Research on genotyping of methicillin-resistant Staphylococcus aureus in China / 中华流行病学杂志

Objective To investigate the source and genetic background of methicillin-resistant Staphylococcus aureus in the year of 2006,in China. Methods From January to December 2006,a total number of 302 consecutive and non-repetitive methicillin-resistant Staphylococcus aureus were collected from 17 Teaching hospitals in 15 areas. Genotypes of SCCmec were determined by multiplex PCR and multilocus sequence typing (MLST) was used to type the house-keeping genes. The implementation of the spa typing method was straightforward,and the results obtained were reproducible,unambiguous,and easily interpreted. Results All areas but Dalian harbored SCCmec Ⅲ while Dalian harbored SCCmec Ⅱ most. There were two strains in Guangzhou,harboring SCCmec Ⅳ. There were four strains of sequence type(ST),with ST239 accounted for 46.7% and ST5 accounted for 44.4%. ST59 accounted for 6.7% and ST88 accounted for 2.2%. There were fourteen strains of Spa typing,with t30 accounted for 52.6% ; t37 accounted for 27.2% ; t2 accounted for 12.9% ; t632 accounted for 2.3% ; t437 accounted for 1.3% ; t570,t601 accounted for 0.7% ; t377,t459,t796,t899,t1152,t2649 accounted for 0.3% ; no-typing accounted for 0.3%,respectively,pvl gene was not detected. Conclusion The main clone strains were ST239-MRSA-SCCmec Ⅲ-t30,ST5-MRSA-SCCmec Ⅱ-t2,with unique geographic distributions across the whole nation.

Molecular characterization of vancomycin-resistant Enterococci / 中国医学科学院学报

<p><b>OBJECTIVE</b>To investigate the homology and resistant mechanism of vancomycin-resistant Enterococci (VRE) isolates.</p><p><b>METHODS</b>A total of 9 VRE isolates were collected from 2006 to 2007 at PUMC hospital. The susceptibility of these isolates to 10 different antibiotics including vancomycin was tested by E-test. These strains were processed by brain heart infusion agar screening in the presence of vancomycin (6 microg/ml), and were analyzed for genotypic characteristics using the multiplex PCR. The homology of the isolates was determined by pulsed-field gel electrophoresis (PFGE).</p><p><b>RESULTS</b>All the 9 VRE isolates were identified as Enterococci faecium. The visual analysis of PFGE patterns revealed 6 different PFGE types. The vanA gene was confirmed by PCR and sequencing in 9 VRE isolates, which were consistent between phenotype and genotype for glycopeptides resistance.</p><p><b>CONCLUSIONS</b>Only vanA genotype was detected in PUMC hospital. Clonal dissemination, horizontal gene transfer, and the selective pressure of antimicrobial agents may contribute to the increase of VRE.</p>

In vitro antimicrobial activity of ampicillin-sulbactam,clindamycin and cefoperazone determined by E test / 中国感染与化疗杂志

Objective To investigate the in vitro antimicrobial activity of ampicillin-sulbactam,clindamycin and cefoperazone a- gainst common clinical isolates.Methods MICs of these three antibiotics were determined by E test.Results Ampicillin-sulbae- tam showed inhibition rate of 100% for methicillin susceptible S.aureus (MSSA),E.faecalis,Group A Streptococcus,H. influenzae,penicillin-susceptible S.pneumoniae (PSSP),M.catarrhalis and anaerobes (including 10 strains of Bacteroid spp.,2 strains of P.aches,1 strain of E.lentum,1 strain of Fusobacterium innocuum,and 2 strains of Peptostreptococcus spp.).Ampicillin-sulbactam was active against 86.7% of extended-spectrum?-lactamase non-producing K.pneumoniae (NES- BL-KPN) and 53.3% of non ESBL-producing E.coli (NESBL-ECO).Ampicillin-sulbactam only inhibited 23.3% of A.bau- mannii isolates and 25.0% of E.faecium isolates.For MSSA,anaerobes,PSSP and group A Streptococcus,about 60.0%, 31.2%,30.0% and 10.0% of the isolates were susceptible to clindamycin,respectively.For MSSA,NESBL-ECO and NES- BL-KPN,96.7% to 100% of the isolates were susceptible to cefoperazone.About 40.0% of P.aeruginosa isolates were sus- ceptible to cefoperazone.No A.baumannii isolate was susceptible to cefoperazone.Conclusions The ampicillin-sulbactam has good antimicrobial activity against MSSA,E.faecalis,Group A Streptococcus,NESBL-KPN,H.influenzae,PSSP,M.ca- tarrhalis and anaerobes.In this study,clindamycin is active against 60% of MSSA isolates.Most of other species are relatively resistant to clindamycin.Cefoperazone shows good activity against MSSA,NESBL-ECO,and NESBL-KPN.These three anti- microbial agents can be used as empirical treatment for community-acquired infections.

Preliminary analysis on the treatment of infection caused by pandrug-resistant Acinetobacter baumannii / 中国感染与化疗杂志

Objective To analyze the clinical features of pandrug-resistant Acinetobacter baumannii (PDR-Ab) in a hospital and compare the efficacy of different antibiotic treatments on patients with pneumonia caused by PDR-Ab.Methods Data were ret- rospectively collected from all isolated PDR-Ab strains in our hospital from February 2004 to March 2005.The clinical features and outcomes were reviewed.Results A total of 77 strains of PDR-Ab were collected, 45 of which were pathogens causing clini- cal infections (35 strains from lower respiratory tract, 6 from bloodstream, 3 from drainage fluid, and 1 from wounds).Lower respiratory tract was the most common source of PDR-Ab.More than 90% of the isolated PDR-Ab strains produced OXA-23 type?-lactamase.Cefoperazone-sulbactam plus minocyeline showed good efficacy for patients with PDR-Ab pneumonia.The total clinical cure rate was 68.4%.Bacterial eradication rate was 42.1%.The factors influencing bacterial clearance were pro- longed mechanical ventilation prior to positive culture (17.5 d vs 5.5 d).mixed infection (100% vs 12.5%) and lower GCS score (9.1?0.7 vs 13.2?2.1).Concomitant septic shock (OR=13.8) and APACHEⅡscore (OR=2.1) were independent factors of clinical outcome.Conclusions Nosocomial infections caused by PDR-Ab are not untreatable.Our analysis suggests that cefoperazone-sulbactam plus minocycline may be an effective treatment for lower respiratory tract infections caused by PDR-Ab in our hospital.

Application of metabonomics in complicated theory system research of traditional Chinese medicine / 中国中药杂志

Metabonomics, a new and rapid-developing technology, will be powerful means to the research of complexed theory system and modernization of traditional Chinese medicine (TCM). Discovery of biomarkers and analysis of common properties from the metabolome of a specific TCM syndrome will facilitate the modernized study of TCM system, promote the quantitative and scientific elucidation of TCM syndrome differentiation, provide an in-depth understanding of the TCM theory of Zang-xiang, help predict the disease on-set, and achieve a comprehensive evaluation of systemic clinical efficacy, safety and mechanism of action of the TCM combination formulas along with a better understanding of intestinal microflora ecology. The new approach with combined metabonomics and TCM methodologies will provide a new pathway and methodology for the study of complicated theory system of TCM and its modernization.

Comparison of antimicrobial susceptibility of common gram-negative isolates from blood stream between Hong Kong and Beijing patients / 中国感染与化疗杂志

Objective To compare the antimierobial resistance of the gram-negative isolates from blood stream between Beijing and Hong Kong patients.Methods Non duplicate blood stream isolates were collected between 1998 and 2003 from Peking U- nion Medical College Hospital(n=530)and Hong Kong Prince of Wales Hospital(n=2913).Disk diffusion method and broth microdilution(MB)method were used to determine the antimierobial susceptibility of these strains to 13 antimicrobial a- gents including imipenem,ceftazidime,cefepime,etc.Results The resistance rates of E.coli to amikaein,ceftazidime and cefepime were 0.6%-5.0% and 7.5%-23.5%,and to gentamicin,cefuroxime,ciprofloxacin and cefuroxime were 12.6%- 28.4% and 29.4%-68.4% in Hong Kong isolates(n=1471)and Beijing isolates(n=213),respectively.The resistance rates of Klebsiella spp.to piperacillin-tazobactam and ceftazidime were 3.3%-11.3% and 4.3%-17.7%,and to amikacin, gentamicin,cefotaxime and ceftriaxone were 1.5%-10.1% and 5.8%-27.1% in Hong Kong isolates(n=586)and Beijing i- solates(n=70),respectively.The strains above and the ECS group of bacteria in Hong Kong(consisting of Enterobacter spp.,Citrobacter spp.,and Serratia spp.,n=333)were all susceptible to imipenem and meropenem,but 4.6%(n=65)of the ECS group bacteria in Beijing were resistant.About 8.8% and 14% of ECS group isolates were resistant to cefepime.Such isolates resistant to the other?-lactams ranged from 28.4% to 96%.In Hong Kong,Salmonella typhi remained susceptible to most of the antimierobial agents tested,but in Beijing,the resistance rates to ampicillin and piperacillin were from 9.1% to 18.2%.In Hong Kong,The resistance rates of Acinetobacter spp.and P.aeruginosa to imipenem and meropenem were lower than 10%,but in Beijing their resistance rates to imipenem were 13.6%-15.3% and 8.8%-30.8%,respectively.Conclusions The resistance rates of gram-negative bacteria isolated from blood stream in Beijing to most antimicrobial agents were higher than the corresponding rates in Hong Kong.This result will be useful for empirical therapy of local bacteremia.

Mechanism of carbapenems resistance in Acinetobacter baumannii / 中国医学科学院学报

<p><b>OBJECTIVE</b>To investigate the mechanism of carbapenems resistance in Acinetobacter baumannii.</p><p><b>METHODS</b>WHONET-5 software was used to analyze the trend of carbapenem resistance in Acinetobacter baumannii collected from 1999 to 2001 at Peking Union Medical College Hospital. Analytical isoelectric focusing was used to measure the pI of the beta-lactamase. Conjugation experiment was used to study the transfer of carbapenem resistance and plasmid DNA was extracted and purified with Qiagen Plasmid Mini Kit. The homology of the isolates was determined by pulsed field gel electrophoresis (PFGE). Integrase genes and blaIMP-, blaVIM-, blaOXA- genes for resistant isolates were amplified and sequenced.</p><p><b>RESULTS</b>Imipenem resistance in A. baumannii was ranged from 1.8%-8.5%, but only 9 resistant isolates were viable. They were co-resistant to other carbapenems, ceftazidime, aztreonam, and gentamicin, and four isolates were resistant to ciprofloxacin. Impipenem resistance could not be transferred to susceptible strains. No plasmid was extracted. Each isolate produced TEM-1, AmpC, and two enzymes (pI 6.7, 6.0), which can not be inhibited by cloxacillin and clavulanic acid. Each isolate had class I intergase gene. Nine isolates were all negative for PCR of blaIMP- and blaVIM- genes, but positive for blaOXA-23 specific PCR. Sequencing found 100% homology with blaOXA-23. PFGE found 3 clones (A type: 5 isolates; B type: 3 isolates; C type: 1 isolate). Control isolates (imipenem-susceptible, but ceftazidime, ciprofloxacin, and gentamicin resistant) were also A clone.</p><p><b>CONCLUSIONS</b>Production of OXA-23 carbapenemase in A. baumannii was one of the main mechanisms of carbapenems resistance at our hospital. It brings concern that imipenem-resistant clone has evoluted from nosocomial multiple-resistant strains.</p>

Identification of the habitat of Ligusticum chuangxiong with chromatographic fingerprinting / 中国中药杂志

<p><b>OBJECTIVE</b>To establish the chromatographic fingerprinting for identifying the habitat of Ligusticum chuangxiong.</p><p><b>METHOD</b>HPLC system was applied to obtain the chromatograms of L. chuangxiong samples from different areas, and 15 peaks were measured from the chromatograms. Then some computer-based methods including principle component analysis, clustering analysis, similarity calculation and fisher factor analysis were applied for data analysis.</p><p><b>RESULT</b>There was obvious difference among chromatographic fingerprints of L. chuangxiong samples from different areas. The 15 measured peaks could be used as the fingerprint features.</p><p><b>CONCLUSION</b>Chromatographic fingerprinting can be used for identifying the habitat of L. chuangxiong.</p>

The molecular epidemiology of methicillin-resistant Staphylococcus aureus in China in 2005 / 中华检验医学杂志

Objective To investigate the molecular epidemiology of methicillin-resistant Staphylococcus aureus in China in 2005.Methods From January to December 2005,395 consecutive and non-repetitive isolates of methicillin-resistant Staphylococcus aureus were collected from 17 teaching hospitals in 14 cities.The genotypes of SCCmec were determined by multiplex PCR pulsed-field gel electrophoresis (PFGE)was used to type the chromosome DNA of MRSA.Muhilocus sequence typing(MLST)was used to type the housekeeping genes.Fifty-three strains were selected for MLST typing according to the antimicrobials susceptibility patterns,PFGE types,SCCmec types and the distribution of the regions.The toxin gene was detected by PCR.Results Among 395 isolates of MRSA,SCCmec Ⅲ,untypeable type and type Ⅱ accounted for 61.5%(243/395),24.3%(96/395)and 14.2%(56/395)respectively.In Shenyang,60.7%(17/28)of the isolates were SCCmec Ⅱ,which was significantly higher than other areas. Twenty-four different types and 42 subtypes were found by PFGE typing.Clone A accounted for 50.1%, existing in 13 teaching hospitals in 12 cities and clone R accounted for 23.5%,existing in 9 teaching hospitals in 8 cities.Six sequence types(ST)were found in these isolates with ST239 and ST5 accounting for 75.5% and 17.0% among these isolates,respectively.The prevalence of pvl gene was 2.5% among 395 isolates of MRSA.Conclusions The most types of SCCmec in China were Ⅲ and Ⅱ,and distribution of SCCmec types differed among regions.MRSA outbreaks caused by epidemic multiple-drug resistant clones occurred in big teaching hospitals in China.Meanwhile,the same PFGE pattern may spread among areas. Several international epidemic MRSA clones may exist in China.

Evaluation of Vitek 2 Compact for antimicrobial susceptibility testing of clinically relevant bacteria / 中华检验医学杂志

Objective To evaluate a new system,Vitek 2 Compact,for antimicrobial susceptibility testing(AST)of gram-negative and gram-positive bacteria.Methods Eighty-nine clinical isolates of Peking Union Medical College Hospital,including 48 gram-negative strains and 41 gram-positive strains,and 66 reference strains kept in our laboratory,including 41 gram-negative strains and 25 gram-positive strains, were studied.The antimicrobial susceptibility of these strains were tested by Vitek 2 Compact with AST- GN09(for gram-negative bacteria),AST-P536(for Staphylococci),AST-P534(for Enterococci and S.agalactiae),and AST-P533(for S.pneumoniae)susceptibility cards.The Etest was used as the reference method for comparision.Thirty-two ESBL-producing strains assessed with the confirmatory tests for ESBLs of CLSI(16 strains of them had been confirmed by PCR amplified and sequencing)were detected for ESBLs by Vitek 2 Compact.Results According to the breakpoints of Clinical and Laboratory Standards Institute (CLSI),for the 1 626 microorganism-antibiotic combinations,Vitek 2 Compact gave 90.83% strains with category agreement(CA),4.91% strains with very major errors(VME),2.09% strains with major errors (ME),6.40% minor errors(MIE).The AST for more than 90% of Enterobacteriaceae,nonfermenting bacteria,micrococci and streptococci were completed within 11h,13h,11h and 12h,respectively.The ESBLs tests for thirty-two strains by V-itek 2 Compact are all positive.Conclusions Vitek 2 Compact system can give rapid,reliable and reproducible result with high sensitivity and specificity in assessment of antimicrobial susceptibility testing for clinically relevant gram-negative and gram-positive bacteria,and would become a powerful tool in clinical microbiology laboratory.

Let us understand clinical outcome in surveillance of resistance of bacteria / 中华检验医学杂志

It is an important task to lab of clinical microbiology to surveille multi-drag or pan-drug resistant strains,such as penicillin-or macrolide-resistant Streptococcus pneumoniae,methicillin-resistant Staphylococcus aureus(MRSA),3rd generation cephalosporin-or quinolone-resistant Enterobacteriaceae, carbapenem-resistant Pseudomonas aeruginosa or Acinetobacter baumannii,and so on.We must understand characteristics of these resistant strains to guide doctors' empirical therapy of infective diseases.

Controlled comparison of two supplemented aerobic and anaerobic blood culture bottles to detect simulated bacteremia specimens / 中华检验医学杂志

Objective To compare BACTEC Plus aerobic and anaerobic bottles with BacT/ALERT FA aerobic bottles and FN anaerobic bottles in the ability of detecting simulated bacteremia specimens.Methods The 202 pairs of specimens were composed of 5ml sterile blood and defined loads of microorganisms.112 pairs of specimens in them also contained defined doses of antibiotics to simulate the patients undertaking antibiotic therapy.Time-to-detect(TTD)and positive percentages were evaluated in four groups,including aerobic bottles detecting aerobic bacteria,anaerobic bottles detecting anaerobic bacteria and facultative anaerobic bacteria,and aerobic bottles contained antibiotics detecting aerobic bacteria.Results The positive percentages of two kinds of aerobic bottles were both 100%.For the specimens with bacterial concentration of 10~2 and 10~3 CFU/ml,average TTDs of BACTEC Plus aerobic bottles[(13.69?3.74)h,(11.54?2.87)h]were faster than those of BacT/ALERT FA bottles [(16.76?5.62)h,(14.47?4.30)h;t=-5.674,-7.294,P

Evaluation of Vitek 2 Compact for identification of clinically relevant bacteria and yeasts / 中华检验医学杂志

Objective To evaluate a new system,Vitek 2 Compact,for identification of bacteria and yeasts.Methods 185 clinical isolates of Peking Union Medical College Hospital,including 69 gram- positive strains,66 gram-negative strains and 50 yeasts,and 50 reference strains in our laboratory,including 25 gram-positive and gram-negative strains respectively,were studied.All the strains were identified by Vitek 2 Compact with GP,GN or YST identification cards.The API method was used as the reference method.Results Among the 93 gram-positive strains,85 strains(91.40%)were correctly identified, including 5 low discrimination identified strains,and 8 strains(8.60%)were correctly identified to the genus level,but misidentified to the species level.About 90% of gram-positive strains were identified within 7 h.Out of 91 gram-negative strains,90 strains(98.90%)were correctly identified,with 5 low discrimination identified strains,only 1 strain(1.1%)was correctly identified to the genus level,but misidentified to the species level.Above 90% of Enterobacteriaceae were identified within 5 h,and over 90% of nonfermenting bacteria were identified within 10 h.In the 50 strains of yeasts,46 strains(92%) were correctly identified,including 8 low discrimination identified strains,and 4 strains(8%)were correctly identified to the genus level,but misidentified to the species level.In all the yeasts,45 strains (90%)were identified in 18.25 h,and another 5 strains(10%)were identified in 18.50 h.Conclusions As Vitek 2 Compact system can give us reliable identification results of clinically relevant bacteria and yeasts,together with its significant reduction of handling time,it will definitely become a powerful tool in clinical microbiology laboratory.