Objective To monitor the susceptibility of clinical isolates to antimicrobial agents in tertiary hospitals in major regions of China in 2022.Methods Clinical isolates from 58 hospitals in China were tested for antimicrobial susceptibility using a unified protocol based on disc diffusion method or automated testing systems.Results were interpreted using the 2022 Clinical &Laboratory Standards Institute(CLSI)breakpoints.Results A total of 318 013 clinical isolates were collected from January 1,2022 to December 31,2022,of which 29.5％were gram-positive and 70.5％were gram-negative.The prevalence of methicillin-resistant strains in Staphylococcus aureus,Staphylococcus epidermidis and other coagulase-negative Staphylococcus species(excluding Staphylococcus pseudintermedius and Staphylococcus schleiferi)was 28.3％,76.7％and 77.9％,respectively.Overall,94.0％of MRSA strains were susceptible to trimethoprim-sulfamethoxazole and 90.8％of MRSE strains were susceptible to rifampicin.No vancomycin-resistant strains were found.Enterococcus faecalis showed significantly lower resistance rates to most antimicrobial agents tested than Enterococcus faecium.A few vancomycin-resistant strains were identified in both E.faecalis and E.faecium.The prevalence of penicillin-susceptible Streptococcus pneumoniae was 94.2％in the isolates from children and 95.7％in the isolates from adults.The resistance rate to carbapenems was lower than 13.1％in most Enterobacterales species except for Klebsiella,21.7％-23.1％of which were resistant to carbapenems.Most Enterobacterales isolates were highly susceptible to tigecycline,colistin and polymyxin B,with resistance rates ranging from 0.1％to 13.3％.The prevalence of meropenem-resistant strains decreased from 23.5％in 2019 to 18.0％in 2022 in Pseudomonas aeruginosa,and decreased from 79.0％in 2019 to 72.5％in 2022 in Acinetobacter baumannii.Conclusions The resistance of clinical isolates to the commonly used antimicrobial agents is still increasing in tertiary hospitals.However,the prevalence of important carbapenem-resistant organisms such as carbapenem-resistant K.pneumoniae,P.aeruginosa,and A.baumannii showed a downward trend in recent years.This finding suggests that the strategy of combining antimicrobial resistance surveillance with multidisciplinary concerted action works well in curbing the spread of resistant bacteria.

Objective To examine the changing antimicrobial resistance profile of Enterobacter spp.isolates in 53 hospitals across China from 2015 t0 2021.Methods The clinical isolates of Enterobacter spp.were collected from 53 hospitals across China during 2015-2021 and tested for antimicrobial susceptibility using Kirby-Bauer method or automated testing systems according to the CHINET unified protocol.The results were interpreted according to the breakpoints issued by the Clinical & Laboratory Standards Institute(CLSI)in 2021(M100 31st edition)and analyzed with WHONET 5.6 software.Results A total of 37 966 Enterobacter strains were isolated from 2015 to 2021.The proportion of Enterobacter isolates among all clinical isolates showed a fluctuating trend over the 7-year period,overall 2.5％in all clinical isolates amd 5.7％in Enterobacterale strains.The most frequently isolated Enterobacter species was Enterobacter cloacae,accounting for 93.7％(35 571/37 966).The strains were mainly isolated from respiratory specimens(44.4±4.6)％,followed by secretions/pus(16.4±2.3)％and urine(16.0±0.9)％.The strains from respiratory samples decreased slightly,while those from sterile body fluids increased over the 7-year period.The Enterobacter strains were mainly isolated from inpatients(92.9％),and only(7.1±0.8)％of the strains were isolated from outpatients and emergency patients.The patients in surgical wards contributed the highest number of isolates(24.4±2.9)％compared to the inpatients in any other departement.Overall,≤ 7.9％of the E.cloacae strains were resistant to amikacin,tigecycline,polymyxin B,imipenem or meropenem,while ≤5.6％of the Enterobacter asburiae strains were resistant to these antimicrobial agents.E.asburiae showed higher resistance rate to polymyxin B than E.cloacae(19.7％vs 3.9％).Overall,≤8.1％of the Enterobacter gergoviae strains were resistant to tigecycline,amikacin,meropenem,or imipenem,while 10.5％of these strains were resistant to polycolistin B.The overall prevalence of carbapenem-resistant Enterobacter was 10.0％over the 7-year period,but showing an upward trend.The resistance profiles of Enterobacter isolates varied with the department from which they were isolated and whether the patient is an adult or a child.The prevalence of carbapenem-resistant E.cloacae was the highest in the E.cloacae isolates from ICU patients.Conclusions The results of the CHINET Antimicrobial Resistance Surveillance Program indicate that the proportion of Enterobacter strains in all clinical isolates fluctuates slightly over the 7-year period from 2015 to 2021.The Enterobacter strains showed increasing resistance to multiple antimicrobial drugs,especially carbapenems over the 7-year period.

Objective To understand the changing distribution and antimicrobial resistance profiles of Proteus,Morganella and Providencia in hospitals across China from January 1,2015 to December 31,2021 in the CHINET Antimicrobial Resistance Surveillance Program.Methods Antimicrobial susceptibility testing was carried out following the unified CHINET protocol.The results were interpreted in accordance with the breakpoints in the 2021 Clinical & Laboratory Standards Institute(CLSI)M100(31 st Edition).Results A total of 32 433 Enterobacterales strains were isolated during the 7-year period,including 24 160 strains of Proteus,6 704 strains of Morganella,and 1 569 strains of Providencia.The overall number of these Enterobacterales isolates increased significantly over the 7-year period.The top 3 specimen source of these strains were urine,lower respiratory tract specimens,and wound secretions.Proteus,Morganella,and Providencia isolates showed lower resistance rates to amikacin,meropenem,cefoxitin,cefepime,cefoperazone-sulbactam,and piperacillin-tazobactam.For most of the antibiotics tested,less than 10％of the Proteus and Morganella strains were resistant,while less than 20％of the Providencia strains were resistant.The prevalence of carbapenem-resistant Enterobacterales(CRE)was 1.4％in Proteus isolates,1.9％in Morganella isolates,and 15.6％in Providencia isolates.Conclusions The overall number of clinical isolates of Proteus,Morganella and Providencia increased significantly in the 7-year period from 2015 to 2021.The prevalence of CRE strains also increased.More attention should be paid to antimicrobial resistance surveillance and rational antibiotic use so as to prevent the emergence and increase of antimicrobial resistance.

Objective To understand the changing distribution and antimicrobial resistance profiles of Klebsiella strains in 52 hospitals across China in the CHINET Antimicrobial Resistance Surveillance Program from 2015 to 2021.Methods Antimicrobial susceptibility testing was carried out according to the unified CHINET protocol.The susceptibility results were interpreted according to the breakpoints in the Clinical & Laboratory Standards Institute(CLSI)M100 document.Results A total of 241,549 nonduplicate Klebsiella strains were isolated from 2015 to 2021,including Klebsiella pneumoniae(88.0％),Klebsiella aerogenes(5.8％),Klebsiella oxytoca(5.7％),and other Klebsiella species(0.6％).Klebsiella strains were mainly isolated from respiratory tract(48.49±5.32)％.Internal medicine(22.79±3.28)％,surgery(17.98±3.10)％,and ICU(14.03±1.39)％were the top 3 departments where Klebsiella strains were most frequently isolated.K.pneumoniae isolates showed higher resistance rate to most antimicrobial agents compared to other Klebsiella species.Klebsiella isolates maintained low resistance rates to tigecycline and polymyxin B.ESBLs-producing K.pneumoniae and K.oxytoca strains showed higher resistance rates to all the antimicrobial agents tested compared to the corresponding ESBLs-nonproducing strains.The K.pneumoniae and carbapenem-resistant K.pneumoniae(CRKP)strains isolated from ICU patients demonstrated higher resistance rates to majority of the antimicrobial agents tested than the strains isolated from non-ICU patients.The CRKP strains isolated from adult patients had higher resistance rates to most of the antimicrobial agents tested than the corresponding CRKP strains isolated from paediatric patients.Conclusions The prevalence of carbapenem-resistant strains in Klebsiella isolates increased greatly from 2015 to 2021.However,the Klebsiella isolates remained highly susceptible to tigecycline and polymyxin B.Antimicrobial resistance surveillance should still be strengthened for Klebsiella strains.

Objective To investigate the changing distribution and antibiotic resistance profiles of clinical isolates of Staphylococcus in hospitals across China from 2015 to 2021.Methods Antimicrobial susceptibility testing was conducted for the clinical isolates of Staphylococcus according to the unified protocol of CHINET(China Antimicrobial Surveillance Network)using disk diffusion method and commercial automated systems.The CHINET antimicrobial resistance surveillance data from 2015 to 2021 were interpreted according to the 2021 CLSI breakpoints and analyzed using WHONET 5.6.Results During the period from 2015 to 2021,a total of 204,771 nonduplicate strains of Staphylococcus were isolated,including 136,731(66.8％)strains of Staphylococcus aureus and 68,040(33.2％)strains of coagulase-negative Staphylococcus(CNS).The proportions of S.aureus isolates and CNS isolates did not show significant change.S.aureus strains were mainly isolated from respiratory specimens(38.9±5.1)％,wound,pus and secretions(33.6±4.2)％,and blood(11.9±1.5)％.The CNS strains were predominantly isolated from blood(73.6±4.2)％,cerebrospinal fluid(12.1±2.5)％,and pleural effusion and ascites(8.4±2.1)％.S.aureus strains were mainly isolated from the patients in ICU(17.0±7.3)％,outpatient and emergency(11.6±1.7)％,and department of surgery(11.2±0.9)％,whereas CNS strains were primarily isolated from the patients in ICU(32.2±9.7)％,outpatient and emergency(12.8±4.7)％,and department of internal medicine(11.2±1.9)％.The prevalence of methicillin-resistant strains was 32.9％in S.aureus(MRSA)and 74.1％in CNS(MRCNS).Over the 7-year period,the prevalence of MRSA decreased from 42.1％to 29.2％,and the prevalence of MRCNS decreased from 82.1％to 68.2％.MRSA showed higher resistance rates to all the antimicrobial agents tested except trimethoprim-sulfamethoxazole than methicillin-susceptible S.aureus(MSSA).Over the 7-year period,MRSA strains showed decreasing resistance rates to gentamicin,rifampicin,and levofloxacin,MRCNS showed decreasing resistance rates to gentamicin,erythromycin,rifampicin,and trimethoprim-sulfamethoxazole,but increasing resistance rate to levofloxacin.No vancomycin-resistant strains were detected.The prevalence of linezolid-resistant MRCNS increased from 0.2％to 2.3％over the 7-year period.Conclusions Staphylococcus remains the major pathogen among gram-positive bacteria.MRSA and MRCNS were still the principal antibiotic-resistant gram-positive bacteria.No S.aureus isolates were found resistant to vancomycin or linezolid,but linezolid-resistant strains have been detected in MRCNS isolates,which is an issue of concern.

Objective To study the effect of amino acid site variation of HIV-1 Nef protein on its inhibition of neuronal autophagy and explore the mechanism of Nef protein-induced central nervous system injury.Methods HIV-1 nef genes were amplified and cloned from the temporal cortex (TC) of the central nervous system in 1 case of HIV-associated dementia (HAD) H and 1 case of non-HAD AIDS patient N.The amino acid sequences were aligned by NCBI BLAST tools and MEGA6.0 software to study the variation of amino acid sites.The eukaryotic expression vectors pEGFP-N1-nef derived from H-TC and N-TC were constructed and transfected into U87 cells to observe green fluorescence.At the same time,the expression of Nef protein,LC3-Ⅱ and p62 protein in U87 cells were detected by Western blot,and the effects of different sources of Nef on autophagy of U87 cells were analyzed.Results The nef genes were amplified by PCR and clone vectors pMD-19T-nef of H-TC and N-TC were successfully constructed.The sequencing confirmed that they were HIV-1B subtypes.The amino acid sequence analysis showed that there were differences between H-TC and N-TC key amino acid sites.The recombinant plasmid pEGFP-N1-nefwas successfully constructed and expressed Nef protein in U87 cells.Western blot analysis showed that the expression of LC3-Ⅱ protein was significantly different among groups (F =11.764,P =0.001).There was no significant difference in the expression of LC3-Ⅱ between cell control and plasmid control(P=0.169).The content of LC3-Ⅱ was low in the two groups of cells,which could not be detected by Western blot.The expression of LC3-Ⅱ in H-TC,N-TC and positive control CQ group increased,compared with blank control or blank vector.The difference was statistically significant (P=0.017,P=0.039,P=0.031),and the expression of LC3-Ⅱ in H-TC group was higher than that in N-TC group (P =0.023);the expression of p62 protein in H-TC,N-TC and positive control CQ group was higher than that in blank control or blank vector group,but there was no significant difference between groups (F=2.049,P =0.163).Conclusions HIV-1 Nef amino acid sites in the central nervous system of patients with HAD and non-HAD were different,and their effects on autophagy of U87 cells were different.The expression of LC3-Ⅱ,an autophagic marker protein,was more strongly induced by Nef from H-TC.

Objective:To analyze the differential expression of silent information regulator transcript-1 (SIRT1) in tissues and cells of nasopharyngeal carcinoma (NPC), to explore the effects of SIRT1 on the proliferation and migration of NPC cells, as well as the effects on and mechanisms of lipid metabolism in NPC cells.Methods:Experimental subjects: In this study, tissue specimens were obtained from patients who visited the Department of Otolaryngology and performed nasopharyngeal tissue biopsy in the Affiliated Hospital of Nantong University from 2019 to 2020. Among them, 6 cases were male, 6 cases were female, age range: 27-72 years old, including 7 cases of NPC diagnosed by pathology and 5 cases of normal nasopharyngeal mucosa. Experimental methods and outcome measures: Western Blot and quantitative real time polymerase chain reaction (qRT-PCR) were used to detect the protein and mRNA levels of SIRT1. CNE2 cell line was selected for subsequent experiments. Cell viability and migratory ability were evaluated by CCK8, wound healing and Transwell assays respectively. Animal xenograft tumor model was used to explore the role of SIRT1 inhibitor Ex527 on tumor growth in nude mice. Oil red and Bodipy were used to stain intracellular lipids. For the mechanical investigation, the interactions between SIRT1 and hypoxia inducible factor-1α (HIF-1α) were analyzed by immunoprecipitation (IP) and chromatin immunoprecipitation (ChIP). Finally, statistical analysis was performed by SPSS 26.0 software, P<0.05 was considered statistically significant. Results:The levels of SIRT1 protein (1.005±0.168) and mRNA (5.829±2.395) in NPC tissues were higher than those in normal nasopharyngeal mucosa (0.181±0.042,1.995±1.605). Differences were statistically significant ( t values were 6.438 and 2.759, both P<0.05). The mRNA and protein levels of CNE1, CNE2, 5-8F and 6-10B cell lines were also higher than those in normal nasopharynx epithelial cell line NP69. Besides, overexpression of SIRT1 correlated with the proliferation and migration of NPC cells. The tumorigenesis ability of nude mice in the Ex527 group was lower than that in the control group. The low SIRT1 expression reduced the protein level of the key enzymes of liposynthesis in NPC cells, improved the expression of lipolysis enzymes, while HIF-1α overexpression promoted lipid synthesis enzymes in NPC cells. SIRT1 inhibited HIF-1α transcription by enhancing deacetylation levels. The binding ability of HIF-1α to SIRT1 promoter regions decreased when NPC cells were hypoxic. Conclusions:SIRT1 promotes the proliferation, migration and lipid metabolism of nasopharyngeal carcinoma cells, which might be expected to provide new theoretical basis for prognosis judgment and gene therapy.

Objective: To investigate the toxic effect of HIV-1 Vpr protein on neurons. Methods: HIV-1 vpr gene was amplified by nested PCR in four parts of peripheral spleen (SPL) and central nervous tissue meninges (MG) of HIV-associated dementia (HAD) patients and non-HAD patients. Eukaryotic expression vector pEGFP-N1-vpr was constructed. The gene sequence and key amino acid sites were analyzed by BLAST and MEGA6. The expression of Vpr protein in N2a cells was detected by Western-blotting. The effects of Vpr proteins from different sources on the activity and cell cycle of N2a cells were studied by flow cytometry. Results: HIV-1 vpr gene was successfully amplified by PCR. Sequence analysis showed that the vpr gene sequence belonged to HIV-1B subtype. There were amino acid mutations at C-terminal 84, 86 and 87 sites of central Vpr protein from HAD and non-HAD patients. Vpr protein could inhibit the activity of nerve cells, leading to G2 phase arrest. Different sources of Vpr had different intensity of action. Compared with other groups, Vpr protein from the meninges of HAD patients showed stronger inhibition of cell activity and G2 phase arrest ability. Conclusions Variations in key amino acid sites of Vpr protein could cause significant changes in its biological functions, and its significance in the pathogenesis of HAD remains to be further studied.

Objective: To study the sequence characteristics and variation of HIV-1 Vpr gene in different parts of an AIDS dementia complex (ADC) patient and provide basis for the study of the neurologic pathogenesis of HIV-1-assciatd dementia. Methods: Genomic DNA was extracted from peripheral samples (lymph nodes, spleen, liver) and central nervous system (meninges, frontal lobe, temporal lobe gray matter, frontal white matter, basal ganglia cortex) of an ADC patient, The Vpr gene was amplified with nested polymerase chain reaction (PCR). PCR products were cloned into the pMD19-T vector. After transformation into DH5α competent E. coli, five positive clones were sequenced. The phylogenetic tree was built and genetic distance was calculated through MEGA6, and the values of ds/dn was calculated through SNAP, then the changes of the amino acid sites were analyzed. Results: HIV-1 Vpr genes isolated from different tissues of the ADC patient had variations. Vpr HIV-1 gene sequences from central nervous system and peripheral tissues were intercrossed together in the phylogenetic tree. Central nervous system and peripheral HXB2 Vpr had no significant differences in genetic distance. The ds/dn of all the HIV-1 Vpr gene sequences were 3.3749. Conclusions The HIV-1 Vpr sequences were different in the ADC patient, and there were different variations in different parts of the peripheral and central regions. Whether these variations are related to the pathogenesis of ADC remains to be further studied.

Objective: BG-derived HIV-1 Tat protein from an HIV-associated dementia (HAD) patient was expressed in E. coli BL21(DE3) and purified in order to research the effects on human umbilical vein endothelial cells (HUVECs) activity. Methods: The recombinant plasmid pGEX-KG-tat with HIV-1 tat stored in our laboratory was amplified by PCR. The PCR product was cloned into pET-32a-tat. The recombinant plasmid pET-32a-tat was transfected into E. coli, and Tat protein was expressed in BL21(DE3), which was induced by IPTG. Then it was purified by Ni-chelating chromatography column and gel filtration preloaded column, and identified by SDS-PAGE and Western blot(WB). The concentration was determined by BCA Kit. Different concentrations of Tat were added into HUVECs to detect their effects on cell activity by cck-8. Results: The Tat with high purity was efficiently expressed in BL21 (DE3) and obtained by using the Ni-chelating chromatography column and gel filtration preloaded column. The concentration was 0.47 mg/ml by using BCA Kit. As the concentration of Tat increased, HUVECs activity decreased. There was no significant difference in cells viability between negative control with 100 ng/ml and 200 ng/ml group (P>0.05). There was significant difference in cells viability between negative control with 300 ng/ml, 400 ng/ml, 500 ng/ml and 1000 ng/ml group (P<0.05). But the difference between 300 ng/ml, 400 ng/ml, 500 ng/ml and 1000 ng/ml group was not statistically significant (P>0.05). Conclusions The HIV-1 Tat with biological activity was efficiently expressed in BL21 (DE3), and the activity of HUVECs was significantly decreased when the concentration reached 300 ng/ml.