Transconjugation and genotyping of the plasmid-mediated AmpC β-lactamase and extended-spectrum β-lactamase genes in Klebsiella pneumoniae

Bsckgroud AmpC β-lactamases and extended-spectrum β-lactamases （ESBLs） are becoming predominant causes of resistance to third and forth-generation cephalosporins in Klebsiella pneumoniae （K. pneumoniae）. It is very difficult to treat infectious diseases caused by multidrug-resistant K. pneumoniae. The purpose of the present study was to investigate transconjugation and characteristics of β-lactamase genes in K. pneumoniae producing AmpC β-lactamases and ESBLs.
Methods AmpC β-lactamases were detected by three-dimension test and ESBLs by disc confirmatory test. Minimum inhibitory concentrations （MICs） were determined by agar dilution. Transfer of resistance to EC600 （Rifr） was attempted by conjugation in broth and screened on agar containing cefotaxime （2 μg/ml） plus rifampin （1024 μg/ml）. The genes encoding AmpC or ESBLs and their transconjugants were detected by PCR and verified by DNA sequencing.
Results The resistant rates to ampicillin and piperacillin were 100% in 18 isolates of K. pneumoniae. However, imipenem was still of great bactericidal activity on K. pneumoniae, and its MIC50 was 0.5 μg/mL. Eleven β-lactamase genes, including TEM-1, TEM-11, SHV-13, SHV-28, CTX-M-9, CTX-M-22, CTX-M-55, OXA-1, LEN, OKP-6 and DHA-1, were found from 18 isolates. And at least one β-lactamase gene occurred in each isolate. To our surprise, there were six β-lactamase genes in the CZ04 strain. Among 18 isolates of K. pneumoniae, the partial resistant genes in 8 isolates were conjugated successfully, which had 100% homological sequence with donors by sequence analysis. Compared with donors, 8 transconjugants had attained resistance to most β-lactams, including ampicillin, piperacillin, cefoxitin, cefotaxime and aztreonam, or even amikacin and gentamicin.
Conclusions R plasmids can be easily transferred between the resistant and sensitive negative bacilli. It is very difficult to block and prevent the spread of antimicrobial resistance. So more attention should be paid to reducing the frequency, times and dosage of antimicrobials, especially third or fourth cephalosporins.     

Drug-resistance mechanisms and prevalence of Enterobacter cloacae resistant to multi-antibiotics

The main drug-resistance mechanism of gram-negative bacteria is producing β-lactamases. Two kinds of enzymes cause drug resistance by hydrolyzing oxyimino-cephalosporins and aztreonam: one is chromosomally encoded AmpC β-lactamases, the other is plasmid-mediated extended-spectrum β-lactamases (ESBLs). Enterobacter cloacae can produce both of them, so that these strains are seriously resistance to many antibiotics. In order to study the main drug-resistant mechanism in Enterobacter cloacae, PCR and nucleotide sequencing were performed on 58 multidrug resistant strains.     

Prevalence of β-lactamase and Antimicrobial Resistance among Clinical Pseudomonas Aeruginosa Isolates

Pseudomonas aeruginosa is the most common pathogen with an increasing resistance to antimicrobials. The objective of this study was to investigate the prevalence of β-lactamases and their relationships to β-lactam resistance in clinical isolates of P. aeruginosa. A total of 101 consecutive, non-duplicate isolates of P. aeruginosa were studied. Minimum inhibitory concentrations （MICs） of eight kinds of antibacterial agents were determined by the agar dilution method. AmpC was identified by the AmpC disk test and metallo-β-lactamases by the inhibitor-potentiated disk diffusion （IPD） test. PCR amplification and sequencing of Ambler class A and D genes were performed. The MICs of all antibacterial agents used in this study were quite high. The MIC90 of piperacillin/tazobactam was achieving to 256μg/ml, and cefoperazone/sulbactam and imipenem MIC90 values were 128μg/ml and 32μg/ml, respectively. The most effective antimicrobial agent was meropenem, however, it still only inhibited 80.2% of P. aeruginosa strains. A total of 56 isolates （55.4%） yielded one or more kinds of β-lactamase and were more resistant than β-lactamase negative isolates. In conclusion, resistance of P. aeruginosa to β-lactams seems very common in our hospital and β-1actamase is a major mechanism. The early recognition of β-1actamase producers is critical for selection of antimicrobial agents in the treatment of clinical infection and for the prevention of their widespread dissemination.     

A Five-year Surveillance of Carbapenemase-producing Klebsiella pneumoniae in a Pediatric Hospital in China Reveals Increased Predominance of NDM-1

Objective To characterize carbapenem(CPM)-non-susceptible Klebsiel a pneumoniae(K. pneumoniae) and carbape-nemase produced by these strains isolated from Beijing Children's Hospital based on a five-year surveillance. Methods The Minimal Inhibition Concentration values for 15 antibiotics were assessed using the Phonix100 compact system. PCR amplification and DNA sequencing were used to detect genes encoding carbapenemases. WHONET 5.6 was finally used for resistance analysis. Results In total, 179 strains of CPM-non-susceptible K. pneumoniae were isolated from January, 2010 to December, 2014. The rates of non-susceptible to imipenem and meropenem were 95.0% and 95.6%, respectively. In the 179 strains, 95(53.1%) strains carried the blaIMP gene, and IMP-4 and IMP-8 were detected in 92(96.8%) and 3(3.2%) IMP-producing isolates, respectively. 65(36.3%) strains carried the blaNDM-1 gene. 6(3.4%) strains carried the blaKPC gene, and KPC-2 were detected in 6 KPC-producing isolates. In addition, New Delhi-Metallo-1(NDM-1) producing isolates increased from 7.1% to 63.0% in five years and IMP-4 producing isolates decreased from 75.0% to 28.3%. Conclusion High frequencies of multiple resistances to antibiotics were observed in the CPM-non-susceptible K. pneumoniae strains isolated from Beijing Children's Hospital. The production of IMP-4 and NDM-1 metallo-β-lactamases appears to be an important mechanism for CPM-nonsusceptible in K. pneumoniae.     

Genetic environment of β-lactamase genes of extended-spectrum β-lactamase-producing Klebsiella pneumoniae isolates from patients with lower respiratory tract infection in China

Background Extended-spectrum β-lactamase （ESBL）-producing Klebsiella pneumoniae （K.pneumoniae） is one of the most popular pathogens that cause refractory respiratory tract infection.The genetic environment,including insertion sequences and the types of promoter,plays a key role in exploration of the mechanism of prevalence and dismission of the ESBL-producing K.pneumoniae isolates.The aim of the investigation was to target analysis the genetic environment and promoter sequences of blaCTX-M,blaSHV and blaTEM,the most popular β-lactamase genes harbored by ESBL-producing K.pneumoniae isolates.Methods From February 2010 to July 2011,158 of 416 K.pneumoniae isolates producing ESBL from patients with lower respiratory tract infection were collected from seven tertiary hospitals from Beijing,Anhui,Fujian,Liaoning,Hebei and Inner Mongolia Autonomous Region in China.The genetic environment including promoters of 10 types of blaCTX-M,18 types of blaSHVand 2 types of blaTEM were analyzed by amplification and direct sequencing with various sets of PCR primers.Results ISEcp1 was located upstream of the 5＇ end of the blaCTX-M gene in 130 （97.0％） out of 134 K.pneumoniae isolates harboring blaCTX-M and provided a conserved promoter to blaCTX-M.A non-coding sequence preceded by kdpC and recF was identified in all of the blaSHV genes except blaSHV-12 and blaSHV-2a.IS26 was also found upstream of 1 blaCTX-M-15,10 blaSHV-1 strains,4 blaTEM-1 and all of the blaSHV-2,blaSHV-2a,blaSHV-5 and blaSHV-12.Eighty-seven of 91 strains harboring blaTEM-1 carried a copy of Tn2 and IS26-blaTEM-1 fragments were also detected in 4 strains.With respect to K.pneumoniae,the genetic environment of blaCTX-M-38,blaSHV-142 and blaTEM-135 were firstly elaborated,and four kinds of novel genetic environment of blaCTX-M-3,blaCTX-M-15 and blaTEM-1 have been detected as well.Conclusions Perfective implementation of the genetic environment information of β-lactamase gene needs to be further explored and supplemented.ISEcp1 and IS26 elements ar     

A new blaLEN-17 gene in a clinical isolate of Staphylococcus epidermidis in Shanghai, China

The introduction of the antibiotics into clinical practice has significantly reduced the mortality of infectious diseases. Although chromosomally mediated β-1actamase is natural in many genera of bacteria, the intensive use of antibiotics is the main cause for the increasing emergence of new β-1actamases. So far, more than 340 β-lactamases have been identified,1 among which, more than 200 are extended-spectrum β-lactamases （ESBLs）.2 The most prevalent β-lactamases are class A enzymes, including SHV and TEM. Genes encoding these enzymes generally located in large transferable plasmids. The dissemination of these plasmids attributes to the increasing incidence and spread of v-lactam resistance. It is important to investigate the prevalence and allelic distribution of genes encoding β-lactamase in the bacterial population in order to prevent the emergence of ESBLs in those bacteria and the spread of ESBLs in the clinical setting.     

Multi-drug Resistant Uropathogenic Escherichia coli and Its Treatment by Chinese Medicine

Objectives: To investigate the resistance and virulence profiles of uropathogenic Escherichia coli (UPEC) and its treatment by Chinese medicine (CM) Fuzheng Qingre Lishi Formula (扶正清热利湿方, FQLF). Methods: UPEC strains were isolated from recurrent urinary tract infections (UTIs) patients. Patient sensitivities to 17 antibiotics were tested by the disk diffusion method. Virulence genes were screened by plolymerase chain reaction. A mouse model was constructed using a multi-drug resistant and virulent UPEC strain and treated with FQLF or the antibiotic imipenem. The treatment efficacy was evaluated by bacterial clearance from urine and the urinary organs. Results: A total of 90 UPEC strains were collected, and 94.4% of the isolates were resistant to at least 1 antibiotic. Approximately 66.7% of the UPEC strains were multi-drug resistant. More than one virulence gene was found in 85.6% of the isolates. The extended-spectrum β-lactamases (ESBL)-positive strains were more resistant than the negative ones. The virulence gene number was positively correlated with the resistance number (P<0.05). A mouse model was successfully constructed using UPEC10. Treatment with either FQLF or antibiotics significantly cleared bacteria from the mouse urine after 14 days. In the untreated control, the bacteria lasted for 28 days. FQLF treatment of the UTI mouse model greatly reduced the bacterial number in the kidney and bladder, but could not completely clear the bacteria. Conclusions: Multi-drug resistance is common among UPEC isolates, and the resistance is positively related with virulence. FQLF could treat UPEC UTIs, but could not completely clear the bacteria from the host.     

Multi-drug Resistant Uropathogenic Escherichia coli and Its Treatment by Chinese Medicine

Objectives: To investigate the resistance and virulence profiles of uropathogenic Escherichia coli(UPEC) and its treatment by Chinese medicine(CM) Fuzheng Qingre Lishi Formula(扶正清热利湿方, FQLF). Methods: UPEC strains were isolated from recurrent urinary tract infections(UTIs) patients. Patient sensitivities to 17 antibiotics were tested by the disk diffusion method. Virulence genes were screened by plolymerase chain reaction. A mouse model was constructed using a multi-drug resistant and virulent UPEC strain and treated with FQLF or the antibiotic imipenem. The treatment efficacy was evaluated by bacterial clearance from urine and the urinary organs. Results: A total of 90 UPEC strains were collected, and 94.4% of the isolates were resistant to at least 1 antibiotic. Approximately 66.7% of the UPEC strains were multi-drug resistant. More than one virulence gene was found in 85.6% of the isolates. The extended-spectrum β-lactamases(ESBL)-positive strains were more resistant than the negative ones. The virulence gene number was positively correlated with the resistance number(P0.05). A mouse model was successful y constructed using UPEC10. Treatment with either FQLF or antibiotics significantly cleared bacteria from the mouse urine after 14 days. In the untreated control, the bacteria lasted for 28 days. FQLF treatment of the UTI mouse model greatly reduced the bacterial number in the kidney and bladder, but could not completely clear the bacteria. Conclusions: Multi-drug resistance is common among UPEC isolates, and the resistance is positively related with virulence. FQLF could treat UPEC UTIs, but could not completely clear the bacteria from the host.     

Characterization of multidrug-resistant and metallo-beta- lactamase-producing Pseudomonas aeruginosa isolates from a paediatric clinic in China

Background In the present study, we characterized multidrug-resistant Pseudomonas aeruginosa （MDRP） clinical isolates from a paediatric facility and investigated the types and features of the metallo-β-lactamases （MBLs） produced by carbapenem-resistant strains. Methods Four hundred and ninety-eight strains of Pseudomonas aeruginosa were isolated from patients at Beijing Children＇s Hospital between January 2005 and December 2006. The minimal inhibition concentrations （MICs） of the strains for 13 antibiotics were measured. A combination of the E test and PCR amplification/DNA sequencing was used to define the carbapenem-resistant strains. Results We found that 24.1% （120/498） of the isolates were MDRP. The frequencies of resistance to imipenem and meropenem were 34.2% and 35.8%, respectively, and the MIC50 and MIC90values for the two antibiotics were identical at 4 pg/ml and 32 pg/ml, respectively. The detection rate for carbapenem resistance was 49.2% （59/120）. Among the 59 carbapenem-resistant Pseudomonas aeruginosa strains, 39 （66.1%） were positive for the MBL genotype; 35 （89.7%） strains carried the blaiMp gene and 4 （10.3%） strains carried the blavm gene. Neither blasPM nor blaGiM was amplified from any of the 59 isolates. DNA sequencing revealed that IMP-1 was present in 35 IMP-producing isolates and VIM-2 was detected in four VIM-producing isolates. Conclusions These MDRP isolates exhibited high frequencies of resistance to carbapenems among clinical isolates from a paediatric facility in Beijing, China. The production of MBL appears to be an important mechanism for carbapenem resistance in Pseudomonas aeruginosa.     

Common bacteria distribution and antibiotics choice in trauma patients with wounds

Objective The distribution and antibiotics resistance of common bacteria in the trauma patients with wounds were studied to direct the using antibiotics correctly. Methods Secretion bacteriology and bacterial sensitivity were detected for therapy in trauma patients with wounds from 1996 to 2000. The antibiotics resistance were examined. Results A total of 2 396 strains in 3 545 cases-times from wounds were isolated, the positive rate is 67.59%,the first five common strains were Staphylococ-cusaureus, S. epidermidis, Pseudomonasaeruginosa, Enterococcus,and Escherichia coli. The resistances rate to common antibiotics of S.aureus was≥80 % , imipenem/ cilastatin (Tienam) and vancomycin was still effective to the G+ cocci. G- bacteria had higher resistance against the 3rd generation of cephalosporins. Conclusion The bacteriology and the surveillance of antibiotics resistance are important to using antibiotics reasonably. 6 refs,3 tabs.     

肠杆菌科细菌超广谱β—内酰胺酶的检测及药酶分析

目的：了解超广谱β－内酰胺酶（ESBL5）在肠杆菌科细菌中的产生情况及其对部分药物的敏感性，以指导临床合理用药。方法：用双纸片确证试验检测肠杆菌科细菌产ESBL5的情况，用 片扩散法对8种抗生素的体外药敏试验结果进行初步分析。结果；产ESBL5的肠杆菌科细菌47株，其中大肠埃希菌25株、肺炎克雷伯菌14株、阴沟肠杆菌5株、催产克雷菌1株、鼻硬结克雷伯菌1株、液化沙雷菌1株。在8种抗生素的体外药敏试验中，亚胺培南和美洛培南手敏感率最高（100％），其次为哌拉西林／他唑巴坦（89.4%）、头孢西丁（72.4%)和头孢替坦（65.9%）。结论：产ESBL5的肠杆菌科细菌主要以大肠埃希菌和肺炎克雷伯菌为主，对于由产ESBL5株引起的感染，亚胺增南和美洛培南可作为首选治疗用药。哌拉西林／他唑巴坦优于头霉菌素类药物和其他β－内酰胺酶抑制剂的复合制剂。     

产ESBLs大肠埃希菌和肺炎克雷伯菌的耐药性分析

目的了解产超广谱β-内酰胺酶（ESBLs）大肠埃希菌和肺炎克雷伯菌的检出率及其耐药率，为临床合理使用抗生素提供依据。方法收集2007年1～12月海口市人民医院临床各类标本中分离出（非重复）的大肠埃希菌和肺炎克雷伯菌，采用CLSI推荐的K—B法和表型确证试验分别对其进行药敏试验和ESBLs检测。采用WHO推荐的Whonct5．4软件进行耐药率统计分析。结果2007年海口市人民医院共分离出278株大肠埃希菌和220株肺炎克雷伯菌，其中产ESBLs的大肠埃希菌和肺炎克雷伯菌的检出率分别为69．1％（192／278）和45．9％（101／220），ESBLs阳性的菌株对同一类抗生素的耐药率均高于ESBLs阴性的菌株（P〈0．05），其中产ESBLs的大肠埃希菌和肺炎克雷伯菌对头孢噻肟的耐药率分别为81．7％和64．4％，对头孢西丁的耐药率分别为39．6％和31．8％，未发现对碳青酶烯类药物（亚胺培南、美洛培南）耐药的菌株。结论开展检出菌产ESBLs的检测，以便临床根据药敏试验结果合理使用抗生素，对预防和控制ESBk的产生及传播十分重要。     

临床分离的肺炎克雷伯菌和大肠埃希菌中超广谱β-内酰胺酶的检测

目的：检测临床分离的临床分离的肺炎克雷伯菌和大肠埃希菌中产超广谱β-内酰胺酶（ESBL）菌株的发生率、耐药性、流行性以及酶的基因型别。方法：采用双纸片法、琼脂稀释法、PCR、脉冲场电泳对1999年复旦大学附属华山医院临床分离的559株肺克雷伯菌和427株大肠埃希菌进行检测。结果：肺炎克雷伯菌和大肠埃希菌中产ESBL菌株的发生率分别为51％和23.6％,产ESBL菌株主要分布于ICU和神经外科病房,对大多数的β-内酰胺酶和非β-内酰胺类抗菌药物耐药;PFGE显示,产ESBL菌株（尤其是产ESBL肺炎克雷伯菌株）在ICU病房中存在同一菌株的克隆传播;PCR检测显示TEM型是最为常见的β-内酰胺酶型别,CTX-M型ESBL亦较为普遍。结论：产ESBL菌株在临床分离的肺炎克雷伯菌和大肠埃希菌中较为普遍,而且为多重耐药菌株,在医院内中存在流行与传播。     

某院肺炎克雷伯菌产质粒AmpC酶基因型及耐药性研究

目的调查该院临床分离肺炎克雷伯菌产质粒AmpC酶表型和基因型携带情况及其对常用抗生素的耐药性,为临床合理用药提供参考。方法采用Vitek2-compact全自动细菌鉴定药敏系统对临床分离菌株进行鉴定及药物敏感试验,采用头孢西丁三维试验检测AmpC酶表型,采用多重PCR方法检测AmpC基因并经DNA测序确定其基因型别。结果 2010年7月至2011年6月共分离到116株肺炎克雷伯菌,产AmpC酶肺炎克雷伯菌占18.1%(21/116)。产AmpC酶肺炎克雷伯菌多重耐药情况严重,对氨基糖甙类、喹诺酮类及大多数头孢菌素类抗菌药物的耐药率在57.1%～100%,对加酶抑制剂复合药氨苄西林/舒巴坦、阿莫西林/克拉维酸、头孢哌酮/舒巴坦及哌拉西林/他唑巴坦的耐药率分别为90.5%、85.7%、42.9%、38.1%,所有菌株对碳青霉烯类抗生素亚安培南和美罗培南仍全部敏感。产AmpC酶菌株对头孢西丁、第3代头孢菌素及氨苄西林/舒巴坦、阿莫西林/克拉维酸等抗生素的耐药率明显高于不产酶株(P<0.05)。21株产酶菌株均携带DHA-1型AmpC酶基因。结论该院肺炎克雷伯菌产AmpC酶株检出率较高,产酶菌株多重耐药情况严重。临床应根据药敏结果合理选用抗菌药物,以减少耐药菌株的产生。     

产超广谱β-内酰胺酶肺炎克雷伯菌和大肠埃希菌引起新生儿严重感染的治疗分析

目的:探讨新生儿病房产超广谱β-内酰胺酶(ESBLs)肺炎克雷伯菌和大肠埃希菌耐药特点,指导临床用药。方法:经痰、血、脑脊液培养确诊为产ESBLs肺炎克雷伯菌及大肠埃希菌引起新生儿感染23例,分析药敏试验结果及治疗情况。结果:产ESBLs菌对亚胺培南普遍敏感,对舒普深耐药率低,肺炎克雷伯菌耐药率为36.36％,大肠埃希菌为25.0％,对头孢他啶、头孢曲松、头孢噻肟及氨曲南耐药率高达75％～100％,且部分体外敏感菌株在体内却表现出临床意义的耐药,对磺胺类、氨基糖甙类、氟喹诺酮类均表现出较高的耐药性。结论:亚胺培南及含β-内酰胺酶抑制剂复合物为新生儿病房产ESBLs菌感染的首选药物。     

我院产ESBLs大肠埃希菌和肺炎克雷伯菌的耐药性分析

目的：了解我院产ESBLs大肠埃希菌和肺炎克雷伯菌的分布及耐药情况，指导临床合理用药。方法：对我院2005年7月～2007年12月的临床标本分离的大肠埃希菌218株，肺炎克雷伯菌195株，采用纸片扩散表型确证试验进行ESBLs检测，用K—B法做药敏试验。结果：在413株菌中共检出产ESBLs菌株106株，总检出率为25．7％；产ESBLs细菌对所有青霉素类抗生素产生耐药，对三代头孢类抗生素耐药率也达到90％以上，对磺胺类、喹诺酮类耐药率为50％～90％，对亚胺培南均敏感。结论：产ESBLs的大肠埃希菌和肺炎克雷伯菌逐年上升，应根据药敏结果结合临床合理使用抗生素。     

超广谱β-内酰胺酶的检测及耐药性分析

目的了解临床产超广谱β-内酰胺酶(ESBLs)大肠埃希菌(E. coli)和肺炎克雷伯菌(K. pneumoniae)的发生率、耐药性,以便于对ESBLs进行监测和治疗。方法对102株E.coli和78株K. pneumoniae采用美国临床实验室标准委员会(NCCLS)规定的ESBLs表型筛选和确证试验确定ESBLs的发生率,并检测产ESBLs的E. coli和K. pneumoniae的耐药性。结果13.7%(14/102)的大肠埃希菌和26.9%(21/78)的肺炎克雷伯菌产ESBLs;产ESBLs菌株对亚胺培南耐药率为0%,除对阿米卡星、头孢西丁、替卡西林/克拉维酸联合酶抑制剂耐药率较低外,对三代头孢菌素、磺胺类和喹诺酮类药物均出现较高耐药。结论对产ESBLs菌株引起的感染,亚胺培南为首选。     

烧伤病区产超广谱β-内酰胺酶革兰阴性菌分离率及耐药性分析

目的了解我院特别是烧伤病区产超广谱β-内酰胺酶(ESBLs)大肠杆菌、肺炎克雷伯杆菌的流行情况,检测其对常用抗生素的耐药性,为临床治疗和控制ESBLs菌感染及流行提供重要依据.方法通过中心化验室收集我院2000年3月～2001年2月住院患者送检标本中大肠杆菌、肺炎克雷伯杆菌共计258株,应用VITEK自动检测系统(GNS-506药敏分析卡)及双纸片扩散法筛选产ESBLs菌.根据VITEK自动检测系统药敏检测结果分析比较产ESBLs菌和非产ESBLs菌对15种抗生素的敏感性,并对其中38株产ESBLs阳性菌进行12种临床常用抗生素MIC检测.结果 258株入选菌株中产ESBLs阳性率分别为:大肠杆菌18.8%(29/154);肺炎克雷伯杆菌12.5%(13/104).按标本种类分析,分泌物标本培养产ESBLs阳性率最高,为25.5%,与其他标本培养的总阳性率间的差别有显著性意义;按病区分析,烧伤病区产ESBLs阳性率(大肠杆菌38.5%;肺炎克雷伯杆菌25.0%)与其他病区产ESBLs阳性率间差别有显著性意义.药敏结果:产ESBLs的大肠杆菌和肺炎克雷伯杆菌对亚胺培南、美洛培南及头孢西丁的敏感率较高,其次是氨基糖苷类抗生素,产ESBLs的肺炎克雷伯杆菌对哌拉西林/三唑巴坦敏感,对其他抗生素的敏感性下降.结论烧伤病区是产ESBLs菌的高发病区,产ESBLs菌对亚胺培南的敏感率最高,其次是美洛培南、头孢西丁和丁胺卡那.     

连续四年ICU病房院内感染病原菌的耐药性分析

目的 :了解我院重症监护病房 (ICU)院内感染病原菌的耐药性变化趋势。方法 :对我院 ICU2 0 0 0年 1月至 2 0 0 3年 12月院内感染的各类感染标本中分离的 74 1株病原菌加以整理分析 ,并按美国国家临床实验室标准委员会 (NCCL s)标准进行药敏试验 ,并对其耐药性进行分析。结果 :分离出的菌株以革兰阴性杆菌为主 ,其次是革兰阳性球菌、真菌 ,分别占 6 2 % ,2 9% ,9% ,感染部位以肺部最多 5 5 1株 (74 .4 % ) ,泌尿道感染 5 0株 (6 .7% ) ,引起败血症35株 (4.7% ) ,来自各种体液 (胸、腹水、胆汁 ) 5 2株 (7.0 % ) ,来自各种引流液和伤口分泌物 2 5株 (3.4 % ) ,静脉导管13株 (1.8% ) ,其他 15株 (2 .0 % )。革兰阴性杆菌以非发酵菌为主 ,其中铜绿假单胞菌 135株 (18.2 % )、嗜麦芽窄食单胞菌 38株 (5 .1% )、不动杆菌属 37株 (4.9% )及其他非发酵菌 5 7株 (7.7% ) ,其次大肠埃希菌 91株 (12 .3% )、肺炎克雷伯菌 5 3株 (7.2 % )、肠杆菌属 33株 (4.5 % )、其他肠杆菌科 17株 (2 .3% )。铜绿假单胞菌对亚胺培南的耐药率达 4 1.0 % ,呈多重耐药 ,阴沟肠杆菌对头孢他啶、氨曲南的耐药率达 6 0 .0 %、73.3% ,大肠埃希菌、肺炎克雷伯菌产超广谱β-内酰胺酶 (ESBL s)的发生率分别是 4 1.0 %、4 5 .0 % ,亚胺培南?     

超广谱β-内酰胺酶的检测及耐药性分析

目的 :了解产超广谱 β-内酰胺酶 (ESBL)肺炎克雷白杆菌、大肠埃希氏杆菌、阴沟肠杆菌的发生率、耐药性及耐药特点 ,指导用药。方法 :应用双纸片协同试验法对从临床感染标本中分离出的 2 1 5株革兰氏阴性菌作 ESBL的检测 ,比较亚胺培南等 1 4种抗生素对产 ESBL耐药菌体外抗菌作用。结果 :产 ESBL耐药菌占全部分离菌的 3 4.4% ,其中 ,大肠埃希氏杆菌占 47.3 % ,肺炎克雷白杆菌占 2 8.4% ,阴沟肠杆菌占 2 4.3 %。各类细菌中产 ESBL所占的比例分别是 ,大肠埃希氏杆菌为 3 1 .8% (3 5 /1 1 0 ) ,肺炎克雷白杆菌为 3 9.6% (2 1 /5 3 ) ,阴沟肠杆菌为 3 4.6% (1 8/5 2 )。在产 ESBL菌中 ,有 3株大肠埃希氏杆菌及 2株肺炎克雷白杆菌均同时对头孢噻肟和头孢他啶敏感。亚胺培南对产 ESBL耐药菌均表现出最强的抗菌作用 ;头孢西丁对产 ESBL肺炎克雷白杆菌及大肠埃希氏杆菌呈现出较好的抗菌作用。产 ESBL耐药阴沟肠杆菌对头孢西丁全部耐药 ;氨基糖苷类、氟喹诺酮类及磺胺类药物对产 ESBL肺炎克雷白杆菌、大肠埃希氏杆菌、阴沟肠杆菌有较高的交叉耐药性。结论 :对产 ESBL耐药菌感染不容忽视 ,对此类感染的治疗亚胺培南可作为首选。