游泳池水中嗜水气单胞菌的毒力因子的研究

目的:对游泳池水检测出的19株嗜水气单胞菌进行毒力因子的研究.方法:通过蛋白酶试验检测嗜水气单胞菌的蛋白酶,采用血平板法观察溶血素,采用PCR方法检测hlyA和aerA两种毒素基因,并进行小白鼠毒力试验.结果:19株嗜水气单胞菌菌株含hlyA基因的占78.95%(15/19),含aerA基因占73.68%(14/19),18株嗜水气单胞菌菌株产生蛋白酶,溶血试验显示的结果与hlyA基因检测的结果相符.菌株对小白鼠的平均致死率达85.96%(49/57).结论:游泳池水中分离出的嗜水气单胞菌大多携带毒力基因.采用多种方法检测其毒力因子能客观地对其毒力进行判定.     

非O1/非O139群霍乱弧菌感染病例分离株分子流行病学分析

目的 分析安徽省马鞍山市连续2个月内监测到的6例具有霍乱疑似症状、感染非O1/非O139群霍乱弧菌的病例,判断疫情的聚集性.方法 对病例分离株进行生化和血清型别鉴定以及溶血试验,药敏试验检测抗生素耐药谱,应用荧光PCR和常规PCR进行霍乱弧菌特异基因、毒力及其相关基因的检测,包括ompW、ctx 、tcpA、toxR、hlyA 、zot、ace、rstR和gⅢCTX,应用脉冲场凝胶电泳(PFGE)分析其分子型别.结果 生化鉴定和血清学试验鉴别腹泻病例6株菌株为非O1/非O139霍乱弧菌,均产生β溶血;14种药物中有12种属于全部敏感;荧光PCR检测霍乱弧菌特异性基因ompW均为阳性,ctx、tcpA 、zot、ace、rstR和gⅢCTX基因均为阴性,toxR 、hlyA基因有5株菌扩增阳性,1株菌(1001434446)为阴性;PFGE显示6株菌带型均不相同,但有2株非常相似,分离株与霍乱弧菌产毒株相似性很低.结论 6例感染非产毒的非O1/非O139群霍乱弧菌病例发病虽相对集中,但属于散发病例,在局部地区频繁出现,提示其公共卫生意义不可忽视.     

天津地区2013年百日咳感染状况及分子流行病学特征分析

目的 了解2013年天津地区百日咳感染状况及分子流行病学特点.方法 选取天津地区监测点181例百日咳疑似病例作为研究对象,采集鼻咽拭子和血清标本,应用Real-time PCR检测百日咳鲍特菌双目标基因,同时采用ELISA检测其特异性百日咳毒素IgG(PT-IgG).30份百日咳DNA阳性标本应用PCR扩增菌毛蛋白2(FIM2)、菌毛蛋白3(FIM3)基因,并对PCR产物进行DNA测序分析.结果 148例百日咳病例Real-time PCR检测阳性率为68.24%;108例PT-IgG检测阳性率为55.56%.101例核酸阳性病例的病程中位数为11 d;60例PT-IgG阳性病例的病程M为21 d.<1岁病例的Real-time PCR检测阳性率为84.28%,与其他年龄段阳性率比较差异有统计学意义.30份标本百日咳鲍特菌基因核苷酸同源性为99.6%～100.0%,与GenBank中国际标准株TohamaI、中国疫苗株同源性为99%.结论 2013年天津地区流行的百日咳鲍特菌与国际标准株及中国疫苗株亲缘关系较近,<1岁病例Real-time PCR检测阳性率高于其他年龄段.     

河南省2011-2014年D群宋内志贺菌病原学监测与分子流行病学研究

目的 分析2011-2014年河南省腹泻患者粪便中分离的216株D群宋内志贺菌毒力基因携带情况、耐药谱及代表性菌株的PFGE指纹图谱特征,为志贺菌病的病原学监测及暴发溯源提供基线数据与方法学参考。方法 采集腹泻患者粪便样本,SS平板分离培养18~24 h,采用克氏双糖铁(KIA)/动力-吲哚-尿素(MIU)与API20E系统进行生化鉴定,利用志贺菌分型血清进行玻片凝集;使用热裂解法制备DNA模板,采用多重PCR鉴定毒力基因种类。根据国际PulseNet细菌性传染病分子分型监测网络公布的宋内志贺菌PFGE分型技术方案进行PFGE分子分型与聚类分析。结果 216株D群宋内志贺菌中,98株为宋内Ⅰ型,118株为宋内Ⅱ型;各菌株均携带不同的毒力因子编码基因,包括SHET-1B、SHET-2、ial、ipaH,具有4种毒力基因组合类型;216株宋内志贺菌均为耐2种以上抗生素的多重耐药菌株,其中耐2~4种为34株(15.7%),耐5~8种为147株(68.1%),耐9~10种为24株(11.1%),耐11种为7株(3.2%),耐13种为4株(1.9%)。100株宋内志贺菌经XbaⅠ酶切与PFGE后共分为31种不同带型,相似度为68.6%~100.0%,各带型包含菌株数为1~13株不等。结论 2011-2014年河南省宋内志贺菌均携带致病性毒力基因,菌株耐药现象比较严重,其PFGE指纹图谱呈现多样性的同时又具有较显著的优势带型特点,部分带型与其对应的耐药谱具有一定的关联性与相同的聚集性。     

ST2928新型耐碳青霉烯类高毒力肺炎克雷伯菌引起的重症肺炎1例

目的 分析耐碳青霉烯类高毒力肺炎克雷伯菌（CR-HvKP）的分子特征和毒力,以加强临床工作者对该菌的认识。方法 对1株分离自重症肺炎患者呼吸道标本的CR-HvKP进行药敏试验,并研究其对碳青霉烯类的耐药机制,通过拉丝试验、毒力基因检测、毒力相关荚膜抗原基因检测、多位点序列分型、大蜡螟感染模型试验和患者临床表现分析该菌的分子及毒力特征。结果 CR-HvKP引起了患者严重的肺部感染,予以纤维支气管镜检查取肺泡灌洗液标本培养分离病原菌,根据其药敏结果及时更改抗菌药物后患者病情得到控制。该菌为多重耐药株,表达IMP-4型碳青霉烯酶,拉丝试验阴性,为ST2928型,prmpA₂毒力基因阳性,K54荚膜抗原基因阳性,在大蜡螟模型试验中表现出较高的体外毒力。结论 此次分离的ST2928型、K54荚膜抗原基因阳性并且产IMP-4型碳青霉烯酶的CR-HvKP系首次报告,CR-HvKP因其高耐药性和高毒力的结合可引起较为复杂和严重的感染,其分子特征呈多样性。     

浦东新区腹泻样本中气单胞菌的分离鉴定及耐药性分析

目的:了解上海浦东新区感染性腹泻病人气单胞菌的感染及耐药情况,为相关防控策略的制定提供科学依据。方法:对2010年上海市浦东新区2个监测点,1245件急性腹泻样本进行气单胞菌检测,阳性菌进行药物敏感试验。结果:从1245件标本中检出气单胞菌93株,阳性率为7.47%,其中嗜水气单胞63株,温和气单胞26株,豚鼠气单胞4株。6月-8月份为高峰期。药敏试验结果:80%以上菌株对庆大,环丙沙星,阿米卡星、头孢噻肟敏感,对氨苄西林,复方新诺明、四环素、头孢噻吩、萘啶酸不同程度耐药。结论:气单胞菌感染存在季节性差异,与夏秋季腹泻关系密切。持续对气单胞菌及其耐药性的监测对细菌性腹泻病的预防与治疗具有指导意义。     

一起由宋内志贺菌引起的寄宿学校细菌性痢疾暴发病原学和流行病学分析

目的 对安徽省阜阳市某寄宿学校感染性腹泻暴发开展流行病学调查与病原学分析,为有效控制和处置疫情提供科学依据。方法 根据病例流行病学特征对2017年9月13-15日发病病例溯源假设进行检验,采集患者和厨师粪便、肛拭子、水样和食堂食品等进行致病菌分离与检测,对可疑致病菌进行生化鉴定、毒力基因检测、药敏试验、PFGE和多位点序列分型。结果 浅水井供水范围内宿舍楼的罹患率（3.41%）高于深水井（0.98%）,差异有统计学意义（χ²=17.215,P<0.001）。从患者样品中分离到16株宋内志贺菌,均携带ipaH基因且不携带set1基因,其中7株携带sen基因和ial基因。16株宋内志贺菌对氨苄西林、四环素、复方新诺明、头孢唑啉、头孢噻肟、庆大霉素、萘啶酸、链霉素高度耐药,9株宋内志贺菌对多西环素耐药。16株宋内志贺菌的PFGE带型相似度为100.0%,ST型均为ST152。结论 本次细菌性痢疾暴发的病原为宋内志贺菌,浅水井水可能为感染来源。     

湖南省2007年狂犬病病原学监测

目的 了解湖南省狂犬病病毒的分布及来源,从病原学角度分析该省狂犬病疫情高发的原因.方法 采集湖南省人间狂犬病高、中、低疫区市售家犬脑组织及疑似病例、病犬标本,用直接免疫荧光法(DFA)和RT-PCR检测狂犬病病毒,RT-PCR阳性标本进行狂犬病病毒N基因片段核苷酸序列分析. 结果 外观正常犬脑组织狂犬病病毒阳性率为2.78%,23株狂犬病病毒N基因片段核苷酸序列同源性范围为88.8%～100.0%,表明主要足同义突变,病毒株在省内的分布无明显的地域性.系统发生树揭示狂犬病病毒在湖南省省内及与周边省份(贵州、湖北、广西)和其他省份(江苏、河南)间存在扩散循环传播.疑似病例的唾液、尿液、血液标本均未检出狂犬病病毒,皮肤标本检出1例阳性. 结论 湖南省内普遍存在狂犬病病毒感染犬只,省内与外省的病毒分离株有高度的亲缘关系,此为疫情高发的主要原因.     

2015-2019年北京市肺炎衣原体流行特征分析

目的 分析北京市2015-2019年急性呼吸道感染患者中肺炎衣原体感染者的流行特征。方法 利用北京市呼吸道病原体监测系统,收集全市35家哨点医院就诊的急性呼吸道感染患者流行病学资料,采集临床标本开展肺炎衣原体检测,并对阳性标本ompA基因的VD4区序列做进化分析。结果 2015-2019年,北京市急性呼吸道感染就诊患者中肺炎衣原体总体阳性率为0.34%（129/37 460）,肺炎衣原体阳性率在每年3月升高,5月达到峰值,7月回落,持续时间约5~8个月,不同年份流行季可能提前或推迟1~2个月;每年流行季肺炎衣原体月阳性率均≥ 0.30%。5~44岁人群高发,其中10~14岁组肺炎衣原体阳性率最高;<25岁患者中,随年龄增加,感染肺炎衣原体的风险增加,≥ 25岁患者,随年龄增加,感染肺炎衣原体的风险降低;男、女性患者阳性率分别为0.33%（68/20 830）和0.37%（61/16 528）,组间差异无统计学意义（χ²=0.486,P=0.486）;普通肺炎患者中的肺炎衣原体阳性率高于上呼吸道感染患者与重症肺炎患者（χ²=36.797,P<0.01）;40.31%（52/129）肺炎衣原体感染者标本中检出≥ 1种其他呼吸道病原体,排名前4位依次是：流感嗜血杆菌（15份）、肺炎链球菌（13份）、鼻病毒（8份）、嗜麦芽窄食单胞菌（7份）;129份肺炎衣原体阳性标本中的101株经测序鉴定均为A型。结论 北京市肺炎衣原体每年呈单峰流行模式,流行季一般为3-7月,流行季节特征可用于与其他呼吸道病原体的鉴别诊断,5~44岁人群好发,基因型以A型为主;如果连续2个月肺炎衣原体核酸阳性率超过0.30%,可初步认为进入肺炎衣原体高流行期;肺炎衣原体感染发生肺炎后进展为重症肺炎的概率较高。     

我国2010－2014年不同城乡类型地区细菌性腹泻病原谱的流行特征

目的 了解我国不同城乡类型地区细菌性腹泻病原谱流行特征。方法 基于2010－2014年我国17省份腹泻症候群感染性腹泻病原学监测。收集门/急诊因急性腹泻就诊病例,采集粪便标本,并进行包括基本人口学信息、临床症状特征等个案调查。对粪便标本进行17种常见致泻细菌病原体的病原学检测。按就诊医院类别将病例分为传统农村、中小城镇/城乡过渡带、大型城市3种类型,比较其病原体阳性率及病原谱构成差异。应用非条件logistic回归分析,比较3种类型病例感染的风险。结果 共纳入传统农村病例5 138例、中小城镇/城乡过渡带病例13 683例、大型城市病例9 253例,3种类型地区病例病原体阳性率城乡差异最大的为福氏志贺菌（阳性率依次为5.81%、2.78%、0.46%）和嗜水气单胞菌（阳性率依次为2.14%、0.96%、0.48%）。中小城镇/城乡过渡带、传统农村相对于大型城市病例感染各种细菌风险差异最大的为福氏志贺菌［OR值及其95% CI分别为6.481（4.666～9.002）、11.304（8.018～15.938）］和嗜水气单胞菌［OR值及其95% CI分别为1.992（1.401～2.832）、4.083（2.833～5.884）］。细菌病原谱中致泻性大肠埃希菌、沙门菌的构成比随城市化程度的提高而增加,志贺菌、嗜水气单胞菌则随城市化程度的提高而降低。志贺菌属血清群构成中大型城市以宋内志贺菌为主（60.00%）,传统农村以福氏志贺菌为主（77.37%）。结论 我国不同城镇化水平地区细菌性腹泻病原谱流行特征存在明显差异,其中以福氏志贺菌和嗜水气单胞菌的差异最为显著。     

Seroepidemiology of rickettsial infections in Morocco

The prevalence of antibodies reactive withRickettsia conorii, Rickettsia typhi, Coxiella burnetii andEhrlichia chaffeensis was investigated using indirect immunofluorescence (IFA) test on human sera obtained from 300 blood donors in Casablanca and 126 sera obtained from clinical laboratories in Fez. In sera from Casablanca, antibodies reactive at titers >=1: 32 were found againstR. conorii (7%), andR. typhi (1.7%), but not againstE. chaffeensis. In the sera from Fez, antibodies were also detected againstR. conorii (5.6%),R. typhi (4%), but not againstE. chaffeensis. By Western immunoblotting, seroprevalence forR. conorii was in Casablanca and 4.8% in Fez. Antibodies reactive at titers >=1:50 againstC. burnetii (phase II) were present in sera from Casablanca (1%) and Fez (18.3%).Abbreviations IFA Immunofluorescence assay - MSF Mediterranean spotted fever - PBS Phosphate-buffered saline     

Antimicrobial antibodies in Danish slaughterhouse workers and greenhouse workers

Summary As a consequence of contact with animals and animal products slaughterhouse workers might be at risk of infection with pathogenic microorganisms. This hypothesis has been supported by some earlier studies. In this study 217 slaughtermen and a control group of 113 greenhouse workers were investigated for the prevalence of serum antibodies to Toxoplasma gondii, Campylobacter jejuni (IgA and IgG), Yersinia enterocolitica types 3 and 9, Yersinia pseudotuberculosis types I, II, III, IV, and V, Salmonella typhi, Salmonella paratyphi, Salmonella enteritidis, Salmonella typhimurium, and Borrelia burgdorferi. No significant differences were found concerning either frequency of positive tests or magnitude of titers. The prevalence of toxoplasma antibodies was remarkably high in both groups.     

Rickettsiae and rickettsioses in Portugal

The only rickettsiae recorded in Portugal till now were Rickettsia conorii and Coxiella burnetii. Boutonneuse fever is one of the most important transmissible diseases in Portugal. Though the annual number of cases is not exactly known, it is estimated to be not far from 20,000 in some years. Q fever is the other rickettsiosis widely disseminated throughout the country. The serological prevalence and the incidence of those rickettsioses in Portugal are presented in this communication. In recent research in southern Portugal, about 4,000 adult ticks of nine species were screened by the haemocyte test for rickettsiae and rickettsia-like organisms (RLO). In addition to R. conorii three microscopically different RLO were observed. Two of them, i.e. ovoid and bacillary-like, were positive in the immunofluorescence test with spotted fever (R. conorii) antiserum. The first occurred mainly in Rhipicephalus sanguineus ticks, the second one also in other tick species. The latter agent was cultivated in half-engorged R. sanguineus females and in Vero cells. The third organism was found in R. sanguineus, where it exhibited a massive infestation in haemocytes resembling that seen in experimentally infected ticks with C. burnetii, but not being this agent. The investigation of the isolates and their identification and characterization are being continued.Presented at the 4th International Symposium on Rickettsiae and Rickettsial Diseases, Pietany, C.S.F.R., 1–6 October, 1990.     

Percutaneous absorption of N,N-dimethylformamide in humans

Summary Skin penetration fo N,N-dimethylformamide (DMF) liquid or vapour was studied in volunteers. Exposure to liquid DMF was performed in two ways: in a dipping experiment, one hand was dipped up to the wrist in DMF for 2–20 min, while in a patch experiment, 2 mmol DMF was applied to the skin and allowed to be absorbed completely. The period of exposure to DMF vapour (50 mg · m^–3) was 4 h. The DMF metabolites N-hydroxymethyl-N-methylformamide (MF), N-hydroxymethylformamide (F), and N-acetyl-S-(N-methylcarbamoyl)cysteine (AMCC) were monitored in the urine. Liquid DMF was absorbed through the skin at a rate of 9.4 mg · cm^–2 · h^–1. Percutaneous absorption of DMF vapour depended strongly on ambient temperature and humidity and accounted for 13%–36% of totally excreted MF. The results suggest that skin absorption of liquid DMF is likely to contribute to occupational exposure substantially more than penetration of DMF vapour. The yield of metabolites after transdermal DMF absorption was only half of that seen after pulmonary absorption. Elimination of MF and F but not that of AMCC was delayed, which supports the contention that AMCC should be used instead of MF as the most suitable biomarker of DMF in cases where percutaneous intake can occur.     

我国几种非嗜肺军团菌感染的血清流行病学研究

本文报告了1986年对我国五个地区994名健康成人、373名儿童和100例肺炎病人进行三种军团菌抗体检测的结果。健康成人抗体阳性率(≥1:16)Lm为9.26%,Ld为9.05%,Lg为3.32%。儿童Lm为5.36%,Ld为2.14%,Lg为3.75%。肺炎病人抗体阳性率以Ld最高(44%),Lm次之(23%),Lg均阴性。提示我国南方和北方地区人群中均存在这三种军团菌感染的可能性,应予以注意。     

Absorption,metabolism and elimination of N,N-dimethylformamide in humans

Summary Excretion of N,N-dimethylformamide (DMF) and DMF metabolites N-hydroxymethyl-N-methylformamide (MF), N-hydroxymethyl-formamide (F) and N-acetyl-S-(N-methylcarbamoyl)cysteine (AMCC) has been monitored in the urine of volunteers during and after their 8-h exposure to DMF vapour at a concentration of 10, 30 and 60 mg · m^–3. The pulmonary ventilation in these experiments was typically about 101 · min^–1 and the retention in the respiratory tract was 90%. After exposure to 30 mg DMF · m^–3, the yield of compound determined in the urine represented 0.3% (DMF), 22.3% (MF), 13.2% (F) and 13.4% (AMCC) of the dose absorbed via the respiratory tract. The excretion curves of the particular compounds attained their maximum 6–8h (DMF), 6–8h (MF), 8–14h (F) and 24–34h (AMCC) after the start of the exposure. The half-times of excretion were approximately 2, 4, 7 and 23 h respectively. In contrast to slow elimination of AMCC after exposure to DMF, AMCC was eliminated rapidly after AMCC intake. This discrepancy could be explained by rate-limiting reversible protein binding of a reactive metabolic intermediate of DMF, possibly methylisocyanate.     

Intestinal Parasites in Healthy Subjects in Albania

The purpose of this study was to evaluate the prevalence of intestinal parasites in 277 healthy subjects in the city of Mamuras (Albania, South Eastern Europe) and the correlation between parasitic infections and possible risk factors. Faecal samples collected with sodium-acetate-formalin fixative were concentrated by formalin ethylacetate sedimentation and examined as wet mounts, permanent stains and by anti-Giardia/Cryptosporidium fluorescent antibodies. Data concerning age, sex, level of education, availability of piped water, number of people living in the same house, and residence in rural or urban area were collected for each subject. Statistical analysis was performed by chi-square test and regression logistic analysis. The overall prevalence of intestinal parasites was 183/277 (66.06%). In particular, pathogenic protozoa or helminths were found in 67 subjects (24.18%), including Trichuris trichiura in 34 (12.27%), Giardia duodenalis in 31 (11.19%), Hymenolepis nana in 5 (1.8%), Ascaris lumbricoides in 3 (1.08%). A significant correlation was observed only between parasite colonization and older age and between Trichuris trichiura infection and residence in rural areas.     

Clinical and laboratory evidence of the importance of the tick D. marginatus as a vector of B. burgdorferi in some areas of sporadic Lyme disease in Bulgaria

56 adult ticks D. marginatus and 38 adult ticks H. punctata were sampled by the flagging method, transferred to the laboratory, dissected and tested for infection with Lyme disease spirochetes. 3 (7.9%) of the adult H. punctata and 2 (3.57%) of the adult D. marginatus were infected with B. burgdorferi (Bb). This report also presents the case of a patient, who developed Lyme disease symptoms after he had been bitten by a D. marginatus tick. The clinical diagnosis was confirmed by serological testing and by a biopsy, taken from the patient's skin lesion. The skin biopsy was examined under an electron microscope and Bb was found in the sections of the deeper strata of the dermis in two structural forms: (a) cylindrical bodies (protoplasm cylinder) with circular ends covered with a three-layered membrane; (b) granules, situated among the collagenous fibres either closely adhered to them or covered with a membrane. The result of the study demonstrates that in single cases in some ecosystems, ticks D. marginatus might be implicated in Bb transmission to humans as secondary vectors.     

Coding and non-coding polymorphisms in VDR gene and susceptibility to pulmonary tuberculosis in tribes, castes and Muslims of Central India

Vitamin D receptor (VDR) plays an important role in activating immune response against various infectious agents. This study was aimed to investigate the association between VDR gene polymorphisms and different clinical forms of pulmonary tuberculosis (TB) in different population groups. Four common polymorphisms (TaqI, ApaI, BsmI and FokI) of VDR gene were studied in clinically diagnosed TB patients and healthy controls from Sahariya tribe (n = 377), Bhil tribe (n = 95), Chhattisgarh tribe (n = 33), general population from North-Central (NC) (n = 1021) and South-Eastern (SE) region (n = 646) and Muslims (n = 217). Genotyping was carried out using PCR-RFLP method and re-confirmed by direct sequencing. The haplotype analysis was performed on Haploview 4.1 and statistical analysis was done using SPSS 13.0 software. We found that bb genotype of BsmI polymorphism conferred significant risk to smear positive and multiple drug resistant (MDR) TB in tribes [OR (CI) = 3.7 (1.5–9.2), p = 0.002], SE population [OR (CI) = 2.1 (1.4–3.3), p = 0.0004] and Muslims [OR (CI) = 6.7 (1.1–39), p = 0.01]. The subjects with FF genotype of FokI polymorphism appeared less likely (p = 0.004) to develop MDR TB in NC population, whereas, those with Ff [OR (CI) = 2.5 (1.3–5.0), p = 0.004] and ff [OR (CI) = 3.4 (1.2–9.3), p = 0.01] genotypes were at high risk of MDR and smear positive disease, respectively. Similarly, tt genotype of TaqI polymorphism was found associated with high risk of smear positive TB in NC [OR (CI) = 3.6 (0.9–14.2), p = 0.05] as well as in SE [OR (CI) = 4.7 (1.8–12.3), p = 0.00003] population. Interestingly, tt genotype appeared strongly associated [OR (CI) = 8.9 (2.7–29), p = 0.00001] with high bacillary load outcome. In conclusion, genetic polymorphisms in VDR gene, alone or in combination (haplotypes) are associated with different clinical outcomes in pulmonary TB.     

Micronucleus test in freshwater fish species: an evaluation of its sensitivity for application in field surveys

Brown trout, Salmo trutta, European eel, Anguilla anguilla, and European minnow, Phoxinus phoxinus, three fish species inhabiting European freshwater ecosystems, were evaluated for their use as in situ pollution biomarkers using the micronucleus test in renal erythrocytes. Experimental exposure (by immersion) to different concentrations of cyclophosphamide, colchicine, and cadmium showed that brown trout are more sensitive to the three compounds than minnows and eels. In situ surveys of wild freshwater ecosystems with different levels of pollution showed that minnows and eels living in polluted sites do not present higher micronuclei averages than those caught in clean rivers systems, whereas micronuclei are induced in brown trout inhabiting polluted sites. Our results demonstrated the suitability of brown trout for in situ biomonitoring of freshwater ecosystems as well as for laboratory tests using the micronucleus test.