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Objective:To report the results of national surveillance on the distribution and antimicrobial resistance profile of clinical bacterial isolates from bloodstream infections in China in 2021.Methods:The clinical bacterial strains isolated from blood culture from member hospitals of Blood Bacterial Resistant Investigation Collaborative System (BRICS) were collected during January 2021 to December 2021. Antibiotic susceptibility tests were conducted by agar dilution or broth dilution methods recommended by Clinical Laboratory Standards Institute (CLSI). WHONET 5.6 was used to analyze data.Results:During the study period, 11 013 bacterial strains were collected from 51 hospitals, of which 2 782 (25.3%) were Gram-positive bacteria and 8 231 (74.7%) were Gram-negative bacteria. The top 10 bacterial species were Escherichia coli (37.6%), Klebsiella pneumoniae (18.9%), Staphylococcus aureus (9.8%), coagulase-negative Staphylococci (6.3%), Pseudomonas aeruginosa (3.6%), Enterococcus faecium (3.6%), Acinetobacter baumannii (2.8%), Enterococcus faecalis (2.7%), Enterobacter cloacae (2.5%) and Klebsiella spp (2.1%). The prevalence of methicillin-resistant Staphylococcus aureus (MRSA) and methicillin-resistant coagulase-negative Staphylococcus aureus were 25.3% and 76.8%, respectively. No glycopeptide- and daptomycin-resistant Staphylococci was detected; more than 95.0% of Staphylococcus aureus were sensitive to ceftobiprole. No vancomycin-resistant Enterococci strains were detected. The rates of extended spectrum B-lactamase (ESBL)-producing isolated in Escherichia coli, Klebsiella pneumoniae and Proteus mirabilis were 49.6%, 25.5% and 39.0%, respectively. The prevalence rates of carbapenem-resistance in Escherichia coli and Klebsiella pneumoniae were 2.2% and 15.8%, respectively; 7.9% of carbapenem-resistant Klebsiella pneumoniae was resistant to ceftazidime/avibactam combination. Ceftobiprole demonstrated excellent activity against non-ESBL-producing Escherichia coli and Klebsiella pneumoniae. Aztreonam/avibactam was highly active against carbapenem-resistant Escherichia coli and Klebsiella pneumoniae. The prevalence rate of carbapenem-resistance in Acinetobacter baumannii was 60.0%, while polymyxin and tigecycline showed good activity against Acinetobacter baumannii (5.5% and 4.5%). The prevalence of carbapenem-resistance in Pseudomonas aeruginosa was 18.9%. Conclusions:The BRICS surveillance results in 2021 shows that the main pathogens of blood stream infection in China are gram-negative bacteria, in which Escherichia coli is the most common. The MRSA incidence shows a further decreasing trend in China and the overall prevalence of vancomycin-resistant Enterococci is low. The prevalence of Carbapenem-resistant Klebsiella pneumoniae is still on a high level, but the trend is downwards.
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Objective:To investigate the distribution and antimicrobial resistance profile of clinical bacteria isolated from blood culture in China.Methods:The clinical bacterial strains isolated from blood culture from member hospitals of Blood Bacterial Resistant Investigation Collaborative System (BRICS) were collected during January 2018 to December 2019. Antibiotic susceptibility tests were conducted with agar dilution or broth dilution methods recommended by US Clinical and Laboratory Standards Institute (CLSI). WHONET 5.6 was used to analyze data.Results:During the study period, 14 778 bacterial strains were collected from 50 hospitals, of which 4 117 (27.9%) were Gram-positive bacteria and 10 661(72.1%) were Gram-negative bacteria. The top 10 bacterial species were Escherichia coli (37.2%), Klebsiella pneumoniae (17.0%), Staphylococcus aureus (9.7%), coagulase-negative Staphylococci (8.7%), Pseudomonas aeruginosa (3.7%), Enterococcus faecium (3.4%), Acinetobacter baumannii(3.4%), Enterobacter cloacae (2.9%), Streptococci(2.8%) and Enterococcus faecalis (2.3%). The the prevalence of methicillin-resistant S. aureus (MRSA) and methicillin-resistant coagulase-negative Staphylococcus were 27.4% (394/1 438) and 70.4% (905/1 285), respectively. No glycopeptide-resistant Staphylococcus was detected. More than 95% of S. aureus were sensitive to amikacin, rifampicin and SMZco. The resistance rate of E. faecium to vancomycin was 0.4% (2/504), and no vancomycin-resistant E. faecalis was detected. The ESBLs-producing rates in no carbapenem-resistance E. coli, carbapenem sensitive K. pneumoniae and Proteus were 50.4% (2 731/5 415), 24.6% (493/2001) and 35.2% (31/88), respectively. The prevalence of carbapenem-resistance in E. coli and K. pneumoniae were 1.5% (85/5 500), 20.6% (518/2 519), respectively. 8.3% (27/325) of carbapenem-resistance K. pneumoniae was resistant to ceftazidime/avibactam combination. The resistance rates of A. baumannii to polymyxin and tigecycline were 2.8% (14/501) and 3.4% (17/501) respectively, and that of P. aeruginosa to carbapenem were 18.9% (103/546). Conclusions:The surveillance results from 2018 to 2019 showed that the main pathogens of bloodstream infection in China were gram-negative bacteria, while E. coli was the most common pathogen, and ESBLs-producing strains were in majority; the MRSA incidence is getting lower in China; carbapenem-resistant E. coli keeps at a low level, while carbapenem-resistant K. pneumoniae is on the rise obviously.
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Objective:To investigate the bacterial composition and antimicrobial resistance profile of clinical isolates from bloodstream infections in China.Methods:The clinical bacterial strains isolated from blood culture were collected during January 2020 to December 2020 in member hospitals of Blood Bacterial Resistant Investigation Collaborative System (BRICS). Antibiotic susceptibility tests were conducted by agar dilution or broth dilution methods recommended by Clinical Laboratory Standards Institute(CLSI, USA). WHONET 5.6 was used to analyze data.Results:During the study period, 10 043 bacterial strains were collected from 54 hospitals, of which 2 664 (26.5%) were Gram-positive bacteria and 7 379 (73.5%) were Gram-negative bacteria. The top 10 bacterial species were Escherichia coli (38.6%), Klebsiella pneumoniae (18.4%), Staphylococcus aureus (9.9%), coagulase-negative Staphylococci (7.5%), Pseudomonas aeruginosa (3.9%), Enterococcus faecium (3.3%), Enterobacter cloacae (2.8%), Enterococcus faecalis (2.6%), Acinetobacter baumannii (2.4%) and Klebsiella spp (1.8%). The prevalence of methicillin-resistant Staphylococcus aureus (MRSA) and methicillin-resistant coagulase-negative Staphylococcus aureus were 27.6% and 74.4%, respectively. No glycopeptide- and daptomycin-resistant Staphylococci were detected. More than 95% of Staphylococcus aureus were sensitive to rifampicin and SMZco. No vancomycin-resistant Enterococci strains were detected. Extended spectrum β-lactamase (ESBL) producing Escherichia coli, Klebsiella pneumoniae and Proteus mirabilis were 48.4%, 23.6% and 36.1%, respectively. The prevalence rates of carbapenem-resistance in Escherichia coli and Klebsiella pneumoniae were 2.3% and 16.1%, respectively; 9.6% of carbapenem-resistant Klebsiella pneumoniae strains were resistant to ceftazidime/avibactam combination. The prevalence rate of carbapenem-resistance in Acinetobacter baumannii was 60.0%, while polymyxin and tigecycline showed good activity against Acinetobacter baumannii. The prevalence rate of carbapenem-resistance of Pseudomonas aeruginosa was 23.2%. Conclusions:The surveillance results in 2020 showed that the main pathogens of bloodstream infection in China were gram-negative bacteria, while Escherichia coli was the most common pathogen, and ESBL-producing strains declined while carbapenem-resistant Klebsiella pneumoniae kept on high level. The proportion and the prevalence of carbapenem-resistant Pseudomonas aeruginosa were on the rise slowly. On the other side, the MRSA incidence got lower in China, while the overall prevalence of vancomycin-resistant Enterococci was low.
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Objective:To investigate the distribution and antimicrobial resistance profile of clinical bacteria isolated from blood culture in China.Methods:The clinical bacterial strains isolated from blood culture from member hospitals of Blood Bacterial Resistant Investigation Collaborative System (BRICS) were collected during January 2016 to December 2017. Antibiotic susceptibility tests were conducted by agar dilution or broth dilution methods recommended by US Clinical and Laboratory Standards Institute (CLSI) 2019. WHONET 5.6 was used to analyze data.Results:During the study period, 8 154 bacterial strains were collected from 33 hospitals, of which 2 325 (28.5%) were Gram-positive bacteria and 5 829 (71.5%) were Gram-negative bacteria. The top 10 bacterial species were Escherichia coli (34.7%), Klebsiella pneumoniae (15.8%), Staphylococcus aureus (11.3%), coagulase-negative Staphylococci (7.4%), Acinetobacter baumannii (4.6%), Pseudomonas aeruginosa (3.9%), Enterococcus faecium (3.8%), Streptococci (2.9%), Enterobacter cloacae (2.7%) and Enterococcus faecalis (2.5%). Methicillin-resistant Staphylococcus aureus (MRSA) and methicillin-resistant coagulase-negative Staphylococcus (MRCNS) accounted for 34.2%(315/922) and 77.7%(470/605), respectively. No vancomycin-resistant Staphylococcus was detected. The resistance rate of Enterococcus faecium to vancomycin was 0.6%(2/312), and no vancomycin-resistant Enterococcus faecium was detected. The ESBLs-producing rates in Escherichia coli, Klebsiella pneumoniae and Proteus were 55.7%(1 576/2 831), 29.9%(386/1 289) and 38.5%(15/39), respectively. The incidences of carbapenem-resistance in Escherichia coli, Klebsiella pneumoniae were 1.2%(33/2 831), 17.5%(226/1 289), respectively. The resistance rates of Acinetobacter baumannii to polymyxin and tigecycline were 14.8%(55/372) and 5.9%(22/372) respectively, and those of Pseudomonas aeruginosa to polymyxin and carbapenem were 1.3%(4/315) and 18.7%(59/315), respectively. Conclusion:The surveillance results from 2016 to 2017 showed that the main pathogens of blood stream infection in China were gram-negative bacteria, while Escherichia coli was the most common pathogen; the MRSA incidence was lower than other surveillance data in the same period in China; carbapenem-resistant Escherichia coli was at a low level during this surveillance, while carbapenem-resistant Klebsiella pneumoniae is on the rise.
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Objective To investigate the distribution of β-lactamase genes in a pan-drug resistant Klebsiella pneumoniae isolate JM45.Methods Klebsiella pneumoniae JM45 was isolated from the blood sample of a patient admitted in the intensive care unit,the Second Affiliated Hospital,Zhejiang University School of Medicine on April 7,2010.The susceptibilities to 26 antibiotics were tested using E-test method.Cica-β-Test was performed to detect β-lactams,and modified Hodge test was performed to detect carbapenemase.Resistant genotypes were detected using PCR,DNA sequencing and BLAST algorithm.Whole genome sequencing (complete graph) was performed by high throughput Roche 454 sequencing approach to analyze the distribution of β-lactamase genes.Results Except polymyxin B and tigecycline,JM45 was resistant to other 24 kinds of antibiotics including cephalosporins and carbapenems.Several β-lactamases were positive in Cica-β-Test,and modified Hodge test was positive.Based on PCR typing,TEM-1,SHV-11,CTX-M-24 and VEB-3 were positive,but carbapenemase genes and metallo-β-lactamase genes were negative.A complete genome (chromosome) sequence (GenBank accession number:CP006656) and 2 plasmids sequences (GenBank accession number:CP006657,CP006658) were obtained by wholegenome sequencing.CTX-M-24 (Locus tag:N559_5233),TEM-1 (Locus tag:N559_5242) and VEB-3 (Locus tag:N559_5248) were positive in plasmid 1.CTX-M-24 located in insertion sequence (IS903-CTXM-24-ISEcp1),while TEM-1 and VEB-3 located in transposons (tnpA-TEM-1-rmtB and VEB-3-tnpA).SHV-11 (Locus tag:N559_2715) was positive in genome (chromosome),and 4 putative β-lactamase genes or β-lactamase domains were obtained:(1) metallo-β-lactamase domain protein (Locus tag:N559_0119,780 bp) ; (2) putative β-lactamase (Locus tag:N559_1633,1308 bp) ; (3) β-lactamase domain protein (Locus tag:N559_2279,813 bp); (4) β-lactamase domain protein (Locus tag:N559_3769,1101 bp).No insertion sequence or transposase gene was observed near SHV-11.Conclusion The resistance to antibiotics including cephalosporins and carbapenems is correlated with TEM-1,SHV-11,CTX-M-24,VEB-3 and 4 kinds of putative β-lactamase genes or β-lactamase domains.
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Objective To analyze molecular evolution of carbapenemase KPC-12 and its binding free energies with β-lactams.Methods Class A beta-lactamases were divided into 2 clusters:those with carbapenemase activities and those without.Minimum Evolution method in MEGA4.1 software was used to analyze molecular evolution of class A beta-lactamases with carbapenemase activity,including KPC-2 to KPC-13,SFC-1,SME-1,IMI-1,NMC-A,and class A beta-lactamases without carbapenemase activity,including TEM-1,SHV-1.Then,tertiary structure of KPC-12 was predicted by homology modeling as reported in SWISS-MODEL database depending on tertiary structure of KPC-2.Moreover,DOCK module in ArgusLab 4.1 software was used to perform molecular docking of KPC-12 to 10 kinds of beta-lactams substrates,and the binding free energies (△ G) were calculated.Results Molecular evolution between KPC-12 and KPC-2 was the closest.The top three decline in binding free energies of β-lactams were penicillin G sodium salt (△G =-8.45149 kcal/mol),ertapenem (△G =-8.36383 kcal/mol) and ampicillin (△G =-8.19326 kcal/mol),while the last two decline in binding free energies of β-lactams were aztreonam (△G =-6.50614 kca]/mol) and clavulanic acid (△G =-6.88533 kcal/mol).Conclusion Carbapenemase KPC-12 has high catalytic activities to penicillin G sodium salt,ertapenem and ampicillin,while has low catalytic activities to aztreonam and clavulanic acid.
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Objective To investigate the synergistic efficacy of different antibiotic combinations against KPC-2 carbapenemase producing Klebsiella pneumoniae strains in vitro and search for effective antibiotic combination.Methods During 2008 - 2009,a total of 24 strains of K.pneumoniae producing KPC-2 carbapenemase were collected from 8 hospitals in the First Affiliated Hospital of Medical School of Zhejiang University,Ningbo LiHuiLi Hospital,Zhejiang People's Hospital,Hangzhou Third Hospital,the Second Hospital of Shaoxing,Hangzhou First Hospital,Fudan University Huashan Hospital,General Hospital of Nanjing Military Region.MLST technique was used for epidemiological analysis.The MIC of antibiotics,such as amikacin,minocycline,imipenem,amoxicillin/clavulanic-acid,ceftazidime,meropenem,gentamicin,cefoxitin,cefepime,rifampicin,polymyxinB,ciprofloxacin were determined by an agar dilution method,the MIC of tigecycline and piperacillin/tazobactain were determined by Etest.The antibacterial activities of cefepime in combination with amoxicillin/clavulanic-acid,amikacin,or ciprofloxacin,amikacin with ciprofloxacin,imipenem with amikacin,ciprofloxacin,polymyxinB,or minocycline,polymyxin B with rifampicin,ceftazidime with amoxicillin/clavulanic-acid were assessed by chequerboard synergy agar dilution tests against all the isolates.Results MLST showed 5 STs among 24 strains of KPC-2 carbapenemase producing K.pneumoniae,and the most prevalent clone was ST11 (15 strains).All isolates were susceptible to polymyxin B and tigecycline,and the resistance rate of minocycline was 4.2％.The synergetic effects were observed in cefepime-amoxicillin/clavulanic acid,imipenem-amikacin,ceftazidime-amoxicillin/clavulanic acid combinations as 19 isolates,13 isolates,and 13 isolates,respectively.Conclusions KPC-2 carbapenemase producing K.pneumoniae is sensitive to polymyxin B,tigecycline and minocycline.The synergetic effect is predominant in cefepime-amoxicillin/clavulanic acid,imipenem-amikacin ceftazidime-amoxicillin/clavulanic acid combinations in vitro,their clinical efficacy are worthy of further observation.
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Objective To investigate the correlation between drug-resistant genes and mobile genetic elements in multi-drug resistant Escherichia coli,and to explore phylogeny among the strains.MethodsTotally 20 strains of multi-drug resistant Escherichia coli were collected from Pan' an Hospital,Zhejiang Province during June 2009 and June 2010.Beta-lactam-resistance genes,aminoglycoside-resistance genes,genetic markers of mobile genetic elements were analyzed by PCR.Index and sample cluster analysis were performed on above results. Results In 20 strains of Escherichia coli,4 kinds of beta-lactamresistance genes,4 kinds of aminoglycoside-resistance genes,and 5 kinds of genetic markers of mobile genetic elements were detected.Index cluster analysis showed that correlation existed between resistance genes TEM,CTX-M-1,aadA5 and mobile genetic elements traA,IS26,ISEcpl; and correlation also existed between resistance genes OXA-1,aac(6′)-Ⅰ b,ant(3)-Ⅰ,rmtB and mobile genetic elements trbC,IS903.Sample cluster analysis showed that this group of Escherichia coli could be divided into 2 groups which were genetically different.ConclusionsDrug-resistant genes in multi-drug resistant Escherichia coli are correlated with mobile genetic elements.Sample cluster analysis can reveal phylogeny among the strains,which is important for hospital infection control.
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ObjectiveTo investigate the prevalence of 16S rRNA methylase genes, aminoglycoside modifying enzymes (AMEs) genes and small multidrug resistance efflux pump gene smr-2 in Klebsiella pneumoniae. MethodsTotally 138 Klebsiella pneumoniae isolates were collected in the First Affiliated Hospital, college of medicine, Zhejiang University from January 2007 to December 2009. Polymerase chain reaction (PCR) and DNA sequencing were performed to screen the presence of six 16S rRNA methylase genes ( rmtA, rmtB, rmtC, rmtD, armA and npmA), seven AMEs genes[aac ( 3 )- Ⅰ , aac ( 3 )- Ⅱ,aac(6′)- Ⅰ b, aac(6′)-Ⅱ, ant(2″)- Ⅰ , ant(3″)- Ⅰ , aph(3′)-Ⅵa]and small multidrug resistance efflux pumps gene (smr-2).Results Thirteen (9. 4％) isolates were found to carry rmtB gene, whereas 87 (63.0％) isolates were found to carry at least one kind of AMEs genes but no smr-2 was detected. The positive rates of aac(3)-Ⅱ, aac(6′)- Ⅰ b, ant (3″)- Ⅰ and ant(2″)- Ⅰ were 40.6％ (56/138), 31.9％ (44/138), 28.3％ (39/138) and 2.2％ (3/138), respectively. All strains harboring rmtB gene carried one to three AMEs genes. Among 44 aac(6′)- Ⅰ b positive strains, 37 (84. 1％ ) were confirmed to carryaac(6′)- Ⅰ b-cr. ConclusionFor Klebsiella pneumoniae, rmtB is the predominant subtype in 16S rRNA methylase genes, accompanying with several AMEs genes.
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ObjectiveTo investigate correlation between drug-resistance related genes and mobile genetic elements of Klebsiella pneumoniae resistant to β-lactams. Methods Forty-seven strains of multidrug-resistant Klebsiella pneumoniae were collected from 6 hospitals in Hangzhou and Huzhou of Zhejiang province from August 2008 to May 2010.Modified Hodge test was performed to detect phenotypes of carbapenemases.Forty kinds of β-lactamases (class A-D),ompK35,ompK36,and 12 kinds of mobile genetic elements were detected by PCR,and the results were analyzed by index cluster.ResultsThirty-five strains were positive in modified Hodge test,and 5 kinds of β-lactamases gene ( including KPC-2-like,GenBank:HQ258934) and 9 kinds of mobile genetic elements were detected.Mutations were observed in ompK35 and ompK36 when compared with sensitive strains.Index cluster analysis showed that correlation existed between KPC-2,KPC-2-like and ISKpn6,between TEM-1 and ISEcpl,IS26,int Ⅰ 1,trbC,IS903,and between CMY-2,OXA-30,DHA-1 and tnpU,tnp513,trbC.ConclusionsFive kinds of β-1actamases genes,and mutations in ompK35 and ompK36 may be associated with the resistance to β-1actams in multidrug-resistant Klebsiella pneumoniae.
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Objective To investigate ehloramphenicol,tetracycline,rifampicin and trimethoprimsulfamethoxazole resistance and the related genes in multi-drug resistant Acinetobacter baumannii(MDR-ABA).Methods Sixty-two strains of MDR-ABA were isolated from clinical samples,and their susceptibilities to 22 antimicrobial agents were detected by Kirby-Bauer disk diffusion tests.Genes related to chloramphenicol(catB and cmlA),rifampicin(arr-2/3),tetracycline(tetA and tetB)and trimethoprimsulfamethoxazole(sull,dfrA1,dfrA5,dfrA7/17,dfrA12,dfr85)resistance and drug emux genes(tehA,emrB,emrD,emrE,smr-2,mdfA)were analyzed by PCR and verified by DNA sequencing.Results Resistant rates of these MDR-ABAs to chloramphenicol,rifampicin,tetracycline and trimethoprimsulfamethoxazole were 100.0%(62/62),100.0%(62/62),90.3%(56/62)and 82.3%(51/62)respectively,while62 strains(100.0%),46 strains(74.2%),36 strains(58.1%)and 8 strains (12.9%)were detected to carry mafA,tetB,sull and tehA genes,respectively.The lest 13 genes were all negative.tetB,sull,tehA and mafa genes(2 for each)chosen optionally from positive ones were verified by DNA sequencing and BLASTn.and all were identified as the same sequences in GenBank.Conclusions MDR-ABAs show hish resistance to chloramphenicol,tetracycline, rifampiein and trimethoprimsulfamethoxazole.Multi-drug resistant phenotypes of MDR-ABAs may be closely related to mdfA genes harboring in strains.
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Objective To investigate the distribution of 22 beta-lactamase genes and enzyme activities in multi-drug resistant Acinetobacter baumannii (MDRAB). Methods Sixty-two MDRAB strains were isolated from the First Affiliated Hospital, College of Medicine, Zhejiang University. Twenty-two beta-lactamase genes were analyzed by PCR and verified by DNA sequencing. Enzyme activities of extended spectrum beta-lactamases (ESBLs) , cephalosporinase ( AmpC) and metallo-beta-lactamases ( MBL) were detected by the modified three-dimensional method using enzyme extraction. Results In 62 MDRABs, 51 (82.3% ) , 50 (80.6% ) and 36 (58.1% ) isolates were found to carry blaTEM, blaOXA-23 cluster, and blaADC, respectively. The rest 19 genes were not detected in this study. DNA sequencing and genomic comparison showed that 5 isolates carrying blaTEM had the same genotype as blaTEM-l , 6 isolates carrying blaOXA-23 cluster had the same genotype as blaOXA-23 carbapenemases (accession; CAB69042. 1) , and 2 isolates carrying blaADC had the same genotype as blaADC-like (accession: EU081908). Thirty-two isolates (51.6% ) produced ESBLs and AmpC, 19 isolates (30.6% ) produced ESBLs only, and 1 isolate (1.6%) produced AmpC only; and no isolate produced MBL. Conclusion MDRAB carrying blaOXA-23 carbapenemase and blaADC AmpC in this study are of high drug resistance.
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Objective To investigate ADC type cephalosporinase genes in muhidrug-resistant strains of Acinetobater baumannii (MDR-ABA). Methods Sixty-two ABA strains were collected during November 2007 to February 2008 from the First Affiliated Hospital, College of Medicine, Zhejiang University. Kirby Bauer disk diffusion method was used to detect the susceptibilities of the strains to antimicrebial agents. PCR and DNA sequencing was performed to analyze the ADC type cephalosporinase gene. Results Sixty-two MDR-ABA strains showed high drag-resistance rate to most antimicrobial agents expect cefoperazone/sulbactam (69.4%), and 36 strains were ACD positive (58.1%). Conclusion MDR-ABA strains in this study are of high drug resistance, which is closely related to ADC type cephalosporinase.
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OBJECTIVE To investigate in vitro activities of 12 antimicrobial agents including cefmetazole against extended-spectrum beta-lactamases-producing Escherichia coli(528 strains),Klebsiella pneumoniae(311 strains) and Proteus mirabilis(15 strains).METHODS They all collected from 15 teaching hospitals in China during 2005 and 2006 and included in the study.The levels of minimal inhibitory concentration(MIC) of 12 antimicrobial agents were determined by agar dilution method.WHONET 5.4 Software was used to analyze the data.RESULTS Against ESBLs-producing E.coli and ESBLs-producing K.pneumoniae,carbapenems were the most active antimicrobial agents(all 100.0% susceptible),followed by cephamycins(80.1-97.3%).Piperacillin/tazobactam(78.5-95.1%)showed a higher activity than cefoperazone/sulbactam(44.1-56.2%).The susceptible rate to ceftazidime against ESBLs-producing E.coli was remarkably higher than the other three cephalosporins,however the differences did not happen to ESBL-producing K.pneumoniae obviously.The susceptible rate to cefuroxime was below 1.6%.ESBLs-producing K.pneumoniae showed high sensitivity to carbapenems,cephamycins and ?-lactam/lactamase inhibitor combinations(all 100% susceptible),however the susceptible rates to cephalosporins were relatively lower.CONCLUSIONS Carbapenems and cephamycins remain the relatively high activity against ESBLs-producing Enterobacteriaceae.
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OBJECTIVE To investigate the antimicrobial resistance of hospital-and community-acquired pathogens collected from 10 teaching hospitals located at different areas in China in 2006.METHODS According to the study protocol,the strains of Streptococcus pneumoniae,meticillin-susceptible Staphylococcus aureus(MSSA),Escherichia coli and Klebsiella pneumoniae were collected and sent to the central lab for reidentification and susceptibility testing.The minimal inhibitory concentrations(MICs) of antimicrobial agents against Str.pneumoniae were determined by Etest method and MICs of antimicrobial agents against S.aureus,E.coli and K.pneumoniae strains were determined by agar dilution method.WHONET5.4 software was used to analyze the data.RESULTS Among 353 Str.pneumoniae strains,74.2% were penicillin-susceptible(PSSP),9.6% were penicillin-intermediate(PISP) and 16.2% were penicillin-resistant(PRSP).Strains from different hospitals showed different sensitivity to penicillin.Among ?-lactam antibiotics,cefuroxime showed the lowest susceptibility rate of 0%(for PRSP) to 76.7%(for PSSP).The susceptibility rate to ceftriaxone and amoxicillin-clavulanic acid was 98.1% and 98.9% in PSSP group,61.8% and 64.7% in PISP group,and 15.8% and 10.5% in PRSP group.The ESBLs rate was 56.2% among 267 Escherichia strains and 42.7% among 206 K.pneumoniae strains.For ESBLs-producing strains,the susceptibility rates to cefotaxime and ceftriaxone were low and the rate to ceftazidime was relatively high among ?-lactam antibiotics.73.4% MSSA strains produced ?-lactamase.?-Lactam antibiotics tested showed high susceptibility against MSSA strains.The susceptibility rate was 98.9-100%.The susceptibility rate to ciprofloxacin and levofloxacin was 80.8% and 88.1%,separately.CONCLUSIONS Fluoroquinolones show high susceptibility against Str.pneumoniae.Ceftriaxone and amoxicillin-clavulanic acid have relatively high susceptibility among ?-lactams.For MSSA and non-ESBLs-producing E.coli and K.pneumoniae strains,?-lactams show high susceptibility.For ESBLs-producing E.coli and K.pneumoniae strains,the susceptibility rates to cefotaxime and ceftriaxone are low and that to ceftazidime,cefepime and cefoperazone-sulbactam are relatively high.