Susceptibility pattern of bacterial isolates in equine ulcerative keratitis: Implications for empirical treatment at a university teaching hospital in Sydney

Corneal ulceration is a common ophthalmic condition in horses. It is frequently caused by trauma to the corneal surface, followed by secondary infection by commensal or pathogenic organisms including Streptococcus equi subspecies zooepidemicus, Pseudomonas aeruginosa and Staphylococcus spp. Emerging antimicrobial resistance amongst these organisms has raised the need for appropriate antimicrobial therapy selection, to optimise treatment efficacy while minimising further antimicrobial resistance. Medical records of 38 horses presented at the University Veterinary Teaching Hospital Camden for ulcerative keratitis between 2010 and 2020 were reviewed to identify those with positive bacterial cultures and antimicrobial susceptibility profiles (13/38). Common susceptibility patterns were identified and used to guide the empirical treatment of equine bacterial corneal ulcers. Pseudomonas spp. (64.3%), Streptococcus equi subspecies zooepidemicus (14.3%) and Actinobacillus spp. (14.3%) were most commonly identified. Susceptibility to amikacin, gentamicin and ciprofloxacin was observed in 100%, 66.7% and 85.7% Pseudomonas spp. isolates respectively. Resistance to polymyxin B and neomycin occurred in 85.7% and 71.4% of Pseudomonas spp., respectively. All Streptococcus equi subspecies zooepidemicus organisms in this study were susceptible to ceftiofur, cephalexin, penicillin and ampicillin, while they were all resistant to gentamicin, neomycin, enrofloxacin and marbofloxacin. Predominating in this study, Pseudomonas spp. maintained overall aminoglycoside susceptibility despite some emerging resistance, and good fluoroquinolone susceptibility. High resistance to Polymyxin B could have arisen from its common use as first-line therapy for bacterial corneal ulcers. Although further research is required, these new findings about predominant bacteria in equine corneal ulceration in the Camden region and their antimicrobial susceptibility patterns can be used to guide the empirical treatment of bacterial corneal ulcers in horses.     

Tooth brushing inhibits oral bacteria in dogs

In this study, scaling, polishing and daily tooth brushing were performed in 20 beagle dogs, and the number of oral bacteria was determined using a bacterial counter. The dogs were randomized into the scaling (S), scaling + polishing (SP), scaling + tooth daily brushing (SB) and scaling + polishing + tooth daily brushing (SPB) groups. Samples were collected from the buccal surface of the maxillary fourth premolars of the dogs immediately after scaling and every week thereafter from weeks 1 to 8. Throughout the study, the number of bacteria was significantly lower in the SB and SPB groups compared with the S group. The findings suggest that daily tooth brushing inhibited oral bacterial growth in the dogs.     

安徽药用牡丹炭疽病病原菌鉴定

<正>牡丹(Paeonia suffruticosa Andr.)是芍药科植物,为多年生落叶灌木,具有很高的观赏和药用价值。因其风姿华丽、色彩艳丽、品种繁多、深受大家喜爱,是中国传统名花和世界著名花卉之一。其根皮也被称为丹皮,具有抗炎、抑制血小板、止痛、清热等作用,是六味地黄丸等著名中成药的主要配方,也是饮片中的常用品[1-2]。近年来,随着牡丹种植面积的不断扩大,造成牡丹病害的大面积发生,已给牡丹生产带来严重影响。     

巨大芽胞杆菌YB-3的筛选、鉴定及其对生姜青枯病的生防效果研究

青枯病（bacterial wilt）是生姜上的一种细菌土传毁灭性病害,化学防治易污染环境且常规化学药剂很难在土壤中起到持续控病的作用,生物防治是其理想的防治方法。为开发对生姜青枯病有效的生防措施,对从生姜根际土壤中分离的一株生防细菌YB-3进行了鉴定,并对其生物学特性及生防效果进行了研究,以丰富生防菌株资源库。采用抑菌圈法筛选拮抗细菌,对效果最好的拮抗菌株做盆栽试验,测定其对生姜青枯病的防治效果,根据形态特征、生理生化特性以及16S rDNA序列对筛选得到的优良菌株进行鉴定。试验结果表明,该拮抗菌在平皿上对青枯菌的抑菌率为50.67%,盆栽试验对青枯病的防治效果为60.86%;经16S rDNA序列分析,并结合形态学和生理生化特征,将菌株YB-3鉴定为巨大芽胞杆菌Bacillus megaterium。YB-3是一株具有开发利用价值的姜青枯病生防菌株。     

竹鼠肠道中厌氧纤维素降解菌的分离与鉴定

本试验旨在从竹鼠肠道中分离厌氧纤维素降解菌并鉴定。取中华竹鼠盲肠内容物稀释,采用含2种不同纤维素[微晶纤维素(MCC)和羧甲基纤维素钠(CMC-Na)]的培养基在厌氧条件下对纤维素降解菌进行初筛,后又经以纤维二糖为唯一碳源的培养基的多次复筛,选出的菌株进行经形态学和分子生物学的鉴定。结果表明:经过初筛和复筛,筛选出了2株厌氧纤维素降解菌。初筛培养基采用MCC和CMC-Na最终筛选出的2株纤维素降解菌的纤维素酶活力分别为6.599和5.268U/m L。菌株经PCR鉴定、测序,用所得序列构建系统发育树,得出这2株菌与酪酸梭状芽孢杆菌(Clostridium butyricum)具有很高的同源性,达99%,二者均属于梭菌属(Clostridium)。本试验从竹鼠盲肠中成功筛选出2株纤维素降解菌,经鉴定确定属于梭菌属。     

应用PCR-DGGE技术比较绵羊瘤胃、网胃、瓣胃和皱胃菌群的多样性

本研究采用聚合酶链式反应-变性梯度凝胶电泳(PCR-DGGE)技术结合DGGE图谱条带的克隆和测序比较了绵羊瘤胃、网胃、瓣胃和皱胃菌群的多样性,同时对菌群进行了聚类分析和主成分分析。结果表明:绵羊瘤胃、网胃、瓣胃和皱胃内容物DGGE图谱的平均条带数分别为18、13、16和15条;瘤胃和瓣胃内菌群的多样性指数、均匀度和丰富度均较高,分别为2.83、0.79、17.00和2.82、0.79、16.80,而网胃和皱胃内容物较低,分别为2.52、0.70、12.60和2.73、0.76、15.40;聚类分析结果显示不同胃的内容物菌群具有一定差异,但不同动物个体相同胃的内容物相似性系数均高于0.63;PCR-DGGE图谱中测序的条带大多数归为拟杆菌门(Bacteroidetes)和厚壁菌门(Firmicutes),优势菌群为厚壁菌门(Firmicutes)细菌、拟杆菌门(Bacteroidetes)细菌、未培养瘤胃细菌(uncultured rumen bacterium)、未培养细菌(uncultured bacterium)和韦荣球菌科(Veillonellaceae)细菌,特异性细菌为不动杆菌属(Acinetobacter sp.)细菌和瘤胃球菌属(Ruminococcaceae)细菌。结果提示,绵羊4个胃中均含有种类丰富和数量巨大的细菌,且随着消化道部位由前往后的顺序,菌群的多样性呈现先高后降低再升高的趋势。     

苯甲酸在松材线虫病中的作用

在室内条件下,初步研究苯甲酸对松树和松材线虫病的作用.用不同浓度的苯甲酸溶液分别处理松枝,显示低浓度苯甲酸溶液能显著延长松枝的存活期,高浓度苯甲酸溶液处理的松枝针叶出现褐变现象,但对松枝的存活期没有影响,其症状与松材线虫病不同.分别用1.0 mmol·L-1的苯甲酸溶液和自来水培养接种松材线虫的松枝,在用苯甲酸溶液处理的接种松枝中,虽然松材线虫仍能大量增殖,但与用自来水培养的接种松枝相比,其蒸腾强度显著增强,失水萎蔫程度显著降低,存活期显著延长,这说明苯甲酸在松材线虫病树中可能起着抑制与病害相关的致病菌或提高松树抗病能力的作用.     

应用白僵菌防治靖远松叶蜂的研究

利用病原菌防治害虫是森林可持续发展的重要途径。本研究采用2003年4月从山西省灵丘县下关林区油松林内采集的越冬油松毛虫DendrolimustabulaeformisTsaietLiu幼虫的僵虫尸,经实验室分离、培养和鉴定后得到的白僵菌Beauveriabassiana菌株,用2×108孢子/mL、2×107孢子/mL和2×106孢子/mL3种浓度的孢子液对靖远松叶蜂DiprionjingyuanensisXiaoetZhang幼虫分别进行室内和林间感染,试验结果显示:室内感染4龄幼虫校正致死率分别为83.37%、78.82%、62.05%,LT50分别为5.794d、6.237d、7.603d;感染5龄幼虫校正死亡率分别为68.23%、59.1%、45.79%,LT50分别为7.244d、8.414d、12.274d;林间感染幼虫校正死亡率分别为65.26%、54.21%、38.23%,LT50分别为16.788d、19.187d、30.2d。结果表明靖远松叶蜂幼虫校正死亡率与白僵菌孢子液浓度呈正相关,与LT50呈负相关,与龄期呈负相关。