Iron is an essential element for living organisms that plays critical roles in the process of bacterial growth and metabolism. However, it remains to be elucidated whether piuB encoding iron-uptake factor is involved in iron uptake and pathogenicity of Xanthomonas axonopodis pv. glycines (Xag). To investigate the function of piuB, we firstly generated a piuB deletion mutant (ΔpiuB) by homologous recombination. Compared with the wild-type, the piuB mutant exhibited significantly reduced growth and virulence in host soybean. The mutant displayed markedly increased siderophore secretory volume, and its sensitivity to Fe³⁺, Cu²⁺, Zn²⁺ and Mn²⁺ was significantly enhanced. Additionally, the H₂O₂ resistance, exopolysaccharide yield, biofilm formation, and cell mobility of ΔpiuB were significantly diminished compared to that of the wild-type. The addition of exogenous Fe³⁺ cannot effectively restore the above characteristics of ΔpiuB. However, expressing piuB in trans rescued the properties lost by ΔpiuB to the levels in the wild-type. Taken together, our results demonstrated that PiuB is a potential factor for Xag to assimilate Fe³⁺, and is necessary for Xag to be pathogenic in host soybean.
Iron ; Glycine max ; Virulence ; Xanthomonas axonopodis/genetics* ; Hydrogen Peroxide

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 investigate the distribution and antimicrobial resistance profiles of the common pathogens isolated from urine from 2015 to 2021 in the CHINET Antimicrobial Resistance Surveillance Program.Methods The bacterial strains were isolated from urine and identified routinely in 51 hospitals across China in the CHINET Antimicrobial Resistance Surveillance Program from 2015 to 2021.Antimicrobial susceptibility was determined by Kirby-Bauer method,automatic microbiological analysis system and E-test according to the unified protocol.Results A total of 261 893 nonduplicate strains were isolated from urine specimen from 2015 to 2021,of which gram-positive bacteria accounted for 23.8％(62 219/261 893),and gram-negative bacteria 76.2％(199 674/261 893).The most common species were E.coli(46.7％),E.faecium(10.4％),K.pneumoniae(9.8％),E.faecalis(8.7％),P.mirabilis(3.5％),P.aeruginosa(3.4％),SS.agalactiae(2.6％),and E.cloacae(2.1％).The strains were more frequently isolated from inpatients versus outpatients and emergency patients,from females versus males,and from adults versus children.The prevalence of ESBLs-producing strains in E.coli,K.pneumoniae and P.mirabilis was 53.2％,52.8％and 37.0％,respectively.The prevalence of carbapenem-resistant strains in E.coli,K.pneumoniae,P.aeruginosa and A.baumannii was 1.7％,18.5％,16.4％,and 40.3％,respectively.Lower than 10％of the E.faecalis isolates were resistant to ampicillin,nitrofurantoin,linezolid,vancomycin,teicoplanin and fosfomycin.More than 90％of the E.faecium isolates were ressitant to ampicillin,levofloxacin and erythromycin.The percentage of strains resistant to vancomycin,linezolid or teicoplanin was＜2％.The E.coli,K.pneumoniae,P.aeruginosa and A.baumannii strains isolated from ICU inpatients showed significantly higher resistance rates than the corresponding strains isolated from outpatients and non-ICU inpatients.Conclusions E.coli,Enterococcus and K.pneumoniae are the most common pathogens in urinary tract infection.The bacterial species and antimicrobial resistance of urinary isolates vary with different populations.More attention should be paid to antimicrobial resistance surveillance and reduce the irrational use of antimicrobial agents.

Objective To understand the distribution and changing resistance profiles of clinical isolates of Enterococcus in hospitals across China from 2015 to 2021.Methods Antimicrobial susceptibility testing was conducted for the clinical isolates of Enterococcus according to the unified protocol of CHINET program by automated systems,Kirby-Bauer method,or E-test strip.The results were interpreted according to the Clinical & Laboratory Standards Institute(CLSI)breakpoints in 2021.WHONET 5.6 software was used for statistical analysis.Results A total of 124 565 strains of Enterococcus were isolated during the 7-year period,mainly including Enterococcus faecalis(50.7％)and Enterococcus faecalis(41.5％).The strains were mainly isolated from urinary tract specimens(46.9％±2.6％),and primarily from the patients in the department of internal medicine,surgery and ICU.E.faecium and E.faecalis strains showed low level resistance rate to vancomycin,teicoplanin and linezolid(≤3.6％).The prevalence of vancomycin-resistant E.faecalis and E.faecium was 0.1％and 1.3％,respectively.The prevalence of linezolid-resistant E.faecalis increased from 0.7％in 2015 to 3.4％in 2021,while the prevalence of linezolid-resistant E.faecium was 0.3％.Conclusions The clinical isolates of Enterococcus were still highly susceptible to vancomycin,teicoplanin,and linezolid,evidenced by a low resistance rate.However,the prevalence of linezolid-resistant E.faecalis was increasing during the 7-year period.It is necessary to strengthen antimicrobial resistance surveillance to effectively identify the emergence of antibiotic-resistant bacteria and curb the spread of resistant pathogens.

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 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.

OBJECTIVETo explore the changes in HBsAg titer and HBV DNA load and their correlation in patients with chronic hepatitis B (CHB) and HBV-related liver cirrhosis (HBV-LC).

METHODSForty-six patients with mild to moderate CHB (CHB-LM), 24 patients with severe CHB (CHB-S), and 28 patients with HBV-LC at admission, and 51 patients with HBV-LC at 4.08 ± 3.06 months during antiviral treatment were tested for serum HBsAg titer and HBV DNA load using Abbott chemiluminescence and fluorescence quantitative PCR, respectively.

RESULTSThe serum HBsAg titer and HBV DNA load gradually decreased with increased disease severity (from CHB-LM, CHB-S to HBV-LC; χ(2)=12.537 and 8.381, respectively, P<0.05). HBsAg titer and HBV DNA load were significantly higher in CHB-LM and CHB-S groups than in HBV-LC group (P<0.05), but comparable between CHB-LM and CHB-S groups (Z=-0.649 and 0.032, respectively, P>0.05). Among HBeAg-positive patients, HBsAg titer and HBV DNA load tended to decrease with increased disease severity (from CHB-LM, CHB-S to HBV-LC; χ(2)=6.146, P=0.046 and χ(2)=1.017, P>0.05; respectively), and CHB-LM group had significantly higher HBsAg titer than HBV-LC group (Z=-2.247, P=0.025). Among the HBeAg-negative patients, serum HBsAg and HBV DNA load gradually declined with the disease severity (χ(2)=8.660 and 13.581, respectively, P<0.05), and were obviously higher in CHB-LM and CHB-S groups than in HBV-LC group (P<0.05). Positive correlations were found between serum HBsAg and HBV DNA levels in CHB-LM (r=0.389, P=0.009) and HBV-LC groups (r=0.431, P=0.022), but not in CHB-S group (r=0.348, P=0.104). After antiviral therapy, the serum HBsAg titer was slightly decreased (Z=-1.050, P=0.294) while HBV DNA load markedly reduced (Z=-5.415, P<0.001), showing no correlation between them (r=0.241, P=0.111) or between the measurements before and after treatment (r=0.257, P=0.085).

CONCLUSIONSerum HBsAg titer and HBV DNA load decreases progressively from CHB-LM to CHB-S and HBV-LC in both HBeAg- positive and -negative patients. The serum HBsAg titer is positively correlated with HBV DNA load, but their levels are not consistently parallel.

Antiviral Agents ; therapeutic use ; DNA, Viral ; blood ; Hepatitis B Surface Antigens ; blood ; Hepatitis B, Chronic ; blood ; Humans ; Liver Cirrhosis ; blood ; virology ; Viral Load

Objective To explore the changes in HBsAg titer and HBV DNA load and their correlation in patients with chronic hepatitis B (CHB) and HBV-related liver cirrhosis (HBV-LC). Methods Forty-six patients with mild to moderate CHB (CHB-LM), 24 patients with severe CHB (CHB-S), and 28 patients with HBV-LC at admission, and 51 patients with HBV-LC at 4.08± 3.06 months during antiviral treatment were tested for serum HBsAg titer and HBV DNA load using Abbott chemiluminescence and fluorescence quantitative PCR, respectively. Results The serum HBsAg titer and HBV DNA load gradually decreased with increased disease severity (from CHB-LM, CHB-S to HBV-LC;χ2=12.537 and 8.381, respectively, P<0.05). HBsAg titer and HBV DNA load were significantly higher in CHB-LM and CHB-S groups than in HBV-LC group (P<0.05), but comparable between CHB-LM and CHB-S groups (Z=-0.649 and 0.032, respectively, P>0.05). Among HBeAg-positive patients, HBsAg titer and HBV DNA load tended to decrease with increased disease severity (from CHB-LM, CHB-S to HBV-LC;χ2=6.146, P=0.046 andχ2=1.017, P>0.05;respectively), and CHB-LM group had significantly higher HBsAg titer than HBV-LC group (Z=-2.247, P=0.025). Among the HBeAg-negative patients, serum HBsAg and HBV DNA load gradually declined with the disease severity (χ2=8.660 and 13.581, respectively, P<0.05), and were obviously higher in CHB-LM and CHB-S groups than in HBV-LC group (P<0.05). Positive correlations were found between serum HBsAg and HBV DNA levels in CHB-LM (r=0.389, P=0.009) and HBV-LC groups (r=0.431, P=0.022), but not in CHB-S group (r=0.348, P=0.104). After antiviral therapy, the serum HBsAg titer was slightly decreased (Z=-1.050, P=0.294) while HBV DNA load markedly reduced (Z=-5.415, P<0.001), showing no correlation between them (r=0.241, P=0.111) or between the measurements before and after treatment (r=0.257, P=0.085). Conclusion Serum HBsAg titer and HBV DNA load decreases progressively from CHB-LM to CHB-S and HBV-LC in both HBeAg- positive and-negative patients. The serum HBsAg titer is positively correlated with HBV DNA load, but their levels are not consistently parallel.

Objective To explore the changes in HBsAg titer and HBV DNA load and their correlation in patients with chronic hepatitis B (CHB) and HBV-related liver cirrhosis (HBV-LC). Methods Forty-six patients with mild to moderate CHB (CHB-LM), 24 patients with severe CHB (CHB-S), and 28 patients with HBV-LC at admission, and 51 patients with HBV-LC at 4.08± 3.06 months during antiviral treatment were tested for serum HBsAg titer and HBV DNA load using Abbott chemiluminescence and fluorescence quantitative PCR, respectively. Results The serum HBsAg titer and HBV DNA load gradually decreased with increased disease severity (from CHB-LM, CHB-S to HBV-LC;χ2=12.537 and 8.381, respectively, P<0.05). HBsAg titer and HBV DNA load were significantly higher in CHB-LM and CHB-S groups than in HBV-LC group (P<0.05), but comparable between CHB-LM and CHB-S groups (Z=-0.649 and 0.032, respectively, P>0.05). Among HBeAg-positive patients, HBsAg titer and HBV DNA load tended to decrease with increased disease severity (from CHB-LM, CHB-S to HBV-LC;χ2=6.146, P=0.046 andχ2=1.017, P>0.05;respectively), and CHB-LM group had significantly higher HBsAg titer than HBV-LC group (Z=-2.247, P=0.025). Among the HBeAg-negative patients, serum HBsAg and HBV DNA load gradually declined with the disease severity (χ2=8.660 and 13.581, respectively, P<0.05), and were obviously higher in CHB-LM and CHB-S groups than in HBV-LC group (P<0.05). Positive correlations were found between serum HBsAg and HBV DNA levels in CHB-LM (r=0.389, P=0.009) and HBV-LC groups (r=0.431, P=0.022), but not in CHB-S group (r=0.348, P=0.104). After antiviral therapy, the serum HBsAg titer was slightly decreased (Z=-1.050, P=0.294) while HBV DNA load markedly reduced (Z=-5.415, P<0.001), showing no correlation between them (r=0.241, P=0.111) or between the measurements before and after treatment (r=0.257, P=0.085). Conclusion Serum HBsAg titer and HBV DNA load decreases progressively from CHB-LM to CHB-S and HBV-LC in both HBeAg- positive and-negative patients. The serum HBsAg titer is positively correlated with HBV DNA load, but their levels are not consistently parallel.