A bioluminescent method of determining the sensitivity of microflora to antibiotics]

A bioluminescent rapid method (a three-hour test) has been developed to assess the susceptibility of microflora to antibiotics. It is based on comparison of intracellular ATP content in a sample (pus) after 3 h incubation at 37 degrees C in liquid culture medium (dilution: sample/culture medium--1:9) on a shaker in the presence and absence (control) of a single antibiotic concentration. A criterion has been offered for quantitative estimation of antibiotic susceptibility of microorganisms. The authors have optimized the measurements of intracellular ATP by the rapid bioluminescent method using immobilized firefly luciferase-based ATP reagent. The results of the method are in good correlation with those of the standard agar diffusion technique.     

Sensitivity and resistance of Legionella pneumophila to some antibiotics and combinations of antibiotics

For the treatment of Legionella pneumophila infections erythromycin and rifampicin are the antibiotics of choice. In view of reported therapy failures other antibiotics, e.g. the quinolones, are currently under investigation. The sensitivity of L. pneumophila to four antibiotics and to combinations of antibiotics was investigated and the rate of mutations was calculated. For 20 L. pneumophila strains we determined the MIC of rifampicin (0.002-0.004 mg/l), erythromycin (0.063-0.125 mg/l), norfloxacin (0.125 mg/l) and ciprofloxacin (0.016-0.032 mg/l). Mutation rates ranged from 1 x 10(-8) for ciprofloxacin to greater than 1 x 10(-7) for erythromycin, resulting in high-level resistance to rifampicin in most strains and erythromycin resistance in one strain, but not in resistance to the quinolones. The combination of erythromycin and rifampicin was synergistic (FIC index less than 0.5) against four of the L. pneumophila strains and showed indifference (FIC index 0.5-2.0) for the remainder (mean FIC index 0.79). Combinations of ciprofloxacin and erythromycin and of rifampicin and ciprofloxacin showed only indifference (mean FIC index respectively 1.05 and 1.21). Combining rifampicin with ciprofloxacin was not effective in reducing the number of mutants for either of these antibiotics, whereas the other combinations did prevent this.     

首都医科大学附属北京友谊医院近期临床细菌分布及药敏监测分析

目的:分析首都医科大学附属北京友谊医院2007年12月1日至2008年4月30日的临床细菌分布及药敏监测检查资料,为临床合理应用抗生素提供依据。方法:使用HX-21细菌鉴定/药敏分析仪进行分析。结果:共分离菌株910株,其中革兰氏阴性菌共750株(82.42%);革兰阳性菌共160株(17.58%)。750株革兰氏阴性菌中,鲍曼氏不动杆菌256株(34.13%),大肠埃希菌204株(34.13%),铜绿假单胞菌131株(17.47%),肺炎克雷伯菌78株(10.40%),阴沟肠杆菌60株(8%),产气肠杆菌21株(2.8%)。革兰阴性菌综合抗生素耐药率最低的分别是丁胺卡那霉素、亚胺培南、美洛培南和派拉西林/他唑巴坦。丁胺卡那霉素对所有的革兰阴性菌都保持了90%以上的敏感性;亚胺培南除对鲍曼不动杆菌的敏感性为22.6%,对绿脓杆菌的敏感率为74.1%外,其余的均为100%的敏感率。在160株革兰阳性菌中,表皮葡萄球菌67株(41.88%),粪肠球菌42株(26.25%),金黄色葡萄球菌34株(21.25%),屎肠球菌17株(10.63%)。万古霉素、替考拉宁、利奈唑烷对革兰阳性菌保持了较高的敏感性,金黄色葡萄球...     

Automated amidolytic method for determining heparin, a heparinoid, and a low-Mr heparin fragment, based on their anti-Xa activity

Using the chromogenic substrate S-2222, we have optimized and automated an amidolytic assay for heparin. The assay is based on the detection of anti-Xa activity generated by heparin in plasma. The method is reproducible (intra- and interassay CVs of 2.4 and 3.3%, respectively) and reliable in antithrombin III-deficient plasma. Results of this assay, obtained for plasma samples from patients and volunteers treated with heparin, correlate well (r = 0.899) with those of the test for activated partial thromboplastin time. Upon administration of a low-Mr heparinoid (Org 10172) and heparin fragment ( Kabi 2165), however, the activated partial thromboplastin time failed to detect anticoagulant activity, whereas the chromogenic heparin assay revealed anti-Xa activity. This automated amidolytic assay for heparin is therefore suitable not only for monitoring standard therapy with heparin but also for measuring the activity of recently developed heparin fractions.     

Automated enzymatic method for determining ammonia in plasma, with 14-day reagent stability

This is an automated, cost-efficient enzymatic method for determining ammonia in plasma. In most assays for ammonia the reagents are stable for only one or two days at 4 degrees C, but the reagents in our method are stable for at least 14 days. Our method was developed for use with a Cobas-Fara analyzer but can be easily adapted to other automated analyzers. It is essential to use closed sample vials. Our results, obtained at much less cost, correlate well with those by the Du Pont aca method. Precision studies gave the following results: within-run (n = 20 each), for x = 46 mumol/L, SD = 0.7 mumol/L, CV = 1.6%, and for x = 593 mumol/L, SD = 4.0 mumol/L, and CV = 0.7%; day-to-day precision during a year: for x = 47.7 mumol/L, SD = 2.4 mumol/L, CV = 5.0% (n = 360); and for x = 643 mumol/L, SD = 20.5 mumol/L, and CV = 3.2% (n = 365). The standard curve was linear to 1000 mumol of NH3 per liter.     

骨科内植物或关节置换后的细菌感染及抗生素敏感性

2000—03／2003—03天津医院创伤科收治的需再次手术的骨科内植物置换后感染患者15例，男6例，女9例，再次置换时平均年龄56岁，初次置换到诊断为感染的时间为0～19个月。4例关节置换感染患者，均行假体取出、含抗生素骨水泥临时固定，间隔6个月后再次行关节置换。11例骨折内固定感染患者，2例内固定有效，伤口引流换药，骨折愈合后去除内固定；9例内固定无效，一期行内固定取出，病灶清除，含抗生素灌洗液灌洗，二期再次行内固定。结果采集的15例脓汁标本培养结果均呈阳性，慢性感染11例，占733％，其中骨折内固定后9例，全髋置换后2例；急性感染4例，占26．7％，其中膝关节置换后2例，骨折内固定后2例；未出现血源性感染病例。在不考虑分型和感染部位的情况下，革兰氏阳性菌-金黄色葡萄球菌、表皮葡萄球菌和肠球菌占致病菌的绝大多数，革兰氏阳性菌一金黄色葡萄球菌最为常见。致病菌的药物敏感性顺序为：万古霉素〉利福平〉妥布霉素〉庆大霉素〉环丙沙星。根据感染的类型不同，抗生素敏感性差异也很大。15例标本中2例检出同时感染2种细菌，均来源于骨折内固定后患者。提示骨科内植物置换后革兰氏阳性菌-金黄色葡萄球菌、表皮葡萄球菌和肠球菌是高风险致病菌，选择敏感抗生素和长时间给药是治愈骨科内植物感染的有效方法。     

Identification and sensitivity of Streptococci to antibiotics

In the first part of this research, the author accentuates the quick and easy identification of the Streptococcus by means of Latex-test, testing at the same time the bacitracin. In the second part, the antibiotic sensitivity is tested on 354 strains of Streptococci.     

Chequerboard titrations: the influence of the composition of serial dilutions of antibiotics on the fractional inhibitory concentration index and fractional bactericidal concentration index

Chequerboard titrations carried out with modified serial dilutions of antibiotics such that consecutive concentrations in these series were four times smaller than those in two-fold serial dilutions enable MICs and MBCs to be determined with greater accuracy. Interaction indices calculated by this method can differ markedly from those calculated on the basis of two-fold serial dilutions. The differences calculated in this study ranged from -0.30 to +1.06.