Relative virulences of a drug-resistant and a drug-sensitive strain of Eimeria acervulina, a coccidium of chickens

The virulence of a field strain of the chicken coccidian parasite Eimeria acervulina (Boreham I), dually resistant to the chemically unrelated anticoccidial agents decoquinate and clopidol, was compared with that of a drug-sensitive laboratory strain (Ongar) of the same species. Following a single heavy infection (prevented from recycling), both strains exhibited pathogenic effects typical of their species, viz., pathognomonic lesions, adverse effects on body weight gain and feed conversion ratio (FCR), but no mortality. One week after infection, chicks infected with either strain had a statistically significantly worse weight gain than the uninfected control; the Boreham I strain produced more oocysts, and caused slightly more severe duodenal lesions and poorer FCRs than the Ongar strain (all those effects being non-significant). After 3 weeks, there were no significant differences between any cumulative effects of either strain, nor any differences from the uninfected control. However, from 2 to 3 weeks after infection, chicks infected with either strain had a greater feed consumption and growth rate than uninfected chicks. When chicks reared on solid floors were given lighter infections of either strain, which were allowed subsequently to recycle naturally, there were no consistent reductions in weight gains, but feed consumption was higher than that of uninfected chicks. Whatever, the mode of infection, there were no significant differences between the weights of infected and uninfected chicks after 3 weeks, but the FCR of infected chicks was usually poorer than that of uninfected chicks. The difference between the virulences of the Boreham I and Ongar strains was not greater than that between various drug-resistant strains or between various sensitive strains of several Eimeria species recorded in the literature. It is therefore concluded that there was no difference between the virulences of the two strains of E. acervulina that could be attributed to the drug-resistance of one of them.     

Tracing the emergence of drug-resistance in coccidia (Eimeria spp.) of commercial broiler flocks medicated with decoquinate for the first time in the United Kingdom

Decoquinate is a quinolone coccidiostat introduced during 1967 as an in-feed prophylactic for broiler chickens. Despite early drug-resistance problems and its age, the drug is still used commercially worldwide. Decoquinate here serves as a valuable model in a field study that addresses the dynamics and economic impact of the development of coccidial resistance to potent synthetic anticoccidial drugs. The results of this unique, hitherto unpublished, study on the initial emergence of resistance of avian coccidia (Eimeria spp.) to a new drug in the field may be of strategic value in the continued use of decoquinate or the introduction of new drugs. The commercial performance of the first 3-5 crops of broilers to be medicated with decoquinate on each of six farms was monitored during 14 months in 1968-1969, supplemented by assessments of the species, population dynamics and decoquinate-resistance of coccidia isolated from each farm. During the rearing of each flock in a single shed on each farm, oocysts were counted in fresh faecal samples collected on three occasions, and the species were identified by their morphology if possible, supported if necessary by the biological characteristics of infections in chickens. E. acervulina was the most common species, followed by E. mitis, E. maxima, E. tenella and E. praecox. E. brunetti occurred rarely, and E. necatrix was not found. Decoquinate-resistance was evident in several species during the rearing of the first decoquinate-medicated crop on each farm, although clinical coccidiosis did not occur. It was concluded that inherently resistant mutants of E. acervulina, E. brunetti, E. maxima, E. tenella, and probably also E. mitis and E. praecox, were selected from field populations by 6 weeks during their first exposure to decoquinate. During up to four more subsequent crops, cycling of resistant parasites stimulated host immunity, which had no obvious adverse impact on commercial performance. There was no apparent seasonal effect. A hypothesis is proposed to explain the sudden and rapid emergence of quinolone-resistance in the coccidia, and why bird health was not thereby compromised in these circumstances.     

Construction of DNA vaccines encoding Eimeria acervulina cSZ-2 with chicken IL-2 and IFN-γ and their efficacy against poultry coccidiosis

The study describes vaccination experiments with highly immunogenic sporozoite E. acervulina cSZ-2 co-administered with chicken IL-2 (chIL-2) and interferon-γ (chIFN-γ) to determine their efficacies against homologue challenge. The entire coding sequence of cSZ2, chIL-2 and chIFN-γ were cloned into eukaryotic expression vector pVAX1, constructing DNA vaccines pVAX1-cSZ2, pVAX1-chIL-2, pVAX1-chIFN-γ, pVAX1-cSZ2-chIL-2 and pVAX1-cSZ2-chIFN-γ. The expression of target genes in vivo was detected by RT-PCR and Western blot. Chicken experiments were carried out by vaccinating chickens two times at dose rate of 100 μg intramuscularly. At 28 days of age, all chickens were inoculated orally with 1 × 10⁵ sporulated oocysts of E. acervulina except the unchallenged control group. Seven days after challenge, all chickens were weighted and slaughtered for duodenum collection. The results indicated that these DNA vaccines were successfully constructed and the antigen genes could be expressed effectively in vivo. The findings also demonstrated best synergistic effect of IL-2 with this protein which suggested that co-administration of cytokines with this antigen was a powerful method to enhance immunity by alleviating intestinal lesions, body weight loss and oocyst count imparting partial protection against homologous challenge.     

鸡巨型艾美耳球虫单卵囊分离及雏鸡扩增试验

采用饱和食盐水漂浮法收集就诊病死球虫阳性鸡小肠中段内容物中的球虫卵囊,恒温培养至孢子化后,用2%琼脂薄板进行球虫单卵囊分离,分别感染7只5日龄雏鸡,对据形态学鉴定为巨型艾美耳球虫的分离株进行2代单卵囊分离和雏鸡感染,取其后代以每只1.0×10⁴个卵囊感染10只10日龄雏鸡进行卵囊扩增,获得大量纯种巨型艾美耳球虫卵囊。结果表明,刀片切割琼脂薄板单卵囊分离法操作简便,单卵囊感染成功率较高,准确率达100%,适用于纯种卵囊的分离与扩增。     

Efficacy of danofloxacin 18% injectable solution in the treatment of Escherichia coli diarrhoea in young calves in Europe

The efficacy of danofloxacin 18% against naturally occurring Escherichia coli diarrhoea was investigated in calves at seven European sites. Treatment commenced on day 0, with either a single subcutaneous injection of danofloxacin 18% (n=267) at 6 mg/kg repeated on day 2 if required, or reference product containing baquiloprim/sulphadimidine (n=37) or gentamicin (n=98) administered as recommended. E. coli was isolated from 90% to 100% of calves pre-treatment, and the prevalence of serotypes K99 and F41 was 8-46% and 46-92%, respectively. In both treatments, the majority of calves (93.2-93.9%) showed clinical improvement and completed the studies. There were significant reductions for both treatments, in severity of clinical signs on days 4 and 10 compared to day 0 (P<0.0001), and between days 4 and 10 (P<0.05), but no significant differences between treatments (P>0.05). Danofloxacin 18% was clinically safe, and as effective as the reference products in the treatment of E. coli diarrhoea in calves.     

Preslaughter diet management in sheep and goats: effects on physiological responses and microbial loads on skin and carcass

Sixteen crossbred buck goats (Kiko x Spanish; BW = 32.8 kg) and wether sheep (Dorset x Suffolk; BW = 39.9 kg) were used to determine the effect of preslaughter diet and feed deprivation time (FDT) on physiological responses and microbial loads on skin and carcasses. Experimental animals were fed either a concentrate (CD) or a hay diet (HD) for 4 d and then deprived of feed for either 12-h or 24-h before slaughter. Blood samples were collected for plasma cortisol and blood metabolite analyses. Longisimus muscle (LM) pH was measured. Skin and carcass swabs were obtained to assess microbial loads. Plasma creatine kinase activity (863.9 and 571.7 ± 95.21 IU) and non-esterified fatty acid concentrations (1,056.1 and 589.8 ± 105.01 mEq/L) were different (P < 0.05) between sheep and goats. Species and diet treatments had significant effects on the ultimate pH of LM. Pre-holding total coliform (TCC) and aerobic plate counts (APC) of skin were significantly different between species. Goats had lower (P < 0.05) TCC (2.1 vs. 3.0 log₁₀ CFU/cm²) and APC (8.2 vs. 8.5 log₁₀ CFU/cm²) counts in the skin compared to sheep. Preslaughter skin E. coli counts and TCC were different (P < 0.05) between species. Goats had lower (P < 0.05) counts of E. coli (2.2 vs. 2.9 log₁₀ CFU/cm²) and TCC (2.3 vs. 3.0 log₁₀ CFU/cm²) in the skin compared with those in sheep. Diet, species, and FDT had no effect (P > 0.05) on E. coli and TCC in carcass swab samples. The APC of carcass swab samples were only affected (P < 0.05) by the FDT. The results indicated that preslaughter dietary management had no significant changes on hormone and blood metabolite concentrations and sheep might be more prone for fecal contamination than goats in the holding pens at abattoir.     

曲靖地区仔猪腹泻细菌性病原的分离鉴定与耐药性分析

为了解曲靖地区仔猪出现腹泻的细菌性病因,对5个养殖场148份出现仔猪腹泻症状的样品进行细菌分离培养及耐药性分析,结果显示,检出致病性大肠杆菌(E.coli)114份,阳性率为77.03%;沙门氏菌(Salmonella)26份,阳性率为17.57%,混合感染率为17.57%.致病性大肠杆菌和沙门氏菌对多种抗生素产生了耐药性,其中114株致病性大肠杆菌中97株呈多重耐药性,占总菌数的85.09%,26株沙门氏菌中20株呈多重耐药性,占总菌数的76.92%.结果表明,致病性大肠杆菌是导致当地哺乳仔猪腹泻的主要细菌性病原,部分仔猪继发感染沙门氏菌,两种细菌对多种抗生素产生了耐药性,多重耐药现象较严重.     

2株枯草芽孢杆菌对大肠杆菌和沙门氏菌的体外抑菌试验研究简

本试验旨在检测2株枯草芽孢杆菌对致病性大肠杆菌和沙门氏菌抑菌作用。以致病性大肠杆菌和沙门氏菌作为指示菌,采用2株枯草芽孢杆菌与大肠杆菌和沙门氏菌同时接种及先后接种的方法,对其与大肠杆菌和沙门氏菌的生物颉颃作用进行了研究。结果表明,先接种枯草芽孢杆菌再接种致病菌抑制作用最明显且在24 h时抑菌作用最强,同时接种枯草芽孢杆菌和致病菌抑制作用次之,先接种致病菌再接种枯草芽孢杆菌的抑制作用最弱。提示,2株枯草芽孢杆菌对致病性大肠杆菌和沙门氏菌都有一定的抑制作用,但抑制作用的强弱有差异,且与枯草芽孢杆菌和致病菌接种的时间长短有关。     

乳酸菌―芽孢菌发酵黄芪对小鼠免疫功能作用的研究简

试验旨在探讨乳酸菌―芽孢菌发酵黄芪对小鼠免疫功能的影响。将84只小鼠分成6组,每组14只,分别为生理盐水组（阴性对照组）、未发酵黄芪组（阳性对照组,黄芪生药浓度为150 mg/mL）、试验Ⅰ组（黄芪生药浓度为60 mg/mL）、试验Ⅱ组（黄芪生药浓度为90 mg/mL）、试验Ⅲ组（黄芪生药浓度为120 mg/mL）、试验Ⅳ组（黄芪生药浓度为150 mg/mL）。小鼠采用灌胃方式给药30 d,最后处死小鼠测定其体重、免疫器官（胸腺和脾脏）系数、免疫因子（IgG、IL-6、sIgA）。结果显示,给药30 d后,试验组小鼠体重明显升高;试验Ⅰ组免疫器官系数极显著高于对照组（P＜0.01）;试验Ⅲ、Ⅳ组免疫因子IgG和sIgA均极显著高于对照组（P＜0.01）。由此可知,乳酸菌―芽孢菌发酵黄芪对小鼠的免疫功能有很好的促进作用。     

Piroplasmosis in Donkeys—A Hematological and Serological Study in Central Ethiopia

Working donkeys (n = 395) originating from three different districts of the Oromia region of Ethiopia were examined October 2009 and April 2010 for the prevalence of equine piroplasmosis between. Apart from hematological and serological examination, tick vectors were collected and determined. Intraerythrocytic stages of Theileria equi and Babesia caballi were detected in 12.2% and 1.8% of examined stained blood smears, respectively. The seroprevalence of T. equi and B. caballi was 55.7% and 13.2%, respectively. The majority of active infection coincided with anemia. Only 16 donkeys were infested with four species of hard ticks: Rhipicephalus turanicus, Rhipicephalus evertsi evertsi, Rhipicephalus pulchellus, and Amblyomma variegatum.     

Avian colibacillosis caused by an intestinal pathogenic Escherichia coli isolate from calf diarrhea

An intestinal pathogenic Escherichia coli isolate from calf diarrhea, containing the iutA, f17A, afa-8D, and cnf2 genes, was able to cause avian colibacillosis after experimental infection in chickens. Intra-tracheal inoculation and spray of this strain caused 10% of mortality and gross lesions, including airsacculitis, pericarditis, and perihepatitis. These results suggest that some bovine pathogenic E. coli can cause extra-intestinal infections in other animal species.     

广东地区猪源大肠杆菌耐药性及其系统发育群的研究简

为分析广东地区猪源大肠杆菌耐药性及其系统进化背景,试验于2011年从患病猪分离出264株大肠杆菌,包括粪便源131株和肝源133株,采用琼脂稀释法测定18种抗菌药物的敏感性,多重PCR法确定系统进化关系,并对不同来源菌株的耐药性和系统进化背景进行分析比较。结果发现,大肠杆菌多重耐药现象严重,共存在128种耐药谱型。分离菌株对氨苄西林、复方新诺明、萘啶酸和四环素高度耐药,对黏菌素、头孢他啶和阿米卡星较敏感。种群进化分析结果表明,分离菌株主要分布在共生型的A组和B1组（91.66%）,且不同来源菌株的种群进化分布差异不显著(P＞0.05)。结合药敏试验结果发现,不同进化组别的分离菌株对特定抗菌药物的耐药性存在显著差异（P＜0.05）。通过对大肠杆菌耐药性及其系统发育群进行综合分析,为兽医临床用药提供依据。     

Detection of Escherichia coli O157 and Escherichia coli O157:H7 by the immunomagnetic separation technique and stx1 and stx2 genes by multiplex PCR in slaughtered cattle in Samsun Province, Turkey

This study was conducted to investigate the presence of Escherichia (E.) coli O157 and E. coli O157:H7 and stx1 and stx2 genes on cattle carcasses and in rectal samples collected from Samsun Province of Turkey. A total of 200 samples collected from cattle carcasses and the rectal contents of 100 slaughtered cattle from two commercial abattoirs were tested using the immunomagnetic separation technique and multiplex PCR methods. E. coli O157 and E. coli O157:H7 were detected in 52 of the 200 samples (26%) tested. Of the positive samples, 49 were E. coli O157 and three were E. coli O157:H7. The E. coli O157 strain was isolated from 24 carcasses and 25 rectal samples, while E. coli O157:H7 was isolated from two carcasses and one rectal sample. Of the 49 samples positive for E. coli O157, 32 were from the rectal and carcass samples of the same animal, while two E. coli O157:H7 isolates were obtained from rectal swabs and carcasses of the same animal. The stx1 and stx2 genes were both detected in 35 E. coli O157 isolates and one E. coli O157:H7 isolate, but the stx2 gene was only detected alone in two E. coli O157 isolates. Overall, 16 carcasses tested positive for E. coli O157 and one carcass tested positive for E. coli O157:H7 based on both carcass and rectal samples. Overall, the results of this study indicate that cattle carcasses pose a potential risk to human health due to contamination by E. coli O157 and E. coli O157:H7 in the feces.     

金黄色葡萄球菌及其肠毒素等指标在发酵牛肉加工过程中变化规律的研究

作者对自然状态发酵牛肉、接种金黄色葡萄球菌的发酵牛肉和接种发酵剂(植物乳杆菌、戊糖片球菌)与金黄色葡萄球菌的发酵牛肉中金黄色葡萄球菌及其肠毒素等指标在加工过程中的变化规律做了研究。研究结果表明,自然发酵牛肉中没有金黄色葡萄球菌及其肠毒素;接种发酵剂和金黄色葡萄球菌的发酵牛肉中金黄色葡萄球菌先是上升然后快速下降,且金黄色葡萄球菌肠毒素为阴性;接种金黄色葡萄球菌的发酵牛肉中金黄色葡萄球菌及其肠毒素都显著高于接种发酵剂的发酵牛肉(P＜0.05)。由试验结果可知,发酵剂植物乳杆菌和戊糖片球菌对金黄色葡萄球菌有很强的抑制作用。     

Effect of heat killed Mycobacterium phlei on body weight gain and management of caecal coccidiosis in broiler chickens

The objective of this study was to evaluate the immunotherapeutic potential of heat killed Mycobacterium phlei in broiler chicken against experimentally produced Eimeria tenella infection. The selected dose of E. tenella oocyst (5 × 10³ sporulated oocysts per bird) was capable of producing a mild form of caecal coccidiosis as observed by significant difference in body weight gain, clinical findings and caecal lesion score. Heat killed M. phlei was fed orally at 10 mg per bird with sterile PBS vehicle at alternate day for four doses. Our study reveals that per day body weight gain was significantly (p < 0.01) higher for healthy control compared to coccidia infected group. The group fed M. phlei along with coccidial challenge showed significantly (p < 0.05) higher body weight gain than infected control group. Heat killed M. phlei feeding also found effective to reduce the caecal lesion score significantly (p < 0.05) in comparison to E. tenella infected untreated group. IgA concentrations in serum and bile at 7-day post challenge of coccidial oocyst was also significantly (p < 0.01) higher in M. phlei fed group when compared to coccidia infected and healthy control group. We concluded that use of heat killed M. phlei has a beneficial role as an immunostimulant against caecal coccidiosis in broiler chicken.     

Naturally acquired attaching and effacing Escherichia coli in sheep

In a series of experiments involving the inoculation of sheep with Escherichia coli O157:H7, and subsequent detailed histopathological examination of the intestinal mucosa, attaching-effacing (AE) lesions formed by elements of the natural flora were observed in 18% of animals. These incidental AE lesions typically were small and sparse, and were not associated with clinical disease. It was possible to identify further some of the lesional bacteria, revealing that E. coli O115 had formed lesions in one of the seven affected animals, and similarly E. coli O26 had formed some of the lesions in another. As AE strains, source flocks, housing and feed sources were diverse, a common source of lesion-forming bacteria appears to be unlikely. It is postulated that subclinical AE lesions are a mechanism of persistence of AE bacteria in sheep.     

A health evaluation in a colony of captive collared peccaries (Tayassu tajacu) in the Eastern Amazon

This study pretends to determine baseline data on the health and mortality of a colony of captive collared peccaries in the Eastern Amazon (Belém, State of Pará, Brazil) during a 65-months survey. Thirty-nine out of 166 animals (23.5%) died and were examined post-mortem. Monthly mortality averaged 1.2%. The highest mortality rate was observed in newborns (74.4%). Abandonment by the mother and aggression were responsible for 24.1% and 13.8% of the total newborn deaths, respectively. Most frequent causes of non-neonatal death were food poisoning (50.0%) due to an episode of accidental bitter cassava leaves ingestion and traumatism due to aggressions between animals (10.0%). Results from serology for different infectious diseases showed that 4.9% (2/41) collared peccaries had antibodies against Brucella spp. and 9.8% (4/41) animals had antibodies to two different Leptospira spp. serovars, butembo and autumnalis. This is the first survey of morbidity and mortality in captive collared peccaries in the Amazon region.     

Immunoregulatory effects of Taishan Pinus massoniana pollen polysaccharide on chicks co-infected with avian leukosis virus and Bordetella avium early in ovo

In recent years, co-infection of chicken embryos with immunosuppressive viruses and bacteria occurs with an annually increasing frequency. Consequently, studies on new and safe immunoregulators, especially plant polysaccharides, have become a popular topic in the poultry industry. In the present study, we selected 300 specific pathogen free embryonated eggs, which were injected with subgroup B avian leukosis virus (ALV-B) and Bordetella avium (B. avium) to establish an artificial co-infection model. The chicks that hatched from these co-infected embryonated eggs were treated with Taishan Pinus massoniana pollen polysaccharide (TPPPS). Results indicated that relevant indices in the co-infection group were significantly lower than that in B. avium-only group. Furthermore, pathogenicity of B. avium was exacerbated, with the chicks exhibiting decreased body weights. The TPPPS groups exhibited gradual improvements in immune function and developmental status. Therefore, in terms of improving immunologic function and production performance, TPPPS could be used as immunoregulator for immune responses.     

新疆某猪场不同生长期的猪源大肠杆菌对抗生素耐药性调查

为了调查新疆某规模化养猪场不同生长期的猪源大肠杆菌对临床常用抗生素的耐药情况,从该猪场分别采集育肥猪、妊娠猪、保育猪和哺乳猪的粪样。试验采用微量肉汤稀释法,对从粪样中分离出的大肠杆菌进行最小抑菌浓度测定。结果显示,育肥猪、妊娠猪、保育猪和哺乳猪源大肠杆菌分离率分别为85.2%、83.0%、81.0%和83.0%。不同生长期的猪源大肠杆菌均对氨苄西林和阿莫西林/克拉维酸2种抗生素高度耐药,对头孢噻呋都较为敏感。哺乳猪和保育猪源大肠杆菌耐药情况严重,对多种抗生素高度耐药,以5耐为主;妊娠猪源大肠杆菌轻度耐药,以0耐为主;育肥猪源大肠杆菌以3耐为主。不同生长期的猪源大肠杆菌对临床常用抗菌药物的耐药程度不同。     

Ethanolic extract of Azadirachta indica (A. Juss.) causing apoptosis by ROS upregulation in Dirofilaria immitis microfilaria

Dirofilaria immitis is the causative agent of cardiopulmonary dirofilariasis in the Canine family. The aim of the study was to evaluate the efficacy of the ethanolic extract of Azadirachta indica leaves (EEA) against the microfilaria (mf) of D. immitis in vitro. EEA was evaluated for different compound classes through HPTLC. Relative motility, mortality and morphological alterations were observed in the mf after exposure to EEA. The effect of EEA on redox status in the treated mf was evaluated by some key enzymatic and non-enzymatic parameters. An enhanced reactive oxygen species (ROS) level in the treated mf along with altered redox status was evident. DNA fragmentation and terminal-deoxynucleotidyl-transferase dUTP nick end labeling (TUNEL) confirmed apoptosis. In addition, western blotting revealed down-regulation of anti-apoptotic protein and up-regulation of pro-apoptotic proteins. Taken together, the microfilaricidal activity of EEA can be attributed to its capacity to inflict oxidative stress culminating in apoptosis.