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Objective:To investigate the resistance and transmission mechanism of carbapenem-resistant Enterobacterales (CRE), so as to provide the scientific evidence for the treatment and prevention of CRE infection.Methods:Seventy-six isolates of CRE isolated from Shaoxing Second Hospital between May 2016 and August 2018 were included. The isolates were re-identified by matrix-assisted laser desorption ionization time-of-flight mass spectrometry (MALDI-TOF MS). The minimum inhibitory concentrations (MICs) of colistin, tigecycline, ceftazidime-avibactam, fosfomycin and other antibacterial drugs were determined using broth microdilution or agar dilution methods. PCR and sequencing analysis were performed to detect carbapenemase encoding genes ( blaKPC, blaNDM, blaIMP, blaVIM, blaOXA-48). Pulsed field gel electrophoresis (PFGE) and multilocus sequence typing (MLST) were used to analyze homology of strains. S1-PFGE combined with Southern blot hybridization were used to locate the carbapenamase genes. Filter mating test were performed to determine the horizontal transfer ability of plasmids harboring carbapenamase genes. Results:Among the 76 isolates of CRE, 51 isolates were Klebsiella pneumoniae; 10 isolates were Escherichia coli; 15 isolates were other Enterobacterales. The 76 CREs were mainly isolated from urine, sputum and blood samples. The distribution rate of ICU was the highest (55.26%). The 76 CREs showed low resistance rates (0%, 1.33%, 18.42%) to colistin, tigecycline and ceftazidime-avibactam. The resistance rates to amikacin and fosfomycin were <45%, and the resistance rates to other drugs were >97%. The detection rate of KPC-2 carbapenemase was the highest (85.33%). The ST11 CRKP producing KPC-2 carbapenemase accounted for the highest proportion (62.75%), mainly distributed in the ICU (62.50%). Southern blot hybridization showed that blaKPC-2 was mainly located on a plasmid about 90 kb (39/63). Filter mating test showed that blaKPC, blaNDM and blaIMP could be transferred horizontally to recipient bacteria through plasmids. Conclusions:The 76 CRE isolates were only susceptible to a few antibacterial drugs, such as colistin, tigecycline and ceftazidime-avibactam. The production of KPC-2 carbapenemase was the main reason for the resistance of Enterobacterales to carbapenems. KPC-2 carbapenemase-producing ST11 Klebsiella pneumoniae was the main epidemic clone of carbapenem-resistant Klebsiella pneumoniae (CRKP). The 90 kb size plasmid was the main plasmid encoding blaKPC-2 gene. Carbapenemase genes can be transferred horizontally through plasmids. The hospital should strengthen prevention of nosocomial infections to control the clonal prevalence of CRE.
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Objective:To monitor the susceptibility of common used antimicrobial agents against nosocomial Gram-negative bacilli in 2018 across China.Methods:Prospective collection of Gram-negative bacilli from 13 teaching hospitals nationwide from January to December 2018. The minimal inhibitory concentration (MICs) of antibiotics such as meropenem was determined by agar dilution methods and broth microdilution methods. Interpretation of results using the Clinical and Laboratory Standards Institute(CLSI) 2019 M100S (29th Edition) standard. Data were analyzed by using WHONET-5.6 software.Results:A total of 1 214 non-repetitive Gram-negative bacilli were collected, accounting for 96.7% (1 174/1 214) of blood and sterile body fluid samples. The activity of antimicrobial agents against 871 strains of Enterobacteriaceae was as follows in descending order of susceptible rate: amikacin (93.2%, 812/871), meropenem (92.0%, 801/871), ertapenem (88.9%, 774/871), imipenem (88.4%, 770/871), piperacillin-tazobactam (84.0%, 732/871), cefoperazone-sulbactam (83.1%, 724/871), cefepime (71.4%, 622/871), minocyline (68.9%, 600/871), ceftazidime (66.9%, 583/871), levofloxacin (54.4%, 474/871).The resistance rates of Escherichia coli to the third generation cephalosporins were 61.5% (155/252) (ceftriaxone) and 60.7% (153/252) (cefotaxime), respectively. The resistance rates of Klebsiella pneumoniae to the third generation cephalosporins were 56.6% (126/222) (ceftriaxone) and 57.9% (129/222) (cefotaxime), respectively. The incidence of extended-spectrum β lactamase (ESBLs) positive E. coli and K. pneumoniae was 50.2% (127/252) and 18.2% (40/222), respectively. Over 95% of all the ESBLs positive strains were susceptible to imipenem and meropenem. The incidence of carbapenem-resistant Escherichia coli and Klebsiella pneumoniae was 2.8% (7/252) and 20.4% (45/222), respectively. For Enterobacter cloacae, Klebsiella aerogenes, Citrobacter freundii, the most susceptible agent were tigecycline (96.3%-100%), followed by amikacin (94.9%-97.1%), meropenem (89.8%-96.6%)and imipenem (89.8%-94.9%).The susceptibility of Proteus mirabilis, Morganella morganii and Serratia marcescens to meropenem and amikacin was over 90%.A total of 67 strains of carbapenems resistant enterobacteriaceae(CRE) were detected. Modified carbapenem inactivation method showed, 45 strains were serine carbapenemase and 20 were metalloenzymes. The susceptibility of Pseudomonas aeruginosa to meropenem and imipenem were 73.2% (112/153) and 66.0% (101/153), respectively. Acinobacter baumannii has the highest sensitivity to colistin (100%, 163/163), followed by tigecycline (87.1%, 142/163).Compared with other sources of infection, specimens of bloodstream infections were less resistant to Klebsiella pneumoniae (17.6%, 27/153 vs 21.7%, 15/69) and Acinetobacter baumannii (68.3%, 71/104 vs 71.2%, 42/59). Escherichia coli (2.5%,4/198 vs 0%,0/54) and Pseudomonas aeruginosa (37%, 33/89 vs 18.8%, 12/64) have a high proportion of carbapenem resistance. Conclusions:Carbapenems still maintain high antibacterial activity against Enterobacteriaceae bacteria, especially strains producing only ESBLs. Carbapenem-resistant Klebsiella pneumoniae should be given sufficient attention. Carbapenemase is the most important drug resistance mechanism of carbapenem-resistant Enterobacteriaceae in China.
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Objective To investigate the expressions of Toll-like receptors and NOD-like receptor (TLR/NLRP) in septic rats with acute kidney injury (AKI) and influence of Radix notoginseng. Methods One hundred and fifty male Sprague-Dawley (SD) rats were selected, and they were divided into three groups: sham operation group, model group and Radix notoginseng pretreatment group with 50 rats in each group. Sepsis rats with AKI models were established by cecal ligation puncture (CLP); only was laparotomy performed in the sham operation group without ligation. The rats in Radix notoginseng pretreatment group were given Radix notoginseng (3 g/kg) for consecutive 3 days by gastric perfusion before treatment, and the sham operation group and sepsis model group rats were given equal amount of normal saline by gastric perfusion. After their blood was collected, at each following time points 6, 12 and 24 hours after modeling, 10 rats in each group were sacrificed, and the kidney specimens were collected. The endotoxin levels were detected by limulus assay; the levels of serum creatinine (SCr) and urea nitrogen (BUN) were detected by automatic biochemical analyzer; serum levels of interleukins (IL-1β, IL-18, IL-6) and tumor necrosis factor-α (TNF-α) were measured by enzyme-linked immunosorbent assay (ELISA); the expression levels of NLRP1/3 and TLR2/4 mRNA and protein in renal tissue were detected by real-time fluorescence quantitative polymerase chain reaction (qPCR) and Western Blot, respectively; the pathological changes of renal tissues were observed by optical microscope. The 4-day and 7-day survival rates were observed in the remaining 20 rats in each group. Results The levels of endotoxin, SCr, BUN, IL-1β, IL-6, IL-18, and TNF-α and the expressions of NLRP1/3, TLR2/4 mRNA and proteins in sepsis model group and Radix notoginseng pretreatment group were significantly higher than those in sham operation group, and the levels of endotoxin, IL-18, and the expressions of NLRP1/3, TLR2/4 mRNA and proteins showed statistically significant differences at 6-hour after operation [endotoxin (kU/L): 61.3±25.7, 56.9±18.6 vs. 0.2±0.1, IL-18 (ng/L): 16.7±5.0, 13.8±2.9 vs. 10.6±2.8, NLRP3 mRNA (2-ΔΔCt): 6.3±1.9, 4.0±1.2 vs. 1.1±0.4, TLR mRNA (2-ΔΔCt): 5.7±1.3, 2.0±0.8 vs. 0.9±0.3, TLR4 mRNA (2-ΔΔCt): 4.4±1.2, 2.3±0.7 vs. 0.6±0.2, NLRP3/β-actin: 38.2±9.3, 26.1±7.2 vs. 18.3±5.1, TLR4/β-actin: 21.9±6.1, 16.2±4.4 vs. 10.9±2.8, TLR4/β-actin: 18.3±6.7, 12.0±3.9 vs. 7.5±2.0, all P < 0.05], the levels of SCr, BUN, IL-1β, TNF-α and IL-6 showed statistically significant differences at 12-hour after operation [SCr (μmol/L): 62.3±21.6, 38.1±13.9 vs. 36.0±11.9, BUN (mmol/L): 16.5±7.2, 6.9±2.6 vs. 6.8±2.5, IL-1β (ng/L): 37.6±10.9, 31.2±9.3 vs. 20.3±6.5, TNF-α (ng/L): 15.6±3.9, 10.2±2.8 vs. 7.3±2.1, IL-6 (ng/L):9.3±2.5, 6.8±1.7 vs. 5.0±1.3, all P < 0.05], the levels of expressions of NLRP3 mRNA and protein were obviously lower than those in sham operation group, and there were statistical significant differences immediately after 6-hour after operation [NLRP1 mRNA (2-ΔΔCt): 0.5±0.1, 0.8±0.2 vs. 1.6±0.5, NLRP3/β-actin: 8.0±2.1, 16.8±5.0 vs. 35.6±10.5, all P < 0.05], and the amplitude changes of the above indexes in Radix notoginseng pretreatment group were obviously smaller than those in sepsis model group (all P < 0.05); the survival rates of 4-day and 7-day in sepsis model group were significantly lower than those in sham operation group [4-day: 25% (5/20) vs. 95% (19/20), 7-day: 15% (3/20) vs. 95% (19/20), both P < 0.05], while the survival rate in Radix notoginseng pretreatment group was significantly higher than that in sepsis model group [respectively 65% (13/20) vs. 25% (5/20), 60% (12/20) vs. 15% (3/20), both P < 0.05]. Conclusions TLR2/4 and NLRP1/3 may be involved in the pathogenesis of AKI of septic rats. Traditional Chinese medicine Radix notoginseng possibly via regulating the expressions of TLR2/4 and NLRP1/3 can reduce the inflammatory response, in turn ameliorate kidney injury in septic rats and improve their renal functions.
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Objective To evaluate the performance of Xpert C. difficile multiplex real-time PCR assay for diagnosis of Clostridium difficile infections in Chinese hospital settings. Methods This study was performed in Huashan Hospital, Ruijin Hospital, Beijing Hospital, Nanfang Hospital and Sir Run Run Shaw Hospital using a standard study protocol. Unique unformed stools from patients with acute hospital-acquired diarrhea were simultaneously analyzed by toxigenic anaerobic cultures and the Xpert C. difficile assay. All specimens displaying discordant results between the Xpert assay and toxigenic culture were sent for Sanger tcdB gene sequencing. Sensitivity, specificity, positive predictive value (PPV), negative predictive value (NPV), total concordance rate, and 95％ confidence interval (CI) were calculated before and after resolution of discordant results using SAS 9.3. Results A total of 745 stool specimens were collected and 46 were excluded due to failure of C. difficile recovery. The remaining 699 specimens were included. Compared to the results of toxigenic culture, the sensitivity, specificity, PPV, and NPV of Xpert C. difficile assay were 94.1％ (144/153)(95％CI:89.1％-97.3％), 93.2％ (509/546)(95％CI:96.7％-99.2％), 79.6％ (144/181)(95％CI:72.9％-85.2％)and 98.3％ (509 / 518) (95％CI: 96.7％-99.2％), respectively. Both methods had a Kappa of 0.819. Xpert C. difficile assay showed sensitivity of 98.4％(62/63) (95％ CI: 90.3％-99.9％) and specificity of 93.2％(509/546) (95％ CI: 90.8％-95.2％) for toxin A-negative toxin B-positive strains. After the discordant results resolved by tcdB gene sequencing, PCR assay provided better performance with high sensitivity, specificity, positive predictive value, and negative predictive value [98.8％ (171 / 173), 98.1％ (516 / 526), 94.5％ (171/181) and 99.6％ (516/518), respectively]. Conclusions Compared to the results of toxigenic culture, the sensitivity, specificity and NPV of Xpert C. difficile assay were 94.1％ (144/153) and 93.2％(509/546), respectively. With the results available within 1 h, Xpert C. difficile assay provides prompt and precise laboratory diagnosis in Chinese clinical settings.
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Infectious disease is still one of the leading causes of death nowadays .More than half of pathogens causing infections are still unclear through conventional microbiological diagnostics in clinical laboratory.Recently, the metagenomic sequencing is being applied in the pathogenic diagnosis with full coverage, high efficiency and few bias.Though metagenomic sequencing has shown good performance in pathogenic diagnosis for respiratory tract infection , central nervous system infection and bloodstream infection, it still cannot replace the conventional microbiological tests ; however, this state-of-the-art tool should be considered as an effective supplement to pathogen diagnosis .This article reviews the current application of metagenomic sequencing in clinical scenarios and related pitfalls , with the aim of promoting better utilization of the tool.
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Cryptococcal meningitis is a common and refractory central nervous system infection,with high rates of mortality and disability.The experts of the Society of Infectious Diseases of Chinese Medical Association have reached this consensus after a thorough discussion.Based on the current situation of cryptococcal meningitis in China,the management of cryptococcal meningitis includes 6 aspects:introduction,microorganism identification,clinical manifestations and diagnosis,principles of antifungal therapy,treatment of refractory and recurrent meningitis,treatment of intracranial hypertension.There is not a separate consensus on human immunodeficiency virus (HIV) infection in patients with cryptococcal meningitis.This article focuses on different antifungal regimens and reducing intracranial pressure by reference to Infectious Disease Society of America (IDSA) guidelines.The importance of early diagnosis,combined long-term antifungal therapy,control of intracranial hypertension are emphasized.
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Objective To compare the antibacterial activity in vitro of Haizhengmeite and Mepem. Methods Four hundreds and eighteen bacteria isolated were collected from clinical settings in different area,including 104 strains of Escherichia coli(52 strains of ESBLs +and 52 strains of ESBLs -), 104 strains of Klebsiella pneumonia(52 strains of ESBLs +and 52 strains of ESBLs -),56 strains of Proteus spp. (28 strains of ESBLs +and 28 strains of ESBLs -), 52 strains of other Enterobacteriaceae, 51 strains of Acinetobacter baumanii and 51 strains of Pseudomonas aeruginosa.Two pharmaceutical products of meropenem injection were Mepem from Japan Sumitomo Pharmaceuticals Co., Ltd and Haizhengmeite from Zhejiang Haizheng Pfizer pharmaceuticals Co.Ltd in China, respectively.Minimum inhibitory concentrations(MIC)of two products of meropenem were determined by broth microdilution method and agar dilution method according to the Clinical and Laboratory Standards Institute(CLSI,2016).Results The sensitive rates of Escherichia coli, Klebsiella pneumoniae, and Proteus spp.to Haizhengmeite and Mepem were >85%,while the rates of the sensitivity to Acinetobacter baumanii and Pseudomonas aeruginosa were lower,with the rates of 33.3%,31.4% and 58.8%,52.9%,respectively.Conclusions Haizhengmeite and Mepem both show good antibacterial activity against Enterobacteriaceae, but lower activity against Acinetobacter baumanii and Pseudomonas aeruginosa.Both products are stable to ESBLs,and no significant difference is observed between the two products in antibacterial activity in vitro.
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Objective To retrospectively investigate the distribution,molecular epidemiology and carbapenemases-encoding genes of carbapenem resistant K lebsiella pneumoniae(CRKP)in Zhejiang Province.Methods A total of 772 clinical isolates of K.pneumoniae isolated from 9 hospitals in Zhejiang Province in 2011 were selected,and antimicrobial susceptibility testings were carried out with disk diffusion or broth microdilution method.Polymerase chain reaction(PCR)was used to detect resistant genes,and molecular typing was performed by multilocus sequence typing(MLST)and pulsed field gel electrophoresis(PFGE).Results A total of 48 CRKP(6.2%)were screened in 9 hospitals. Carbapenemase-encoding genes were detected in 39 isolates by PCR,among which 37(77.1%)were identified as blaKPC-2and 2 were blaIMP-4.MLST showed that ST11 was the dominant ST type(30, 62.5%).Results of PFGE showed that 48 CRKP can be divided into 15 types.CRKP was found in 6 hospitals except hospitals in Wenzhou,Jiaxing and Shaoxing.Conclusions In 2011,CRKP is distributed in most areas of Zhejiang Province.The production of KPC-2 is the most important carbapenem resistance mechanism and ST11 is the most prevalent ST type.
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Objective To investigate the antimicrobial resistance profile of the clinical isolates collected from selected hospitals across China. Methods Twenty-nine general hospitals and five children's hospitals were involved in this program. Antimicrobial susceptibility testing was carried out according to a unified protocol using Kirby-Bauer method or automated systems. Results were interpreted according to CLSI 2017 breakpoints. Results A total of 190 610 clinical isolates were collected from January to December 2017, of which gram negative organisms accounted for 70.8％ (134 951/190 610) and gram positive cocci 29.2％ (55 649/190 610). The prevalence of methicillin-resistant strains was 35.3％ in S. aureus (MRSA) and 80.3％ in coagulase negative Staphylococcus (MRCNS) on average. MR strains showed much higher resistance rates to most of the other antimicrobial agents than MS strains. However, 91.6％ of MRSA strains were still susceptible to trimethoprim-sulfamethoxazole, while 86.2％ of MRCNS strains were susceptible to rifampin. No staphylococcal strains were found resistant to vancomycin. E. faecalis strains showed much lower resistance rates to most of the drugs tested (except chloramphenicol) than E. faecium. Vancomycin-resistant Enterococcus (VRE) was identified in both E. faecalis and E. faecium. The identified VRE strains were mainly vanA, vanB or vanM type based on phenotype or genotype. The proportion of PSSP or PRSP strains in the non-meningitis S.pneumoniae strains isolated from children decreased but the proportion of PISP strains increased when compared to the data of 2016. Enterobacteriaceae strains were still highly susceptible to carbapenems. Overall, less than 10％ of these strains (excluding Klebsiella spp.) were resistant to carbapenems. The prevalence of imipenem-resistant K. pneumoniae increased from 3.0％ in 2005 to 20.9％ in 2017, and meropenem-resistant K. pneumoniae increased from 2.9％ in 2005 to 24.0％ in 2017, more than 8-fold increase. About 66.7％ and 69.3％ of Acinetobacter (A. baumannii accounts for 91.5％) strains were resistant to imipenem and meropenem, respectively. Compared with the data of year 2016, P. aeruginosa strains showed decreasing resistance rate to carbapenems. Conclusions Bacterial resistance is still on the rise. It is necessary to strengthen hospital infection control and stewardship of antimicrobial agents. The communication between laboratorians and clinicians should be further improved in addition to surveillance of bacterial resistance.
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Objective To investigate the prevalence of colistin resistance and mcr-1 gene in pa-tients with bloodstream infection caused by Escherichia coli (E.coli) and Klebsiella pneumoniae (K.pneu-moniae) in Zhejiang Province. Methods A total of 869 clinical strains of the Enterobacteriaceae family, including 611 E.coli and 258 K.pneumonia strains, were isolated from patients with bloodstream infection (BSI) in Zhejiang Province from March 2014 to April 2015. Broth microdilution method and PCR were re-spectively performed to detect colistin resistance and mcr-1 gene in those stains. Susceptibilities of mcr-1-positive strains to other antibiotics were assessed by E-test. Pulsed-field gel electrophoresis(PFGE) and multilocus sequence typing(MLST) were used for molecular typing. Location of mcr-1 gene was determined by analysis of PFGE profiles of S1-digested genomic DNA and Southern blot hybridization. Plasmid transfer to E.coli recipients was investigated using filter mating test. Clinical data of the patients infected with mcr-1-positive strains was collected and analyzed. Results The minimum inhibitory concentration (MIC) values of colistin to the 869 Enterobacteriaceae strains ranged from ≤0.06 μg/ml to 16 μg/ml. Six (0.69%) E.coli strains were identified to be colistin-resistant and mcr-1-positive and the MIC values against them ranged from 8 μg/ml to 16 μg/ml. No colistin-resistant or mcr-1-positive K.pneumonia strain was identified. All mcr-1-positive strains were susceptible to carbapenems and most of them(83.33%,5/6) were suscepti-ble to tigecycline and β-lactamase inhibitor combinations tested in this study. The six mcr-1-positive strains were of different sequence types (STs) and the mcr-1 genes carried by them located on three types of plas-mids with the sizes of 33 kb,61 kb and 244.4 kb. Conclusion The prevalence of mcr-1 gene in E.coli and K.pneumonia strains isolated from patients with BSI in Zhejiang Province was relatively low, only ac-counting for 0.69% of all isolated Enterobacteriaceae strains.Those strains carrying mcr-1 gene showed low drug resistance to colistin. The mcr-1-positive strains were usually non-pathogenic clones and remained sus-ceptible to many antimicrobial agents, which was conducive to favorable outcomes. In order to clarify the clinical impact of this novel resistance gene on public health,further studies should be conducted.
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Objective To investigate antimicrobial resistance among nosocomial gram-negative bacilli in 2016 across China.Methods About 1 394 consecutive and non-repetitive gram-negative bacilli were isolated from 14 teaching hospitals from March to August in 2016 across China.All of these isolates were sent to the central laboratory for reidentification and susceptibility testing.The minimal inhibitory concentration(MICs)of meropenem and other antibacterial agents were determined by agar dilution method.The data were analyzed by using WHONET-5.6 software.Results The activity of antimicrobial agents against Enterobacteriaceae was as follows in descending order of susceptible rate: meropenem (95.2%,891/936), amikacin (94.6%,885/936), ertapenem (92.1%,862/936), piperacillin/tazobactam (88.1%,825/936), imipenem (88.0%,823/936), cefoperazone-sulbactam (83.1%,778/936), cefepime (72.2%,676/936), cefiazidime (72.2%,676/936), levofloxacin(68.8%,644/936), ciprofloxacin (63.2%,592/936), minocyline (62.9%,589/936), cefiriaxone (54.9%,514/936), cefotaxime (54.0%,505/936), cefoxitin (44.3%,415/936).The sensitivities of E.coli to carbapenems, amikacin, piperacillin-tazobactam, polymyxin B and cefoperazone-sulbactam were over 80%.The more sensitive antibiotic to Klebsiella pneumoniae was polymyxin B (99.0%), followed by amikacin (84.9%), meropenem (84.4%) and imipenem (82.0%).The prevalence of extended-spectrum β-lactamase was 62.8%(137/218)in Escherichia coli and 28.3%(58/205)in Klebsiella pneumonia.The activity of antimicrobial agents against E.cloacae, E.aerogenes and Citrobacter freundii was as follows in descending order of susceptible rate: meropenem (97.0%-98.5%), amikacin (95.8%-98.3%), imipenem (94.5%-97.5%), polymyxin B (96.4%-100%), cefoperazone-sulbactam (76.5%-90.0%), ertapenem (73.3%-90.1%), piperacillin/tazobactam (82.4%-88.3%).The most active agents against Pseudomonas aeruginosa were polymyxinB (100%), followed by amikacin (89.3%) and ciprofloxacin (82.4%).The most active agents against Acinetobacter baumannii were polymyxinB (100%).The sensitivities of Acinetobacter baumannii to meropenem, imipenem, minocycline and cefoperazone-sulbactam were 20.3%(39/202), 19.3%(41/202), 66.3%(134/202) and 24.8%(50/202), respectively.Conclusions Carbapenems remain high sensitive against Enterobacteriaceae.Controlling carbapenem resistant Klebsiella pneumoniae is urgent.Drug antimicrobial resistance in A.baumanni is a still serious problem.
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Objective To study the epidemiology and genotypes of extended-spectrum beta-lactamases (ESBL)-producing Escherichia coli (EC) and Klebsiella pneumoniae (KP) that caused community-onset bloodstream infections (COBSI) in 9 county hospitals of Zhejiang Province.Methods This is a multi-center, prospective, observational study.The cases and isolates with COBSI caused by EC and KP were consecutively collected from 9 county hospitals in Zhejiang Province between 1st March 2014 and 30th April 2015.The double disk diffusion method was used to confirm the production of ESBL.The ESBL genotypes were determined by polymerase chain reaction(PCR) amplification and sequence analysis.Multi-locus Sequence Typing (MLST) was used to analyze the homology of ESBL-producing isolates.Minimal inhibitory concentration (MIC) of frequently used drugs for ESBL-producing isolates was determined by in-vitro antimicrobial susceptibility tests.Results During the study period, a total of 172 cases with COBSI were collected and 171 cases were eligible, among which 126 were caused by EC and 45 were caused by KP.The overall prevalence of ESBL was 34.5% (59/171),and the prevalence of ESBL-EC and-KP was 41.3% (52/126) and 15.6% (7/45), respectively.CTX-M-type ESBL accounted for 96.6% (57/59) of all the ESBLs-producing isolates, and the most common type was CTX-M-14 (27.1%, 16/59), followed by CTX-M-55 (22%, 13/59).MLST analyses revealed significant genetic diversity among ESBL-EC and-KP.The most prevalent ST of ESBL-EC was ST131 (23.1%).In addition to carbapenems, cefoperazone/sulbactam, piperacillin/tazobactam, moxalactam, amikacin and fosfomycin also showed good in-vitro activity against ESBL-EC and-KP.Conclusions The prevalence of ESBL in EC and KP is high in 9 county hospitals of Zhejiang Province, and the most common genotypes are CTX-M-14 and CTX-M-55.The detection rate of ESBL in EC is higher than in KP.It could be considered adequate empirical therapy according to the results of antimicrobial susceptibility tests.Carbapenems, cefoperazone/sulbactam, piperacillin/tazobactam, moxalactam, amikacin and fosfomycin have good in-vitro activity against ESBL-EC and-KP.
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Objective To investigate the mechanism and epidemiological characteristics of carbap-enem-resistant Proteus mirabilis ( PM) strains deficient in swarming motility. Methods PM strains were isolated from Hangzhou General Hospital of CAPF ( Chinese People′s Armed Police Forces) during January 2013 to December 2014. Bacterial motility and flagella of the PM strains were observed through semi-solid agar culture and flagella staining. Pulsed-field gel electrophoresis ( PFGE) was performed for homology anal-ysis. Antimicrobial susceptibility test and phenotypic confirmatory test were also carried out. PCR analysis and DNA sequencing were performed to confirm the genotype of resistant genes. Plasmid electroporation and S1-PFGE in combination with Southern blot hybridization were used to determine the location of the carbap-enem-resistant genes. Genetic structure of the blaKPC-2 gene was obtained by PCR mapping. Results A total of 42 PM isolates deficient in swarming motility were screened out and the resistance rates to imipenem and meropenem were 57. 1% and 52. 4%, respectively. PCR analysis and DNA sequencing confirmed that 24 carbapenem-resistant PM isolates deficient in swarming motility carried blaKPC-2 gene and belonged to three clones as indicated by the results of PFGE. Southern blot hybridization indicated that the blaKPC-2 gene was located on plasmids varying in size (26 kb, 55 kb and 139 kb). In addition, some of the strains harbored several resistant genes, such as blaTEM-1 , blaCTX-M-65 and rmtB. The genetic structures of strains carrying blaKPC-2 gene were ISKpn8, blaKPC-2 and ISKpn6-like from upstream to downstream. Conclusion Compared with the PM strains with swarming motility, the carbapenem-resistance rate was significantly higher in these PM strains deficient in swarming motility. Carbapenemases KPC-2 played an important role in the carbapen-em-resistant PM strains deficient in swarming motility. There was a cloning spread trend for carbapenem-re-sistant PM strains in our hospital. Clinicians should pay more attention to the risk of spreading.
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Community-acquired methicillin-resistant Staphylococcus aureus ( CA-MRSA ) has been increasingly frequently isolated from patients worldwide, and is an emerging threat to public health.CA-MRSA strains differ from hospital-acquired MRSA strains in their epidemiologies, clinical features and genetic backgrounds, and the predominant CA-MRSA strains vary between geographic settings.This paper reviews literatures on the definition, epidemiology, clinical manifestations, treatment and virulent factors of CA-MRSA or CA-MRSA infection, and points out that we should further promote studies on epidemiology, molecular genetic properties of CA-MRSA and clinical management of CA-MRSA infection.
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Objective To evaluate the changing pattern of antibiotic resistance inKlebsiella strains isolated from the patients in 19 hospitals across China based on the data from CHINET Antimicrobial Resistance Surveillance Program during the period from 2005 through 2014.Methods Kirby-Bauer disk diffusion and automated susceptibility testing methods were used to test the susceptibility ofKlebsiella isolates to the commonly used antibiotics. The results were interpreted according to the criteria of the Clinical and Laboratory Standards Institute (CLSI) Performance Standards for Antimicrobial Susceptibility Testing (CLSI-2014).Results A total of 61 406Klebsiella strains were identified between 2005 and 2014, includingK. pneumoniae (56 281 strains), K. oxytoca(4 779),Klebsiella pneumoniae subsp.Ozaenae (300) and otherKlebsiella species (46). Most (89.0%, 54 664/61 406) of theKlebsiella strains were isolated from inpatients, and 60.0% (36 835/61 406) were from respiratory tract speciems. About 16.7% (10 248/61 406) of the strains were isolated from pediatric patients aged 0-17 years and 83.3% (51 158/61 406) from adult patients. The prevalence ofKlebsiella spp. increased with time from 10.1% in 2005 to 14.3% in 2014. Based on the surveillance data during the 10-year period, we found a marked increase of resistance to imipenem (2.9% to 10.5%) and meropenem (2.8% to 13.4%) inKlebsiella spp. The prevalence of ESBLs-producing isolates inK. pneumoniae andK. oxytoca decreased from 39.0% in 2005 to 30.1% in 2014. The resistance to amikacin, ceftazidime, ciprolfoxacin, pipracillin-tazobactam and cefoperazone-sulbactam was on decline. The resistance rate to cefotaxime remained high about 49.5%. Carbapenem resistantance was identiifed in 5 796 (9.4%) of the isolates, including 5 492 strains ofK. pneumoniae and 280 strains ofK. oxytoca. Overall, 4 740 (7.8%) strains were identiifed as extensively-drug resistant (XDR), including 4 520 strains ofK. pneumoniae and 202 strains ofK. oxytoca. The carbapenem-resistant strains showed high (>60%) resistance rate to majority of the antimicrobial agents tested, but relatively low resistance to tigecycline (16.8%), amikacin (54.4%), and trimethoprim-sulfamethoxazole (55.5%).Conclusions During the 10-year period from 2005 through 2014, carbapenem resistance amongKlebsiella isolates has increased dramatically in the hospitals across China. The level of resistance to other antibiotics remains stable.
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Objective To investigate the distribution and antibiotic resistance proifle of clinicalEnterobacter isolates using the data from CHINET during the period from 2005 through 2014.Methods A total of 20 558 clinical strains ofEnterobacter spp. were collected from 2005 to 2014 in CHINET Antimicrobial Resistance Surveillance Program. Antimicrobial susceptibility testing was performed with Kirby-Bauer or minimum inhibitory concentration method. The results were analyzed according to CLSI 2014 breakpoints.ResultsEnterobacter cloacae andEnterobacter aerogenes accounted for 71.1% (14 617/20558) and 20.1% (4 129/20 558) of all theEnterobacterisolates, respectively. The proportion ofEnterobacter spp. increased with time from 3.5% in 2005 to 4.3% in 2014. The main source of the isolates was respiratory tract, accounting for 55.2% (11 358/20 558). More than 90% of theEnterobacterisolates were resistant to cefazolin and cefoxitin, but less than 30% of the strains were resistant to cefepime, piperacillin-tazobactam, cefoperazone-sulbactam, amikacin, gentamicin, ciprolfoxacin, meropenem, imipenem and ertapenem. TheEnterobacterisolates showed a trend of declining resistance to most antibiotics except ertapenem and meropenem. The resistance proifle ofEnterobacterisolates varied with departments where they were isolated. The strains from ICU and Department of Surgery were relatively more resistant to antibiotics. The prevalence of multi-drug resistant (MDR) strains was decreasing, but the prevalence of carbapenem-resistantEnterobacter (CRE, resistant to any of imipenem, meropenem or ertapenem) was increasing. The MDR and CRE strains were primarily isolated from ICU and Department of Surgery. At least 30% of the MDREnterobacter strains were resistant to any of the antimicrobial agents tested except meropenem, imipenem and ertapenem and at least 35% of the CRE strains were resistant to any of the antimicrobial agents tested except amikacin and ciprolfoxacin.Conclusions TheEnterobacter isolates in CHINET Antimicrobial Resistance Surveillance Program showed decreasing resistance to most of the antimicrobial agents tested since 2011, but the prevalence of CRE strains increased progressively. Effective measures should be carried out to prevent the spread of CRE strains in hospitals.
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Objective To understand the changing resistance proifle ofProteus,Serratia,Citrobacter,Morganella andProvidencia in hospitals across China according to the data from CHINET Antimicrobial Resistance Surveillance Program 2005-2014.Methods Antimicrobial susceptibility was tested by using Kirby-Bauer method or automatic minimum inhibitory concentration determination according to a uniifed protocol.Results A total of 21 663 clinical isolates were collected from January 2005 to December 2014. The proportion ofProteus andSerratia isolates increased with time from 1.41% in 2005 to 2.09% in 2014, and from 0.99% in 2005 to 1.28% in 2014 among all the isolates. No change was found for the proportion ofCitrobacter,Morganella, orProvidencia. Less than 10% of theProteus isolates were resistant to cefoperazone-sulbactam, piperacillin-tazobactam, ceftazidime, cefoxitin, amikacin and tigecycline. Less than 10% of theSerratia isolates were resistant to cefoperazone-sulbactam, piperacillin-tazobactam, amikacin and tigecycline. Less than 20% of theCitrobacter isolates were resistant to cefoperazone-sulbactam, piperacillin-tazobactam, cefepime, amikacin and tigecycline. Less than 10% of theMorganella isolates were resistant to cefoperazone-sulbactam, piperacillin-tazobactam, cefepime, amikacin and tigecycline. Less than 20% of theProvidencia isolates were resistant to cefoperazone-sulbactam, piperacillin-tazobactam, cefepime, cefoxitin and tigecycline.Conclusions The antibiotic resistance ofProteus,Serratia, Citrobacter,Morganella andProvidencia isolates in hospitals across China is growing during the period from 2005 to 2014. Strengthening infection control and rational antibiotic use are effective to slow the growth of drug resistance.
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Objective To investigate the distribution and changing resistance proifle ofSalmonella isolates in hospitals across China during the period from January 2005 to December 2014.Methods Seventeen general hospitals and two children’s hospitals were involved in this program. Antimicrobial susceptibility testing was carried out by means of a unified protocol using Kirby-Bauer method or MIC determination. The results were analyzed according to CLSI 2014 breakpoints.Results The proportion ofSalmonella isolates increased with time from 0.2% in 2005 to 0.7% in 2014. A total of 3 478Salmonella strains were collected from 19 hospitals. The proportion ofSalmonella typhimurium andSalmonella enteritidis was 27.4% and 24.4%, respectively. During the 10-year period, theSalmonella strains showed highest resistance rate to ampicillin (33.3%-64.8%), but low resistance to cefoperazone-sulbactam (0-5.3%) and ciprofloxacin (2.4%-14.3%).S. typhimurium showed higher resistance rate thanS. typhi,S. paratyphi andS. enteritidis. About 76.8% and 50.5% ofS. typhimurium were resistant to ampicillin and trimethoprim-sulfamethoxazole. The average prevalence of multi-drug resistantSalmonellawas 3.9% in the ten-year period, the highest (7.5%) was in 2005, the lowest (1.5%) in 2013.Conclusions During the period from 2004 to 2015, majority of theSalmonella isolates in hospitals across China wasS. typhimurium andS. enteritidis. Ampicillin and trimethoprim-sulfamethoxazole are no longer appropriate for empirical treatment ofS. typhimurium infection due to high resistance rate.Salmonella isolates are relatively more susceptible to third-generation cephalosporins and quinolones. Ongoing monitoring is necessary to identify multi-drug resistant strains ofSalmonella.
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Objective To analyze the resistance proifle of bacterial strains isolated from geriatric patients in 17 hospitals across China from 2005 to 2014.Methods A total of 17 representative general hospitals were involved in this program. Bacterial susceptibility testing was carried out by means of a uniifed protocol using Kirby-Bauer method and MIC determination. The results were analyzed according to CLSI 2014 breakpoints.Results The proportion of the strains isolated from geriatric patients among all the clinical isolates increased with time from 30.0% in 2005 to 32.7% in 2014. A total of 159 888 clinical isolates were collected from geriatric patient during the period from 2005 to 2014, about 33.1% of the whole patient population. Gram negative organisms and gram positive cocci accounted for 77.1% (123 229/159 888) and 22.9% (36 659/159 888), respectively. Majority (92.8%, 148 376/159 888) of the isolates were from inpatients and more than half (55.2%, 88 201/159 888) of the isolates were from sputum or other respiratory tract specimens. Methicillin-resistant strains inS. aureus (MRSA) and coagulase negativeStaphylococcus (MRCNS) accounted for an average of 67.1% and 75.9%, respectively. The resistance rates of methicillin-resistant strains to β-lactams and other antimicrobial agents were much higher than those of methicillin-susceptible strains. No staphylococcal strains were found resistant to vancomycin, teicoplanin or linezolid. Some strains ofE. faecalis (0.4%) andE. faecium (4.6%) were resistant to vancomycin, which was higher than average national level (0.3%, 3.2%). Vancomycin-resistant strains ofE. faecalisandE. faecium were mainly VanA type and VanB type based on their phenotype. The prevalence of penicillin-susceptibleS. pneumoniae strains was 78.2%, slightly lower than the 95.0% in Chinese adults in year 2014. The prevalence of ESBLs-producing strains was 67.5% inE. coli, 40.4% inKlebsiella (K. pneumoniae andK. oxytoca) and 34.3% inProteus mirabilis isolates on average. The strains ofEnterobacteriaceae were still highly susceptible to carbapenems (<10% resistant), followed by amikacin and the beta-lactam and beta-lactamase inhibitor combinations. Overall, 35.9% and 33.0% of theP. aeruginosa strains were resistant to imipenem and meropenem. More than 50% of theA. baumannii strains were resistant to imipenem and meropenem. The prevalence of extensively drug-resistant (XDR)P. aeruginosa (4.0%-1.8%) was higher than the average national level (2.1%-1.6%). The prevalence of XDR A. baumannii (19.2%-15.5%) and XDREnterobacteriaceae (0.1%-1.0%) was lower than the average national level (21.4%-19.7% and 0.3%-3.2%).Conclusions The proportion of clinical isolates from geriatric patients is different from average national level at the same period. The isolates from geriatric patients are more likely from inpatients, respiratory tract specimens and more likely non-fermentative gram-negative bacilli compared to average national level. The proportion of fastidious bacteria andEnterobacteriaceae species is generally lower than average national level. MRSA, VRE, ESBLs-producing strains and XDRP. aeruginosa are more prevalent in geriatric patients than in general Chinese patient population. This study suggests that surveillance of antimicrobial resistance for the clinical isolates from geriatric patients is very important for rational antimicrobial therapy.
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Objective To analyze the epidemiological characteristics of Klebsiella pneumoniae car-bapenemase(KPC)-producing Escherichia coli(E. coli)strains isolated in Hangzhou,China. Methods A total of 25 KPC-producing Escherichia coli strains were collected from four hospitals in Hangzhou from July 2012 to January 2014. Antibiotic susceptibility of the isolates to 22 common antimicrobial agents was deter-mined by using Kirby-Bauer(K-B)disk diffusion method. PCR analysis and gene sequencing were used for bla KPC gene screening. The modified Hodge test was performed to detect the production of carbapenemase. Pulsed-field gel electrophoresis(PFGE)and multi-locus sequence typing(MLST)were used for homology analysis. Results All of the 25 clinical isolates were confirmed to be KPC-producing E. coli strains,harbo-ring the blaKPC-2 gene. These KPC-producing isolates showed high drug resistance rates and were resistant to almost all β-lactam antibiotics. PFGE typing classified the 25 isolates into three main homologous clone groups,including clone group A(4 isolates),clone group B(5 isolates)and clone group C(2 isolates), and some single clones(14 isolates). MLST typing classified the isolates into eight ST types,including ST131(14 isolates),ST167(3 isolates),ST2003(3 isolates),ST410(1 isolate),ST457(1 isolate), ST1463(1 isolate),STnew1(1 isolate)and STnew2(1 isolate). The typing results of PFGE and MLST were consistent with each other. Conclusion The prevalent KPC-producing E. coli strains in Hangzhou, China were ST131 type,which were resistant to multiple antibiotics and had been detected in several hospi-tals. The epidemic of KPC-producing E. coli strain often occurred at some special wards,such as Intensive Care Unit(ICU)and emergency ICU.