Colostral transfer of Clostridium perfringens type C beta antitoxin in swine

Nine bred gilts were vaccinated with 2 doses of a Clostridium perfringens type C toxoid at a 5-week interval. Time of vaccination during gestation differed among the gilts. Clostridium perfringens beta antitoxin in colostral samples and in serum samples was titrated in mice. Blood was collected from 2 to 5 neonatal pigs from each dam (total = 32 pigs) when the pigs were 36 to 48 hours old. Antitoxin titers in colostrum were 123 to 4.5 IU/ml, indicating considerable variation in individual responses of the gilts to toxoid. Serum titers of neonatal pigs reflected colostrum titers of their dams. This colostrum-to-serum titer correlation was essentially a straight-line fit by least-squares linear regression analysis, establishing a direct proportional relationship between colostrum titers and serum titers of neonatal pigs. In the dams, a correlation was not found between colostral titers and serum titers of blood samples collected 2 weeks after collection of colostrum.     

Genotyping of Clostridium perfringens isolated from domestic and exotic ruminants and swine

Clostridium perfringens types A, B, C, D and E are known to cause severe enteritis/enterotoxaemia and diseases (especially caused by type A) belonging to the gas oedema complex in many species. Samples from the small intestine as well as faeces of domestic and exotic animals suffering from enterotoxaemic signs or having died within days after first occurance of toxaemia were submitted for typing C. perfringens toxovars by multiplex PCR. The following species have been investigated: domestic sheep (Ovis ammon; n = 10), domestic goat (Capra aegagrus hircus; n = 26), Japanese serow (Capricornis sumatraensis; n = 4), lechwe waterbuck (Hydrotragus leche; n = 1), blackbuck (Antilope cervicapra; n = 1), European reindeer (Rangifer tarandus tarandus; n = 4), domestic swine (Sus scrofa; n = 52), and collared peccary (Tayassu albirostris; n = 1). Interestingly, the predominant C. perfringens toxovar in domestic sheep was type A. This toxovar could also be diagnosed in all reindeer, in three Japanese serows, one lechwe waterbuck and most pigs (n = 47), the majority of those being at suckling age. Type D was the most prevalent toxovar (n = 18) in domestic goats, but also types A and E could be identified as pathogens in this species. Type C could only be found in domestic swine (n = 5) and in one case of clostridiosis in a Japanese serow. Two cases of enterotoxaemia in goats, one case in reindeer, and a single case in blackbuck and collared peccary were caused by C. perfringens type E. Genotyping of C. perfringens is recommended before starting vaccination programmes as it could be shown, that the importance of specific toxovars has been underestimated in specific species and/or age groups.     

Pharmacokinetic and pharmacodynamic integration and modelling of marbofloxacin in calves for Mannheimia haemolytica and Pasteurella multocida

The pharmacokinetics (PK) and pharmacodynamics (PD) of marbofloxacin were established in calves for six strains of each of the pneumonia pathogens Mannheimia haemolytica and Pasteurella multocida. The distribution of marbofloxacin into inflamed (exudate) and non-inflamed (transudate) tissue cage fluids allowed comparison with the serum concentration–time profile. To establish the PD profile, minimum inhibitory concentration (MIC) was determined in Mueller–Hinton broth (MHB) and calf serum.Moderately higher MICs were obtained for serum compared to MHB. An initial integration of PK–PD data established C_max/MIC ratios of 45.0 and AUC_24h/MIC values of 174.7 h, based on serum MICs, for both bacterial species. Using bacterial time-kill curves, generated ex vivo for serum marbofloxacin concentrations, PK–PD modelling established three levels of growth inhibition: AUC_24h/MIC ratios for no reduction, 3 log₁₀ and 4 log₁₀ reductions in bacterial count from the initial inoculum count were 41.9, 59.5 and 68.0 h for M. haemolytica and 48.6, 64.9 and 74.8 h for P. multocida, on average respectively. Inter-strain variability for 3 log₁₀ and 4 log₁₀ reductions in bacterial count was smaller for P. multocida than for M. haemolytica. In conjunction with literature data on MIC₉₀ values, the present results allowed prediction of dosages for efficacy for each organism for the three levels of growth inhibition.     

猪魏氏梭菌病诊治与病理组织学观察

本病 8 0年代已在我省零星散发 ,近几年有上升趋势 ,在仔猪和种猪中发生率高于育肥猪。仔猪发病可暴发流行 ,常整窝发病 ,病死率 2 0 %～ 70 % ,种猪和育肥猪呈零星散发 ,病程短或突然死亡 ,病死率很高。1　病原分离与鉴定1 .1　涂片镜检　肠内容物、肝、脾涂片 ,瑞氏染色 ,镜检菌体可见多量两端钝圆的粗大杆菌 ,有荚膜 ,部分菌体中央或近端有芽胞 ,芽胞小于菌体横径 ,多成双排列。1 .2　培养特性与生化试验　病料 80℃水浴15～ 2 0 min后接种于溴甲酚紫牛奶培养基和疱肉基 ,厌氧培养 1 8～ 2 4h。前者表现为产酸、产气、胨化、暴烈发酵 ;后…     

猪A型产气荚膜梭菌病研究

家畜A型产气荚膜梭菌病是我省首先发现的一种多种家畜共患的传染病。目前全国许多省市都有发生。由于该病往往没有任何前驱症状，突然发病死亡，在没有确定该病病原之前，人们通常称之家畜“猝死症”。我省该病最初见于1985年河南周口市某县，当时呈零星散发，患病家畜以犊牛和仔猪为主。近几年来，仔猪对该病的感染率呈上升趋势，为了有效控制该病，笔者曾系统参与了我省A型产气荚膜梭菌病的研究，现将其研究结果报告于后。     

Pharmacokinetic behavior and pharmacokinetic/pharmacodynamic integration of marbofloxacin after subcutaneous administration in goats

The pharmacokinetic behavior of marbofloxacin was studied in goats after single-dose subcutaneous (SC) administration of 2mg/kg bodyweight. Drug concentration in plasma was determined by high performance liquid chromatography and the data obtained were subjected to non-compartmental kinetic analysis. Marbofloxacin peak plasma concentration (C(max)=1.77+/-0.24microg/mL) was reached 1.25+/-0.50h (T(max)) after SC administration. The elimination half-life (t(1/2beta)) and area under curve (AUC) were 5.74+/-1.21h and 8.15 vs 2.33microg h/mL, respectively. Taking into account the values obtained for the efficacy indices, it was concluded that a SC dose of 2mg/kg/24h of marbofloxacin could be adequate to treat infections caused by high susceptible bacteria like Escherichia coli or Salmonella spp.     

Multiplex PCR assay for detection of Clostridium perfringens in feces and intestinal contents of pigs and in swine feed

A multiplex polymerase chain reaction (PCR) assay, developed to detect the alpha-toxin and enterotoxin genes (cpa and cpe, respectively) of Clostridium perfringens, was used to identify enterotoxigenic isolates of this organism from feces and intestinal contents of pigs and from feed samples from pig farms in Iowa. The organism was grown on tryptose-sulfite-cycloserine (TSC) agar, TSC agar without egg-yolk, sheep blood agar, or in brain heart infusion broth or cooked meat medium. DNA was extracted by boiling and the PCR assay was carried out using reagents from a commercial kit. The 319 bp amplification product of cpa and the 364 bp product of cpe were visualized under UV light after electrophoresis in a 2% agarose gel containing ethidium bromide. The average sensitivity of the assay, determined on artificially contaminated feces, was 9.2×10⁴ colony forming units per gram. Assay of 97 isolates from feces and intestinal contents revealed cpa in 89, but all were negative for cpe. While 28% of the 442 total samples cultured yielded C. perfringens, only 5% of 298 fecal or intestinal contents samples were positive upon direct examination by the PCR assay. Ninety-one and eight-tenths % of isolates with the phenotype of C. perfringens were cpa positive by PCR. Forty-three percent of feed samples were culture positive, while 48.3% were PCR positive for cpa. None of these were cpe positive. We conclude that PCR is a useful assay for rapid detection of C. perfringens in feed, and for confirmation of the identity of isolates presumed to be C. perfringens.     

Pharmacokinetic/pharmacodynamic integration and modelling of amoxicillin for the calf pathogens Mannheimia haemolytica and Pasteurella multocida

The antimicrobial properties of amoxicillin were determined for the bovine respiratory tract pathogens, Mannheima haemolytica and Pasteurella multocida. Minimum inhibitory concentration (MIC), minimum bactericidal concentration (MBC) and time‐kill curves were established. Pharmacokinetic (PK)/pharmacodynamic (PD) modelling of the time‐kill data, based on the sigmoidal E_max equation, generated parameters for three levels of efficacy, namely bacteriostatic, bactericidal (3log₁₀ reduction) and 4log₁₀ reduction in bacterial counts. For these levels, mean AUC_(0–24 h)/MIC serum values for M. haemolytica were 29.1, 57.3 and 71.5 h, respectively, and corresponding values for P. multocida were 28.1, 44.9 and 59.5 h. Amoxicillin PK was determined in calf serum, inflamed (exudate) and noninflamed (transudate) tissue cage fluids, after intramuscular administration of a depot formulation at a dosage of 15 mg/kg. Mean residence times were 16.5 (serum), 29.6 (exudate) and 29.0 h (transudate). Based on serum MICs, integration of in vivo PK and in vitro PD data established maximum concentration (C_max)/MIC ratios of 13.9:1 and 25.2:1, area under concentration–time curve (AUC_0–∞)/MIC ratios of 179 and 325 h and T>MIC of 40.3 and 57.6 h for P. multocida and M. haemolytica, respectively. Monte Carlo simulations for a 90% target attainment rate predicted single dose to achieve bacteriostatic and bactericidal actions over 48 h of 17.7 and 28.3 mg/kg (M. haemolytica) and 17.7 and 34.9 mg/kg (P. multocida).     

Pharmacokinetic/pharmacodynamic integration and modelling of oxytetracycline for the porcine pneumonia pathogens Actinobacillus pleuropneumoniae and Pasteurella multocida

Pharmacokinetic–pharmacodynamic (PK/PD) integration and modelling were used to predict dosage schedules of oxytetracycline for two pig pneumonia pathogens, Actinobacillus pleuropneumoniae and Pasteurella multocida. Minimum inhibitory concentration (MIC) and mutant prevention concentration (MPC) were determined in broth and porcine serum. PK/PD integration established ratios of average concentration over 48 h (C_av0–48 h)/MIC of 5.87 and 0.27 μg/mL (P. multocida) and 0.70 and 0.85 μg/mL (A. pleuropneumoniae) for broth and serum MICs, respectively. PK/PD modelling of in vitro time–kill curves established broth and serum breakpoint values for area under curve (AUC_0–24 h)/MIC for three levels of inhibition of growth, bacteriostasis and 3 and 4 log₁₀ reductions in bacterial count. Doses were then predicted for each pathogen, based on Monte Carlo simulations, for: (i) bacteriostatic and bactericidal levels of kill; (ii) 50% and 90% target attainment rates (TAR); and (iii) single dosing and daily dosing at steady‐state. For 90% TAR, predicted daily doses at steady‐state for bactericidal actions were 1123 mg/kg (P. multocida) and 43 mg/kg (A. pleuropneumoniae) based on serum MICs. Lower TARs were predicted from broth MIC data; corresponding dose estimates were 95 mg/kg (P. multocida) and 34 mg/kg (A. pleuropneumoniae).     

Pharmacokinetic/pharmacodynamic integration of cefquinome against Pasteurella Multocida in a piglet tissue cage model

To explore the in vivo antimicrobial activity of cefquinome against Pasteurella multocida in piglets, a piglet tissue cage infection model was used in this study. After the population of P. multocida reached 10⁷ CFU/mL in a tissue cage, piglets received an intramuscular administration of cefquinome at 0.2, 0.4, 0.8, 1, 2, and 4 mg/kg once daily for 3 days. To assess the tissue cage pharmacokinetics (PKTCF) of cefquinome, tissue cage fluid was collected for cefquinome analysis at 1, 3, 6, 9, 12, and 24 hr after each of the 3 daily drug administrations. Bacteria were counted every 24 hr after drug administration and at 48 and 72 hr after the last administration. Evaluation of the relationship between pharmacokinetic/pharmacodynamic (PK/PD) parameters and the antibacterial effect showed that the surrogate of %T > minimum inhibitory concentration (MIC) (R² = 0.981) was the best PK/PD index that correlated with effectiveness of cefquinome against P. multocida. The respective values of %T > MIC required for continuous 1/3‐log, 1/2‐log, and 1‐log reductions were 14.23, 34.45, and 73.44%, respectively, during each 24‐hr treatment period. In conclusion, cefquinome exhibited a potent antibacterial effect against P. multocida. When %T > MIC reached 73.44%, cefquinome exhibited a bactericidal effect against P. multocida after three successive daily administrations.     

Clostridium perfringens type C and Clostridium difficile co-infection in foals

Clostridium perfringens type C is one of the most important agents of enteric disease in newborn foals. Clostridium difficile is now recognized as an important cause of enterocolitis in horses of all ages. While infections by C. perfringens type C or C. difficile are frequently seen, we are not aware of any report describing combined infection by these two microorganisms in foals. We present here five cases of foal enterocolitis associated with C. difficile and C. perfringens type C infection. Five foals between one and seven days of age were submitted for necropsy examination to the California Animal Health and Food Safety Laboratory. The five animals had a clinical history of acute hemorrhagic diarrhea followed by death and none had received antimicrobials or been hospitalized. Postmortem examination revealed hemorrhagic and necrotizing entero-typhlo-colitis. Histologically, the mucosa of the small intestine and colon presented diffuse necrosis and hemorrhage and it was often covered by a pseudomembrane. Thrombosis was observed in submucosal and/or mucosal vessels. Immunohistochemistry of intestinal sections of all foals showed that many large bacilli in the sections were C. perfringens. C. perfringens beta toxin was detected by ELISA in intestinal content of all animals and C. difficile toxin A/B was detected in intestinal content of three animals. C. perfringens (identified as type C by PCR) was isolated from the intestinal content of three foals. C. difficile (typed as A(+)/B(+) by PCR) was isolated from the intestinal content in 3 out of the 5 cases. This report suggests a possible synergism of C. perfringens type C and C. difficile in foal enterocolitis. Because none of the foals had received antibiotic therapy, the predisposing factor, if any, for the C. difficile infection remains undetermined; it is possible that the C. perfringens infection acted as a predisposing factor for C. difficile and/or vice versa. This report also stresses the need to perform a complete diagnostic workup in all cases of foal digestive disease.     

Proposed scheme for isolation and identification of Clostridium perfringens and Clostridium perfringens-like organisms.

The properties of 220 strains of Clostridium perfringens and Clostridium perfringens-like organisms were studied. A scheme was designed for the identification of these strains. The scheme was based on the presence/or absence of lecithinase enzyme, synergestic haemolysis with Streptococcus group B toxin, their inhibition with appropriate antisera and reaction in the lactose gelatin nitrate motility test (LGNM) with the fermentation of a few sugars.