Antimicrobial susceptibility of Clostridium difficile isolated from neonatal pigs with enteritis

The minimum inhibitory concentration (MIC) of eight antimicrobial agents was determined by the agar dilution method for 80 isolates of Clostridium difficile from neonatal pigs with enteritis. MICs(50) for erythromycin, tilmicosin, and tylosin were relatively low (0.25-0.50 microg/mL), but MICs(90) (64 or > or =256 microg/mL) suggest in vivo resistance of a proportion of isolates. Susceptibility to tetracycline varied widely, with MIC(50) and MIC(90) of 8 and 32 microg/mL, respectively. The MICs(90) for tiamulin (8 microg/mL) and virginiamycin (16 microg/mL) suggest moderate susceptibility. Bacitracin and ceftiofur (MICs(90) > or =256 microg/mL) have little activity against C. difficile. Tiamulin and virginiamycin may decrease fecal shedding of C. difficile by sows, and erythromycin, tetracycline, and tylosin may be useful for treatment of infected piglets.     

Nationwide Surveillance Study of Clostridium difficile in Australian Neonatal Pigs Shows High Prevalence and Heterogeneity of PCR Ribotypes

Clostridium difficile is an important enteric pathogen of humans and the cause of diarrhea and enteritis in neonatal pigs. Outside Australia, prevalence in piglets can be up to 73%, with a single PCR ribotype (RT), 078, predominating. We investigated the prevalence and genotype of C. difficile in Australian pig herds. Rectal swabs (n = 229) were collected from piglets aged <7 days from 21 farms across Australia. Selective culture for C. difficile was performed and isolates characterized by PCR for toxin genes and PCR ribotyping. C. difficile was isolated from 52% of samples by direct culture on chromogenic agar and 67% by enrichment culture (P = 0.001). No association between C. difficile recovery or genotype and diarrheic status of either farm or piglets was found. The majority (87%; 130/154) of isolates were toxigenic. Typing revealed 23 different RTs, several of which are known to cause disease in humans, including RT014, which was isolated most commonly (23%; 36/154). RT078 was not detected. This study shows that colonization of Australian neonatal piglets with C. difficile is widespread in the herds sampled.     

Clostridium difficile PCR ribotype 078 toxinotype V found in diarrhoeal pigs identical to isolates from affected humans

In diseased piglets from two Dutch pig-breeding farms with neonatal diarrhoea for more than a year, culture and PCR analyses identified the involved microorganism as Clostridium difficile PCR ribotype 078 harbouring toxin A ( tcdA ) and B ( tcdB ), and binary toxin genes. Isolated strains showed a 39 bp deletion in the tcdC gene and they were ermB gene-negative. A number of 11 porcine and 21 human isolated C. difficile PCR ribotype 078 toxinotype V strains were found genetically related by multiple-locus variable-number tandem-repeat analysis (MLVA). Moreover, a clonal complex was identified, containing both porcine and human isolates. The porcine isolates showed an antimicrobial susceptibility profile overlapping that of isolates from Dutch human patients. On the basis of these pheno- and genotypical analyses results, it was concluded that the strains from affected piglets were indistinguishable from increasingly encountered C. difficile PCR ribotype 078 strains of human C. difficile infections in the Dutch population and that a common origin of animal and humans strains should be considered.     

Qualitative and quantitative comparison of gut bacterial colonization in enterally and parenterally fed neonatal pigs

Total parenteral nutrition (TPN) has been associated with mucosal atrophy, impaired gut barrier function, and translocation of luminal bacteria with resultant sepsis in preterm human infants. Currently, we examined the effects of enteral (ENT) or TPN treatments on translocation events in neonatal pigs and on colonization and composition of microbiota in the neonatal gut. Newborn, colostrum-deprived pigs (<24 hours old) were fitted with intravenous catheters and were fed either ENT (n = 13) or TPN (n = 13) for 7 days. After 7 days of treatment, pigs were euthanized and samples were collected for bacterial culture from the blood, intestinal tract and organs. ENT pigs had increased numbers of bacterial genera isolated, higher concentrations of bacteria (CFU/g), and increased colonization of all segments of the intestinal tract compared to the TPN pigs. Translocation of bacteria from the intestinal tract to tissues or blood was similar (8 of 13) for both groups. The ENT group had 1/13 positive for Clostridium difficile toxin A whereas the TPN group had 5/13. We concluded that ENT favored increased bacterial concentrations comprised of more speciation in the gastrointestinal tract compared to TPN, and that TPN-treated piglets were at higher risk of colonization by toxin-expressing strains of C. difficile.     

The epidemiology of clostridium perfringens type a on Ontario swine farms, with special reference to cpb2-positive isolates

ABSTRACT: BACKGROUND: There is poor understanding of most aspects of Clostridium perfringens type A as a possible cause of neonatal diarrhea in piglets, and the prevalence and types of C. perfringens present on Ontario swine farms is unknown. To study the prevalence of fecal C. perfringens and selected toxin genes, 48 Ontario swine farms were visited between August 2010 and May 2011, and 354 fecal samples were collected from suckling pigs, lactating sows, weanling pigs, grower-finisher pigs, and gestating sows, as well as from manure pits. The fecal samples were cultured quantitatively, and toxin genes were detected by real-time multiplex polymerase chain reaction (PCR). RESULTS: In mixed multivariable linear analysis, log10 C. perfringens in fecal samples from suckling pigs were higher than that of weanling pigs, grower-finisher pigs, and manure pit samples (P <0.05). In mixed multivariable logistic analysis, the C. perfringens isolates recovered from lactating sows (OR = 0.069, P <0.001), gestating sows (OR = 0.020, P <0.001), grower-finishers (OR = 0.017, P <0.001), and manure pits (OR = 0.11, P <0.001) were less likely to be positive for the consensus beta2 toxin gene cpb2 compared to the isolates from suckling pigs. The prevalence of cpb2 in the isolates recovered from weanlings did not differ significantly from suckling pigs. C. perfringens isolates that were positive for cpb2 were more likely to carry the atypical cpb2 gene (atyp-cpb2) (OR = 19, P <0.001) compared to isolates that were negative for cpb2. Multivariable analysis did not identify farm factors affecting the presence of consensus cpb2 and atyp-cpb2 genes. CONCLUSIONS: This study provides baseline data on the prevalence of C. perfringens and associated toxin genes in healthy pigs at different stages of production on Ontario swine farms. The study suggests that if C. perfringens type A are involved in neonatal enteritis, there may be strains with specific characteristics that cannot be identified by the existing genotyping system.     

Perinatal asphyxia pathophysiology in pig and human: a review

In utero fetuses are evidently exposed to several factors that cause an interruption of the oxygen flow through the umbilical cord causing asphyxia leading to hypoxia and metabolic acidosis. These conditions are important causes of intra-partum and neonatal mortality. The main objective of this review is to provide current information regarding the pathophysiology of asphyxia in piglets around parturition; the physiological mechanisms invoked by affected piglets to compensate perinatal hypoxemia are discussed. This review also addresses some similarities and differences of asphyxia between piglets and other mammals, including human neonates. Metabolic acidosis and hypoxia are sequela to asphyxia and can cause profound health effects in postnatal performance because of an abnormal suckling, a reduced absorption of colostrum and inadequate passive transfer of neonatal immunity. Acidosis also cause hypothermia, increased mortality and reduced survival in neonates. One of the first deleterious effects of intrauterine hypoxia is the expulsion of meconium into the amniotic sac leading to meconium staining of the skin, and in severe cases, meconium aspiration into the lungs. Even though there have been technological changes and improvements in husbandry, piglet mortality due to asphyxia remains a major problem. One potential alternative to reduce neonatal mortality in pigs is the monitoring of fetal stress during birth and the implemention of strategies such as the Apgar score, that is often used in human pediatrics. It is also important to consider the physiological, behavioral and biochemical changes that take place during parturition which subsequently impact the vitality, maturity and development of neonatal pigs. Understanding the pathophysiology of fetal hypoxia should help practitioners and farmers implement more effective delivery techniques aimed at reducing neonatal mortality and improving postnatal performance.     

Clostridium perfringens type E enteritis in calves: two cases and a brief review of the literature

Toxigenic types of Clostridium perfringens are important causes of enteric disease in domestic animals, although type E is putatively rare, appearing as an uncommon cause of enterotoxemia of lambs, calves, and rabbits. We report here two geographically distinct cases of type E enterotoxemia in calves, and diagnostic findings which suggest that type E may play a significant role in enteritis of neonatal calves. The cases had many similarities, including a history of diarrhea and sudden death, abomasitis, and hemorrhagic enteritis. In both cases, anaerobic cultures of abomasum yielded heavy growth of C. perfringens genotype E. Four percent of > 1000 strains of C. perfringens from cases of enteritis in domestic animals were type E, and all (n=45) were from neonatal calves with hemorrhagic enteritis. Furthermore, type E isolates represented nearly 50% of all isolates submitted from similar clinical cases in calves. Commercial toxoids available in North America have no label claims for efficacy against type E infections. Consideration should be given to type E-associated enteritis when planning for the health care of calves.     

Detection of the β2 toxin gene of Clostridium perfringens in diarrhoeic piglets in The Netherlands and Switzerland

The two studies presented here were done to determine the prevalence of the alpha, beta, epsilon and enterotoxin genes and the novel beta2 toxin gene of Clostridium perfringens in neonatal or pre-weaned piglets with diarrhoea or necrotic enteritis. All C. perfringens isolates were positive for the alpha and negative for the epsilon and enterotoxin gene, implying that only non-enterotoxigenic type A and C strains were detected. The most important findings were the relatively high prevalence of the beta2 toxin gene in isolates from diarrhoeic piglets in both studies, and, in one of the two studies, absence of strains with only the alpha and beta toxin gene. These data are supportive for the suggestion of a causal relationship of beta2 toxin-producing strains with digestive tract diseases in piglets.     

In utero infection by porcine reproductive and respiratory syndrome virus is sufficient to increase susceptibility of piglets to challenge by Streptococcus suis type II

Porcine reproductive and respiratory syndrome (PRRS) consistently elevates the frequency of disease and mortality in young pigs. Many different secondary bacterial diseases occur in PRRS virus (PRRSV)-infected pigs. However, to date, establishing a reproducible experimental model of PRRSV infection in weaned pigs, with subsequent clinical disease following secondary bacterial challenge, has been difficult. PRRSV is frequently isolated during outbreaks from weak-born piglets affected by secondary bacterial diseases. This study was performed to investigate the potential role of intrauterine PRRSV infection on piglet susceptibility to secondary bacterial infection. PRRSV-free pregnant sows were intranasally infected at 98 days of gestation with PRRSV strain SD 23983. All piglets born to the PRRSV-infected sows were viremic. Piglets were removed from the sows at birth and deprived of colostrum. Piglets from PRRSV-infected and noninfected sows were randomly assigned to Streptococcus suis challenge or control subgroups. At 5 days of age, piglets were challenged intranasally with strain MN 87555 of S. suis type II. Total and differential leukocyte counts were performed on blood samples collected at 3 days of age. The numbers of leukocytes, lymphocytes, and monocytes were significantly reduced in the PRRSV-infected piglets. Lesions were observed in bone marrow, brain, lung, heart, spleen, lymph node, tonsil, and thymus of PRRSV-infected piglets. Thymus/body weight ratios of in utero PRRSV-infected piglets were significantly reduced compared to those of non-PRRSV-infected piglets, and thymic lesions were characterized by severe cortical depletion of thymocytes. Lesions were not observed in piglets born to PRRSV-free sows. Overall, 20 out of 22 piglets in the PRRSV-S. suis dual-infection group died within 1 week after challenge with S. suis (10 of 11 in each of two trials). This contrasts with 1 of 18 piglets in the PRRSV-infection-only group and 5 of 23 piglets in the S. suis-challenge-only group (1 of 12 in trial 1 and 4 of 11 in trial 2). No piglets died in the uninfected control groups. Most of the piglets in the PRRSV-S. suis dual-infection group developed suppurative meningitis. S. suis type II was recovered from their brains and joints. These results indicate that in utero infection by PRRSV makes piglets more susceptible to infection and disease following challenge by S. suis type II. In utero infection by PRRSV may provide a useful model to study the interaction between PRRSV and bacterial coinfections in piglets.     

Infrared thermography – a non-invasive tool to evaluate thermal status of neonatal pigs based on surface temperature

Hypothermia is a major cause of mortality in neonatal pigs. Infrared (IR) thermography is a promising non-invasive method to assess thermal status, but has not been evaluated for use on neonatal pigs from birth. The aim of this study was to evaluate the application of IR thermography as a non-invasive tool to estimate body temperature and assess the thermal status in newborn pigs by (1) estimating the relationship between surface temperature and rectal temperature (RT) in neonatal pigs; and (2) estimating the influence of air temperature (AT), birth weight and the time from birth on the relationship between surface temperature and RT. The method was evaluated on the basis of 1695 thermograms and 915 RTs on 91 neonatal pigs born in loose farrowing pens with floor heating at 34°C, and three different ATs (15°C, 20°C and 25°C). Full-body thermograms of the back and the side of the pigs and RT were acquired at 11 sampling times between birth and 48 h after birth. The maximum (IR_max), minimum, average of the full body and ear minimum IR surface temperatures were derived from the thermograms. IR_max had the highest correlation with RT (0.82) and was therefore used in the statistical analysis. The relation of RT by IR_max depended on time at: 0 h (slope: 0.20°C, P<0.001), 0.25 h (slope: 0.42°C, P<0.01), and 0.5 and 1 h after birth (slope: 0.68°C, P<0.001). After the 1st hour (1.5 to 48 h) the relation of RT by IR_max was no longer affected by time (slope: 0.63°C, P<0.001). The agreement between RT and IR_max was improved (P<0.001) after the 1st hour (RT−IR_max 0 to 1 h: 2.02 (1.44)°C; 1.5 to 48 h: 0.95 (0.85)°C). IR_max below 30°C was indicative of piglets having RT<32°C (91.3%). The location of IR_max was identified predominantly at the base of the ears (27/50), other sites in the region of the head (12/50) and the axilla area (8/50). There was a small but significant effect of the angle as IR_max_side–IR_max_back: mean 0.20°C (P<0.001). On the basis of the low difference between IR_max from back and side view thermograms, and the location of IR_max, the angle seems less important and thus the method has the potential to be used without the need for manual restraint of the pigs. On the basis of the results of this study, we propose that IR_max temperature from full-body thermograms has implication as a valid tool to assess the thermal status in neonatal piglets but not as an identical substitute for RT.     

Bile salts and glycine as cogerminants for Clostridium difficile spores

Spore formation by Clostridium difficile is a significant obstacle to overcoming hospital-acquired C. difficile-associated disease. Spores are resistant to heat, radiation, chemicals, and antibiotics, making a contaminated environment difficult to clean. To cause disease, however, spores must germinate and grow out as vegetative cells. The germination of C. difficile spores has not been examined in detail. In an effort to understand the germination of C. difficile spores, we characterized the response of C. difficile spores to bile. We found that cholate derivatives and the amino acid glycine act as cogerminants. Deoxycholate, a metabolite of cholate produced by the normal intestinal flora, also induced germination of C. difficile spores but prevented the growth of vegetative C. difficile. A model of resistance to C. difficile colonization mediated by the normal bacterial flora is proposed.     

Experimental Infection of Newborn Piglets and Weanling Pigs with Haemolytic E. Coli,Strain A1, Serotype 0149:K91:H10

The first outbreak in Denmark of enteritis in newborn piglets due to infection with E. coli serotype 0149:K91:H10 was demonstrated in the autumn 1966 (Knox & Dam 1970). Since then this serotype has spread rapidly and is to-day responsible for the vast majority of cases of enteric E. eoli infection in newborn piglets, while among pigs at weaning age it occurs with much the same frequency as haemolytic E. coli serotypes 08: K87, 0138:K81, and 0141:K85 ab.     

Porcine enteritis associated with Eimeria spinosa Henry, 1931 infection

Coccidia of the genus Eimeria are present in most pigs raised on dirt in the United States. They are generally considered nonpathogenic in weaned pigs. Oocysts of Eimeria spinosa Henry, 1931 were observed in tissue sections and intestinal contents of a weaned male pig that died suddenly on a farm in Iowa. Microscopically, necrotizing enteritis associated with many thick-walled coccidial oocysts was present in intestinal sections. Examination of intestinal contents demonstrated oocysts that were thick-walled and had small projections on the surface of the oocyst wall, characteristic of E. spinasa Henry, 1931 of swine. Twenty-live oocysts in intestinal contents measured 20.4 by 14.2 microm. No pathogenic bacteria were detected in the pig by culture methods, but lesions suggestive of salmonellosis were observed in some tissues. The specific cause of death was not determined; however, E. spinosa infection was considered to have contributed to the death of this pig. The results suggest that E. spinosa may be pathogenic for pigs.     

人艰难梭菌感染的致病机制与防治策略研究进展

艰难梭菌是一种非常重要的医院感染病原菌,其感染占抗菌素相关腹泻的10．25％,占抗菌素相关肠炎的50．75％,占抗菌素相关伪膜炎的90．100％。而且越来越多的证据表明艰难梭菌的感染与其它疾病,如活性关节炎、婴儿突发性死亡、溶血性尿毒症、坏死性肠炎、希施斯普龙病等有关。更糟糕的是艰难梭菌存在着复发性感染,15—20％的病人在成功治愈后会复发。近年来,随着强毒株的出现,艰难梭菌的感染率和发病率逐年上升,病情也越来越严重,由艰难梭菌感染引起的死亡率也成倍增加。到目前为止,艰难梭菌发病率升高的原因及其致病机制还有待进一步研究。由于艰难梭菌是一种孢子产生菌,对大部分抗菌素都有抗性,目前用于艰难梭菌防治的主要抗菌素甲硝唑和万古霉素的治疗效果也在不断下降,所以正确认识艰难梭菌的感染与流行,进一步了解其致病机制,寻找新的替代疗法已是迫在眉睫。本文对艰难梭菌感染和流行的病因进行了较为全面的分析,对其致病机制进行了深入的总结,并探讨了艰难梭菌防治的最新策略和方法,将有利于更好的认识和研究艰难梭菌,为艰难梭菌的防治提供新思路。     

Behavioural responses of piglets to castration: the effect of piglet age

It has long been assumed that neonatal animals are less sensitive than older animals to pain, and this reasoning has been used to recommend that routine surgical procedures be performed at an early age. In this study we tested if vocal and other behavioural responses to castration increase with piglet age. Piglets (n=84) from 14 litters were assigned to one of six treatment groups: castration or sham castration at 3, 10 or 17 days of age. During the procedure castrated piglets produced high-frequency calls (>1000Hz) at more than three times the rate of piglets in the sham-castrate group. The rate of low-frequency (<1000Hz) calls was also higher for piglets in the castrate group. The rate of high-frequency calling was lower for the youngest pigs but there was no relationship between age and the effect of treatment for any of the vocal responses measured (i.e. no age by treatment interaction). During the first 2h after castration, castrated piglets spent more time sitting or standing and less time lying. During the subsequent 22h, castrated piglets spent marginally more time at the udder and less time lying down. Older piglets missed more nursings. However, the effect of castration did not vary with the age of the piglet for any measure. We conclude that while the factors affecting both the shams and the castrates (e.g. distress due to restraint) may vary with age, the pain of castration is not affected by age within the range of ages that we tested.     

The development of Clostridium difficile genetic systems

Clostridum difficile is a major cause of healthcare-associated disease in the western world, and is particularly prominent in the elderly. Its incidence is rising concomitant with increasing longevity. More effective countermeasures are required. However, the pathogenesis of C. difficile infection is poorly understood. The lack of effective genetic tools is a principal reason for this ignorance. For many years, the only tools available for the transfer of genes into C. difficile have been conjugative transposons, such as Tn916, delivered via filter mating from Bacillus subtilis donors. They insert into a preferred site within the genome. Therefore, they may not be employed for classical mutagenesis studies, but can be employed to modulate gene function through the delivery of antisense RNA. Attempts to develop transformation procedures have so far met with little success. However, in recent years the situation has been dramatically improved through the demonstration of efficient conjugative transfer of both replication-proficient and replication-deficient plasmids from Escherichia coli donors. This efficient transfer can only be achieved in certain strains through negation of the indigenous restriction barrier, and is generally most effective when the plasmid employed is based on the replicon of the C. difficile plasmid, pCD6.     

Udder preference in wild boar piglets

Competition to access the front teats in the domestic pig is strong during the first days of life, despite the fact that the number of piglets is fewer than the number of teats. Preference has been explained in terms of greater milk production (although it might also be the consequence rather than the cause), or reduced risk of crushing when the female lies down to begin a suckling session. Here, with the aim of determining whether one cause might be the body and reproductive modifications caused by artificial breeding, we analysed teat preferences of wild boar piglets in the wild. Fifty-one hunted females in lactation in the Western Iberian Peninsula were analysed. In contrast to domestic pigs, wild boar piglets showed a clear preference for rear udders. This preference was consistent for females of different ages and body characteristics, as well as for females hunted in different seasons. We suggest that the choice of rear udders in the wild boar may be related to the advantages of suckling at places offering higher protection from low temperatures and from predators, in contrast to domestic pigs, for which crushing is the main cause of mortality.     

酶解乳蛋白对初生仔猪小肠组织学结构及隐窝细胞增殖的影响(英文)

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