IV-IS26. The backbone of pEC012 was similar to that of several other IncI1 ST71 plasmids: pV408, pM105, and pC271, but these plasmids had different arrangements of multidrug resistance region. In addition, the novel ISEc57 element was identified, which is in the IS21 family.

Characterization of an rmtB-carrying IncI1 ST136 plasmid in avian Escherichia coli isolates from chickens.

The rmtB gene, one of the 16S rRNA methylase genes whose products confer high-level resistance to aminoglycosides, is most prevalent among Enterobacteriaceae strains. In this study, eight non-duplicate rmtB-carrying avian Escherichia coli strains from a farm in China were isolated and characterized, and further examined by phylogenetic grouping, conjugation experiments and PCR-based replicon typing. In addition, the genetic environment of rmtB was investigated by cloning and sequencing.

The complete mitochondrial genome of Archangel pigeon.

The Archangel pigeon mitochondrial DNA has 17,235 bp and its structural organization is conserved compared to those of other birds. In this study, we report the basic characteristics of the Archangel mitochondrial genome, including structural organization and base composition of the rRNAs, tRNAs and protein-coding genes, as well as characteristics of tRNAs. These features are applicable for the study of phylogenetic relationships in pigeons.

Prevalence of tetracycline resistance genes and identification of tet(M) in clinical isolates of Escherichia coli from sick ducks in China.

Tetracycline resistance is one of the most frequently encountered resistance properties in bacteria of animal origin. The aim of the present study was to investigate the prevalence and diversity of tetracycline resistance (tet) genes among Escherichia coli clinical isolates from diseased ducks in China and to report the identification and sequencing of the tet(M) gene. The susceptibility of 85 Escherichia coli strains to tetracyclines was determined by broth microdilution, and the presence of tet genes was investigated by multiplex PCR.

Novel arrangement of the blaCTX-M-55 gene in an Escherichia coli isolate coproducing 16S rRNA methylase.

A multi-drug resistant Escherichia coli C21 was isolated from a chicken in China. It was shown to be positive for the presence of the blaTEM-1, blaCTX-M-55 and rmtB genes by PCR. This strain was examined by phylogenetic grouping, conjugation experiments, plasmid analysis, PCR-based replicon typing and multi-locus sequence typed (MLST).