Biodegradation of estrogens in stream water

Estrogens of human and animal origin that reach the aquatic environment may enter human or animal organism and act as endocrine disruptors.To investigate the persistency of estrogens in laboratory experiments, estrone respectively 17beta-estradiol were added to stream water sampled from river Spree in Berlin. The concentration of estrone and 17beta-estradiol was quantified using enzyme-immuno-assay. The estrone concentration decreased to less than 5 % of the starting concentration at storage temperature of 5 degrees C within 56 days and at storage temperature of 20 degrees C within 14 days. If the estrone were added to autoclaved stream water, no biodegradation was observed. Biodegradation was enhanced when activated sludge was added. Escherichia coli, Pseudomonas fluorenscens and Aeromonas hydrophila in monoculture did not degrade estrone in autoclaved stream water.The concentrations of 17beta-estradiol and estrone decreased similarly.The logistic function proved to be suitable to describe the course of time for the decrease of concentration.     

丁酸梭菌对致病菌和有益菌的体外作用效果研究

试验研究了丁酸梭菌在体外对致病菌的抑制作用和对有益菌的增殖作用。将丁酸梭菌分别与大肠杆菌、沙门氏菌、产气荚膜梭菌、乳酸杆菌、双歧杆菌按不同的比例混合后进行培养,并与菌种单独培养进行比较。结果表明:培养36～48 h,联合培养组大肠杆菌、沙门氏菌、产气荚膜梭菌菌数均显著低于单独培养组;菌数比例为(1～100)∶1至100∶1时,丁酸梭菌对沙门氏菌均有较强的抑菌作用;菌数比例为100∶1时,丁酸梭菌对大肠杆菌和产气荚膜梭菌抑菌作用较强;菌数比例为10∶1时,丁酸梭菌对乳酸杆菌和双歧杆菌的增殖效果最好。联合培养8 h后,菌数比例为10∶1时,丁酸梭菌对双歧杆菌有显著的增殖效果。     

Protection of the nursing pig against experimentally induced enteric colibacillosis by vaccination of dam with fimbrial antigens of E coli (K88, K99 and 987P)

Pregnant gilts were vaccinated with two doses of alhydrogel adsorbed fimbrial antigens of Escherichia coli (K88ab, K88ac, K99 and 987P) supplemented with beta toxoid of Clostridium perfringens type C. Their piglets, and piglets of nonvaccinated gilts, were subsequently orogastrically challenged with one or other of the four fimbrial types of enteropathogenic E coli. Some of the vaccinated animals were reinjected with a single dose of the vaccine during second gestation and their piglets, and piglets of non-vaccinated sows, were challenged the same way as were litters of gilts. Blood serum and colostra were examined for antibodies to the four fimbrial antigens of E coli and for antitoxin to beta toxin of C perfringens type C. It was found that: (1) a highly significant reduction in mortality and morbidity was achieved in vaccinated litters against all four challenge strains of E coli; (2) excretion of K88ab and K88ac but not of K99 and 987P challenge strains was significantly reduced; (3) revaccination of sows by a single dose of the vaccine during second gestation conferred complete protection against mortality and highly significant protection against morbidity; (4) no correlation was noted between colostral or seroagglutinins to fimbrial antigens of E coli and mortality rates in litters challenged with homologous fimbrial types of E coli, but good correlation was found between colostral precipitins to K88 antigens and mortality rates in litters; (5) antitoxin value in 97 per cent of colostrum of vaccinated sows was 10 iu equivalent of C perfringens type C toxin or more per ml of colostrum.     

Survival of clostridium perfringens during simulated transport and stability of some plasmid-borne toxin genes under aerobic conditions

Clostridium perfringens is a pathogen of great concern in veterinary medicine, because it causes enteric diseases and different types of toxaemias in domesticated animals. It is important that bacteria in tissue samples, which have been collected in the field, survive and for the classification of C. perfringens into the correct toxin group, it is crucial that plasmid-borne genes are not lost during transportation or in the diagnostic laboratory. The objectives of this study were to investigate the survival of C. perfringens in a simulated transport of field samples and to determine the stability of the plasmid-borne toxin genes cpb1 and etx after storage at room temperature and at 4 degrees C. Stability of the plasmid-borne genes cpb1 and etx of C. perfringens CCUG 2035, and cpb2 from C. perfringens CIP 106526, JF 2255 and 6 field isolates in aerobic atmosphere was also studied. Survival of C. perfringens was similar in all experiments. The cpbl and etx genes were detected in all isolates from samples stored either at room temperature or at 4 degrees C for 24-44 h. Repeated aerobic treatment of C. perfringens CCUG 2035 and CIP 106526 did not result in the loss of the plasmid-borne genes cpb1, cpb2 or etx. Plasmid-borne genes in C. perfringens were found to be more stable than generally reported. Therefore, C. perfringens toxinotyping by PCR can be performed reliably, as the risk of plasmid loss seems to be a minor problem.     

Effect of Eimeria tenella infection on the caecal population of lincomycin-resistant Clostridium perfringens introduced into chickens

The effect of Eimeria tenella infection on the caecal population of lincomycin-resistant Clostridium perfringens (KGW 851) newly introduced into chickens was studied. Four groups of chickens consisted of: (1) Uninoculated controls; (2) inoculated with C perfringens (KGW 851); (3) inoculated with E tenella; and (4) inoculated with C perfringens (KGW 851) followed by E tenella. Five chickens in each group were necropsied on each of days 0, 3, 5, 7, 10 and 14 after the E tenella inoculation. The mean total C perfringens counts in the caecal contents increased at five days after E tenella inoculation and reached maximum counts at seven days after the inoculation. Also lincomycin-resistant C perfringens readily established itself at approximately one 10th of the total C perfringens population in the presence or absence of E tenella infection.     

Coccidia-induced mucogenesis promotes the onset of necrotic enteritis by supporting Clostridium perfringens growth

This study tested the hypothesis that a host mucogenic response to an intestinal coccidial infection promotes the onset of necrotic enteritis (NE). A chick NE model was used in which birds were inoculated with Eimeria acervulina and E. maxima and subsequently with Clostridium perfringens (EAM/CP). A second group of EAM/CP-infected birds was treated with the ionophore narasin (NAR/EAM/CP). These groups were compared to birds that were either non-infected (NIF), or infected only with E. acervulina and E. maxima (EAM), or C. perfringens (CP). The impact of intestinal coccidial infection and anti-coccidial treatment on host immune responses and microbial community structure were evaluated with histochemical-, cultivation- and molecular-based techniques. Barrier function was compromised in EAM/CP-infected birds as indicated by elevated CFUs for anaerobic bacteria and C. perfringens in the spleen when compared to NIF controls at day 20, with a subsequent increase in intestinal NE lesions and mortality at day 22. These results correlate positively with a host inflammatory response as evidenced by increased ileal interleukin (IL)-4, IL-10 and IFN-gamma RNA expression. Concurrent increases in chicken intestinal mucin RNA expression, and goblet cell number and theca size indicate that EAM/CP induced an intestinal mucogenic response. Correspondingly, the growth of mucolytic bacteria and C. perfringens as well as alpha toxin production was greatest in EAM/CP-infected birds. The ionophore narasin, which directly eliminates coccidia, reduced goblet cell theca size, IL-10 and IFN-gamma expression, the growth of mucolytic bacteria including C. perfringens, coccidial and NE lesions and mortality in birds that were co-infected with coccidia and C. perfringens. Collectively the data support the hypothesis that coccidial infection induces a host mucogenic response providing a growth advantage to C. perfringens, the causative agent of NE.     

携带非典型cpb2基因牛源A型产气荚膜梭菌重组α毒素的免疫保护性研究

为验证重组α毒素对携带非典型cpb2基因的A型产气荚膜梭菌的免疫保护性,本研究应用PCR技术,从某牛场牛源A型产气荚膜梭菌G1分离株中扩增出1 194 bp的α毒素编码基因(cpa)和795 bp的β2毒素编码基因(cpb2)。经BLAST分析显示,G1分离株携带的cpb2基因与14个菌株的非典型cpb2基因的氨基酸序列同源性为95.1%～98.9%,与典型cpb2基因(L77695)的氨基酸序列同源性为61.7%。这表明,G1的cpb2基因为非典型cpb2基因。同时分别将cpa和cpb2基因扩增产物克隆于原核表达载体中,构建重组表达质粒pET-a和pET-b2,重组菌经IPTG诱导表达重组蛋白,将其纯化后单独及联合免疫小鼠进行免疫保护试验。结果显示,单独免疫重组α毒素蛋白组以及联合免疫重组β2毒素蛋白组的小鼠,均可以抵抗至少6倍最小致死量(MLD)的G1外毒素(包含α毒素和非典型β2毒素)的攻击,也可以完全抵抗至少6 MLD的G2外毒素(不包含β2毒素)的攻击。表明,重组α毒素蛋白对含有及不含有非典型β2毒素的A型产气荚膜梭菌均具有良好的免疫保护作用。     

Antimicrobial susceptibilities of canine Clostridium difficile and Clostridium perfringens isolates to commonly utilized antimicrobial drugs

Clostridium difficile and Clostridium perfringens are anaerobic, Gram-positive bacilli that are common causes of enteritis and enterotoxemias in both domestic animals and humans. Both organisms have been associated with acute and chronic large and small bowel diarrhea, and acute hemorrhagic diarrheal syndrome in the dog. The objective of this study was to determine the in vitro antimicrobial susceptibilities of canine C. difficile and C. perfringens isolates in an effort to optimize antimicrobial therapy for dogs with clostridial-associated diarrhea. The minimum inhibitory concentrations (MIC) of antibiotics recommended for treating C. difficile (metronidazole, vancomycin) and C. perfringens-associated diarrhea in the dog (ampicillin, erythromycin, metronidazole, tetracycline, tylosin) were determined for 70 canine fecal C. difficile isolates and 131 C. perfringens isolates. All C. difficile isolates tested had an MIC of or=256 microg/ml for both erythromycin and tylosin. A third C. perfringens isolate had an MIC of 32 microg/ml for metronidazole. Based on the results of this study, ampicillin, erythromycin, metronidazole, and tylosin appear to be effective antibiotics for the treatment of C. perfringens-associated diarrhea, although resistant strains do exist. However, because there is limited information regarding breakpoints for veterinary anaerobes, and because intestinal concentrations are not known, in vitro results should be interpreted with caution.     

Necrotizing enteritis in suckling pigs (Clostridium perfringens type C enterotoxemia). II. Toxin formation, heat and drug resistance of Clostridium perfringens strains isolated from suckling pigs and broilers with necrotizing enteritis]

Nineteen Clostridium perfringens Type C strains and ten foreign control strains of subtypes C1, C3, and C4 were tested for their toxin formation and spore resistance to heat. The 19 Type C strains had been isolated from unweaned piglets in the context of necrotising enteritis outbreaks in the GDR. The Clostridium perfringens Type C strains formed beta-toxin, but they failed to form epsilon-toxin or gamma-toxin, alpha-toxin was successfully recorded from 15 of the 19 strains tested from unweaned piglets. The minor-lethal toxin fractions were also tested, with delta-toxin being recorded from all strains, non-alpha-delta-theta-toxin from six, theta-toxin from five, and K-toxin from one. Tests for delta-toxin, lambda-toxin, and mu-toxin were negative. The Clostridium perfringens Type C strains isolated in the GDR from unweaned piglets with necrotising enteritis were, basically, identical with those described in Denmark by von Hogh (1967) with regard to toxin formation. Clostridium perfringens strains cultured in broilers with necrotising enteritis were characterised by regular toxin production in the context of alpha, theta, delta as well as non-alpha-delta-theta. They failed to form beta, epsilon, gamma and lambda, while mu-toxin was formed by them quite irregularly. They, consequently, are Type A strains. Resistance to chloramphenicol and/or oxytetracycline was exhibited by 78.5 per cent of 237 tested Clostridium perfringens strains which had been isolated from unweaned piglets and broilers with necrotosing enteritis. Multiple resistance was recorded from 33.9 per cent. All strains were susceptible to penicillin, nitrofurantoin, and erythromycin.     

Experimental induction of abdominal tympany, abomasitis, and abomasal ulceration by intraruminal inoculation of Clostridium perfringens type A in neonatal calves

The etiologic role of Clostridum perfringens type A in the acute abdominal syndrome characterized by abomasal and rumen tympany, abomasitis, and abomasal ulceration was investigated in neonatal calves. Eight calves, 4 to 12 days old, were inoculated intraruminally with toxigenic C perfringens type A. Before and after C perfringens inoculation, blood samples were collected from all calves for blood gas and serum biochemical analysis and for determination of serum copper concentration; ruminal fluid was obtained for isolation of C perfringens. Calves were monitored daily for clinical signs of the syndrome and, depending on the severity of clinical signs, they were either euthanatized or redosed within 4 to 7 days. After necropsy, specimens obtained from the abomasum and rumen for macroscopic and microscopic examination and for anaerobic bacteriologic culture were processed in routine manner. Intraruminal inoculation of C perfringens type A into healthy calves induced anorexia, depression, bloat, diarrhea, and in some calves, death. Serum copper concentration was within normal range. Necropsy revealed variable degrees of abomasitis, petechial and ecchymotic hemorrhages, and ulcers (ranging from pinpoint to nearly perforate) in the abomasum. Seven of those calves also had multiple trichobezoars in the rumen. These necropsy findings were not seen in calves (controls) given distilled H2O only. In affected calves, acute abdominal syndrome was unrelated to copper deficiency, and C perfringens type A given intraruminally was able to induce clinical signs similar to those of the naturally acquired disease.     

Genotypic and phenotypic characterization of Clostridium perfringens and Clostridium difficile in diarrheic and healthy dogs

The objectives of this study were to examine the potential roles of Clostridium difficile and enterotoxigenic Clostridium perfringens in diarrhea in dogs by comparison of isolation, determination of toxin status via enzyme-linked immunosorbent assay (ELISA), and application of multiplex polymerase chain reaction (PCR). These techniques were used to evaluate fecal specimens in 132 healthy and diarrheic dogs. These dogs were prospectively evaluated by grouping them into the following 3 categories: hospitalized dogs with diarrhea (n = 32), hospitalized dogs without diarrhea (n = 42), and apparently healthy outpatient dogs without diarrhea (n = 58). All fecal specimens were cultured using selective media for C difficile, Salmonella spp., and Campylobacter spp. and selective media after heat shock for C perfringens. No significant difference was found in the isolation of C perfringens or C difficile among the 3 groups. A significant association was found between the presence of diarrhea and detection of C perfringens enterotoxin (CPE) or toxin A via ELISA for both C perfringens and C difficile, respectively. PCR performed on C difficile isolates for toxin A and toxin B genes revealed no significant differences among the 3 groups, but diarrheic dogs were significantly more likely to be positive for the enterotoxin gene of C perfringens. Based on the results of this study, the use of ELISA for detection of CPE in feces combined with the detection of enterotoxigenic fecal isolates obtained via heat shock provides the strongest evidence for the presence of C perfringens-associated diarrhea.     

A role for the Clostridium perfringens beta2 toxin in bovine enterotoxaemia?

Non-enterotoxigenic type A Clostridium perfringens are associated with bovine enterotoxaemia, but the alpha toxin is not regarded as responsible for the production of typical lesions of necrotic and haemorrhagic enteritis. The purpose of this study was to investigate the putative role of the more recently described beta2 toxin. Seven hundred and fourteen non-enterotoxigenic type A C. perfringens isolated from 133 calves with lesions of enterotoxaemia and high clostridial cell counts (study population) and 386 isolated from a control population of 87 calves were tested by a colony hybridisation assay for the beta2 toxin. Two hundred and eighteen (31%) C. perfringens isolated from 83 calves (62%) of the study population and 113 (29%) C. perfringens isolated from 51 calves (59%) of the control population tested positive with the beta2 probe. Pure and mixed cultures of four C. perfringens (one alpha+beta2+, one alpha+enterotoxin+ and two alpha+) were tested in the ligated loop assay in one calf. Macroscopic haemorrhages of the intestinal wall, necrosis and haemorrhages of the intestinal content, and microscopic lesions of necrosis and polymorphonuclear and mononuclear cell infiltration of the intestinal villi were more pronounced in loops inoculated with the alpha and beta2-toxigenic C. perfringens isolate. These results suggest in vivo synergistic role of the alpha and beta2 toxins in the production of necrotic and haemorrhagic lesions of the small intestine in cases of bovine enterotoxaemia. However, isolation of beta2-toxigenic C. perfringens does not confirm the clinical diagnosis of bovine enterotoxaemia and a clostridial cell counts must still be performed.     

Evaluation of in vitro properties of di-tri-octahedral smectite on clostridial toxins and growth

REASONS FOR PERFORMING STUDY: Clostridial colitis and endotoxaemia of intestinal origin are significant causes of morbidity and mortality in horses. Intestinal adsorbents are available for treatment of these conditions; however, little information exists supporting their use. OBJECTIVES: To evaluate the ability of di-tri-octahedral smectite to bind to Clostridium difficile toxins A and B, C. perfringens enterotoxin and endotoxin, inhibit clostridial growth and the actions of metronidazole in vitro. METHODS: Clostridium difficile toxins, C. perfringens enterotoxin and endotoxin were mixed with serial dilutions of di-tri-octahedral smectite, then tested for the presence of clostridial toxins or endotoxin using commercial tests. Serial dilutions of smectite were tested for the ability to inhibit growth of C. perfringens in culture broth, and to interfere with the effect of metronidazole on growth of C. perfringens in culture broth. RESULTS: Clostridium difficile toxins A and B, and C. perfringens enterotoxin were completely bound at dilutions of 1:2 to 1:16. Partial binding of C. difficile toxins occurred at dilutions up to 1:256 while partial binding of C. perfringens enterotoxin occurred up to a dilution of 1:128. Greater than 99% binding of endotoxin occurred with dilutions 1:2 to 1:32. No inhibition of growth of C. difficile or C. perfringens was present at any dilution, and there was no effect on the action of metronidazole. CONCLUSIONS: Di-tri-octahedral smectite possesses the ability to bind C. difficile toxins A and B, C. perfringens enterotoxin and endotoxin in vivo while having no effect on bacterial growth or the action of metronidazole. POTENTIAL RELEVANCE: In vivo studies are required to determine whether di-tri-octahedral smectite might be a useful adjunctive treatment of clostridial colitis and endotoxaemia in horses.     

Role of Coccidia in the occurrence of necrotic enteritis of chickens

Clostridium perfringens type A, Eimeria acervulina, and Eimeria necatrix were used to produce necrotic enteritis in chickens. The disease was produced in all groups of birds that received feed contaminated with C. perfringens. Mortality due to necrotic enteritis was highest (53%) in birds infected with E. acervulina before infection with clostridia. There was a significant difference in mortality rates between birds infected with E. acervulina and birds infected with E. necatrix before infection with C. perfringens. Mortality rates also differed significantly between the group infected with E. necatrix and the group that received only feed contaminated with C. perfringens. It was concluded that under field conditions, coccidia can play a significant role in the occurrence of necrotic enteritis when a sufficient number of toxigenic strain of C. perfringens type A is present. The pathological changes induced by clostridia and coccidia are described.     

Diagnosis of Clostridium perfringens intestinal infections in sheep and goats.

Clostridium perfringens produces enteric diseases, generically called enterotoxemias, in sheep, goats, and other animals. This microorganism can be a normal inhabitant of the intestine of most animal species, including humans, but when the intestinal environment is altered by sudden changes in diet or other factors, C. perfringens proliferates and produces potent toxins that act locally or are absorbed into the general circulation with usually devastating effects on the host. History, clinical signs, and gross postmortem findings are useful tools for establishing a presumptive diagnosis of clostridial enterotoxemia in sheep and goats. Definitive diagnosis requires laboratory confirmation. Isolation of some types of C. perfringens (e.g., B and C) can be of diagnostic value, but other types (e.g., A) are so commonly found in the intestine of normal animals that isolation is meaningless from a diagnostic point of view. The most accepted criterion in establishing a definitive diagnosis of enterotoxemia is detection of C. perfringens toxins in intestinal contents. Also, histopathological examination of brain is very useful for diagnosis of type D disease, as lesions produced by epsilon toxin in the brains of sheep and goats are pathognomonic for type D enterotoxemia. Ancillary tests, such as measuring urine glucose or observing Gram-stained smears of intestinal mucosa, can be used. However, although such tests have a presumptive diagnostic value when positive, they cannot be used to rule out a diagnosis of enterotoxemia when negative.     

Prevalence of Clostridium perfringens in commercial broiler hatcheries.

Clostridium perfringens, a cause of human foodborne and poultry disease, has been isolated from the intestinal tract of poultry and from the processed carcass. Little is known about the incidence and sources of this pathogen in the poultry production environment. To determine if the broiler hatchery is a possible source of C. perfringens, we collected samples from three hatcheries, each operated by a different poultry integrator, and the presence of C. perfringens in these samples was determined. For each sampling period, eggshell fragments, chick fluff from the hatcher, and paper pads stored in the hatchery before use with chicks and after placement beneath chicks for 1 hr were evaluated. Clostridium perfringens was found in eggshell fragments, fluff, and paper pads in each of the three hatcheries. The percentages of C. perfringens-positive samples from the three hatcheries ranged from 13% to 23%, with an overall incidence of 20%. Positive samples were consistently found, i.e., detected on each of the nine sampling days (three sampling days for each of three hatcheries). These results suggest that the hatchery is a potential source/reservoir for C. perfringens in the integrated poultry operation.     

益生菌剂对仔猪肠道菌群的影响

为研究益生菌剂对仔猪肠道菌群的影响,选择60头7.5 kg左右的"杜洛克猪×长白猪×大白猪"原种猪,随机分成2组,每组3个重复,每个重复10头。将仔猪分为试验组和对照组,对照组饲喂基础日粮,试验组饲喂基础日粮+0.1%益生菌剂,检测各组仔猪生产性能及肠道菌群等。试验结果表明,益生菌制剂能显著降低仔猪腹泻率(P<0.05),促进仔猪的生长;大肠杆菌和肠球菌是仔猪肠道非常住菌群(过路菌),乳酸杆菌、双歧杆菌、产气荚膜梭菌为常住菌群;益生菌剂能极显著减少仔猪肠道的好氧菌(P<0.01),极显著增加仔猪肠道的厌氧菌、双歧杆菌和乳酸杆菌(P<0.01),显著降低仔猪肠道的产气荚膜梭菌(P<0.05)。因此,饲料中添加益生菌剂能有效改善仔猪肠道菌群。     

Competitive exclusion by Bacillus subtilis spores of Salmonella enterica serotype Enteritidis and Clostridium perfringens in young chickens

Cost effective control of avian diseases and food borne pathogens remains a high priority for all sectors of the poultry industry with cleansing and disinfection, vaccination and competitive exclusion approaches being used widely. Previous studies showed that Bacillus subtilis PY79(hr) was an effective competitive exclusion agent for use in poultry to control avian pathogenic Escherichia coli serotype O78:K80. Here we report experiments that were undertaken to test the efficacy of B. subtilis PY79(hr) in the control of Salmonella enterica serotype Enteritidis and Clostridium perfringens in young chickens. To do this, 1-day-old and 20-day-old specific pathogen free (SPF) chicks were dosed with a suspension of B. subtilis spores prior to challenge with S. Enteritidis (S1400) and C. perfringens, respectively. For both challenge models, a single oral inoculum of 1x10(9) spores given 24h prior to challenge was sufficient to suppress colonisation and persistence of both S. Enteritidis and C. perfringens. In particular, the faecal shedding of S. Enteritidis, as measured by a semi-quantitative cloacal swabbing technique, was reduced significantly for the 36 days duration of the experiment. B. subtilis persisted in the intestine although with decreasing numbers over the same period. These data add further evidence that B. subtilis spores may be effective agents in the control of avian diseases and food borne pathogens.     

A prospective study of the roles of clostridium difficile and enterotoxigenic Clostridium perfringens in equine diarrhoea

Faecal samples from adult horses and from foals with diarrhoea or with normal faeces were evaluated for the presence of Clostridium difficile, C. difficile toxins, C. perfringens enterotoxin (CPE) and C. perfringens spore counts. Clostridium difficile was isolated from 7/55 horses (12.7%) and 11/31 foals (35.5%) with colitis, but from 1/255 normal adults (0.4%) and 0/47 normal foals (P<0.001). Clostridium difficile toxins A and/or B were detected in 12/55 diarrhoeic adults (21.8%) and 5/30 diarrhoeic foals (16.7%) but in only 1/83 adults (1.2%) and 0/21 foals with normal faeces (P<0.001 and P<0.05, respectively). Clostridium perfringens enterotoxin was detected in 9/47 diarrhoeic adults (19%) and 8/28 diarrhoeic foals (28.6%), but was not detected in 47 adult horses (P<0.002) or 4 foals (P = 0.22) with normal faeces. The positive predictive value of isolation of C. perfringens with respect to the presence of CPE was only 60% in adult horses and 64% in foals. There was no association between total C. perfringens spore count and CPE in the faeces. The overall mortality rate from colitis was 22% for adult horses and 18% for foals. Clostridium difficile toxin-positive adult horses with colitis were less likely to survive than C. difficile-negative horses with colitis (P = 0.03). This study provides further evidence that C. difficile and enterotoxigenic C. perfringens are associated with equine enterocolitis.     

Longitudinal study of Clostridium difficile and antimicrobial susceptibility of Escherichia coli in healthy horses in a community setting

Point prevalence studies have reported carriage rates of enteric pathogens in healthy horses, but longitudinal data are lacking. Commensal E. coli is an indicator organism to evaluate antimicrobial resistance of enteric bacteria, yet there are limited data for horses. The objectives of this study were to investigate and molecularly characterize isolates of Clostridium difficile, Clostridium perfringens and Salmonella, collected sequentially over a one year period, and to determine the antibiotic susceptibility profile for E. coli. Fecal samples were collected monthly from 25 adult horses for one year. Selective cultures were performed for all above bacteria. C. difficile isolates were characterized via PCR toxin gene profiling and ribotyping. Broth microdilution was performed to assess antimicrobial susceptibility profiles of E. coli. Toxigenic Clostridium difficile was isolated from 15/275 (5.45%) samples from 10/25 (40%) horses. Four horses were positive at multiple sampling times but different ribotypes were found in three. Ribotypes included 078 (n=6), 001 (n=6) and C (n=3). C. perfringens was not isolated, nor was Salmonella. E. coli was isolated from 232/300 (77%) fecal samples. Resistance to ≥1 and ≥ 3 antimicrobials was present in 31/232 (13.4%) and 6/232 (2.6%) respectively. Only two horses shed the same strain of toxigenic C. difficile for more than one month, indicating that shedding is transient. The high number of ribotype 078 is consistent with recent emergence of this strain in the local horse population. The low prevalence of antibiotic resistance in commensal E. coli suggests that healthy horses are not likely a major reservoir of resistance for enteric bacteria.