应用质粒分析探讨医院内细菌感染的流行病学特点

为探讨医院内细菌感染的流行病学特点，作者借助临床分离的６４株肺为克雷伯菌，４５株阴沟肠杆菌和６３株醋酸钙不动杆菌，进行质粒图谱分３种细菌分别有５８株，３５株和４１株含有质粒，且分别构成４６个，２１个和２３个质粒图谱型。结果表明：质粒分析为查明医院内细菌感染源和感染途径提供了较为直接，准确的客观依据，同时也看到了质粒分析的局限性。     

A study of the value of electrophoretic and other techniques for typing Acinetobacter calcoaceticus

Forty-four isolates of Acinetobacter calcoaceticus var anitratus collected during hospital outbreaks were studied using polyacrylamide gel electrophoresis (PAGE), plasmid analysis, antibiograms and biochemical tests to determine their degree of similarity. Reproducibility tests were also carried out on the PAGE and biochemical techniques to determine their validity when used to compare bacteria of the same type isolated intermittently. PAGE data was analysed densitometrically and isolates compared using a similarity matrix. All methods were able to subdivide the isolates, but results did not always correlate well between methods. Reproducibility data indicated that careful attention to technique is required when organisms are examined by PAGE sequentially. Results suggest that no single biotyping technique is likely to be adequate and that electrophoretic, biochemical and antibiogram data may complement one another and other epidemiological data in the typing of these organisms.     

Hospital outbreak caused by a carbapenem-resistant strain of Acinetobacter baumannii: patient prognosis and risk-factors for colonisation and infection

Between October 2001 and August 2002, 30 hospital patients became infected or colonised by a multiresistant (including to carbapenems) epidemic strain of Acinetobacter baumannii (AbMR) in a hospital outbreak. This study analysed the risk-factors associated with acquisition of this epidemic strain and investigated the prognosis of patients infected by AbMR, with the aim of elucidating factors which lead to mortality. A case-control study of the acquisition of AbMR in patients infected or colonised in the hospital outbreak was performed. Independent risk-factors leading to death were studied by logistic regression analysis. Multivariate analysis of the risk-factors for colonisation/infection with AbMR revealed an independent association with the presence of an arterial catheter (OR, 1.13; 95% CI, 1.03-1.25) and administration of imipenem as monotherapy (OR, 11.12; 95% CI, 2.33-53.09). Multivariate analysis of the prognostic features leading to mortality revealed a significant association with hypotension or shock (OR, 24.63; 95% CI, 1.56-387.56) at the time of bacterial isolation.     

鲍氏不动杆菌致慢性阻塞性肺疾病患者肺部感染临床及耐药性分析

目的 探讨慢性阻塞性肺疾病(COPD)患者肺部鲍氏不动杆菌感染的临床特点和耐药情况.方法 对78例COPD患者肺部鲍氏不动杆菌感染的临床表现及药敏情况进行回顾分析.结果 药物敏感性测定提示该菌对头孢哌酮/舒巴坦耐药率最低,为14.9%,其次为亚胺培南和美罗培南,分别是24.8%和28.2%;对氨苄西林、头孢他啶,头孢吡肟、哌拉西林、左氧氟沙星、莫西沙星、阿米卡星、氨曲南和替卡西林/克拉维酸有较高耐药率,为48.5%～74.8%.结论 COPD患者肺部鲍氏不动杆菌感染与年老体弱,广谱抗菌药物及激素应用、呼吸道侵入性操作及呼吸机使用有关,临床表现无特异性,耐药严重,病死率高,应注意预防.     

Alert surveillance of intensive care unit-acquired Acinetobacter infections in a Sicilian hospital

The epidemiological impact of Acinetobacter baumannii nosocomial infections in a Sicilian intensive care unit (ICU) was investigated to determine the Acinetobacter-specific infection rates, to estimate the preventable proportion of Acinetobacter infections, i.e., those resulting from cross-transmission, and to investigate the molecular epidemiology of antimicrobial resistance in Acinetobacter. The impact of Acinetobacter nosocomial infection in the ICU was determined to be 3.0 new cases per 100 admissions. Site-specific rates confirmed that ICU-acquired pneumonia was the most important infection type. The incidence rate, adjusted by the number of patient-days, was 3.3 infections/1000 patient-days. The estimated preventable proportion of A. baumannii nosocomial infections in the ICU was 66.7%. A class 1 integron, characterised by its gene cassette content, was present in all A. baumannii isolates of four different pulsed-field gel electrophoresis types, and was associated significantly with clones implicated in cross-transmission episodes. Furthermore, the same integron was detected in two genetically distinct isolates responsible for recurrent infection in the same patient, suggesting the occurrence of horizontal gene transfer in vivo. Even in an endemic setting with low infection rates, spread of A. baumannii was caused mainly by infection control shortcomings that require appropriate surveillance and control policies.     

PCR-amplified 16S and 23S rDNA restriction analysis for the identification of Acinetobacter strains at the DNA group level

The genus Acinetobacter is phenotypically rather homogeneous, but genotypicaliy heterogeneous. In this study, a simple method based on restriction analysis of a PCR-amplrfied large fragment (4.5 kb) of most of the ribosomal operon (16S and 23S ribosomal genes and the spacer in-between) was investigated. Sixty-seven collection strains belonging to the 20 DNA groups proposed until 1993 were studied. Using the enzyme Sau3AI, 25 DNA profiles were obtained. Strains belonging to DNA groups 1, 3, 6, TU13 and TU15 showed two profiles each, and DNA groups 4, 5 and 7 showed profiles with variants showing less intensive additional bands. The remaining 12 groups showed 12 different profiles. The profiles obtained were DNA-group-specific except for one profile which was shared between the unnamed DNA group 3 and a rarely encountered genotypicaliy related DNA group. These two DNA groups could be separated by using the enzyme Hinf1. Twenty-five additional clinical isolates previously characterized by standard DNA-DNA hybridization were selected in a double-blind fashion for identification at the DNA group level to check the reliability of the assay. All strains were correctly identified at the DNA group level. PCR-amplified 16S and 23S rDNA restriction analysis is both an accurate and rapid method for the identification of Acinetobacter at the DNA group level.     

Activities of various β-lactams and β-lactam/β-lactamase inhibitor combinations against Acinetobacter baumannii and Acinetobacter DNA group 3 strains

Acinetobacter baumannii and Acinetobacter DNA group 3 are members of the so-called A. calcoaceticus-A. baumannii complex and are important nosocomial pathogens. Multiresistance in these organisms is increasingly frequent, and alternative treatment options are needed. The beta-lactamase inhibitors clavulanate, sulbactam and tazobactam have intrinsic activity against Acinetobacter strains. In the present study, broth microdilution was used to assess the in-vitro activities of currently available beta-lactam/beta-lactamase inhibitor combinations and sulbactam alone against 469 Acinetobacter isolates (A. baumannii, n=395; Acinetobacter DNA group 3, n=74) collected from various laboratories in Germany. Fixed concentrations and fixed ratios of beta-lactamase inhibitors were used. Sulbactam-containing combinations (susceptibility rates of 90.4-92.7% for A. baumannii and 97.3-100% for Acinetobacter DNA group 3) and sulbactam alone were superior to clavulanate- and tazobactam-containing combinations. The activity of sulbactam-containing combinations against members of the A. calcoaceticus-A. baumannii complex was conferred exclusively by the intrinsic activity of the beta-lactamase inhibitor and did not result from enhanced beta-lactam activity. Testing with the inhibitor added at a fixed ratio of inhibitor to beta-lactam appeared to give more reliable results than testing at a fixed concentration of the inhibitor. Resistance to carbapenems (0.3%) remains low in Germany.     

鲍曼不动杆菌对喹诺酮类耐药机制

目的 探讨鲍曼不动杆菌对氟喹诺酮类药物的耐药机制。方法 采用K-B法检测35株鲍曼不动杆菌对氟喹诺酮类药物的药敏情况。十二烷基磺酸钠一聚丙酰胺凝胶电泳(SDS-PAGE)法检测鲍曼不动杆菌的外膜蛋白(OMP)，直接荧光法检测鲍曼不动杆菌对环丙沙星的吸收和积累，PCR法扩增gyrA基因并对其进行测序。结果 35株鲍曼不动杆菌中有20株对氟喹诺酮类药物耐药，耐药菌株与敏感菌株相比，外膜蛋白在约29Ku条带处消失，在26Ku条带处明显增强。耐药菌株药物积累量不及敏感菌株，经叠氮钠处理后，积累量上升并接近敏感菌株，对PCR扩增产物gyrA测序未发现有突变。结论 鲍曼不动杆菌对氟喹诺酮类药物的耐药与外膜蛋白的低通透性和主动外运有关。     

铜绿假单胞菌和不动杆菌对抗生素耐药性研究

〔目的〕探讨 2 0 0 0年 7月至 2 0 0 3年 6月期间我院患者分离的铜绿假单胞菌和不动杆菌对 11种常用抗生素耐药性。〔方法〕采集患者痰、血、尿及其它标本进行铜绿假单胞菌和不动杆菌培养、鉴定及药敏试验。〔结果〕我院分离的铜绿假单胞菌和不动杆菌主要来自呼吸道标本 ;在 2 0 0 0年 7月 -2 0 0 3年 6月期间 ,分离的 491株铜绿假单胞菌对 11种抗生素的合计敏感率在 80 % -90 %之间的抗生素只有哌拉西林 他唑巴坦 ,70 % -80 %之间的抗生素有头孢他啶、环丙沙星、亚胺培南和左旋氧氟沙星 ,<60 %的抗生素有氨曲南、庆大霉素、妥布霉素、替卡西林、头孢曲松和头孢噻肟。 14 8株不动杆菌对 11种抗生素的合计敏感率在 80 % -90 %之间的抗生素有亚胺培南和哌拉西林 他唑巴坦 ,70 % -80 %之间的抗生素有环丙沙星和左旋氧氟沙星 ,<60 %的抗生素有头孢他啶、氨曲南、庆大霉素、妥布霉素、替卡西林、头孢曲松和头孢噻肟 ;在 2 0 0 0年 7月 -2 0 0 3年 6月期间铜绿假单胞菌多重耐药率合计为 2 6.2 7% ,不动杆菌多重耐药率合计为 2 6.3 5 %。〔结论〕铜绿假单胞菌和不动杆菌对绝大多数抗生素耐药性呈逐年上升趋势 ,通过对耐药性监测研究使我们提高抗生素耐药性问题的认识 ,为抗生素使用和调控提供基础。