ObjectiveTo investigate the risk factors for pyogenic liver abscess （PLA） comorbid with sepsis by analyzing clinical features， and to construct a predictive model. MethodsA retrospective analysis was performed for 489 patients who were hospitalized and diagnosed with PLA in The Affiliated Hospital of Xuzhou Medical University from January 2019 to December 2023， and according to the presence or absence of sepsis， they were divided into sepsis group with 306 patients and non-sepsis group with 183 patients. Related data were collected， including general information， laboratory markers， and outcome measures. The patients were further divided into a training set of 342 patients and a validation set of 147 patients at a ratio of 7∶3， and the training set was used for screening of variables and construction of a predictive model， while the validation set was used to test the performance of the model. An LASSO regression analysis was used for the screening of variables， and a multivariate Logistic regression analysis was used to construct the predictive model and plot a nomogram. The calibration curve， the receiver operating characteristic （ROC） curve， and the decision curve analysis were used for the validation of the model， and internal validation was performed for assessment. The independent-samples t test was used for comparison of normally distributed continuous data between two groups， and the Mann-Whitney U test was used for comparison of non-normally distributed continuous data between two groups； the chi-square test was used for comparison of categorical variables between groups. ResultsThere were significant differences between the sepsis group and the non-sepsis group in pulse rate， mean arterial pressure， duration pf symptoms， comorbidity of liver cirrhosis or malignant tumor， leukocyte count， neutrophil count， lymphocyte count， platelet count （PLT）， activated partial thromboplastin time， fibrinogen， C-reactive protein， aspartate aminotransferase， alanine aminotransferase， albumin， total bilirubin （TBil）， creatinine， potassium， and prognostic nutritional index （PNI） （all P<0.05）. In the training set， the LASSO regression analysis identified four predictive factors of pulse rate， PLT， TBil and PNI， and the multivariate Logistic regression analysis showed that pulse rate （odds ratio ［OR］=1.033， 95% confidence interval ［CI］： 1.006‍ ‍—‍ ‍1.061， P=0.018）， PLT （OR=0.981， 95%CI： 0.975‍ ‍—‍ ‍0.987， P<0.001）， TBil （OR=1.086， 95%CI： 1.053‍ ‍—‍ ‍1.125， P<0.001）， and PNI （OR=0.935， 95%CI： 0.882‍ ‍—‍ ‍0.988， P=0.019） were independent influencing factors for the risk of sepsis in patients with PLA. The model constructed based on these factors showed a good predictive ability， with an area under the ROC curve of 0.948 （95%CI： 0.923‍ ‍—‍ ‍0.973） in the training set and 0.912 （95%CI： 0.848‍ ‍—‍ ‍0.976） in the validation set. The decision curve analysis showed that the model has a good net benefit within the range of 0.3‍ ‍—‍ ‍0.9 for threshold probability. ConclusionThe nomogram prediction model constructed based on pulse rate， PLT， TBil， and PNI has a certain clinical value and can well predict the risk of sepsis in patients with PLA.

Objective:To report the results of national surveillance on the distribution and antimicrobial resistance profile of clinical Gram-negative bacteria isolates from bloodstream infections in China in 2022.Methods:The clinical isolates of Gram-negative bacteria from blood cultures in member hospitals of national bloodstream infection Bacterial Resistant Investigation Collaborative System（BRICS）were collected during January 2022 to December 2022. Antibiotic susceptibility tests were conducted by agar dilution or broth dilution methods recommended by Clinical and Laboratory Standards Institute（CLSI）. WHONET 5.6 and SPSS 25.0 software were used to analyze the data.Results:During the study period，9 035 strains of Gram-negative bacteria were collected from 51 hospitals，of which 7 895（87.4%）were Enterobacteriaceae and 1 140（12.6%）were non-fermenting bacteria. The top 5 bacterial species were Escherichia coli（ n=4 510，49.9%）， Klebsiella pneumoniae（ n=2 340，25.9%）， Pseudomonas aeruginosa（ n=534，5.9%）， Acinetobacter baumannii complex（ n=405，4.5%）and Enterobacter cloacae（ n=327，3.6%）. The ESBLs-producing rates in Escherichia coli， Klebsiella pneumoniae and Proteus spp. were 47.1%（2 095/4 452），21.0%（427/2 033）and 41.1%（58/141），respectively. The prevalence of carbapenem-resistant Escherichia coli（CREC）and carbapenem-resistant Klebsiella pneumoniae（CRKP）were 1.3%（58/4 510）and 13.1%（307/2 340）；62.1%（36/58）and 9.8%（30/307）of CREC and CRKP were resistant to ceftazidime/avibactam combination，respectively. The prevalence of carbapenem-resistant Acinetobacter baumannii（CRAB）complex was 59.5%（241/405），while less than 5% of Acinetobacter baumannii complex was resistant to tigecycline and polymyxin B. The prevalence of carbapenem-resistant Pseudomonas aeruginosa（CRPA）was 18.4%（98/534）. There were differences in the composition ratio of Gram-negative bacteria in bloodstream infections and the prevalence of main Gram-negative bacteria resistance among different regions，with statistically significant differences in the prevalence of CRKP and CRPA（ χ2=20.489 and 20.252， P<0.001）. The prevalence of CREC，CRKP，CRPA，CRAB，ESBLs-producing Escherichia coli and Klebsiella pneumoniae were higher in provinicial hospitals than those in municipal hospitals（ χ2=11.953，81.183，10.404，5.915，12.415 and 6.459， P<0.01 or <0.05），while the prevalence of CRPA was higher in economically developed regions（per capita GDP ≥ 92 059 Yuan）than that in economically less-developed regions（per capita GDP <92 059 Yuan）（ χ2=6.240， P=0.012）. Conclusions:The proportion of Gram-negative bacteria in bloodstream infections shows an increasing trend，and Escherichia coli is ranked in the top，while the trend of CRKP decreases continuously with time. Decreasing trends are noted in ESBLs-producing Escherichia coli and Klebsiella pneumoniae. Low prevalence of carbapenem resistance in Escherichia coli and high prevalence in CRAB complex have been observed. The composition ratio and antibacterial spectrum of bloodstream infections in different regions of China are slightly different，and the proportion of main drug resistant bacteria in provincial hospitals is higher than those in municipal hospitals.

Objective To analyze the resistance mechanism,characteristics of drug sensitivity,and homology of polymyxin resistant Escherichia coli,and provide molecular epidemiological basis for the effective prevention and control of its outbreak and epidemic.Methods The strains of polymyxin resistant Escherichia coli isolated from our hospital during May 2016 and June 2022 were collected.The PCR technology was used to screen for the mobile colistin resistance(MCR)gene and the micro broth dilution method was used to determine the minimum inhibitory concentration.The clinical data of the patients were collected.The homology of the collected strains was analyzed by the pulsed field gel electrophoresis(PFGE).One of the strains was performed whole genome sequencing.Results Four strains of polymyxin resistant Escherichia coli carrying the MCR-1 gene were isolated and identified.Except for being sensitive to tigecycline,all four strains showed varying degrees of resistance to the vast majority of clinically common antibiotics.Clinical data showed that no polymyxin was used in the patients with polymyxin resistant Escherichia coli.The four strains of bacteria could be divided into two types,including three strains of type A and one strain of type B.The whole genome sequencing analysis of one of the bacteria revealed that the MCR-1 gene was located on a plasmid with a size of 70 kb.Conclusion The Escherichia coli carrying the MCR-1 gene has a potential threat to clone transmission and exhibits high resistance to common antibiotics in clinical practice,posing a serious challenge to clinical treatment.Therefore,it is necessary to strengthen protective measures to prevent its outbreak and epidemic.

Objective:To report the results of national surveillance on the distribution and antimicrobial resistance profile of clinical Gram-positive bacteria isolates from bloodstream infections in China in 2022.Methods:The clinical isolates of Gram-positive bacteria from blood cultures in member hospitals of National Bloodstream Infection Bacterial Resistant Investigation Collaborative System（BRICS）were collected during January 2022 to December 2022. Antibiotic susceptibility tests were conducted by agar dilution or broth dilution methods recommended by Clinical and Laboratory Standards Institute（CLSI）. WHONET 5.6 and SPSS 25.0 software were used to analyze the data.Results:A total of 3 163 strains of Gram-positive pathogens were collected from 51 member units，and the top five bacteria were Staphylococcus aureus（ n=1 147，36.3%），coagulase-negative Staphylococci（ n=928，29.3%）， Enterococcus faecalis（ n=369，11.7%）， Enterococcus faecium（ n=296，9.4%）and alpha-hemolyticus Streptococci（ n=192，6.1%）. The detection rates of methicillin-resistant Staphylococcus aureus（MRSA）and methicillin-resistant coagulase-negative Staphylococci（MRCNS）were 26.4%（303/1 147）and 66.7%（619/928），respectively. No glycopeptide and daptomycin-resistant Staphylococci were detected. The sensitivity rates of Staphylococcus aureus to cefpirome，rifampin，compound sulfamethoxazole，linezolid，minocycline and tigecycline were all >95.0%. Enterococcus faecium was more prevalent than Enterococcus faecalis. The resistance rates of Enterococcus faecium to vancomycin and teicoplanin were both 0.5%（2/369），and no vancomycin-resistant Enterococcus faecium was detected. The detection rate of MRSA in southern China was significantly lower than that in other regions（ χ2=14.578， P=0.002），while the detection rate of MRCNS in northern China was significantly higher than that in other regions（ χ2=15.195， P=0.002）. The detection rates of MRSA and MRCNS in provincial hospitals were higher than those in municipal hospitals（ χ2=13.519 and 12.136， P<0.001）. The detection rates of MRSA and MRCNS in economically more advanced regions（per capita GDP≥92 059 Yuan in 2022）were higher than those in economically less advanced regions（per capita GDP<92 059 Yuan）（ χ2=9.969 and 7.606， P=0.002和0.006）. Conclusions:Among the Gram-positive pathogens causing bloodstream infections in China， Staphylococci is the most common while the MRSA incidence decreases continuously with time；the detection rate of Enterococcus faecium exceeds that of Enterococcus faecalis. The overall prevalence of vancomycin-resistant Enterococci is still at a low level. The composition ratio of Gram-positive pathogens and resistant profiles varies slightly across regions of China，with the prevalence of MRSA and MRCNS being more pronounced in provincial hospitals and areas with a per capita GDP≥92 059 yuan.

Objective:To investigate the bacterial distribution of secondary infection and the status of drug resistance in hospitalized patients of hematology department.Methods:The clinical data of 1 125 inpatients in the Hematology Department of the Affiliated Hospital of Xuzhou Medical University from January 2015 to December 2019 were retrospectively analyzed, and the distribution of infectious pathogens and the status of drug resistance of these inpatients were analyzed.Results:A total of 9 335 microbial samples from 1 125 inpatients were submitted for examination, among which 1 349 were positive samples. Among 1 349 positive samples, the gram-negative bacteria-positive samples accounted for 66.4% (895/1 349) and the gram-positive bacteria-positive samples accounted for 33.7% (454/1 349); the blood samples accounted for 44.7%(603/1 349), the sputum samples accounted for 33.9% (457/1 349), and the urine samples accounted for 9.4%(127/1 349). The isolated bacteria whose proportion ranked as the top 3 were Escherichia coli (31.0%), Staphylococcus aureus (21.0%) and Klebsiella pneumoniae (18.0%). The drug resistance rate of Escherichia coli to ceftriaxone was as high as 77.2%, and that of Staphylococcus aureus and coagulase-negative Staphylococcus to benzoxicillin was 58.2% and 66.7%, but both had no resistance to vancomycin.Conclusions:There are a wide variety of infectious pathogens in hospitalized patients of hematology department, and the Escherichia coli and Klebsiella pneumonia are predominant. More attention should be paid to antibiotic prescribing training for clinicians to optimize and standardize the use of antibiotics.

Objective: To investigate the clinical and microbiological characteristics of Myroides odoratimimus producing MUS-1 carbapenemase. Methods: A strain of gram-negative bacterium isolated from the urine sample of one patient hospitalized in the oncology department of Affiliated Hospital of Xuzhou Medical University was identified by the Vitek 2 automatic microbial analyzer and 16S RNA sequencing, and its bla MUS-1 gene was detected with PCR. The minimum inhibitory concentrations (MICs) of antimicrobial drugs were determined by the broth dilution method. Results: One strain of MUS-1 carbapenemase producing Myroides odoratimimus was found. The drug susceptibility test showed that it was resistant to most of antibiotics conventionally used, but sensitive to minocycline and meropenem, the MIC of imipenem was 8 μg/mL, which was judged as intermediate. Conclusion The bla MUS-1 gene may be the cause leading Myroides odoratimimus to resistant carbapenems drugs.

Objective To understand the prevalence of resistance gene and homology of carbapenem-resistant Klebsiella pneumoniae (CRKP) isolated from ICU of emergency.Methods A total of 19 CRKP isolates were obtained from emergency ICU of the Affiliated Hospital of Xuzhou Medical University from July 2015 to August 2016.PCR was performed to screen the genes encoding carbapenemase,extended spectrum beta-lactamase (ESBL) and AmpC.Pulsed field gel electrophoresis (PFGE) and multi-locus sequence typing (MLST) were used for molecular typing of these bacterial strains.Results Among the 19 CRKP,carbapenemase-resistant genes were detectable in 18 CRKP isolates,including 17 isolates of harboring blaKPC gene and 1 strain of harboring blaNDM gene.All the 18 strains carried ESBLs genes which were identified as 8 blaSHV-12,3 blaSHV-11,5 blaSHV-2a,15 blaTEM-1,10 blaCTX-M-65,3 blaCTX-M-15,1 blaCTX-M-14 and 1 blaCTX-M-27.The 13 strains harboring cephalosporin-resistant genes were all identified as blaDHA-1.PFGE results revealed that the 19 CRKP strains were grouped into 4 types (A,B,C and D) and 4 subtypes(A1,2,3 and 4):A1 (n =12),A2(n =1),A3 (n=1),A4(n=1),B(n=2),C(n=1) and D(n=1).MLST showed that ST11 was the predominant sequence type (n=15) among the 19 CRKP strains,and ST48 (n =2),ST37 (n =1) and untyped (n =1) were also identified.The 15 blaKPC-2-producing CRKP ST11 clone shared the A type of PFGE pattern.Conclusion The report on CRKP suggested the dissemination of blaKPC-2-producing ST11 clone was existed in the ICU of emergency department in this hospital.The surveillance for drug-resistance and effective disinfectant quarantine measures should be strengthened.

Objective To identify the drug resistance-related genes in a clinically isolated strain of Enterobacter cloacae.Methods A strain of Enterobacter cloacae was isolated from sputum of a patient with chronic obstructive pulmonary disease from the Affiliated Hospital of Xuzhou Medical University in March 2013.Modified Hodge test and metal enzyme inhibition test were performed for drug-resistant phenotype screening.Carbapenemase genes blaMUS-1, blaVIM-1, blaVIM-2, blaIMP, blaKPC-2, blaNDM-1, blaOXA-48 and blaGESwere amplified by polymerase chain reaction (PCR), and the positive products were sequenced and analyzed.Plasmid conjugation and transformation experiments were used to confirm that the resistance gene mediated by plasmids.Agar dilution method was used for antibiotic susceptibility test.Results Both modified Hodge test and metal enzyme inhibition test were positive in this strain of Enterobacter cloacae.blaNDM-1 gene and blaKPC-2 gene were detected by PCR, and further confirmed by sequencing.blaNDM-1 gene was carried by IncX plasmid with 54×103 bp, KPC-2 gene was carried by untyping plasmid with 42×103 bp.The strain was only sensitive to tetracycline (MIC=2 μg/mL) and tigecycline (MIC=1 μg/mL).The symptoms were improved after the patient was treated by tigecycline combined with Piperacillin/Tazobactam.Conclusion blaNDM-1 and blaKPC-2 genes in Enterobacter cloacae can be mediated by plasmids, and appropriate therapy for its infection should be based on the result of antibiotic susceptibility test.

Objective To evaluate the applicationof the double-disk synergy test(DDST) and combined disk test(CDT) in clini cal metal enzyme phenotype deteetion.To evaluate the value of multiplex PCR in detecting the metallo-β-1actamase in clinical.Methods 56 strains of metallo-β-1actamase-positive strains were identified [NDM-1(n=9),VIM(n=32),IMP(n=15)]for appraise the two methods.By optimizing the design of PCR primers,3 pairs of primers were designed and detected (IMP,VIM,NDM-1) in one tube for evaluate the method.Results The DDST was 80.36％(45/56),and 100.00％(56/56) in the CDT.The accuracy of multiplex PCR was 100.00 ％ (56/56),and the size of the amplified fragment was used to distinguish three types of metallo-β-lactamase.Conclusion The CDT is more suitable for clinical application than DDST.Multiplex PCR has the characteristics of simple,rapid and accurate in detection of metallo-β-1actamase.It is suitable for daily use of clinical microbiological laboratory,which will help the clinical timely and effective administration.

Objective To investigate the mechanism related to reduced antibiotic sensitivity of Acinetobacter baumannii inducted by meropenem in vitro.Methods Three strains of clinically isolated carbapenems-sensitive Acinetobacter baumannii were induced by meropenem in vitro, and the mutant strains (MS1, MS2 and MS3) were obtained.Minimal inhibitory concentrations (MICs) of antimicrobial agents to strains before and after induction were determined by automatic drug sensitivity analyzer .The homology of strains was analyzed by Enterobacterial repetitive intergenic consensus -polymerase chain reaction ( ERIC-PCR).Modified Hodge test and EDTA-Na2-double disk synergy test were used to detect carbapenemase and metallo-β-lactamase (MBL), respectively.Main carbapenemase genes were detected by PCR and followed by DNA sequencing.Expressions of adeB and outer membrane proteins in strains before and after induction were detected with fluorescence quantitative PCR and SDS -polyacrylamide gel electrophoresis , respectively.t test was used for data analysis .Results The sensitivity of mutant Acinetobacter baumannii strains to meropenem and most antibiotics was reduced , except to imipenem, amikacin and polymyxin; and the reduced sensitivity to meropenem in MS2 and MS3 was of genetic stability.ERIC-PCR showed 100%homology between the mutant strains and parental strains .Both carbapenemase and metallo -β-lactamase were negative in mutant strains and parental strains , and only OXA-51 gene was found.The expressions of adeB gene in mutant strains were 24.26 ±0.91, while those in parental strains were 22.81 ±0.38, and the difference was not significant (t =2.534, P >0.05).Outer membrane protein with molecular weight 54 000 was missing in MS1, while that with molecular weight 47 000 was missing in MS2 and MS3.Conclusion Reduced antibiotics sensitivity in meropenem -induced Acinetobacter baumannii may be correlated with the deficiency of outer membrane protein with molecular weight 47 000.