Objective:To study the risk factors and the molecular epidemiology characteristics for Carbapenem-resistant Enterobacteriaceae(CRE) colonization in neonatal inpatients in Shenzhen region, China, which provide reference for the prevention and control of clinical CRE infection.Methods:This study is a prospective case-control study.Anal samples from inpatients between January 2023 and December 2023 at Longgang Maternity and Child Institute of Shantou University Medical College and Shenzhen Children's Hospital were collected for screening CRE strain. Drug susceptibility test, modified Carbapenem Inactivation Method (mCIM) test, drug resistance-related gene sequencing and multilocus sequence typing (MLST) were performed for isolated CRE strains.Meanwhile, the clinical data were collected for analyzing the risk factors of CRE intestinal colonization by multivariate regression analysis.Results:A total of 1 517 patients were screened, 26 CRE(1.7%, 26/1 517) were identified which including 14 Escherichia coli(53.8%, 14/26), 11 Klebsiella pneumoniae(42.3%, 11/26), 1 Enterobacter cloacae(3.9%, 1/26). The predominant carbapenemase gene was New Delhi Metallo(NDM) (92.4%, 24/26), followed by Imipenem (IMP) (3.8%, 1/26) and Guiana extended spectrum gene (GES) (3.8%, 1/26).Among the carried NDM resistance genes, New Delhi Metallo 5 (NDM5) was the main one, accounting for 84.6% (22/26).The MLST typing of Escherichia coli was mainly Sequence Type 48 (ST48) (6/14), while that of Klebsiella pneumoniae was mainly Sequence Type 35 (ST35) (10/11). All CRE isolates were resistant to penicillin, penicillinase inhibitors, cephalosporins, ertapenem and imipenem.The resistance rates of Escherichia coli to amikacin, levofloxacin was 1/14, 4/14, respectively. All isolates of Klebsiella pneumoniae were sensitive to amikacin, and the resistance rate to levofloxacin is 1/11. Risk factors for CRE colonization include the older age, length of hospital stay, tracheal intubation, invasive respiration, lumbar puncture, Apgar <7 score, and exposure to antibiotics.Conclusions:NDM5 is the predominant resistant gene in CRE isolated from neonatal patients feces in Shenzhen region.It is necessary to strengthen the screening of CRE colonization in neonate for prevention and control of CRE infection.

Objective:To study the risk factors and the molecular epidemiology characteristics for Carbapenem-resistant Enterobacteriaceae(CRE) colonization in neonatal inpatients in Shenzhen region, China, which provide reference for the prevention and control of clinical CRE infection.Methods:This study is a prospective case-control study.Anal samples from inpatients between January 2023 and December 2023 at Longgang Maternity and Child Institute of Shantou University Medical College and Shenzhen Children's Hospital were collected for screening CRE strain. Drug susceptibility test, modified Carbapenem Inactivation Method (mCIM) test, drug resistance-related gene sequencing and multilocus sequence typing (MLST) were performed for isolated CRE strains.Meanwhile, the clinical data were collected for analyzing the risk factors of CRE intestinal colonization by multivariate regression analysis.Results:A total of 1 517 patients were screened, 26 CRE(1.7%, 26/1 517) were identified which including 14 Escherichia coli(53.8%, 14/26), 11 Klebsiella pneumoniae(42.3%, 11/26), 1 Enterobacter cloacae(3.9%, 1/26). The predominant carbapenemase gene was New Delhi Metallo(NDM) (92.4%, 24/26), followed by Imipenem (IMP) (3.8%, 1/26) and Guiana extended spectrum gene (GES) (3.8%, 1/26).Among the carried NDM resistance genes, New Delhi Metallo 5 (NDM5) was the main one, accounting for 84.6% (22/26).The MLST typing of Escherichia coli was mainly Sequence Type 48 (ST48) (6/14), while that of Klebsiella pneumoniae was mainly Sequence Type 35 (ST35) (10/11). All CRE isolates were resistant to penicillin, penicillinase inhibitors, cephalosporins, ertapenem and imipenem.The resistance rates of Escherichia coli to amikacin, levofloxacin was 1/14, 4/14, respectively. All isolates of Klebsiella pneumoniae were sensitive to amikacin, and the resistance rate to levofloxacin is 1/11. Risk factors for CRE colonization include the older age, length of hospital stay, tracheal intubation, invasive respiration, lumbar puncture, Apgar <7 score, and exposure to antibiotics.Conclusions:NDM5 is the predominant resistant gene in CRE isolated from neonatal patients feces in Shenzhen region.It is necessary to strengthen the screening of CRE colonization in neonate for prevention and control of CRE infection.

Objective To investigate the infection status and drug resistance of urogenital tract mycoplasma in Lianyungang district,Jiangsu.Methods Based on retrospective collection of 22 889 cases of suspected mycoplasma genital infection in Lianyungang Mater-nity and Child Health Hospital from 2015 to 2022,the infection and drug resistance rate of genital mycoplasma were analyzed.Results A total of 8 943 genital mycoplasma positive specimens were detected.Among them,the infection rate of Ureaplasma urealyticum(Uu)was the highest,accounting for 33.64％(7 700/22 889),which was significantly higher than that of Mycoplasma hominis(Mh),3.91％(894/22 889),and that of mixed(Uu+Mh)type,1.52％(349/22 889).The difference was statistically significant(P＜0.05).The infection rates of genital mycoplasma and Uu showed increasing trend from 2015 to 2022.The overall infection rates of genital mycoplasma in females were 42.42％,which was significantly higher than that in males of 22.47％.The highest infection rate of 40.84％(6 108/14 955)was found in the group of 20 to 40 years old as compared to those younger than 20 years old as well as those over 40 years old.The genital mycoplasma was highly sensitive to doxycycline,minocycline and josamycin,and the drug resistance rate was lower than 5.00％.From 2015 to 2022,there was an increasing trend of resistance rates to erythromycin,ofloxacin and ciprofloxa-cin in Uu-infected patients(P＜0.05)and erythromycin,roxithromycin,azithromycin and ofloxacin in Mh-infected patients(P＜0.05).Conclusion The incidence of urogenital tract mycoplasma infection in Lianyungang district shows a gradual increase for recent years.Doxycycline,minocycline and josamycin are suitable as the first choice for the treatment of genital mycoplasma infection.Most quinolo-ne drugs have shown high resistance rate,indicating that this type of drugs are possibly overused.The strengthened relevant monitoring of antibacterial drugs should be necessary.

Objective:To investigate the multilocus sequence typing feature of the virulence-associated genes of Staphylococcus aureus(S. aureus) separated from the clinical specimens of a multi-center cohort children in Guangzhou area. Methods:A total number of 412 Staphylococcus aureus strains isolated from 2 059 non-repeated fecal specimens of children by three groups′ researchers in Guangzhou Women and Children′s Medical Center from August 2018 to November 2018. While collecting specimens, patient clinical information is also properly collected and preserved. After extracting the DNA of the strain, the virulence-associated genes were detected by polymerase chain reaction (PCR), including the staphylococcal enterotoxin (SE) genes ( sea, seb, sec, sed, see) and the Panton-Valentine leucocidin-encoding gene ( pvl).The multi-locus sequence typing (MLST) method was performed to reveal the MLST feature of these genes and the statistical difference were examined by the the χ 2 test. Results:Among the 412 isolates of S. aureus, 256 strains (256/412, 62.1%) contains at least one SE gene. Among the enterotoxin gens, the sec (125/412, 30.3%), seb(98/412, 23.8%)and sea (66/412, 16.0%)genes were the three most prevalent members of SEs. The frequency of pvl gene in Staphylococcus aureus was 18.7%(77/412).Among them, the frequency of Staphylococcus aureus sea gene isolated from patients with gastroenteritis (58/319, 18.2%) was significantly higher than that from the non-gastroenteritis group (8/93, 8.6%)(χ2=4.912, P=0.027). The frequency of Staphylococcus aureus pvl gene isolated from the patients with pneumonia (8/21, 38.1%) was greater than that from the non-pneumonia group (6/47, 12.8%)(χ2=4.252, P=0.039). In addition, the virulence-associated gene of S. aureus was closely related to the specific ST type, 82.4% (28/34) of ST6 carried sea gene, all ST338 and ST59 carried seb gene, 96% (48/50) ST45 carried sec gene, and the pvl gene carrying rate of ST338 was 5/5. Conclusions:The SEA toxin produced by ST6 Staphylococcus aureus may be closely related to the diagnosis of gastroenteritis in children. The frequency of pvl virulence gene in Staphylococcus aureus in children with community-acquired pneumonia was higher than that in the non-pneumonia group, and closely related to the CC59.

Objective:To investigate the antiviral efficacy of direct-acting antiviral agents (DAAs) in the treatment of liver transplantation (LT) recipients with hepatitis C virus (HCV) infection.Methods:Twenty-two HCV-infected LT recipients treated with DAAs at Fifth Medical Center of Chinese PLA General Hospital from December 2014 to June 2018 were retrospectively analyzed, Twenty cases of HCV RNA gene type 1b were treated with sofosbuvir (400 mg/d) + ledipasvir (90 mg/d) or sofosbuvir (400 mg/d) + daclatasvir (60 mg/d) for 12 weeks or 24 weeks; 2 cases of gene type 2a were treated with sofosbuvir (400 mg/d) for 12 weeks. The effect of antiviral treatment, adverse reactions during treatment, and laboratory indicators such as HCVRNA quantification, blood routine, liver and kidney function during treatment and follow-up were studied.Results:The LT recipients of HCV infection included 16 males and 6 females, with a median age of 61.5 (36-71) years old, and the median time of antiviral treatment was 48 (2-117) months after transplantation. Among the 22 patients, 16 received a 12-week course of treatment. Except for 2 patients who did not get HCVRNA negative conversion at 4-week, all achieved a negative HCV RNA at 4-week and the end of the treatment. Six LT recipients received a 24-week course of treatment (gene type 1b), and HCVRNA was negative at 4-week and the end of treatment. All patients achieved end of treatment virological response and a sustained virological response (SVR) rate of 100% at 12 weeks and 24 weeks after the end of treatment. The serum levels of alanine aminotransferase (ALT) and creatinine were 71.5 (30, 110) U/L and (89.4±25.7) mmol/L before treatment, respectively. ALT decreased to 22 (17.8, 28.5) U/L after 4 weeks of treatment, and serum creatinine decreased to (77.4±11.5) mmol/L at 24 weeks after the end of treatment. The differences before and after treatment were statistically significant (all P<0.05). No serious adverse events occurred during the treatment. Conclusions:DAAs have a definite antiviral effect in the treatment of LT recipients with HCV infection, and long-term SVR can be obtained.

ObjectiveTo investigate the risk factors for tumor recurrence and death after liver transplantation in patients with hepatocellular carcinoma (HCC) and their survival. MethodsThe patients with HCC who underwent liver transplantation in The Fifth Medical Center of Chinese PLA General Hospital from January 2005 to February 2019 were enrolled, and according to the presence or absence of HCC recurrence after liver transplantation, they were divided into recurrence group and non-recurrence group. The t-test or the Mann-Whitney U test was used for comparison of continuous data between two groups, and the chi-square test was used for comparison of categorical data between two groups. Univariate and multivariate Cox proportional-hazards regression model analyses were used to determine the risk factors for HCC recurrence and death after liver transplantation. The Kaplan-Meier method was used for survival analysis, and the receiver operating characteristic (ROC) curve was used to investigate the predictive value of death-related risk factors after liver transplantation. ResultsA total of 391 HCC patients who underwent liver transplantation were enrolled, with a median follow-up time of 2 years, among whom 78(19.95%) experienced HCC recurrence. Preoperative alpha-fetoprotein (AFP) level＞200 ng/ml (recurrence: hazard ratio ［HR］=252, 95% confidence interval ［CI］: 1.58-4.03, P＜0.001; death: HR=2.99, 95%CI: 1.59-5.62, P＜0.001］, total tumor diameter (recurrence: HR=1.20, 95%CI: 1.12-1.28, P＜0.001; death: HR=1.10, 95%CI: 1.02-1.17, P=0.002), and vascular invasion (recurrence: HR=1.15, 95%CI: 1.04-1.26, P=0.016; death: HR=1.10, 95%CI: 1.03-1.18, P=0.004) were independent risk factors for tumor recurrence and death after liver transplantation. The 1-, 5-, and 10-year overall survival rates after liver transplantation were 94.8%, 84.2%, and 83.5%, respectively, and the 1-, 5-, and 10-year disease-free survival rates were 840%, 75.1%, and 75.1%, respectively. AFP, involvement of major blood vessels, body mass index, and total tumor diameter had a certain value in predicting the death of HCC patients with recurrence, with an area under the ROC curve of 0.789 (95% CI: 0.719-0858). ConclusionTumor biological features before transplantation are the key factors for tumor recurrence after transplantation.

Objective: To explore the inhibitory effect of exosomes secreted by human umbilical cord mesenchymal stem cells(HUCMSC) on apoptosis of human umbilical vein endothelial cells(HUVEC) after model group(oxygen-glucose deprivation reoxygenation), and to clarify its possible mechanism. Methods: Human umbilical cord mesenchymal stem cells were cultured. The collected cell supernatant was stored in a centrifugal tube. The exosomes secreted by human umbilical cord mesenchymal stem cells were extracted by ultracentrifugation and identified. Human umbilical vein endothelial cells were randomly divided into control group, model group and different concentrations of HUCMSC-EXO(20 μg/ml, 40 μg/ml, 60 μg/ml) treatment groups(adding HUCMSC-EXO into the model group) . The morphological changes of HUVEC cells in each group were observed by inverted phase contrast microscope, and the proliferation inhibition rate of HUVEC in each group was measured by CCK-8 reagent. Western blot was used to detect the expression of apoptosis-related proteins Caspase-3, Bax, Bcl-2 and hypoxia-associated protein hypoxia inducible factor 1α(HIF-1α). Inhibitor(HIF-1α inhibitor) + model group and HUCMSC-EXO + inhibitor + model group were added on the basis of the above experiments. Western blot analysis was performed to observe the effects of HUCMSC-EXO, inhibitor and both of them on HIF-1α and Bax expressions in HUVEC. Results: HUCMSC-EXO was successfully extracted and identified. Compared with the control group, the volume of HUVEC in the model group and the HUCMSC-EXO group with different concentrations decreased, became round, connected and evacuated, and the growth state was poor under the inverted phase contrast microscope.CCK-8 detection showed that the cell viability in the HUCMSC-EXO group was significantly higher than that in the model group, the difference was statistically significant (t=9.23, P<0.05). Western blot analysis showed that compared with the control group, the expression levels of Caspase-3 ((0.296±0.038), (0.879±0.088); t=14.92, P<0.05), Bax((0.234±0.034), (0.762±0.084); t=14.36, P<0.05) of HUVEC in the model group were up-regulated, and the expression level of Bcl-2 was down-regulated ((0.863±0.103), (0.387±0.059); t=9.85, P<0.05), with statistically significant differences. Compared with the model group, the expression levels of Caspase-3( (0.586±0.075); t=6.24, P<0.05), Bax((0.311±0.055); t=11.01, P<0.05) and Bcl-2((0.665±0.071); t=7.45, P<0.05) of HUVEC in the HUCMSC-EXO treatment group were down-regulated and the differences were statistically significant. Inhibitor intervention experiments showed that there were no significant differences between the inhibitor+ model group and HUCMSC-EXO+ inhibitor+ model group in the expression of HIF-1α protein ((0.348±0.055), (0.388±0.077); t=1.04, P>0.05)and Bax protein ((0.363±0.069), (0.370±0.064); t=0.18, P>0.05). But both of them were down-regulated compared with the model group (HIF-1α protein (0.919±0.064), Bax protein (0.902±0.071)), the differences were significant( t=13.56, t=13.03, both P<0.05). Conclusion HUCMSC-EXO has a protective effect on OGD/R model of HUVEC, and its mechanism may be related to the down-regulation of HIF-1α expression.

Objective To explore the sample type and drug resistance characteristics of Streptococcus pneu-monia(Spn)isolated from pediatric patients in Guangzhou district,and their age distribution to offer instruc-tions for prevention and clinical treatment.Methods Spn isolates were cultured and identified according to the national standard procedure for clinical laboratory operation,followed by analysis of sample type and age dis-tribution of pediatric patients with positive isolates of Spn in Guangzhou Women and Children′s Medical Cen-ter from 2013 Jan 1st to 2015 Dec 31st,drug resistance status was determined by MIC test.Results Totally, 1 243 strains of Spn were isolated,which were mainly from pediatric patients under 1 year old(42.80%).Spn isolates were mainly isolated from respiratory tract(72.81%),ear secretions(15.37%),blood(5.63%),cere-brospinal fluid(3.06%)and hydrothorax(2.01%).For all Spn isolates,the resistance rate to erythromycin, tetracycline and sulfamethoxazole was especially high as 94.93%,85.76%,73.53% respectively,with relative high resistance to penicillin G(24.70%),amoxicillin(39.59%),ceftriaxone(24.05%),meropenem(22.85%) and cefotaxime(19.89%),low resistance to quinolone antibiotics(<10.00%),and no resistance to vancomycin and linezolid.Conclusion The major age group of children with Spn infection is infants under one year old in Guangzhou,clinicians should be serious about the high resistant rate of Spn to erythromycin,tetracycline and sulfamethoxazole,the significantly increased resistant rate to penicillin,amoxicillin and ceftriaxone.Clinicians should choose antibiotics rationally according to the characteristics of drug sensitivity for better treatment.

Objective To establish and optimize a loop-mediated isothermal amplification (LAMP) method for the rapid detection of Escherichia coli and its microbial toxin.Methods The LAMP reaction system and reaction conditions were determined by optimizing LAMP reaction,and the optimized LAMP system was used for the detection.Results Primers targeting shiga toxin (stx) gene and O157 antigen gene rfbe were designed.The established and optimized LAMP amplification system contained 1.2 mmol/L dNTPs,10 mmol/L MgSO4,0.4 mol/L betaine,1 μl 10 × Bst DNA polymerase Buffer,8 U Bst DNA polymerase fragment,2 μl DNA template,and the ratio of inner-primer (FIP and BIP) and outerprimer (F3 and B3) were 8∶ 1.Time and temperature for LAMP was 60 min,60 ℃.The sensitivity was 103 times higher than polymerase chain reaction (PCR),reached 5 × 101 CFU/ml.When LAMP was applied to 19 reference strains,102 EHEC strains,the specification was 100％ while identification rate of rfbe,stx1 and stx2 gene reached 100％,95.2％,92.9％.Conclusions The LAMP method showed a promising prospect for the rapid detection of common nosocomial pathogens microbial toxin.

Objective To understand the molecular epidemiology of penicillin resistance Streptococcus pneumonia (PNSP) isolated from children in Guangzhou area to provide the experimental basis for clinical prevention and control of Streptococcus pneumonia infectious diseases.Methods Specific primers were designed according to Genebank,penicillin binding protein(PBP) genes PBP1A,PBP1B,PBP2A,PBP2B,PBP2X,PBP3 were amplified by PCR.The sequencing analysis was performed.The PCR products were digested by Hinf I,and the restriction fragment length polymorphism (RFLP) was analyzed.Results DNA of PNSP was successfully extracted,the PCR results showed that in 50 strains of PNSP,the positive rates of bacterial strains containing PBP1A,PBP1B,PBP2A,PBP2B,PBP2X and PBP3 were 48.9%,64.4%,71.1%,31.1%,40.0% and 31.1% respectively.The sequencing showed that their homologies with known sequences in GenBank were 99%,98%,100%,97%,95% and 100% respectively.Using RFLP in Hinf I showed that PBP1A,PBP1B,PBP2A and PBP3 only had one kind of genotype,PBP2B and PBP2X had two kinds of genotypes,the positive rates were 71.4%,28.6%,66.7% and 33.3% respectively.Conclusion The gene distribution of PNSP strains among children in Guangzhou is dominated by PBP2A,PBP1B and PBP1A,there are two subtypes in PBP2B,PBP2X when digested by Hinf I,in which the predominant subtype >65%.