Domestic Cats Constitute a Natural Reservoir of Human Enteropathogenic Escherichia coli Types

Feces of 70 diarrhoeic and 230 non‐diarrhoeic domestic cats from São Paulo, Brazil were investigated for enteropathogenic (EPEC), enterohaemorrhagic (EHEC) and enterotoxigenic (ETEC) Escherichia coli types. While ETEC and EHEC strains were not found, 15 EPEC strains were isolated from 14 cats, of which 13 were non‐diarrhoeic, and one diarrhoeic. None of 15 EPEC strains carried the bfpA gene or the EPEC adherence factor plasmid, indicating atypical EPEC types. The EPEC strains were heterogeneous with regard to intimin types, such as eae‐θ (three strains), eae‐κ (n = 3), eae‐α1 (n = 2), eae‐ι (n = 2), one eae‐α2, eae‐β1 and eae‐η each, and two were not typeable. The majority of the EPEC isolates adhered to HEp‐2 cells in a localized adherence‐like pattern and were positive for fluorescence actin staining. The EPEC strains belonged to 12 different serotypes, including O111:H25 and O125:H6, which are known to be pathogens in humans. Multi locus sequence typing revealed a close genetic similarity between the O111:H25 and O125:H6 strains from cats, dogs and humans. Our results show that domestic cats are colonized by EPEC, including serotypes previously described as human pathogens. As these EPEC strains are also isolated from humans, a cycle of mutual infection by EPEC between cats and its households cannot be ruled out, though the transmission dynamics among the reservoirs are not yet understood clearly.     

Characterization of atypical Enteropathogenic Escherichia coli (aEPEC) isolated from dogs

Enteropathogenic Escherichia coli (EPEC), an important human pathogen has the ability to form attaching and effacing lesions on the intestinal epithelium and has been isolated from a wide range of species. Two EPEC subgroups are recognized: typical (tEPEC) and atypical (aEPEC) strains, differing by the presence of EAF plasmid and bundle-forming pilus (BFP) in typical strains and their absence in atypical strains. This study searched the presence of EPEC strains in 101 fecal samples of diarrheic (n=65) and non-diarrheic (n=36) dogs from two cities in Rio de Janeiro State, Brazil. The isolates were evaluated for the presence of eae, tir, espA, espB and bfpA genes, EAF plasmid, and for the insertion site of the LEE locus. Cell-adherence assays, fluorescent actin staining (FAS) test, hemolysin production and serotyping were also performed. Twenty eight aEPEC isolates were recovered from 48 eae-positive fecal samples, 24 from diarrheic animals and 4 from non-diarrheic ones. PCR showed that most isolates was positive for β or γ intimin, and for β or α subtypes of tir, espA and espB. Six isolates showed a selC insertion of locus LEE. Only two isolates from the same diarrheic animal harbored the bfpA gene, and none presented the EAF plasmid. Most isolates was FAS-positive and showed a localized adherence-like (LAL) in a 6h HeLa cell-adherence assay. A wide diversity of serotypes was detected including O4:H16 and O51:H40, previously described in human disease. The phenotypic and genotypic markers of aEPEC isolated from diarrheic and non-diarrheic dogs were similar to those found in isolates recovered from human disease.     

犊牛大肠杆菌病病原的分离鉴定

从陕西杨凌某发病牛场采取腹泻犊牛病料5份,经微生物学诊断,从中分离出革兰阴性疑似致病菌6株。经生物学特性和生理生化试验鉴定,6株分离菌均为致病性大肠埃希菌。对分离菌进行抗生素敏感性试验,结果表明,该致病菌对氯霉素、菌必治、氧氟沙星、阿米卡星及卡那霉素等高度敏感;对妥布霉素、呋喃妥因和复达欣等中度敏感,对链霉素、庆大霉素、利福平、复方新诺明、四环素及红霉素等有较强的耐药性。动物致病性试验结果表明,该菌对小鼠有强致病性。     

Effect of Enteropathogenic Escherichia coli Infection on the Transmembrane Potential of the Swine Intestine

Transmural potential difference and short-circuit current were measured on membranes of swine small intestine as an index of transport activity for sodium ion. The measurements were made in vitro on membranes prepared from control and E. coli 0138-infected intestinal loops from weanling pigs. Measurements were made on duodenal and upper, middle and lower jejunal segments.

No differences were noted in the transmembrane potential difference and the short-circuit current between the control and the experimentally infected loops.

     

一例牛病毒性腹泻病毒与大肠杆菌混合感染的实验室诊断

为查明贵阳市某养牛场犊牛发病死亡的病因,采集2头病死犊牛的病料进行细菌分离培养鉴定、药敏试验,以及牛支原体、病毒性腹泻病毒核酸检测.结果:分离细菌为革兰氏阴性短杆菌,16S rDNA测序分析鉴定为大肠杆菌,药敏试验显示其对硫酸安普霉素、硫酸粘菌素高度敏感;牛病毒性腹泻病毒核酸检测为阳性,牛支原体核酸检测为阴性.结论:诊...     

宁夏地区犊牛腹泻型产ESBLs大肠埃希氏菌的筛选及相关基因型分析

旨在明确宁夏地区犊牛腹泻型产ESBLs大肠埃希氏菌的阳性率及相关基因型的携带情况。采集犊牛腹泻样本180份,采用麦康凯培养基和伊红美蓝培养基进行筛选,疑似大肠埃希氏菌的菌株进行PCR鉴定,用ESBLs表型检测方法进行产ESBLs菌株的筛选,用PCR进行相关基因的检测。结果显示,共鉴定出大肠埃希氏菌74份,51株为产ESBLs菌株,检出率为68.92%(51/74),其中bla-TEM、bla-CTX、bla-CTX-M-9基因阳性率均为100%,bla-OXA基因阳性率为50.98%,bla-SHV基因阳性率为23.53%。分离株携带CTX+CTX-M-1+CTX-M-9+TEM基因的菌株占比最高,为21.57%。结果表明,优势基因型为bla-TEM、bla-CTX和bla-CTX-M-9。     

Characterization of Necrotoxigenic Escherichia coli (NTEC) Strains Isolated from Healthy Calves in Poland

Faecal samples from 132 healthy, 4–8‐week‐old calves from four different farms were examined for necrotoxigenic Escherichia coli (NTEC) producing the cytotoxic necrotizing factors type 1 (CNF1) and type 2 (CNF2). CNF2 genes were detected by polymerase chain reaction in 24 (6.1%) of the 396 E. coli strains tested; these strains were found in 18 (13.6%) calves used in the study. None of the 396 E. coli isolates examined possessed the gene encoding CNF1. Overall, 28.8% of E. coli examined expressed the F17 fimbrial antigen. A strong association between CNF2 toxin and F17 fimbriae was found (62.5% of CNF2‐positive strains were F17‐positive). Moreover, six out of 24 NTEC strains had the Stx1 or the Stx2 shiga toxin genes, and three additional isolates possessed the eae genetic marker of the intimin protein.     

蟾酥注射液对仔猪人工感染致病性大肠杆菌的保护作用试验

为探讨蟾酥注射液对仔猪致病性大肠杆菌感染的保护作用及其与免疫功能的关系,按体重给仔猪肌肉注射高(0.2 m L/kg),中(0.1 m L/kg),低(0.05 m L/kg)三种剂量的蟾酥注射液,每天1次,连用3 d;用穿心莲注射液(0.2 m L/kg)作为药物对照组。第4天用致病性大肠杆菌进行攻毒(肌肉注射3×109CFU/m L×4.0 m L),观察仔猪腹泻情况及测定外周血T淋巴细胞亚群的变化。结果显示,高、中剂量蟾酥注射液对人工感染猪致病性大肠杆菌具有保护作用,与穿心莲注射液对照组相似,但低剂量组效果稍差。不同剂量的蟾酥注射液在用药后对T淋巴细胞阳性率及猪CD4+细胞增殖均有显著的促进作用。结论:蟾酥注射液能增强猪的非特异性免疫功能,尤其是细胞免疫功能,对猪致病性大肠杆菌感染具有保护作用。     

复方诃子口服液抗犊牛大肠杆菌性腹泻的药理作用研究

试验旨在研究抗犊牛大肠杆菌性腹泻的复方诃子口服液的药理作用,采用中和毒素试验、抗渗出试验、解热试验、镇痛试验、肠蠕动试验及免疫调节试验的方法,验证复方诃子口服液的药理作用。结果显示,抗毒素中和试验中,复方诃子口服液组与阴性对照组差异极显著(P<0.01)。抗渗出试验中,各药物组均能不同程度地减少伊文思蓝的渗出,阿司匹林组及复方诃子口服液高、中、低剂量组的抑制率分别为58.1%、42.8%、31.6%和14.9%,其中复方诃子口服液低剂量组与空白组相比差异显著(P<0.05),其余各组与空白组相比均差异极显著(P<0.01);复方诃子口服液各剂量组与阿司匹林组相比,高剂量组差异不显著(P>0.05),中、低剂量组差异极显著(P<0.01)。解热试验中,复方诃子口服液高剂量组给药后1h快速抑制体温升高,中剂量组给药后2h抑制体温升高;给药后3h,与模型组相比,复方诃子口服液高、中剂量组体温均明显降低,低剂量组与模型组差异不明显。镇痛试验中,与空白组相比,阿司匹林组、复方诃子口服液高、中剂量组镇痛效果差异极显著(P<0.01),扭体抑制率分别为64.55%、52.73%和32.73%,疼痛潜伏期分别为9.59、6.33和5.74min;而复方诃子口服液低剂量组差异不显著(P>0.05)。肠蠕动试验中,与空白组相比,硫酸阿托品组及复方诃子口服液高剂量组对肠蠕动抑制作用差异极显著(P<0.01),推进率分别为44.18%和52.55%,复方诃子口服液中剂量组差异显著(P<0.05),低剂量组差异不显著(P>0.05)。免疫调节试验中,与空白组相比,模型组白细胞数、脾脏指数及胸腺指数均显著降低(P<0.05);而与模型组相比,第14天复方诃子口服液组白细胞数、脾脏指数及胸腺指数均显著提高(P<0.05)。综上所述,复方诃子口服液对犊牛大肠杆菌性腹泻具有抑制肠蠕动、解热、抗疼痛和组织液渗出、中和肠毒素及增强免疫功能等药理作用。     

犊牛大肠杆菌病的诊治

2010年5月,黑龙江省双城市某乡先后有3位畜主来我院对其所养的5头犊牛发病情况进行就诊。通过询问得知,这几头犊牛基本都是刚出生半个月左右。病犊发热,精神沉郁或昏迷。间有腹泻,有2头死前发生腹泻,并有明显的脖颈扭转现象。另外2头犊牛发病初期排出黄色粥样粪便,后期排灰白色水样粪     

犊牛球虫病的诊断和治疗

球虫病是由艾美耳属的球虫寄生于牛的肠道内所引起的一种寄生虫疾病，多发生于犊牛和育成牛阶段。以急性或慢性出血性肠炎为主要特征，临床表现贫血、消瘦租血痢等症状，常呈季节性地方性流行或散在发生。     

犊牛大肠杆菌病的诊治

犊，羔大肠杆菌病又名大肠杆菌性腹泻，或犊，羔白痢，是由致病性大肠杆菌引起的一种新生幼畜的急性传染病，常见于世界各地的牧区和集约化饲的畜群，其特征为败血症的剧烈的腹泻，导致严重脱水，本病可引起幼畜大量死亡或发育不良。     

Detection of Shiga Toxin‐Producing Escherichia coli and Enteropathogenic Escherichia coli in Faecal Samples of Healthy Mithun (Bos frontalis) by Multiplex Polymerase Chain Reaction

Faecal samples obtained from 190 healthy mithuns were examined for the presence of Escherichia coli. Total one‐hundred and five E. coli isolates were obtained from these samples, which belonged to 55 different serogroups. These isolates were subjected to multiplex polymerase chain reaction (m‐PCR) for detection of stx1, stx2, eaeA and hlyA genes. Twenty‐three (21.90%) E. coli isolates belonging to 14 serogroups revealed the presence of at least one virulence gene when examined by m‐PCR. Nineteen percent and 2.85% of the mithuns were found to carry Shiga toxin‐producing E. coli (STEC) and enteropathogenic E. coli, respectively. stx1 and stx2 genes were found to be prevalent in 7 (6.67%) and 18 (17.14%) of the isolates respectively, whereas eaeA and hlyA genes were found to be carried by three (2.85% each) isolates. Interestingly, none of the STEC isolates belonged to serogroup O157.     

Studies on the Mechanism of Diarrhoea Induced by Escherichia coli Heat-Stable Enterotoxin (STa) in Newborn Calves

Enterotoxigenic Escherichia coli (ETEC) produces a heat-stable enterotoxin (STa) that binds to and activates a putative intestinal receptor, guanylate cyclase, causing an increase in the intracellular levels of cyclic guanosine monophosphate (cGMP). Using flow cytometry and ¹²⁵I-STa binding assays, we studied the distribution of STa-receptors on enterocytes isolated from different segments of the newborn calf's intestinal tract. We also investigated the effect of STa on the intracellular levels of cGMP and ion transport to the intestinal lumen. More STa-receptors were found on enterocytes prepared from the ileum than on enterocytes obtained from the other segments of the intestinal tract. Guanylate cyclase activity was higher in the ileum of STa-challenged calves than in the ileum of control calves. No changes were observed in the guanylate cyclase activity of the other intestinal segments of the STa-challenged and control calves. Na⁺ levels, as measured by atomic absorption spectroscopy, were significantly increased in the luminal contents of the ileum of STa-challenged calves, whereas serum Cl^– levels were significantly lower in the STa-challenged calves than in control calves. This study supports previous observations on the role of guanylate cyclase in the initiation of STa-induced secretory diarrhoea and suggests that Na⁺/Cl^– coupling may be the major mechanism for the loss of ions in the diarrhoeal response that is mostly induced in the ileum of newborn calves.