羊源肺炎克雷伯氏菌的分离与鉴定

本研究通过病死羊的肺脏中进行细菌分离、形态学观察、生化试验、致病性试验、药敏试验和16S rRNA扩增。结果从肺中分离到1株具有致病性的革兰氏阴性短杆菌。生化试验鉴定结果符合肺炎克雷伯氏菌的特征。分离株对头孢噻肟、阿米卡星、头孢曲松和链霉敏感外,对强力霉素等12药物具有耐药性。16S rRNA测序结果分析显示分离株与肺炎克雷伯氏菌的核苷酸同源性为97.1%~99.0%,在核苷酸进化树上与肺炎克雷伯氏菌属于同一分支。结果表明本研究从病死羊的肺脏中分离到1株肺炎克雷伯氏菌。     

家兔泛耐药肺炎克雷伯菌的分离鉴定

报告四川省雅安市家兔养殖过程中致病性细菌的检测及生物学特征。通过对发病及死亡的家兔病变组织进行细菌学检查及分离,对分离到的优势菌株进行形态特征、理化性质和16S r RNA序列的分子鉴定,病理学观察及药敏试验,判定为多耐药肺炎克雷伯菌。该菌对家兔有致病性,对供试的氟苯尼考等高度敏感,对氯洁霉素及四环素等多种抗生素耐药,并检测到相关耐药基因(blaTEM、tet A、tet M)的存在。推断此株肺炎克雷伯菌是导致家兔死亡的主要病原菌。     

家养观赏地图鱼肺炎克雷伯氏菌、维氏气单胞菌与黏质沙雷氏菌的分离鉴定及耐药性分析

本试验旨在通过细菌分离鉴定,明确家养观赏地图鱼的死因,筛选敏感药物。采用常规方法分离纯化细菌后,进行细菌形态学观察,并通过小白鼠致病性试验、细菌主要生化鉴定、16SrDNA序列测定分析、药敏试验及耐药基因检测等方法对分离的细菌进行鉴定及耐药分析。分离出3株革兰氏阴性短杆菌,根据细菌形态特征及理化特性,结合16SrDNA序列测定与系统发育分析结果,判定其分别为肺炎克雷伯氏菌(Klebsiella pneumoniae)、维氏气单胞菌(Aeromonas veronii)和黏质沙雷氏菌(Serratia marcescens),其中肺炎克雷伯氏菌具有较强致病性。3株细菌均对洛美沙星、氧氟沙星、阿米卡星、卡那霉素敏感,对阿莫西林、氟苯尼考、克林霉素、甲硝唑等具有较强耐药性。结果表明,肺炎克雷伯氏菌、维氏气单胞菌、黏质沙雷氏菌的混合感染是家养观赏地图鱼的死亡原因。     

兔源肺炎克雷伯氏菌的生物学特性研究

为探究兔源肺炎克雷伯氏菌的生物学特性,本研究对从病兔中采集的病料进行细菌的分离培养、细菌特征性基因(Khe基因)的PCR检测、生化鉴定、药敏试验、致病性试验、毒力基因的扩增及序列分析对细菌分离株进行分析。结果显示麦康凯平板上生长有奶油状菌落且镜检为革兰氏阴性菌;Khe基因扩增为阳性;生化鉴定结果表明分离菌为肺炎克雷伯氏菌;药敏结果显示该菌对诺氟沙星、氧氟沙星、头孢曲松等9种药物高敏,对链霉素、卡那霉素、头孢呋辛等5种药物中敏,对先锋V、庆大霉素等7种药物不敏感甚至耐药;致病性结果显示,分离株能使小白鼠在24h内死亡;分离株携带有wabG、uge和fimH三种毒力基因。本研究结果表明该肺炎克雷伯氏菌具有很强的致病性,是导致兔死亡的主要病原菌。     

肺炎克雷伯氏菌强毒株的分离鉴定及16-23SrRNAITS序列分析

为确诊疑似仔猪肺炎克雷伯氏菌(K.pneumonia)感染,并研究其病原的致病性、耐药性、16-23SrRNA ITS系统进化特征,本研究从云南因肺炎、腹泻而大量死亡的仔猪中分离到1株革兰氏阴性短粗杆菌,命名为KP14013,对其进行生化鉴定、16SrRNA鉴定,研究其对小白鼠和仔猪的致病性,并对其16-23SrRNA ITS基因进行测序和遗传进化分析。结果显示,KP14013分离株生化特征与肺炎克雷伯氏菌相符,其16SrRNA与GenBank中23株肺炎克雷伯氏菌代表株之间的同源性均为99%,将KP14013鉴定为肺炎克雷伯氏菌。KP14013对小白鼠半数致死量(LD50)为3×101.8 CFU,腹腔注射3×108 CFU可使仔猪100%致死。16-23SrRNA ITS系统进化关系结果表明,KP14013与GenBank中收录的15株肺炎克雷伯氏菌形成进化树的一个分支,属于同一个亚群,它们之间的核苷酸同源性为98.4%~99.2%。本研究证实了肺炎克雷伯氏菌是该起仔猪腹泻大量死亡的病原;KP14013分离株为毒力极强菌株,具有多重耐药性,其16-23SrRNA ITS与GenBank中收录的肺炎克雷伯氏菌代表株之间核苷酸存在差异,可用于肺炎克雷伯氏菌菌株间的鉴别。     

羊源肺炎克雷伯菌的分离鉴定及毒力基因检测

为了调查内蒙古通辽市某羊场发病羊死亡的原因,对疑似致病菌进行分离、鉴定及部分生物学特性研究。对病死羊进行剖检,无菌条件下采集心脏、肝脏、脾脏、肺脏等组织脏器进行细菌分离培养;对分离菌进行小鼠致病性试验、细菌生化检测、16S rDNA基因扩增及同源性比对分析和药物纸片扩散法敏感性试验。结果显示,分离菌株符合肺炎克雷伯菌生化特性;16S rDNA序列与GenBank中已登录的肺炎克雷伯杆菌序列同源性为99.59%;小鼠致病性试验结果表明分离株有较强的致死性;分离株携带多种毒力基因致病性较强。药敏试验结果表明分离株对诺氟沙星、环丙沙星、氧氟沙星、多西环素等药物高度敏感,对复方新诺明、卡那霉素等中度敏感,对庆大霉素、头孢哌酮、头孢氨苄等耐药。结果表明,分离株为肺炎克雷伯菌,是该羊场发病羊死亡的致病菌。     

马来穿山甲多种菌混合感染的细菌分离鉴定及小鼠的毒力试验

2017年9月云南省宜良某野生动物收容中心收容了5只马来穿山甲,都有严重的腹泻症状,粪便呈黑绿色、且带有脱落的黏膜,其中2只并发打喷嚏及呼吸困难等症状。试验无菌采集5只穿山甲的粪便棉试子及2份有呼吸道症状的鼻腔棉拭子,通过细菌分离鉴定、革兰染色、生化试验等对菌株进行初步测定,PCR扩增菌株的16S rDNA,测序后在NCBI上利用BLAST和MEGA软件进行序列相似性比较和系统发育学分析,结果表明:分离到的4株菌株分别为肺炎克雷伯菌、变形杆菌、弗氏柠檬酸杆菌及大肠杆菌O83∶H1;动物毒力试验根据小鼠在感染4株菌株96 h时的死亡情况,计算出肺炎克雷伯菌、变形杆菌、弗氏柠檬酸杆菌及大肠杆菌O83∶H1的LD50分别为4.37×10~8,1.15×10~8,1.29×10~8,4.15×10~(12) CFU/mL;药敏试验结果,肺炎克雷伯菌对大观霉素和头孢哌酮极度敏感,对新霉素等高度敏感,对卡那霉素等耐药;变形杆菌对头孢哌酮极度敏感,对链霉素等中度敏感,对头孢曲松等耐药;弗氏柠檬酸杆菌对大观霉素极度敏感,对头孢哌酮高度敏感,对头孢氨苄等低度敏感;大肠杆菌O83∶H1对环丙沙星和左氟沙星极度敏感,对头孢氨苄中度敏感,对卡那霉素低度敏感。     

河南驻马店地区猪源肺炎克雷伯氏菌分离菌株生物学特性

为了分析驻马店地区猪源肺炎克雷伯氏菌分离菌株生物学特性,从驻马店地区不同养殖场中采集患呼吸道疾病猪肺脏、鼻拭子等病料组织74份中分离得到了43株肺炎克雷伯氏菌。采用人工感染小鼠致病性试验、PCR方法和K-B药敏纸片分别检测49株肺炎克雷伯氏菌的致病性、血清型及耐药性。结果显示,30株肺炎克雷伯氏菌对小鼠具有很强的致病性;43株分离菌株以K5、K20为主要流行血清型,分别占分离菌株的37.2%、27.9%;43株分离菌株对氨苄西林、阿莫西林、大观霉素等7种药物耐药性较高,耐药率在51.2%以上,对其他药物的耐药率在18.6%~234.9%之间,且呈现多重耐药性,耐10、9种药物分离菌株最多,分别占分离菌株的25.6%、27.9%。本试验为该地区猪源肺炎克雷伯氏菌病的防治提供理论基础。     

1株雏鸡致病性肺炎克雷伯菌分离鉴定与系统进化发育分析

为了确定引起雏鸡死亡的病原菌,从发病致死的雏鸡体内分离1株病菌,采用细菌常规的分离鉴定、16S rRNA基因测序、致病性试验、K-B药敏纸片法等分别对分离菌株进行鉴定、致病性及耐药性检测。结果显示,分离株鉴定为致病性肺炎克雷伯菌;其16S rRNA基因序列与GenBank登录的12株肺炎克雷伯菌参考株同源性在98%～99%之间,与肺炎克雷伯菌参考株KP262416.1聚于一支,与KJ803938.1聚于一大支,且与2株参考株存在密切的遗传进化关系;该菌株对头孢曲松、头孢克肟、恩诺沙星等4种药物敏感;对环丙沙星、新霉素、丁胺卡那霉素等6种药物中敏;对氨苄西林、阿莫西林、青霉素等6种药物耐药。     

青岛地区兔肺炎克雷伯氏菌分离鉴定

对青岛地区某兔场病死兔的病变器官组织进行细菌分离和纯培养,对所分离的细菌进行形态特征、理化性质和16SrRNA序列的分子鉴定和测序,人工感染以及药敏试验,判定为肺炎克雷伯氏菌。代表菌株16SrRNA序列长度1414bp,与GeneBank登录号为EU360123.1的肺炎克雷伯氏菌16SrRNA序列同源性100%,人工感染小鼠24h全部死亡,对供试的诺氟沙星等药物高度敏感,对供试的强力霉素等中毒敏感,对头孢拉定等耐药。应用筛选的敏感药物,并采取综合防治措施,使疫情得到了有效控制。     

Experimental infection of Swiss webster mice with four rat bartonella strains: host specificity, bacteremia kinetics, dose dependent response, and histopathology

Groups of Swiss Webster outbred mice were each inoculated with one of four bartonella strains originally isolated from Rattus spp. at doses ranging from 10¹ to 10⁷ bacteria per mouse. One strain, Rn1691yn (Bartonella coopersplainensis-like), infected mice and produced bacteremias at levels up to 10⁵ bacteria/ml of blood and from 3 to 8 weeks duration. A dose dependent response was also observed with differing proportions of mice bacteremic following inoculation at different doses. In addition weeks-to-months long lags in bacteremia manifestation occurred following lower dose exposures. The possibility of bacterial transmission from bacteremic mice to uninfected cagemates was assessed and no naïve mice became infected from contacts with infected mice. Finally, a subset of bacteremic mice inoculated with high doses of Rn1691yn were examined histopathologically and multifocal, granulomatous lesions were detected in both liver and kidneys. The host specificity and infectivity of the strains is discussed in relation to their potential for zoonotic transmission to incidental hosts.     

Prevalence,Molecular Characterization and Antimicrobial Resistance of Thermophilic <Emphasis Type="Italic">Campylobacter</Emphasis> Isolates from Cattle,Hens, Broilers and Broiler Meat in South-eastern Italy

Eleven cattle farms, 8 layer farms, 7 broiler farms and 30 broiler meat samples were investigated in south-eastern Italy throughout 2003 to evaluate the prevalence, the molecular type and antimicrobial resistance of thermophilic Campylobacters. A total of 398 samples were analysed. One Campylobacter isolate for each positive faecal swab and three isolates per positive broiler meat sample were selected for further analysis. Multiplex PCR was performed for species-level identification and PCR-RFLP of the flagellin A gene for genotyping. Resistance to 14 antimicrobials was studied in 188 Campylobacter isolates. Prevalence of campylobacters was high both on farms (100%) and in food samples (73%). On 4/11 cattle farms and on 10/15 poultry farms more than one species was isolated. The presence of more than one genotype was found on 8/11 cattle farms, on 10/15 poultry farms and in 8/22 Campylobacter-positive food samples. High rates of resistance to quinolone were observed: 9/31 (29%) C. jejuni bovine isolates, 4/22 (18%) C. jejuni poultry isolates, and 14/26 (54%) C. coli poultry isolates. Resistance to sulphamethoxazole-trimethoprim was also observed frequently: 18/26 (69%) of the avian C. coli strains, 25/31 (80%) of the C. jejuni strains isolated from poultry and 15/22 (68%) of those isolated from cattle were resistant. There was a significant difference between the rate of resistance to macrolides of C. coli and C. jejuni isolated in poultry, which amounted to 23% and 3%, respectively. This study provided data on the prevalence and antimicrobial resistance of thermophilic campylobacters in south-eastern Italy and confirmed that flaA-typing is an efficient tool to study the epidemiology of Campylobacter strains in short-term investigations.     

Virulence genes and plasmid profiles in Rhodococcus equi isolates from domestic pigs and wild boars (Sus scrofa) in Brazil

The virulence genes and plasmid profiles of 23 Rhodococcus equi isolates from 258 lymph nodes from domestic pigs (129 nodes with lesions and 129 without lesions) and 120 lymph nodes from slaughtered wild boars (60 nodes with lesions and 60 without) were characterized. R. equi was obtained from 19 lymph nodes of domestic pigs, 17 with, and two without lesions, and from four lymph nodes with lesions, from wild boars. The 23 isolates were tested for the presence of vapA and vapB genes, responsible for the 15–17 and 20 kDa virulence-associated proteins, respectively, by PCR in order to characterize as virulent (VapA), intermediately virulent (VapB) and avirulent. Plasmid DNAs were isolated and analyzed by digestion with restriction endonucleases to estimate size and compare their polymorphisms. Of the 19 domestic pigs strains, seven (36.8%) were avirulent and 12 (63.2%) were intermediately virulent, with the intermediately virulent isolates being plasmid types 8 (8 isolates), 10 (2 isolates), 1 (1 isolate) and 29 (1 isolate). The plasmid type of four strains isolated from wild boars was also intermediately virulent type 8. None of the domestic pigs and wild boar isolates showed the vapA gene. These findings demonstrate a high occurrence of plasmid type 8 in isolates from pigs and wild boars, and the similarity of plasmid types in the domestic pigs, wild boars and human isolates in Brazil.     

Monoclonal antibodies against the leptospiral immunoglobulin-like proteins A and B conserved regions

Leptospirosis is an infectious disease caused by pathogenic spirochetes of the genus Leptospira that affects humans and a wide variety of animals. Recently the genomes of Leptospira interrogans, Leptospira borgpetersenii and Leptospira biflexa species were sequenced allowing the identification of new virulence factors involved in survival and pathogenesis of bacteria. LigA and LigB are surface-exposed bacterial adhesins whose expression is correlated with the virulence of Leptospira strains. In this study, we produced and characterized five monoclonal antibodies (MAbs) against a recombinant fragment of LigB (rLigBrep) with approximately 54 kDa that comprise the portions of LigA and LigB (domains 2–7). The 5 MAbs obtained were of the IgG1 (2) and IgG2b (3) isotypes and their affinity constants for rLigBrep ranged from 7 × 10⁷ M⁻¹ to 4 × 10⁸ M⁻¹. The MAbs were able to react with the native antigen on the L. interrogans, L. borgpetersenii and Leptospira noguchii surfaces by indirect immunofluorescence, immunoblotting and immunoelectron microscopy. These results demonstrate that the MAbs anti-rLigBrep can be useful to complement genetic studies and to aid studies aiming understanding the role of Lig proteins in Leptospira pathogenesis and the development of Lig-based vaccines and improved diagnostic tests for leptospirosis.     

First isolation and identification of Elizabethkingia meningoseptica from cultured tiger frog, Rana tigerina rugulosa

Elizabethkingia meningoseptica has been recognised as an occasional but serious opportunistic bacterial pathogen to human beings. Recently, it was frequently isolated from tiger frog, Rana tigerina rugulosa, with cataract disease, which is the most common disease of unknown aetiology of frogs in Hainan, China. The purpose of this study was to identify and characterise the bacterial strains isolated from the recent outbreaks of cataract disease in farmed tiger frog in Hainan, China, and to evaluate their pathogenicity to the frog and their sensitivity to 20 chemotherapeutic agents.The 16S rRNA gene sequences of strains W0701 (1478 bp), W0702 (1477 bp) and W0703 (1478 bp) showed 98.6–98.7% similarity with the sequence of E. meningoseptica type strain (ATCC 13253) and 99.9–100% similarity with that of E. meningoseptica NTU 870424-IL. Six strains (W0701–W0706) were selected to represent 24 isolates retrieved from six moribund frogs. The morphological, physiological and biochemical characteristics of the six representative isolates were consistent with those of E. meningoseptica strains. The organisms were only susceptible to vancomycin and moderately susceptible to cefoperazone among the 20 investigated chemotherapeutic agents. Virulence test with strain W0702 was conducted and pathogenicity (by intramuscular injection) was demonstrated in the tiger frog. In conclusion, 24 isolates obtained from frogs with cataract disease were the E. meningoseptica strains highly pathogenic to tiger frog, and this is the first report of E. meningoseptica as a pathogen for tiger frog.     

The Mycobiota and Toxicity of Equine Feeds

Feed contamination can lead to nutrient losses and detrimental effects on animal health and production. The purposes of this study were to investigate the mycobiota in equine mixed feeds and to determine natural contamination with aflatoxin B₁ (AFB₁) and fumonisin B₁ (FB₁). Fungal enumeration of equine feed samples was done. A commercially available enzyme-linked immunosorbent assay kit was applied to quantify AFB₁ and FB₁. A comparison between ELISA and HPLC was carried out. Feed mould counts ranged from <1× 10² to 1× 10⁵ cfu/g. The most frequent genus isolated was Aspergillus (40.54%), followed by Penicillium (18.38%) and Fusarium (16.22%). The most prevalent Aspergillus sp. was A. flavus (36%). AFB₁ values ranged between 0.01 and 99.4 μg/kg. FB₁ levels ranged between 0.01 and 7.49 μg/kg. HPLC and ELISA methods showed positive correlation for AFB₁ and FB₁ determinations (r = 0.9851 and r = 0.9791, respectively). The ELISA analytical method was efficient for AFB₁ and FB₁ detection. The scarcity of studies on natural fungal contamination and on the presence of AFB₁ and FB₁ in materials used as equine feed ingredients highlights the value and contribution of this study.     

Milk hygiene and udder health in the periurban area of Hamdallaye, Niger

The prevalence of intra-mammary infections in dairy herds was studied in Hamdallaye, Niger. A total of 956 milk samples were collected in 2007 from 239 lactating cows of four local breeds in eight traditional herds; the first sampling was undertaken in the dry season at morning milking, and the second in the rainy season at evening milking. Staphylococcus aureus, Coagulase-Negative Staphylococci (CNS) and environmental microorganisms were detected in significantly (p < 0.05) more samples in the rainy season, 55.2%, than in the dry season, 27.1%. Statistically significant (P < 0.05) differences in prevalence were observed among herds and according to lactation number. Infections were assigned to four classes, according to the major pathogen, and the respective mean somatic cell counts during the dry season were: S. aureus, 775 × 10³ cells/ml; CNS, 447 × 10³ cells/ml; environmental microorganisms, 407 × 10³ cells/ml; and non-infected, 262 × 10³ cells/ml. Most of the tested strains were sensitive to antibiotics, and selected strains of S. aureus (n = 15) were negative to the multiplex PCR tests for production of enterotoxins.