ABSTRACT
Objective:To study the clinical features and drug resistance profile of neonatal sepsis caused by different species of Klebsiella.Methods:From January 2009 to December 2018, cryopreserved Klebsiella strains from blood culture of neonatal sepsis cases in NICU of our hospital were reactivated. Molecular identification and antimicrobial susceptibility tests were performed. Clinical features, laboratory tests, drug resistance profile and prognosis of these patients were analyzed retrospectively.Results:A total of 29 strains of Klebsiella were reactivated. Molecular identification assigned 22 cases (75.9%) into Klebsiella pneumoniae (Kpn) group and 7 cases (24.1%) into Klebsiella quasipneumoniae (Kqu) group. Gestational age and birth weight of Kpn group were higher than Kqu group [(33.1±3.2) weeks vs. (30.6±0.9) weeks, (1 847±677) g vs. (1 416±121) g] ( P<0.05). Abdominal distension was more common in Kqu group than Kpn group [42.9% (3/7) vs. 4.5% (1/22), P<0.05]. No significant differences existed in the laboratory tests including white blood cell count, platelet count, hypersensitive C-reactive protein and procalcitonin between the two groups ( P>0.05). Kpn was 100.0% sensitive to Cefazolin-Tazobactam and Amikacinto and less sensitive to Imipenem and Cefperazone-Sulbactam, Meropenem and Ertapenem. Kqu was generally more sensitive than Kpn and the sensitivity of Kqu to Imipenem was 100.0%. No significant differences existed of the prognosis between the two groups ( P>0.05). Conclusions:Kpn is the main pathogen of neonatal Klebsiella sepsis. Kqu sepsis is more common in neonates with smaller gestational age and lower birth weight. Abdominal distention is common presenting symptom in Kpn sepsis and sensitive antibiotics should be used early.
ABSTRACT
Objective To analyze the pathogens distribution and drug resistance of nosocomial infection in patients with end-stage diabetic nephropathy .Methods 96 cases of end-stage diabetic nephropathy were randomly selected in our hospital .The speci-mens of urine ,blood and sputum were collected .The pathogens were identified by the drug susceptibility testing .Results The in-fection rate was 27 .08% .A total of 103 strains of pathogens were isolated ,including 15 strains of fungi ,42 strains of gram-negative bacteria and 46 strains of gram-positive bacteria .The drugs susceptibility rates of the fungi to flucytosine ,amphotericin B and flu-conazole were 100% ,and it also showed that the fungi had higher sensitivity to other common antibiotics ;the drug susceptibility rates of gram-positive bacteria to vancomycin and teicoplanin were 100% ,while its drug susceptibility ability to penicillin ,strepto-mycin and others were weak ;the drug susceptibility rates of gram-negative bacteria to piperacillin and imipenem were high ,while its drug susceptibility ability to aztreonam and cephalosporin were weak .Conclusion The low resistance in the patients with end-stage diabetic nephropathy the abuse of clinical antiseptic drugs lead to the dysbacteriosis ,resulting in a significant increase of the inci-dence of nosocomial infection ,so the analysis of pathogens distribution and drug resistance of nosocomial infection has clinical sig-nificance .
ABSTRACT
ObjectiveTo evaluate the clinical value of prenatal ultrasonography combined with maternal serology screening for chromosomal abnormality in 15 to 20+6 gestational weeks.MethodsSix hundred and twenty-eight pregnant women (628 fetuses) in 15 to 20+6 gestational weeks were selected to undergo prenatal ultrasonography, who were in critical risk of trisomy 21 or trisomy 18 by maternal serology screening. Transabdominal ultrasonography were performed and fetal nasal bone and nuchal fold were detected. Those who had nasal bone hypoplasia, thickened nuchal fold (NF>6 mm) and other abnormal fetal soft markers underwent amniocentesis for karyotyping analysis. ResultsThere were 6 cases of nasal bone hypoplasia (0.96%, 6/628), including one case of thickened nuchal fold, two cases of echogenic bowel, two cases of choroid plexus cysts and 1 case of echogenic cardiac focus. All these 6 cases underwent amniocentesis and 2 were trisomy 21 (33.3%, 2/6). The other 4 cases had no significant chromosomal abnormality.ConclusionsPrenatal ultrasonography may improve the detection rate of chromosomal abnormality for those pregnant women who are in critical risk of chromosomal abnormality prompted by serology screening. But invasive procedures are still needed to verify the chromosomal abnormality.
ABSTRACT
Objective To investigate the prevalence and molecular characteristics of the extended -spectrum β-lactamase ( ESBL) and AmpC enzyme-producing Proteus mirabilis ( P.mirabilis) strains isola-ted in Shenzhen People′s Hospital.Methods The production of ESBLs and AmpC enzymes by P.mirabilis isolates were detected by a screening and confirmatory test for ESBLs and AmpC disk test , respectively .The PCR assays followed by DNA sequencing of the products were employed to analyze the multiple genes inclu -ding the ESBLs genes, AmpC genes, insertion sequences (ISs) upstream of the ESBLs or AmpC genes, plasmid -mediated quinolone resistance ( PMQR ) determinants , quinolone resistance-determining region (QRDR) genes , the integrase genes, and class1 integron cassette.The epidemiological analysis of the iso-lates was performed by pulsed field gel electrophoresis .Results There were 130 P.mirabilis clinical iso-lates collected from Shenzhen People′s Hospital in China during the year 2004 to 2010.Among them, 13 isolates (10%) produced ESBLs, that accounted for 0%-9.1%in the year 2004-2009 and up to 29.4%in 2010, and 3 isolates (2.3%) produced AmpC enzymes.The predominant genotype of ESBLs -producing isolateswas b al CTX-M-14(n=7), followed by blaCTX-M-65(n=3), blaCTX-M-55(n=1), blaCTX-M-24(n=1) and blaPER-1 (n =1).The clinical isolate of PER-1-producing P.mirabilis was reported for the first time in China.Twoisolates carried an AmpC β-lactamase gene of blaCMY-2 and one isolate carried an unidentified AmpC gene .ISEcp1 located upstream of blaCTX-M and blaCMY-2 were detected in 91.7% (11/12) of CTX-M-producing isolatesand one CMY-2-producing isolate, respectively.ISPa12 was present upstream of blaPER-1 in one studiedisolate.Approximately 66.7% (10/15) of ESBL and /or AmpC-producing isolates harbored PMQR genes including2 carrying qnrD, 5 carrying aac-Ib-cr and 3 carrying both qnrD and aac-Ib-cr.Twelve ESBL and /orAmpC-producers with high level of resistance to ciprofloxacin carried the similar mutation profiles of S 83I inGyrA, S80I or S80R in ParC and among them, six strains showed E466D mutation in GyrB.Approximately86.7% (13/15) of ESBL and/or AmpC-producing isolates carried class 1 integron.Fourteen PFGE typeswere observed among 15 ESBL and/or AmpC-producers.Conclusion The prevalence of CTX-M β-lactamasesin P.mirabilis isolates contributed to the increased resistance to extended -spectrum cephalosporins.The qnrD and/or aac-Ib-cr genes were detected among the most of ESBL and /or AmpC-producing P.mirabilis clinical isolates.
ABSTRACT
Objective To evaluate the capability of multilocus variable-number tandem-repeat ( VNTR) analysis ( MLVA) and pulsed-field gel electrophoresis ( PFGE) for genotyping Salmonella enterica serovar Typhi (S.Typhi) isolates.Methods Five polymorphic VNTRs (SAL02,SAL11,SAL16,SAL20, and TR4699 ) that were observed in S.Typhi strains from previous studies were selected to establish MLVA . Twenty-one epidemiologically unrelated S.Typhi strains that were isolated from Shenzhen ,China from 2002 to 2007 were genotyped by the established MLVA , and the results were compared with those by PFGE . Results The Simpson′s index of diversity ( D value ) for all five different VNTRs ranged from 0.838 to 0.943 .A total of 19 MLVA profiles and 19 PFGE profiles were found , respectively .The D value for both MLVA and PFGE were 0.99 and the test results from two analyses were identical .Conclusion The five polymorphic VNTRs analysis could be used as an alternative typing scheme for epidemiologic investigation of S.Typhi infection .
ABSTRACT
Objective To study the epidemiological features of Cryptococcus neoformans and Cryptococcus gattii isolated from clinical samples in Shenzhen and to elucidate the distribution of species,varieties,genotypes and mating types within the strains tested.Methods The strains involved in this study were 55 cryptococcal strains isolated from our clinical samples.The canavanine-glycine bromthymolblue (CGB) culture was performed to distinguish Cryptococcus neoformans from Cryptococcus gattii.The genotype was characterized by polymerase chain reaction (PCR) fingerprinting with primer M13.The Cryptococcus gattii species and varieties of grubii and neoformans together with two opposite mating type α and a were identified by PCR with variety-specific and mating type-specific primers.The GEF1-restriction fragment length polymorphism analysis was conducted to simultaneously determine the genotype and mating types of strains tested.The sequence type of IGS1 region was analyzed for the VG Ⅱ genotype.Results Of the 55 tested cryptococcal strains,52 were Cryptococcus neoformans,all of which were var.grubii,genotype VN Ⅰ and mating type α.The remaining 3 strains were Cryptococcus gattii,among which,one was genotype VG Ⅰ and mating type α,and two were genotype VG Ⅱ and mating type α.The two VGⅡ genotype strains belonged to the sequence type Ⅱ.Conclusions The strains belonging to the Cryptococcus neoformans var.grubii,genotype VN Ⅰ and mating type α predominate in causative pathogens of cryptococcosis in Shenzhen.Cryptococcus gattii accounts for minority of the cryptococcal isolates,and the highly pathogenic VG Ⅱ genotypes in foreign countries are also characterized.The sequence types of IGS1 region of the two VG Ⅱ strains are in accord with VG Ⅱb sub-genotype.
ABSTRACT
Objective To explore the characteristics of nosocomial infection and its related factors among those very low birth weight infant(VLBWI)for coming up with appropriate preventive measures.Methods Fifty-eight infants with birth weight of 1500 g or below in the hospital from January to June in 2012 were studied actively and retrospectively about their nosocomial infection and related risk factors.Results Thirty-five cases of nosocomial infection occurred among the 58 infants with a prevalence of 60.34%. The mainly pathogenic bacteria was Gram-positive bacteria(88.47%)and mostly,infections presented with lung infections(82.90%) within 21 days after birth.The risk factors included mechanical ventilation,PICC,Apga score<7,fluconazole administration and premature rupture of membranes of VLBWI.Conclusion VLBWI are prone to nosocomial infections,mostly lung infection on day 21 after birth.Management should be strengthened within 3 weeks after birth of VLBWI to minimize infections.Reduction of invasive procedures on children and antibiotic use is particularly important.On the other hand,strengthening the health care in the perinatal period and reducing the incidence of preterm birth cannot be ignored.
ABSTRACT
Objective To investigate antimicrobial resistance among Streptococcus pneumoniae clinically isolated from 14 teaching hospitals located at different areas in China in 2005-2008 and to give logical guidance for clinical empirical therapy.Methods A total of 1 317 non-repetitive S.pneumoniae isolates in 14 teaching hospitals from 2005-2008 were collected and sent to the central lab for reidentification and susceptibility testing, including 271 isolates collected in 2005, 391 isolates collected in 2006, 363 isolates collected in 2007 and 292 isolates collected in 2008. Most of the isolates were from community-acquired respiratory tract infections, which were isolated from outpatient or emergency department patients with respiratory tract infections or those patients with respiratory tract infections within ≤48 hours hospitalization.The districts where the organisms were isolated include North China, Northeast China, South China, Central and Northwest China and East China.The patients included adults, teenagers and children.The minimum inhibitory concentrations (MICs) or inhibitory zone diameter of 17 antimicrobial agents were determined by Etest method, agar dilution method or disk diffusion method.WHONET5.5 software was used to analyze susceptibility rate, intermediate rate, resistance rate, MIC50 and MIC90.Results Linezolid (100%) and fluoroquinolones (95.2%-99.7%) showed excellent activities against S.pneumoniae.Among β-lactams, amoxicillin-clavulanic acid remained high activities (73.8%-92.1%),followed by penicillin, ceftriaxone and cefepime with year-over-year decrease in activities.The activities of three second-generation cephalosporins were low (36.3%-38.4% in 2008).The activities of erythromycin, azithromycin, clindamycin, trimethoprim/sulfamethoxazole and tetracycline against S.pneumoniae were poor and decreased year over year.The incidence of penicillin non-susceptible S.pneumoniae (PNSP) was increasing especially for PISP (from 4.4% in 2005 to 20.2% in 2008).The incidence of PNSP in North China was low (6.0%), while this value were high in central China and East China (30.1% and 38.7%, separately).The incidence of PNSP in adults (15.7%) was obviously lower than that in children(≤5 years:33.0%) and teenagers (6-17 years:38.2%).Conclusions linezolid and fluoroquinolones showed excellent in vitro activity against S.pneumoniae, followed by penicillin and cephalosporins with year-over-year decrease of activity. Clinicians should pay more attention when using those antimicrobial agents with poor activity against S.pneumoniae, which include macrolides, clindamycin, trimethoprim/sulfamethoxazole and tetracycline.
ABSTRACT
Objective To investigate the antimicrobial resistance mechanisms and genetic homogeny of Salmonella from community acquired infections in Shenzhen,China.Methods Ninety-three of Salmonella were isolated from 2002 to 2007 at Shenzhen People's Hospital,China.PCR and DNA sequencing were used to investigate the mutation in QRDR of the gyrA,gyrB,parC and parE.Plasmid mediated quinolone resistance genes including qnr and aac(6')-Ib-cr,β-lactamase genes including blaTEM,blaSHV,blaOXA, blaCTX-M, and class 1 integron were detected. All isolates were typed by PFGE. Results S. enterica typhi and S. enterica paratyphi A were susceptible to ampicillin, chloramphenicol, trimethoprim/sulfamethoxazole, ceftriaxone and ciprofloxacin, with the susceptible rate of 96%-100%. Fifty-two percent (13/25) of S. enterica typhi and 95% (61/64) of S. enterica paratyphi A were resistant to nalidixic acid. Twenty-four percent (6/25) of nalidixic acid-resistant S. enterica typhi and 94% (60/64) of nalidixic acid-resistant S. enterica paratyphi A showed decreased susceptibility to ciprofloxacin (MIC of 0. 125-1 μg/ml).All nalidixic acid-resistant (susceptible to ciprofloxacin ) Salmonella (NARS) isolates had a single substitution in the QRDR of GyrA, and 91% (68/75) of these isolates carried the substitution Ser83Phe in GyrA. Two mutations in the QRDR of GyrA were detected in both of two ciprnfloxacin-resistant Salmonella,with the additional one mutation in the QRDR of parC. Plasmid mediated quinolone resistance genes including qnr and aac(6')-lb-cr were not detected in any isolate. The blaCTX-M-14 gene was detected in a ceftriaxoneresistant isolate of S. enterica paratyphi A, with ISEcpl located on the upstream of it. Three muhidrugresistant strains of Salmonella all carried one 1 900 bp classⅠ integron gene cassette dhfrⅫ-orfF-aadA2,with the additional one β-lactamase gene of blaTEM-1, or blaOXA-30. Twenty-two distinct PFGE patterns were observed among twenty-five S. enterica typhi. The PFGE patterns of sixty-four S. enterica paratyphi A showed limited genetic diversity (average similarity of 91% ). Ninety investigated inpatients were infected in the community. Six patients infected by S. enterica paratyphi A had a travel history before infection. Conclusions Nalidixic acid-resistant S. enterica typhi and S. enterica paratyphi A are highly prevalent in Shenzhen,China. The mutation in the QRDR of GyrA is the prevalent mechanism responsible for the resistance to nalidixic acid in Slmonella. The great genetic similarity among S. enterica paratyphi A isolates indicates endemic disease from the presence of a single clone over 6-year period.
ABSTRACT
Objective To evaluate the performance of modified Hodge test on the detection of carbapenemases among Enterobacteriaceae with decreased susceptibility to carbapenems. Methods Fortynine Enterobacteriaceae isolates with decreased susceptibility to carbapenems ( MIC of imipenem, meropenem or ertapenem was ≥ 2 μg/ml ) were collected from 16 teaching hospitals from 2004 to 2008. MICs of imipenem, meropenem and etapenem were determined by agar dilution method. Carbapenemases were detected by modified Hodge test. Carbepenemase-causing positive results and AmpCs-causing positive results were differentiated by phenyl boronic acid and oxacillin. Beta-lactamases encoding genes including blaNDM-1were detected by PCR and sequencing. Results Thirty-six of 49 isolates were non-susceptible to imipenem (MIC >4 μg/ml), 31 were non-susceptible to meropenem (MIC > 4 μg/ml) and 47 were non-susceptible to ertapenem (MIC > 2 μg/ml). Twenty-three isolates showed positive modified Hodge test result, including 9 weak-positive results and 14 strong-positive results. Through PCR detection and sequencing, 2 out of 9 isolates showing weak-positive results carried blaKPC-2 and other 7 did not carry any carbapenemase genes but AmpCs/ESBLs genes. Among the 14 isolates showing strong-positive results, 4 carried blaKPC-2, 8 carried blaIMP-4 and 2 caried blaIMP-8. All 26 isolates with negative modified Hodge test result didn't carry any carbapenemase genes. No isolate carried blaNDM-1. Carbapenemases genes PCR detection was regarded as a gold standard, and the sensitivity, specificity, positive predictive value and negative predictive value of modified hodge test was 100%, 79%, 70% and 100% on the detection of carbapenemases among Enterobacteriaceae with decreased susceptibility to carbapenems. Conclusions Modified Hodge test revealed great sensitivity but showed a few false positive results. True and false positive results can be effectively differentiated by phynel boronic acid and oxacillin.
ABSTRACT
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.
ABSTRACT
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.
ABSTRACT
OBJECTIVE To investigate the susceptibilities of Staphylococcus aureus and Enterococcus isolated from Shenzhen Hospital during 2005 to 2006 to 17 antimicrobial agents.METHODS The minimal inhibitory concentrations(MICs) of 17 antibacterial agents were determined by agar dilution method,WHONET5.3 software was used to analyze the data.RESULTS The prevalence of meticillin-resistant S.aureus(MRSA) was 20.7%.Vancomycin and teicoplanin remained very high activity against MRSA(100%),with the MIC50 and MIC90 of 0.5 and 1 ?g/ml,respectively.Fluoroquinolones(ciprofloxacin,levofloxacin and gatifloxacin),trimethoprim/sulfamethoxazole,erythromycin,and clindamycin showed very low activity against MRSA(0-33.3%).The most active agent against Enterococcus faecalis was vancomycin and teicoplanin(100.0%),followed by piperacillin/tazobactam,imipenem and ampicillin(97.2-100.0%).E.faecium showed high resistance to various agents,except to vancomycin and teicoplanin(susceptible rate 100.0%).Cross-resistance to fluoroquinolones was found among MRSA,MSSA,E.faecalis,and E.faecium.CONCLUSIONS MRSA and E.faecium isolated from our hospital showed high resistance to multiple antimicrobial agents except vancomycin and teicoplanin.
ABSTRACT
OBJECTIVE To investigate the prevalence of multidrug resistance(MDR) mechanisms of Staphylococcus haemolyticus against oxacillin,gentamycin and erythromycin.METHODS Agar dilution method was performed to detect the minimal inhibition concentration(MIC) of 3 antimicrobial agents against 63 strains of S.haemolyticus,and the resistance genes of mecA,aac(6′)+aph(2″),ermA,ermB,ermC and msrA/msrB were investigated by PCR in all clinical isolates.RESULTS mecA Gene was detected in 62 isolates of meticillin-resistant S.haemolyticus(MRSH),and aac(6′)+aph(2″) gene was found in 50 isolates resistant to gentamicin,and the most prevalence erythromycin resistance gene in S.haemolyticus was msrA/msrB(58.7%),followed by ermC(31.7%).Among the 43 MDR strains,the more commonly encountered three genes were mecA,aac(6′)+aph(2″) and msrA/msrB(58.1%)or ermC(20.9%),and 8 isolates(18.6%) were found harboring four genes of mecA,aac(6′)+aph(2″),ermC and msrA/msrB.CONCLUSIONS The mecA,aac(6′)+aph(2″),msrA/msrB and ermC genes are main resistance mechanisms against oxacillin,gentamicin and erythromycin in mutidrug resistant S.haemolyticus.
ABSTRACT
OBJECTIVE To investigate the antimicrobial susceptibility of 9 antimicrobial agents and multidrug(resistance)(MDR) phenotype among Acinetobacter baumannii isolated from hospitalized patients.METHODS Disk diffusion method was used to detect the inhibitory zone diameter of 9(antimicrobial) agents to 221 strains of A.baumannii.according to standard from NCCLS in South China during 2002 to 2004.RESULTS 25.3% and 26.4% of isolates from ICU patients showed resistance to(imipemem) and meropemem,respectively,and the resistance rates were greater among the(isolates) from ICU(patients) than those from non-ICU inpatients by 13.4% and 12.2 %(P
ABSTRACT
Objective To determine the ESBLs of Klebsiella pneumoniae and ESBL typing by molecular genetic procedures. Methods MIC test and ESBLs confirmation test were taken by agar dilution method in 80 strains of Klebsiella pneumoniae isolated in Beijing area from July 1999 to December 1999. To the 20 ESBLs positive conjugates isoelectric focusing was given. And nucleotide sequencing was analysed to conjugate strain CK23. Results 28 (35%) of the 80 strains of Klebsiella pneumoniae produced ESBLs. In the 28 strains, 20 were successfully done with conjugation of resistant plasmid. Isoelectric focusing results revealed that 13 (65%) of the 20 strains produced an ESBLs protein with a pI of 8.8 with or without additional pI 7.6 and pI 5.4. These ? lactamases were all inhibited by clavulanite acid. The strains with pI=8.8 protein were highly resistant to cefotaxime and ceftriaxone but were susceptible or intermediate to ceftazidime. We picked CK23 strain out from 13 conjugates for gene cloning by the primers designed for bla CTX M and nucleotide sequencing. The results showed that the ESBLs gene in CK23 was CTX M, highly similar to CTX M 3 but had 3 amino acids, which were Glu39Gly, Leu122Pro, Asp278His. Conclusions 28 (35%) of the 80 strains of Klebsiella pneumoniae produced ESBLs. Resistant plasmid successfully conjugated in 20 of the 28 ESBLs producing strains. 13 of the 20 (65%) conjugates pruduced a pI =8.8 ESBLs,which was CTX M ESBLs,with only 3 amino acids different from CTX M 3. This paper indicated that a type of CTX M ESBLs existed in Klebsiella pneumoniae in Beijing, which specifically confers resistance to cefotaxime.