Epidemic strain Shigella dysenteriae Type 1 Dt66 encodes several drug resistances by chromosome

BACKGROUND: Multiple antibiotic-resistant strains of Shigella dysenteriae type 1 were isolated from an epidemic in West Bengal, India (1984). During the past two decades, much attention was given to reevaluation of treatment recommendations. However, there are no useful data on drug resistance encoded by chromosome. METHODS: A total of 300 strains of Shigella dysenteriae type 1 were isolated from an epidemic. Strains were biochemically identified by API 20E system and further confirmed serologically. Antibiotic susceptibility was determined by disk diffusion method and plasmid DNA was prepared by alkaline lysis procedure. Elimination of plasmids was achieved by curing with acridine orange from a representative epidemic strain S. dysenteriae 1 Dt66. PFGE was performed for typing of wild-type and plasmid-cured strains. Southern blot of PFGE separated XbaI digested chromosomal DNA was done onto positively charged nylon membrane. For Southern hybridization, plasmid DNA was used as probe. RESULTS: All isolates showed identical drug resistance patterns and plasmid profiles. All these isolates contained six plasmids ranging in sizes from 3 to 145 kb. We have eliminated all the plasmids from a representative strain of S. dysenteriae 1 Dt66 by using acridine orange as curing agent. All epidemic Shigella isolates were resistant to amoxycillin, ampicillin, bacitracin, carbenicillin, cefixime, ceftazidime, chloramphenicol, clarithromycin, erythromycin, fusidic acid, methicillin, penicillin G, polymixin B, streptomycin, rifampicin, tetracycline and vancomycin, among 29 antibiotics used. Out of 17 resistant antibiotics, 12 were encoded by chromosome. Resistance to ampicillin, chloramphenicol, streptomycin, tetracycline and ceftazidime was plasmid encoded. Southern blot hybridization showed the recognition of two clear sites in the chromosome used plasmid DNA of Dt66 strain as probe, which reveled some sequential genetic homology between chromosome and plasmids. Pulsed-field gel electrophoresis (PFGE) was performed for typing of the chromosome of plasmidless strains of Dt66 and wild-type strain Dt66 (having plasmids) that remain unaltered. CONCLUSIONS: Seventy percent drug-resistant loci of Shigella dysenteriae 1 Dt66 are present in chromosome and the remaining are plasmid mediated.     

DNA fingerprinting of methicillin-resistant Staphylococcus aureus (MRSA) by pulsed-field gel electrophoresis (PFGE) in a teaching hospital in Malaysia

Methicillin-resistant Staphylococcus aureus (MRSA) has been prevalent in our hospital over the last three years. Differentiation among MRSA strains by DNA typing in addition to antibiotic resistance pattern surveillance is crucial in order to implement infection control measures. The aim of this study was to characterize MRSA isolates from patients admitted to Hospital Universiti Kebangsaan Malaysia (HUKM) by phenotypic (analyses of antibiotic susceptibility pattern) and genotypic (PFGE) techniques to determine the genetic relatedness of the MRSA involved and to identify endemic clonal profiles of MRSA circulating in HUKM. Seventy one MRSA strains collected between January to March 2000 from patients from various wards in HUKM were tested for antimicrobial resistance and typed by pulsed-field gel electrophoresis (PFGE). Four major types of PFGE patterns were identified (A, B, C and D) among MRSA strains. Two predominant PFGE types were recognised, Type A (59.2%) and Type B (33.8%). Most of these strains were isolated from ICU, Surgical wards and Medical wards. MRSA strains with different PFGE patterns appeared to be widespread among wards. Strains with the same antibiotype could be of different PFGE types. Most of isolates were resistant to ciprofloxacin, erythromycin, gentamicin and penicillin. One isolate with a unique PFGE pattern Type D and susceptible to gentamicin was identified as a different clone. Some isolates obtained from the same patient showed different PFGE subtypes suggesting that these patients were infected/colonized with multiple MRSA strains. PFGE analysis suggests that MRSA strains with different PFGE types was propagated within our hospital. The relationship between antibiotic susceptibility and PFGE patterns was independent. The ability of PFGE technique in differentiating our MRSA strains make it a method of choice for investigating the source, transmission and spread of nosocomial MRSA infection, and thus an appropriate control programme can be implemented to prevent the spread of MRSA infection.     

甲型副伤寒沙门菌的抗生素耐药性及分子分型研究

目的 了解2008年深圳市福田区腹泻病人中分离的甲型副伤寒沙门菌的耐药性及分子分型特征.方法 从辖区内医院腹泻病人中分离得到11株甲型副伤寒沙门菌,选择10种抗生素,用K-B纸片扩散法进行药物敏感试验;细菌基因组DNA经限制性内切酶XbaⅠ酶切,用脉冲场凝胶电泳进行分子分型,使用Quantity-One TM软件成像并使用BioNumerics 6.1软件对其相似性进行分析比较.结果 11株甲型副伤寒沙门菌对氨苄西林、诺氟沙星、替卡西林等8种抗生素敏感率均为100％,对其余抗生素则出现中介或耐药菌株.对复方新诺明和氨苄西林敏感率为81.8％,四环素敏感率达90.9％.11株受试菌株的PFGE图谱经软件分析,可分为5个PFGE型,其相似性系数在93％以上.结论 本次研究的甲型副伤寒沙门菌对大多数抗生素敏感;菌株问有较高的同源性.     

Genotypic Characterization of Methicillin-resistant Staphylococcus aureus Isolated from Pigs and Retail Foods in China

Objective To investigate the genotypic diversity of Methicillin-resistant Staphylococcus aureus (MRSA) isolated from pigs and retail foods from different geographical areas in China and further to study the routes and rates of transmission of this pathogen from animals to food. Methods Seventy-one MRSA isolates were obtained from pigs and retail foods and then characterized by multi-locus sequencing typing (MLST), spa typing, multiple-locus variable number of tandem repeat analysis (MLVA), pulsed-field gel electrophoresis (PFGE), and antimicrobial susceptibility testing. Results All isolated MRSA exhibited multi-drug resistance (MDR). Greater diversity was found in food-associated MRSA (7 STs, 8 spa types, and 10 MLVA patterns) compared to pig-associated MRSA (3 STs, 1 spa type, and 6 MLVA patterns). PFGE patterns were more diverse for pig-associated MRSA than those of food-associated isolates (40 vs. 11 pulse types). Among the pig-associated isolates, CC9-ST9-t899-MC2236 was the most prevalent clone (96.4%), and CC9-ST9-t437-MC621 (20.0%) was the predominant clone among the food-associated isolates. The CC9-ST9 isolates showed significantly higher antimicrobial resistance than other clones. Interestingly, CC398-ST398-t034 clone was identified from both pig- and food-associated isolates. Of note, some community- and hospital-associated MRSA strains (t030, t172, t1244, and t4549) were also identified as food-associated isolates. Conclusion CC9-ST9-t899-MC2236-MDR was the most predominant clone in pigs, but significant genetic diversity was observed in food-associated MRSA. Our results demonstrate the great need for improved surveillance of MRSA in livestock and food and effective prevention strategies to limit MDR-MRSA infections in China.     

汕头地区医院感染多重耐药铜绿假单胞菌的基因型特征分析

目的 了解汕头地区ICU和非ICU医院感染多重耐药铜绿假单胞菌分离株的基因型特征.方法 收集汕头地区两家三级甲等医院的医院感染铜绿假单胞菌菌株,对这些菌株的耐药性和基因型进行分析.采用纸片扩散法进行药敏试验,脉冲场凝胶电泳法对多重耐药菌株进行基因分型,电泳结果 用Bionumerics V4.0软件进行聚类分析.结果 ...     

多重耐药大肠埃希菌质粒介导耐药性的研究

目的：了解临床收集的多重耐药大肠埃希菌克隆播散状况及质粒介导耐药性的特性。方法通过K- B纸片法明确细菌耐药谱,脉冲场凝胶电泳（PFGE）进行耐药菌株的克隆分型,了解其克隆播散情况,通过质粒接合实验获得耐药性质粒的接合菌,用PCR方法筛选接合菌株的常见耐药基因,并利用S1酶切质粒再进行PFGE的方法判读分析质粒的分子大小,分析菌株间的质粒水平迁移状况。结果临床分离95株大肠埃希菌均为多重耐药菌,对青霉素类、头孢菌素类、喹诺酮类、四环素类等药物显示出广泛耐药性,PFGE分型显示克隆传播趋势不明显。耐药菌株常携带可接合性耐药质粒,质粒分子量大小分布在40-330kb,编码多种对青霉素类、头孢菌素类等药物耐药的耐药基因,包括CTX- M型、TEM型β-内酰胺酶基因,以及质粒介导喹诺酮耐药基因qnr等等。结论临床大肠埃希菌多重耐药性严重,耐药性的快速传播已非同源克隆细菌的简单播散,可接合质粒造成的耐药基因水平转移可能起到了相当重要的作用。     

外科重症监护室多重耐药铜绿假单胞菌的对比基因组学研究

目的 对比分析外科重症监护室多重耐药铜绿假单胞菌的基因组差异,探索其与多重耐药性的关系.方法 琼脂稀释法检测49株铜绿假单胞菌对临床常用9种抗菌药物的敏感性,应用4种稀有位点核酸内切酶结合的脉冲场凝胶电泳技术(PFGE)对临床分离的株铜绿假单胞菌进行基因组分型.结果 多重耐药铜绿假单胞菌菌株占外科重症监护室铜绿假单胞菌临床分离株的85.7%;PFGE基因组型A菌株占全部铜绿假单胞菌分离株的61.2%,为主导基因组型,该基因组型全部对阿米卡星和头孢吡肟敏感,对左旋氧氟沙星和美洛培南耐药;PFGE基因组型H、P菌株对6种以上抗生素耐药;PFGE基因组型I和J菌株对所测9种抗生素均敏感.结论 4种稀有位点核酸内切酶结合的PFGE基因组分型可以作为临床多重耐药铜绿假单胞菌监控和鉴定的有效手段.     

DNA fingerprinting of a multi-resistant coagulase-negative staphylococci isolated from biomaterials in dialysis services

BACKGROUND: Coagulase-negative staphylococci (CoNS) have emerged as an important opportunistic pathogen isolated in hospital. Several species of CoNS have been implicated in human infections and disease especially in patients with poor health status. METHODS: A total of 71 clinical strains of CoNS were isolated from dialysis fluid and needles in a dialysis unit and characterized. Susceptibility to antibiotics, biofilm production and molecular typing by pulsed-field gel electrophoresis (PFGE) were achieved. RESULTS: The main isolated CoNS strains were Staphylococcus epidermidis (45%), Staphylococcus hominis (14%) and Staphylococcus haemolyticus (12.7%). The susceptibility profile of all strains revealed high resistance level to penicillin and oxacillin. PCR detection of oxacillin resistance gene (mecA gene) revealed a higher percentage of positive strains than the classic test (ATB Staph). Slime production test was positive in 60.6% of CoNS strains. PFGE analysis showed the presence of 69 restriction profiles clustered in 56 patterns. CONCLUSIONS: Profiles of all isolates were generally heterogeneous, suggesting independent circulation with some evidence of cross-transmission.     

Relationship between clinical and environmental isolates of Pseudomonas aeruginosa in a hospital setting

BACKGROUND: Populations of Pseudomonas aeruginosa have been extensively studied, although there is no general agreement concerning their genetic structure. It has been proposed that P. aeruginosa is a very homogeneous species with 90% of individuals within the same clonal group; nonetheless, other results suggested that Pseudomonas populations are panmictic. Here we compared P. aeruginosa populations from clinical and environmental samples, both isolated from the Bellvitge Hospital of the University of Barcelona in Spain. METHODS: Antibiotic susceptibility determination as well as whole cell and outer membrane protein denaturing gel electrophoresis, pulsed-field electrophoresis, and random amplified polymorphic DNA analysis were performed. RESULTS: Environmental isolates were much more susceptible to antibiotics than those isolated from clinical specimens. The remainder of the analyses revealed high degree of diversity. CONCLUSIONS: Whole-cell proteins, outer-membrane proteins, and pulsed field electrophoresis did not support a close relationship between clinical and environmental isolates. Random amplified polymorphic DNA (RAPD) confirmed the distance between isolates from both sources. This suggests that the origin of hospital infections by P. aeruginosa is due mainly to growth of bacterial strains acquired by patients prior to hospital admission or from patient-to-patient through healthcare workers (HCWs).     

Phenotypes of isolates of Pseudomonas aeruginosa in a diabetes care center

BACKGROUND: Pseudomonas aeruginosa is an invasive organism that frequently causes severe tissue damage in diabetic foot ulcers. A major problem in P. aeruginosa infection may be that this pathogen exhibits a high degree of resistance to a broad spectrum of antibiotics. Some researchers feel that P. aeruginosa is a homogeneous species, whereas others have suggested that they are panmictic. Here we characterized P. aeruginosa populations isolated from diabetic foot ulcer and from hospital environment specimens, both from a tertiary diabetes care center in Chennai, India. METHODS: Phenotypic methods like antibiotic susceptibility determinations using Kirby-Bauer's disc diffusion test and minimum inhibitory concentration (MIC) as well as outer membrane protein SDS-PAGE analysis of P. aeruginosa were performed. RESULTS: Twenty three isolates (29.8%) of P. aeruginosa from 77 diabetic foot ulcers and two environmental isolates (13.3%) from 15 different hospital fomites were detected. Both environmental isolates were sensitive to antibiotics than those isolated from clinical specimens by Kirby-Bauer's disk-diffusion method, which correlated the resistance levels by MIC determination. Outer membrane proteins (OMP) corresponding to 21, 23, 43, 46, 50, and 70 kDa were detected. CONCLUSIONS: The study is captivative as the resistance in P. aeruginosa from diabetic foot ulcers seems very common and because all the isolates were resistant to at least one or more antibiotics tested. Disk-diffusion and MIC results shows that piperacillin, amikacin and imipenem retain high levels of antipseudomonal activities and amikacin two times more active than the aforementioned antibiotics to enable itself as a potent antipseudomonal agent in diabetic foot infections. The OMP profile has revealed that clinical isolates were different from hospital environment isolates, which suggests that the origin of infections by P. aeruginosa is mainly due to growth of bacterial strains acquired by patients prior to hospital admission.     

鲍曼不动杆菌中耐消毒剂基因qacEΔ1-sul1和Ⅰ类整合酶的携带情况调查

目的：调查分析我院临床分离的鲍曼不动杆菌菌株中耐药基因的分布情况及部分多重耐药株的流行病学特点。方法收集2016年1~6月我院院内分离的150株鲍曼不动杆菌,MIC法测定其对抗生素的敏感性;将对三类以上抗生素耐药的菌株定义为多重耐药菌,运用PCR法检测qacEΔ1-sul1和intI 1基因在所分离菌株中的分布,并用PFGE法对其中多重耐药鲍曼不动杆菌进行分子分型。结果鲍曼不动杆菌敏感率排行前三的药物为妥布霉素(50.0%)、庆大霉素(44.2%)和亚胺培南(42.4%);84株多重耐药鲍曼不动杆菌中排行前三的药物为美罗培南(33.3%)、头孢哌酮(33.3%)和左氧氟沙星(13.1%);qacEΔ1-sul1和intI 1在鲍曼不动杆菌中的携带率为46.2%(85/150)和58.0%(88/150);在多重耐药鲍曼不动杆菌中的携带率为59.5%(49/84)和83.4%(70/84)。多重耐药鲍曼不动杆菌经PFGE分型可分为14个克隆,其中A克隆最多见,在ICU、呼吸科和急诊病房均存在集中流行,神经内科和老年科以C克隆多见,其余均为散在流行。结论 qacEΔ1-sul1和intI 1在鲍曼不动杆菌中的携带率很高,在多重耐药株中更高,说明I类整合子是鲍曼不动杆菌产生耐药的原因之一,研发新的消毒剂以消除鲍曼不动杆菌在院内的流行迫在眉睫,此外同一克隆株在同一病区的集中流行和在病区间的交叉流行提示应采取进一步的感染控制和隔离措施。     

An outbreak due to Serratia marcescens in a neonatal intensive care unit typed by 2-day pulsed field gel electrophoresis protocol

BACKGROUND: Serratia marcescens is a well-recognized nosocomial pathogen. The objective of the study was to describe typing results using a rapid pulsed field gel electrophoresis (PFGE) protocol and infection control measures during an outbreak of Serratia marcescens in a 24-bed, referral, neonatal intensive care unit (NICU) of a tertiary-care pediatric hospital. METHODS: Two patients with S. marcescens sepsis were identified in the NICU. Health care personnel of the unit were requested to reinforce infection control measures. Active surveillance was established to detect infected and/or colonized patients and environmental and staff reservoirs. Infected and colonized patients were cohorted on one side of the unit; admissions to NICU were limited. Isolates were typed with a short 2-day pulsed-field gel electrophoresis (PFGE) protocol. RESULTS: Thirty three patients were exposed during a period of 20 days. Ten S. marcescens isolates were obtained from six patients, in two from blood culture and in three from stool culture; a single clone was identified in four. S. marcescens was not isolated from environmental or staff cultures. CONCLUSIONS: PFGE results were obtained in 2 days, infection control measures were reinforced, outbreak was promptly interrupted, and the NICU remained opened.     

Diagnostic multiplex polymerase chain reaction assay for the identification of Pseudomonas aeruginosa from the skin biopsy specimens in burn wound infections and detection of antibiotic susceptibility

OBJECTIVE: To identify Pseudomonas aeruginosa (P. aeruginosa) from the skin biopsy specimens in burn wound infections by multiplex polymerase chain reaction (M-PCR) and detection of antimicrobial susceptibility of isolates from culture. METHODS: We conducted this cross-sectional study in 140 patients with wound infections who admitted to the referral burn center of Motahari, Tehran, Iran, during a 12-month period from 2005-2006. Skin biopsy specimens were aseptically taken from each patient, one for PCR and one for bacterial culture. A M-PCR test based on the simultaneous amplification of 2 lipoprotein genes: oprI and oprL, was used to directly detect fluorescent pseudomonades and P. aeruginosa in skin biopsy specimens. The susceptibility of P. aeruginosa isolates to 16 antibiotics was determined using the disc diffusion method. RESULTS: Out of 140 biopsy specimens, M-PCR detected 66 (47.2%) isolates, while culture detected 57 (40.7%) isolates as P. aeruginosa. Positive results for both genes which observed only for P. aeruginosa, while only one gene, oprI, was amplified from other fluorescent pseudomonades n=12 and all other bacterial tested n=62 were negative by the amplification test. The most effective antibiotics against isolate of P. aeruginosa were cefepime (79%), azetreonam (76%), ticarcillin-clavulanic acid (68%), tobramycin (62%), and amikacin (61%). CONCLUSION: Multiplex PCR assay appears promising for the rapid and sensitive detection of P. aeruginosa from the burned skin biopsy specimens. Simultaneous amplification of 2 lipoprotein genes: oprI and oprL, could detect P. aeruginosa, and oprI gene only for other fluorescent pseudomonades.     

Characterization of Salmonella Enterica Serotype Typhimurium from Outpatients of 28 Hospitals in Henan Province in 2006

Objective To characterize the diarrheal patients with Salmonella typhimurium （S. typhimurium） infections and to set up the first baseline for S. typhimuri_um pulsed-field gel electrophoresis （PFGE） patterns in Henan province, thus laying a foundation for comprehensive surveillance of Salmonella in human as well as foods. Methods S. typhimurium isolates recovered from outpatients with diarrhea in Henan province from May to October of 2006 were characterized. Antimicrobial susceptibility tests of 8 antimicrobial agents and PFGE were carried out to analyze the S. typhimurium isolates. Results Twenty-four （0.9%） S. typhimurium isolates were identified from 2661 stool specimens of diarrheal cases. Eighty-eight percent of isolates showed resistance to at least one antimicrobial agent. The resistance to chloramphenicol （79%） was most common. Fifty-eight percent of isolates were resistant to ciprofloxacin. All the 14 ciprofloxacin-resistant isolates were resistant to more than five antimicrobial agents. Thirty-three percent of S. typhimurium isolates were resistant to ampicillin, chloramphenicol, streptomycin, sulfamethoxazole, and tetracycline （R-type ACSSuT）. Eight antimicrobia-resistant phenotypes were found among the 24 isolates in 16 PFGE patterns. Conclusion The rate of multidrug-resistant S. typhimurium is relatively high in S. typhimurium PFGE patterns of Henan province. Multidrug-resistant S. typhimurium should be considered a public health threat.     

嗜麦芽窄食单胞菌医院感染特点及耐药性分析

目的分析近2年我院发生的嗜麦芽窄食单胞菌(SMA)医院感染的特点及耐药性,为控制感染和临床合理使用抗菌药物提供依据。方法采用美国临床实验室标准化委员会(NCCLS)推荐的纸片扩散法,检测从40例感染患者中分离的50株SMA对24种抗生素的耐药情况,通过脉冲场凝胶电泳(PFGE)全DNA指纹技术对菌株进行分型。结果 SMA感染主要发生在下呼吸道,50岁以上的患者居多,且多数为混合感染。SMA对头孢吡肟/舒巴坦、加替沙星、左氧氟沙星、氧氟沙星、敏感性高,而对多数抗菌药物耐药,对头孢曲松、头孢呋辛、头孢西丁的耐药率达到了100.0%,对亚胺培南、氨曲南、四环素、哌拉西林和庆大霉素耐药率分别为92.3%、88.9%、82.4%、75.0%和70.0%。多数SMA(17/21)没有同源性,仅一对同源菌株来自同一病房,另一对同源菌株来自医院的不同病房。结论患者被医院环境中自然存在的SMA定植可能是SMA基因组的多样性和低同源性的原因。头孢吡肟/舒巴坦、加替沙星、左氧氟沙星、氧氟沙星、头孢哌酮/舒巴坦是治疗SMA感染的有效药物。     

Random Amplification of Polymorphic DNA Based Typing of Pseudomonas Aeruginosa

Pseudomonas aeruginosa was isolated from various sources during the course of an epidemic outbreak of bacterial endophthalmitis following an eye camp at Sangli, Maharashtra. 15 distinct isolates were obtained from clinical samples. Typing of the 15 isolates was performed by random amplified polymorphic DNA (RAPD) analysis, pyocin typing and antibiogram. RAPD typing was rapid, labour friendly and could be done within six hours. RAPD analysis produced reproducible electrophoretic band patterns on the basis of which three distinct amplification patterns could be visualised. The conventional typing methods were labour intensive and took about 48 hours. However, the results of RAPD typing, pyocin typing and antibiogram did not correlate with each other. This study suggests that RAPD typing could be an additional rapid typing method for studying the epidemiology of infectious disease outbreaks due to P aeruginosa.Key Words: Antibiogram, Pseudomonas aeruginosa, Pyocin     

Antimicrobial resistance from enterococci in a pediatric hospital. Plasmids in Enterococcus faecalis isolates with high-level gentamicin and streptomycin resistance

BACKGROUND: Enterococcus spp. is an important nosocomial and community-acquired pathogen. Recent studies have documented the increasing importance of this pathogen in children, particularly in the hospital setting. Our objective in this study was to report the frequency of antimicrobial resistance in enterococci and to determine the characteristics of high-level gentamicin resistance (HLGR) plasmids in Enterococcus faecalis clinical isolates. METHODS: Two hundred eighty-nine enterococcal isolates were collected during an 18-month period from a tertiary-care pediatric hospital in Mexico City. Isolates were screened for antibiotic resistance, including HLGR. High-level, gentamicin-resistant E. faecalis strains were selected for pulsed-field electrophoresis (PFGE) typing and plasmid analysis. Transferability of resistance markers was carried out using filter matings. RESULTS: Seventy-six percent of isolates were E. faecalis, 10% were E. avium, 5.2% E. faecium, 5.2% E. raffinossus, 1.38% E. malodoratus, 0.6% E. hirae, and 0.6% E. casseliflavus. Antimicrobial resistance was ampicillin and penicillin 29%, imipenem 17%, and vancomycin 3%, HLGR 5%. The following 15 high-level, gentamicin-resistant isolates were identified: six E. faecalis; four E. avium; three E. faecium, and two E. casseliflavus. Five of the six E. faecalis isolates were different by PFGE and transferred gentamicin and streptomycin resistance on filter membranes. Transfer frequencies ranged from 8.2 x 10(-4) to 6.92 x 10(-5) transconjugants/recipient cell. The plasmid content of donors and transconjugants were homogeneous (one plasmid of 47 kb). CONCLUSIONS: In this pediatric hospital, antimicrobial resistance in Enterococcus spp. is common. Frequency of high-level, gentamicin-resistant strains is low. Mechanism of HLGR appears to be due to a single plasmid dissemination.     

鲍曼不动杆菌对碳青霉烯类耐药机制的研究

目的 调查我院鲍曼不动杆菌对亚胺培南耐药性变迁及其耐药机制。方法 用WHONET-5软件分析1999～2001年我院分离的鲍曼不动杆菌的耐药性变迁;等电聚焦电泳测定酶的等电点;接合试验证实酶基因有无可转移性,并用碱裂解法提取质粒;脉冲场凝胶电泳(pulsed field gel electrophoresis,PFGE)确定耐药株的亲缘关系;对整合酶基因及碳青霉烯酶基因OXA-、IMP-、VIM-进行聚合酶链式反应(polymerase chain reaction,PCR)及序列分析。结果 1999～2001年,鲍曼不动杆菌对亚胺培南的耐药性分别为8．5％,1．8％及3．9％。存活的亚胺培南耐药株共9株,这9株菌同时对其他碳青霉烯类、头孢他啶、氨曲南、庆大霉素耐药,其中4株同时对环丙沙星耐药。接合试验证实亚胺培南的耐药基因不能转移,9株菌均不含质粒。9株菌均产多种β内酰胺酶：TEM-1酶,AmpC酶及pI为6．7、6．0的2个酶,后2个酶不被邻氯西林、克拉维酸抑制。所有9株菌均含I类整合酶基因。9株菌IMP-、VIM-型PCR均阴性;但用OXA-23特异引物扩增均阳性,经序列分析证明,100％与OXA-23同源。PFGE发现3个耐药克隆(A型5株,B型3株,C型1株),其中A克隆株与对照克隆株(同时耐头孢他啶、环丙沙星、庆大霉素,但亚胺培南敏感)同源关系密切。结论 产生OXA-23型酶是我院鲍曼不动杆菌对碳青霉烯类耐药的主要机制之一,流行的亚胺培南耐药克隆是从院内多重耐药克隆株中演变而来,值得关注．     

耐甲氧西林金黄色葡萄球菌同源性分析及耐药性研究

目的对临床分离的耐甲氧西林金黄色葡萄球菌(MRSA)进行耐药情况和分子流行病学监测,探讨院内MRSA的流行趋势。方法收集我院2009年1月~2011年6月临床标本分离的MRSA菌株60株;采用Microscan WalkAway 40进行菌株鉴定,同时对所有金黄色葡萄球菌进行药物敏感性分析;采用脉冲场凝胶电泳技术对耐甲氧西林金黄色葡萄球菌进行分子分型。结果共收集60株MRSA菌株,其中17株被认为是可疑社区获得(CAMRSA),43株被认为是医院获得(HA-MRSA)。所有菌株均对万古霉素、替考拉宁、利奈唑胺、呋喃妥因和奎奴普丁/达福普汀敏感,未出现耐药菌株。CA-MRSA与HA-MRSA对左旋氧氟沙星和利福平的敏感性有明显差异。临床分离的MRSA菌株PFGE分型较为分散,共分为13种型别,每种型别的菌株数分别为2~6株不等,未出现大范围的院内流行克隆。结论本院收集的临床分离的MRSA菌株多重耐药性严重,其中CA-MRSA相对HAMRSA敏感性稍高。所有金黄色葡萄球菌未出现糖肽类抗菌药物耐药。MRSA菌株未出现大范围的院内流行株,但仍应加强院内感染流行控制。