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1.
Sternums and femurs from B6C3F1, C57black and CD-1 mice, used as controls in carcinogenicity studies, were microscopically examined for the presence of fibro-osseous proliferation (syn. hyperostosis, myelofibrosis, osteofibrosis). The uterus, vagina and ovaries of the same animals were microscopically examined, particularly for the morphological changes indicative of hyperestrogenism. The incidences of each finding in each strain were compared using a chi square test to detect any interstrain variations of statistical significance. Despite the markedly high incidence of endometrial cystic hyperplasia, vaginal epithelial cell hyperplasia and hyperkeratosis, which are morphological changes indicative of hyperestrogenism in all three strains of mice, the incidence of fibro-osseous proliferation in B6C3F1 mice was markedly higher than in the other two strains and statistically significant. This could be explained by a more sustained and higher level of endogenous estradiol in B6C3F1 mice, as brought into evidence by the markedly high, and stastically significant, incidence of follicular development/atresia, with cystic formation, in the ovaries of this strain. However, genetic factors that could determine the general predisposition to fibro-osseous proliferation in B6C3F1 mice cannot be ruled out.  相似文献   

2.
Anthrax, which is caused by the bacterium Bacillus anthracis, is one of the oldest documented infectious diseases in both livestock and humans. The differentiation of B. anthracis strains is difficult because of their highly homogeneous genomes. We used multiple-locus variable-number tandem repeat analysis (MLVA) with 25 markers to genotype 55 B. anthracis isolates from 16 distinct regions of Turkey. The antimicrobial susceptibility of the isolates was investigated using the agar dilution method. An eight-loci MLVA assay revealed six unique genotypes (G(K)13, G(K)27, G(K)35, G(K)43, G(K)44, and G(K)61). However, the 25-loci MLVA was more discriminatory, revealing the presence of ten genotypes instead of six. The additional genotypes resulted from the split of four subtypes: G(K)35 (b and c), G(K)43 (a and f), G(K)44 (d and e), and G(K)61 (i and j). All of the Turkish B. anthracis isolates were susceptible to ciprofloxacin, levofloxacin, tigecycline, linezolid, and vancomycin. One isolate was resistant to penicillin and to doxycycline. A total of 34 isolates were susceptible, 20 isolates were partially susceptible, and one isolate was resistant to erythromycin. None of the isolates exhibited susceptibility to cefotaxime. A total of 53 isolates were susceptible to gentamicin, and two were resistant. The genotypes G(K)35 (n=24), G(K)44 (n=13), and G(K)43 (n=10) were the most prevalent in 10, 6, and 5 regions, respectively, of the total 16 provinces. The B. anthracis isolates collected from these regions implied that the movement of B. anthracis is a result of the increased transportation of livestock and the resultant cross contamination.  相似文献   

3.
A study was conducted to compare immunogenicity of a Brucella abortus lipopolysaccharide (LPS) and the duration of infection in 5 strains of mice. Mice of strains CBA/NJ, BALB/c, CD-1, C3H/HeN, and C3H/HeJ were allotted into 2 large groups (vaccinated with proteinase K-treated LPS or nonvaccinated) and 6 subgroups based on the intervals between challenge exposure to B abortus strain 2308 and the week the response data were obtained. Criteria used in comparing responses between the various strains of mice as well as between vaccinated and nonvaccinated mice were splenomegaly, colony-forming units (CFU) from spleens, and antibody titers. Responses were evaluated at 1, 2, 3, 5, 8, and 12 weeks after challenge exposure. Results indicated that all strains of mice became infected and maintained infection throughout the 12-week period, the percentages of mice infected were significantly (P less than 0.05) less in vaccinated mice for the first 5 weeks after challenge exposure, and there were no direct correlations between increased immunoglobulins (IgM and IgG titers) and reduction in CFU. Vaccinated mice of strains BALB/c, CD-1, C3H/HeN, and C3H/HeJ had increased titers when challenge exposed and also had significantly (P less than 0.05) smaller spleens and lower CFU. Vaccinated CBA/NJ mice did not have marked antibody titers. The overall results indicated that vaccination with LPS offers some initial protection against B abortus strain 2308 infection, but this protection disappears gradually and in various degrees in the 5 strains of mice studied.  相似文献   

4.
From each of two lentogenic Newcastle disease virus (NDV) strains of the type LaSota and Hitchner B1 a virulent subpopulation could be obtained. The two subpopulations were—in comparison to the two parent viruses—more resistant to the lipid solvent chloroform and more stable against thermal degradation. Also, the glycoproteins haemagglutinin and F (fusion) were more stable against thermal inactivation. Electron microscopic observations revealed in terms of size and morphology all of the characteristics of NDV. Both subpopulations possessed, however, the same elution kinetics as their respective parent strains. The intracerebral and intravenous pathogenicity indices as well as the mean death times of the two subpopulations allow to classify these viruses as virulent Newcastle disease viruses.  相似文献   

5.
不同省区鸡源大肠杆菌耐药性调查与系统进化群分析   总被引：1，自引：1，他引：0  
为有效控制鸡大肠杆菌病,对不同省区鸡源大肠杆菌致病菌株的分布情况及耐药特征进行了调查分析,分别采用PCR法和MIC法进行了系统进化群分群检测和药敏试验,采用皮下注射进行了动物致病性试验,并采用SPSS17．0软件进行差异显著性分析。结果显示：低致病群B1（38．13％）和非致病群A（34．02％）菌株分布相对较多,其次是高致病群D（21．23％）和B2（6．16％）;鸡源大肠杆菌耐药严重,12种药物的耐药率在50％以上,多重耐药问题突出,多重耐药率高达98．86％;不同省区鸡源大肠杆菌菌株的耐药程度存在差异,个别药物（如奥格门丁、头孢噻呋等）差异显著;高致病群B2和D群菌株的耐药程度较B1和A群菌株严重,其中氧氟沙星、庆大霉素、大观霉素、头孢噻呋、磺胺异噁唑、复方新诺明、奥格门丁等7种药物差异显著（ P＜0．05）。试验表明,我国鸡源大肠杆菌高致病菌株检出率高,且耐药程度相对严重,在适宜条件下更易导致鸡群发病且较难控制。  相似文献   

6.
The effect of dermonecrotic toxin (DNT) expression of Bordetella bronchiseptica was studied in mice by comparing the pathology induced by a wild type strain with that induced by an isogenic DNT- strain in which part of the structural gene has been replaced by an antibiotic resistance cassette. While extracts of strain B58 proved toxic in intravenously inoculated mice, similar extracts from strain B58GP had lost toxic activity. The parent (B58) and the mutant (B58GP) strains of B. bronchiseptica each possessed comparable virulence for mice. These findings confirmed that DNT production was successfully abolished in strain B58GP while other virulence characteristics required for pathogenicity in mice remained intact, at a comparable level to the parent strain. Turbinate atrophy was observed in mice infected with the DNT+ strain, but not in those infected with the DNT- strain. This indicates that DNT is the cause of turbinate atrophy in the mice and not other factors produced by phase I strains of B. bronchiseptica. B. bronchiseptica DNT showed a lienotoxic effect (lymphocyte depletion and a reduction in the intensity of extramedullar haemocytopoieis) that is considered to adversely alter the immune function of the host animal. In mice infected with strain B58GP, catarrhal pneumonia with characteristic lympho-histiocytic peribronchial and perivascular infiltration was noticed. In mice infected with strain B58, large necrotic areas were seen surrounded by an inflammatory reaction. The DNT appears to directly damage lung tissues, at least in mice. DNT production seems to enhance the establishment of B. bronchiseptica in the lungs, presumably by reducing the local resistance and causing severe local damage to the lung tissues.  相似文献   

7.
The in vitro activities of 15 antimicrobial agents against 195 strains of Escherichia coli isolated from dairy calves affected by neonatal diarrhoea were determined. Of these strains 137 produced one or more potential virulence factors (F5, F41, F17, cytotoxic necrotizing factor, verotoxin and the eae gene), but the remaining 58 strains did not produce any of these factors. The overall percentage of resistant strains to streptomycin, tylosin and tetracycline was very high (above 65%). A high level of resistance (from 23 to 50%) to ampicillin, neomycin, kanamycin, spectinomycin, chloramphenicol, sulphadimethoxine and trimethoprim was also detected. The E. coli strains were very susceptible (89-95%) to apramycin and gentamicin and highly susceptible (99-100%) to polymyxin B, florfenicol and nitrofurazone. Some significant differences (P < 0.05) in the frequencies of resistance to some of the antimicrobials tested and in the rates of multi-drug resistance among the strains producing potential virulence factors and non-fimbriated, non-toxigenic, eae-negative strains were found. Most of the strains showed multi-resistance: 76.9% of the isolates were resistant to at least two antibiotics, 67.7% were resistant to at least four antibiotics and 50.3% were resistant to at least six antibiotics.  相似文献   

8.
为了查清新疆石河子部分规模场引起羔羊死亡的原因,本研究对采集的病羊肺脏组织进行细菌分离,同时对分离菌株进行小鼠致病性试验、特异性基因PCR检测、药物敏感性试验和耐药基因PCR检测.结果显示:从病变肺脏组织分离得到10株细菌,分离菌为大肠杆菌,致病性强;分离菌株呈现多重耐药现象,对诺氟沙星、复方新诺明、氟苯尼考等17种抗生素耐药;检测到iutA、fyuA、ireA、hlyD和afa 5种毒力因子,strA、strB、aadA1/aadA2、Bla(TEM1)、Bla(OXA1)、Tet A和Tet B 7种耐药基因.本研究为该地区规模场绵羊感染大肠杆菌的防控和临床用药提供依据.  相似文献   

9.
The incompatibility plasmids of 101 strains Salmonella typhimurium were detected by PCR-based replicon typing. Eighteen pairs of primers were designed to perform 5 triplex-PCRs and 3 simplex-PCRs, recognizing FIA, FIB, FIC, HI1, HI2, I1, L/M, N, P, W, T, A/C, K, B/O, X, Y, F and FII. 94 strains (93.1%) Salmonella typhimurium carried a total of 10 Inc groups. The results suggested that the method was applicable for a large number of strains to trace the diffusion of specific multi-drug resistance plasmids in different environments.  相似文献   

10.
Fifty-six Staphylococcus aureus isolates recovered between 1998 and 2003 from 31 rabbit farms with and without problems of chronic staphylococcosis, were screened for resistance to enrofloxacin, erythromycin, gentamicin, lincomycin, neomycin, penicillin and tetracyclines using the agar dilution test. For penicillin, a disk diffusion test was also performed. The detection of tetP(B), tet(K), tet(L), tet(M), tet(O), tet(T), tet(W), erm(A), erm(B), erm(C) and mec(A) genes was done via a PCR assay. Four isolates showed resistance to erythromycin and lincomycin. These isolates were positive for the erm(C) gene in the PCR. Eleven strains were resistant to tetracyclines and all harboured the tet(K) gene. In the agar dilution test, five isolates showed resistance to penicillin, whereas in the disk diffusion test 12 isolates showed resistance. None of these 12 resistant isolates carried the mec(A) gene. Only one strain showed resistance to gentamicin, and all strains were susceptible to enrofloxacin and neomycin. This study demonstrates that resistance to antimicrobial agents in S. aureus isolates originating from rabbits is relatively rare compared to resistance in S. aureus isolates originating from other animals and humans.  相似文献   

11.
A study was conducted to establish baseline data on Brucella abortus infection induced in 5 strains of mice (CBA/NJ, BALB/c, CD-1, C3H/HeN, and C3H/HeJ). The strains were compared on the basis of immunologic, histopathologic, and bacteriologic responses. There were 4 treatment groups for each strain of mice: (1) vaccinated with homologous lipopolysaccharide and challenge exposed to B abortus strain 2308; (2) not vaccinated but challenge exposed; (3) vaccinated and not challenge exposed; and (4) not vaccinated and not challenge exposed. Results indicated that mice can be used for comparative studies on the pathogenesis and immunogenesis of B abortus infections; strains of mice may vary in their responses to Brucella infection, regardless of their vaccination status. Bacteriologic and immunologic responses in mouse strains BALB/c, CD-1, C3H/HeN, and C3H/HeJ, but not those of CBA/NJ, were extrapolative among strains.  相似文献   

12.
探讨不同禽源大肠埃希菌中喹诺酮类药物的耐药情况及耐药基因gyrA的分布和突变特征。采用K-B药敏纸片法、gyrA基因的PCR扩增,对9株大肠埃希菌进行喹诺酮类药物试验,并将gyrA基因的PCR产物测序,对测序结果采用DNA MAN、DNA Star、MEGA6等软件分析。药敏试验结果表明,C1、C2、C3菌株对左氧沙星、氧氟沙星、环丙沙星、诺氟沙星敏感,D1、D2、D3、B1、B2和B3菌株对左氧沙星、氧氟沙星、环丙沙星、诺氟沙星均表现为耐药和中介;gyrA基因的测序结果表明,除B1菌株有1处核苷酸突变位点和B2菌株有14处核苷酸突变位点;B2菌株gyrA基因的氨基酸突变发生在87位Ile→Val替代、101位Leu→Met替代、102位Ala→Ser替代、129位Lys→Gln替代。9株禽源大肠埃希菌的同源性和进化树分析表明,不同禽源耐氟喹诺酮类药物的大肠埃希菌菌株中B2菌株gyrA基因与其他9株菌株相比,同源性在90%左右,进化树不在一个分支上,研究中的B2菌株将为大肠埃希菌的氟喹诺酮类耐药机制的研究提供候选菌株。  相似文献   

13.
探索苜蓿苔螨(Bryobia praetions)抗阿维菌素品系(R)与敏感品系(S)生物适合度变化,为延缓苜蓿苔螨抗性发展及其抗性治理提供依据。在室内26℃条件下,系统观察了苜蓿苔螨抗阿维菌素品系试验种群的发育和生殖力参数。结果表明,抗阿维菌素品系的发育历期和寿命缩短,产卵量下降。抗性品系(R)平均寿命为21.9 d,平均每雌产卵量为28.2粒;敏感品系分别为27.9 d和40.9粒。抗阿维菌素品系的净生殖率(R0=28.17)显著低于敏感品系(R0=45.70)(P<0.05)。抗阿维菌素品系周限增长率(λ)和种群加倍时间(p.b.t)分别为1.159 2和2.978 8,均显著低于敏感品系的周限增长率和种群加倍时间(P<0.05)。对苜蓿苔螨的抗性品系与敏感品系进行比较,抗性品系存在着生殖力的不利性。另外,抗性品系的相对适合度(Rf)约为敏感品系的0.49,也存在着明显的相对适合度缺陷。本研究结论有助于解释苜蓿苔螨抗阿维菌素品系存在生物适合度不利的现象,并为苜蓿苔螨抗性治理提供参考。  相似文献   

14.
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15.
In order to characterize potential pathogenic Escherichia coli strains isolated from diarrheic hens and chickens originating from intensive battery rearing in North Algeria, the presence of a large range of virulence factors and markers was studied in 50 strains by DNA-DNA hybridization on colonies and phenotypic tests. The sequences we focused on were those coding for adhesins F5, F41, F17, Pap, Afa, and Sfa; intimin Eae; and toxins STa, STb, LT1, Stx1, Stx2, CNF1, and CNF2. The phenotypes explored were the colicins, aerobactin, hemolysins, and hemagglutinin production and serum resistance. The genotypic and phenotypic tests enabled us to categorize the isolates into two distinct groups: those with a potential to invade the host (27 strains were serum resistant and/or produced aerobactin), among which three strains were also potentially diarrheagenic, one strain was LT1 + F17+ Afa+ Pap+ (enterotoxigenic E. coli) and the two others were Stx1 (verotoxigenic E. coli). Twenty-three strains were colicinogenic, including 19 strains producing colicin V. This latter factor was also detected in isolates negative for the other virulence factors. On the basis of the type of erythrocytes agglutinated, we established 14 mannose-resistant hemagglutination patterns among the 37 strains tested, including 22 serum-resistant and/or aerobactin producing strains and 15 strains negative for these two characters. None of the strains produced alpha hemolysin, whereas two strains produced beta hemolysin and enterohemolysin, respectively. Congo red fixation was observed in 25 strains. No relationship could be detected between Congo red fixation and the presence of other virulence markers, such as serum resistance and aerobactin production. This study shows that among isolates originating from the feces of diarrheic chickens, the proportion of potentially diarrheagenic E. coli strains is low.  相似文献   

16.
为了解甘肃某地区奶牛运动场环境中主要耐药性细菌的分布情况及耐药基因的携带情况,试验采用抗性平板筛选法分离、纯化耐药菌后再通过16S rRNA鉴定;采用PCR方法检测6类22种耐药基因携带情况。结果显示,两年两个奶牛运动场（A和B）分离出不同种属的耐药菌共665株,经16S rRNA PCR鉴定主要为大肠杆菌、屎肠球菌和普通变形杆菌,其中耐药性大肠杆菌数量最多（398株）,A牛场耐药菌数两年相比增长28.50%,B牛场耐药菌数量持平;通过对样品进行10类药物筛选耐药菌结果显示,耐药率前3位的分别为糖肽类（11.13%,74/665）、四环素类和磺胺类（10.98%,73/665）及β-内酰胺类和氨基糖苷类（10.23%,68/665）。采用PCR方法对样品进行耐药基因检测发现,两年两个奶牛运动场的耐药基因携带情况基本相同,喹诺酮类耐药基因qnrB、qnrS的携带率分别为10.81%和83.78%,磺胺类耐药基因Sul1、Sul2和Sul3的携带率分别为100%、100%和56.76%,糖肽类耐药基因VanA、VanB和VanC的携带率分别为78.38%、100%和100%,四环素类耐药基因tetA、tetB、tetC、tetM、tetO、tetL的携带率分别为100%、100%、100%、100%、81.08%和75.68%,KPC、NDM、aac（6'）-Ⅰb-cr耐药基因的携带率分别为32.43%、29.73%及24.32%,未检出qnrC、tetK、tetW、VIM和OXA耐药基因。携带耐药基因与GenBank中登录参考株基因序列的同源性为98%~99%。甘肃地区奶牛运动场中耐药菌对常用抗菌药物普遍耐药且携带相应耐药基因,奶牛运动场中碳青霉烯类及氨基糖苷类耐药基因与上年结果相比数量增加,各相关单位人员应对其加强奶牛场中耐药菌的监测,临床治疗中应合理用药,以降低环境中耐药菌转移给人类的潜在风险。  相似文献   

17.
The first joint Japanese Society of Toxicologic Pathology (JSTP) and National Toxicology Program (NTP) Satellite Symposium, entitled “Pathology Potpourri,” was held on January 29th at Okura Frontier Hotel in Tsukuba, Ibaraki, Japan, in advance of the JSTP’s 29th Annual Meeting. The goal of this Symposium was to present current diagnostic pathology or nomenclature issues to the toxicologic pathology community. This article presents summaries of the speakers’ presentations, including diagnostic or nomenclature issues that were presented, select images that were used for audience voting or discussion, and the voting results. Some lesions and topics covered during the symposium include: treatment-related atypical hepatocellular foci of cellular alteration in B6C3F1 mice; purulent ventriculoencephalitis in a young BALB/c mouse; a subcutaneous malignant schwannoma in a RccHan:WIST rat; spontaneous nasal septum hyalinosis/eosinophilic substance in B6C3F1 mice; a rare pancreatic ductal cell adenoma in a young Lewis rat; eosinophilic crystalline pneumonia in a transgenic mouse model; hyaline glomerulopathy in two female ddY mice; treatment-related intrahepatic erythrocytes in B6C3F1 mice; treatment-related subendothelial hepatocytes in B6C3F1 mice; spontaneous thyroid follicular cell vacuolar degeneration in a cynomolgus monkey; congenital hepatic fibrosis in a 1-year-old cat; a spontaneous adenocarcinoma of the middle ear in a young Crl:CD(SD) rat; and finally a series of cases illustrating some differences between cholangiofibrosis and cholangiocarcinoma in Sprague Dawley and F344 rats.  相似文献   

18.
【目的】 分离鉴定武汉市患皮肤病犬猫细菌性病原,并探索其对传统抗菌药物与天然活性产物藤黄酸(GA)和6-溴靛玉红-3’-肟(BIO)的敏感性。【方法】 对患皮肤病犬猫采样并分离病原,通过生长特性观察、革兰氏染色镜检、PCR等方法鉴定并利用SPF小鼠验证致病性;通过药敏纸片验证其对传统药物的耐药性,并测定天然产物对其最小抑菌浓度(minimum inhibitory concentration,MIC)值。【结果】 分离得到2株金黄色葡萄球菌、3株伪中间型葡萄球菌、2株猫葡萄球菌、1株犬链球菌及1株奇异变形杆菌。SPF小鼠皮肤创伤感染验证分离菌株均有致病性。犬链球菌及奇异变形杆菌对各自受试药物均敏感;葡萄球菌对复方新诺明、青霉素、红霉素、四环素、左氧氟沙星、苯唑西林、庆大霉素、克林霉素及氯霉素存在不同程度耐药。天然活性产物GA和BIO对上述9株菌均具有良好抑菌效果,且除分离菌株F5外GA对分离菌株的MIC值均小于BIO。【结论】 本研究共分离得到5种、9株犬猫皮肤细菌。犬链球菌、奇异变形杆菌对传统抗菌药物均敏感,部分葡萄球菌存在耐药。GA和BIO对犬猫皮肤病原菌均有明显抑菌活性,显示其可作为防控犬猫细菌性皮肤病的候选药物。  相似文献   

19.
The antimicrobial susceptibility of Clostridium perfringens strains isolated from Belgian broilers between May and September 2007 was investigated. All 39 tested isolates were sensitive to enrofloxacin, erythromycin, tylosin, florfenicol and bacitracin. Twenty-six (66%) and 24 (61%) out of the 39 tested isolates showed acquired resistance to tetracycline and lincomycin, respectively. The C. perfringens isolates were also screened by PCR for the presence of the resistance genes tet(K), tet(L), tet(M), tetB(P), tet(O), tet(W), lnu(A) and lnu(B). In 22/26 tetracycline resistant strains and 7/24 lincomycin resistant strains, resistance could be attributed to one or more of these genes. An extended frequency distribution range of MICs was seen for ampicillin. These data are consistent with data derived from studies carried out in 1980 and in 2004, indicating that no changes in antimicrobial resistance patterns have taken place during time in C. perfringens isolates from broilers in Belgium.  相似文献   

20.
Recent data from the European and Hungarian Antimicrobial Resistance Monitoring Systems have indicated that the routine use of gentamicin in human and veterinary medicine frequently leads to the selection of gentamicin resistance in Escherichia coli. The aim of this study was to provide molecular characterization of gentamicin resistance in clinical and commensal E. coli strains representing humans and food producing animals by genotyping for antimicrobial resistance and virulence using a miniaturized microarray. All 50 strains tested proved to be multidrug resistant defined as resistance to three or more antimicrobial classes. Antimicrobial resistances genes such as aadA1-like, strB, bla(TEM), sul1 and tet(A) or tet(B), and corresponding phenotypes (streptomycin-, ampicillin-, sulfamethoxazole- and tetracycline resistance) were detected in >50% of isolates regardless of the host or clinical background. However, certain genes encoding gentamicin resistance such as aac(6')-Ib and ant(2″)-Ia as well as catB3-like genes for phenicol resistance were only detected in human isolates. Among virulence genes, the increased serum survival gene iss was predominant in all host groups. Although the majority of gentamicin resistant E. coli strains were characterized by diverse antimicrobial resistance, and virulence gene patterns, accentuated links between catB3-like, aac(6')-Ib, bla(CTX-M-1) and sat genes could be detected in human strains. Further resistance/virulence gene associations (tet(A) with iroN and iss) were detected in poultry strains. In conclusion, the simultaneous characterization of antimicrobial resistance and virulence genotypes of representative clinical and commensal strains of E. coli should be useful for the identification of emerging genotypes with human and or animal health implications.  相似文献   

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