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1.
Young pigs were exposed to an aerosol of a nonpathogenic strain of Escherichia coli and then were retained in air-pollutant exposure chambers for a 2-hour clearance period. In series 1 (n = 80 pigs), 40 exposed young pigs (principals; 15.5 days of age) were placed in an atmosphere of filtered room air + 50 ppm of atmospheric NH3 during the clearance period; control pigs were exposed to filtered room air without added NH3. In series 2 (n = 24 pigs), 12 exposed young pigs (principals; 6.2 days of age) were similarly maintained, but at a lower concentration of atmospheric NH3 (75 ppm). At the end of the clearance period pigs were killed and pulmonary bacterial clearance was determined. Pigs kept in the NH3-contaminated atmospheres (either concentration) harbored more bacteria, on the average, in their lungs than did the controls. If series 1 and 2 data were combined, pigs kept in the NH3-contaminated atmospheres had 51% more bacteria in their lungs than did the controls. Pulmonic weight and ratio of pulmonic weight to body weight of pigs kept in the NH3-contaminated atmosphere were greater than those of the controls in series 1, but not in series 2. Gross and histopathologic examinations of lung tissue generally revealed no differences between controls and principals in either series 1 or 2.  相似文献   

2.
The influence of pulmonary edema, hydrocortisone, immunization against Pasteurella hemolytica and concurrent infection with parainfluenza-3 virus upon pulmonary clearance of aerosolized P. hemolytica was studied in 31 calves. Following the various treatments calves were challenged with an aerosol of P. hemolytica. One control calf was killed immediately after the aerosol and the numbers of bacteria in the lung taken as 100%. Two calves were killed four hours after challenge and the numbers of bacteria in the lungs were compared to the 100% of the control calf. The result was the percentage clearance of bacteria at four hours.

Pulmonary edema was induced by three different methods: by an aerosol of histamine, by intravenous injection of endotoxin and by intravenous injection of croton oil emulsion. The edema impaired the clearance of P. hemolytica, which was reflected in high numbers of P. hemolytica present in the lungs at four hours after challenge: 260% after histamine, 300% and 400% after endotoxin and 92% after croton oil.

Six days of treatment of four calves with high doses of hydrocortisone acetate produced inconsistent results: two calves treated with a higher daily dose (36 mg/kg) had normal clearance whereas two calves treated with a lower dose had pulmonary edema and displayed lowered clearance with 111% and 31% respectively of P. hemolytica retained in the lungs four hours after challenge.

Immunization of calves by three different methods, a subcutaneously injected bacterin of P. hemolytica (2 calves), single aerosol (2 calves) and four aerosols (4 calves) of live P. hemolytica was reflected in an accelerated pulmonary clearance of P. hemolytica (with a mean of 1.55% of bacteria retained at four hours).

Concurrent infection with parainfluenza-3 virus did not lower the clearance of P. hemolytica in the lungs of 12 calves over 15 days except on the first day following the exposure to parainfluenza-3 virus. These calves had hemagglutinating antibodies against P. hemolytica before exposure.

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3.
The objective of the experimental study was to examine whether aerial ammonia alone could predispose the respiratory system of pigs to infection with toxigenic Pasteurella multocida type A. Two groups of 5 pigs each were continuously exposed to 50 ppm ammonia and less than 5 ppm ammonia, respectively, for a 59-day period (from 37 kg to 90 kg bodyweight) followed by necropsy. In an aerosol chamber all pigs were exposed to an aerosol of toxigenic P. multocida type A (mean bacterial concentration in the aerosol-exposure chamber: 10(5) colony forming units/m3; exposure period: 25 min) at day 10, 21, 35 and 49 after the onset of ammonia exposure. During the experiment none of the pigs showed clinical signs of pneumonia nor did they develop visible distortion of the snout. None of the pigs had gross lesions in the lungs at necropsy and toxigenic P. multocida was not detected by culture from the lungs from any of the pigs. The chance of recovering toxigenic P. multocida from nasal swabs (collected during experiment) was 2-4 times greater in the test group compared to the control group. The average daily weight gain was lower for the ammonia exposed pigs compared to the control group. In conclusion the results from this study suggest that ammonia in concentrations of 50 ppm is unlikely to predispose growing pigs to pulmonary infection with toxigenic P. multocida.  相似文献   

4.
The purpose of this study was to determine if parainfluenza-3 virus in calves interfered with normal pulmonary bacterial clearance. Three groups (A, B and C) of four calves each were exposed to an aerosol of parainfluenza-3 virus. Three days later the four hour pulmonary clearance of Pasteurella hemolytica was determined on the first group (A), seven days later on the second (B) and 11 days later on the third (C). Group A had a mean pulmonary bacterial retention of 3.6 +/- 3.5%. Group B was 83.1 +/- 35.9% and Group C was 41.2 +/- 30.9%. The results demonstrate that parainfluenza-3 virus interfered with the pulmonary bacterial clearance of Pasteurella hemolytica particularly on day 7 and also on day 11 but not on day 3. This inhibition of pulmonary clearance caused by the virus may be a key factor in the pathogenesis of pneumonic pasteurellosis. Histological examination of the lungs did not demonstrate a correlation between pulmonary retention of bacteria and the development of pathological changes.  相似文献   

5.
Retention in the lungs of 24 piglets of bacteria inhaled following exposure to an aerosol (dv(50)4 micron) of Staphylococcus aureus (SG511 strain), with clearance periods of differentiated lengths, is reported in this paper. Aerosol inhalation led to heterogeneous deposition patterns in the lung. The highest germ count per gram of lung tissue could be re-isolated from the base lobe, while the lowest germ count was retained in the apical lobe. Germ retention in the other lung lobes was somewhere in between these findings. Such differentiation was detectable as early as 20 minutes from the onset of aerosol application and continued to be largely stable even after clearance periods of 2 and 6 hours.  相似文献   

6.
Pulmonary Clearance of Bacillus subtilis Spores in Pigs   总被引：3，自引：3，他引：0       下载免费PDF全文
The pulmonary clearance rate of Bacillus subtilis was determined in ten pigs (23-39 kg) exposed simultaneously for 15 minutes to an aerosol generated by an ultrasonic nebulizer. Two pigs were killed at each interval of zero, two, four, eight and 12 hours and the concentrations of B. subtilis in lungs (all lobes), dorsal and ventral nasal turbinates, trachea, pharyngeal and bronchial lymph nodes were determined. The mean percent (± standard error) pulmonary clearance of B.subtilis was 54.2±11.7, 53.0±11.8, 77.4±5.2 and 88.1±3.7 at two, four, eight and 12 hours, respectively. The numbers of B. subtilis retained in the posterior (caudal and accessory) lobes at zero time were significantly greater than those in the anterior (cranial and middle) lobes (P<0.05). However, by 12 hours postinoculation the numbers of organisms retained in the two regions did not differ significantly (P>0.05). The mean percentage of B. subtilis retained by the turbinates, trachea, pharyngeal and bronchial lymph nodes varied between pigs at each time interval, but was usually less than that retained by the lungs.

It was concluded that deposition of B. subtilis spores took place in all parts of the respiratory tract when pigs were exposed to aerosols and that the spores were progressively cleared by the normal lung.

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7.
The effects of aerogenic long-time exposure of 1,990 female Wistar rats to 30, 50, 100 and 150 nl/l of NH3 for 3, 14, 28 and 42 days on clearance of inhaled bacteria (Staphylococcus aureus, SG 511 strain) were studied together with effects on the clinical condition and behaviour of these test animals. For concentrations below 100 nl/l, action upon pulmonary clearance was found to depend above all on the length of exposure, whereas effects of 150 nl/l proved to depend more strongly on concentration. All concentrations tested tended to act on pulmonary clearance in the form of increased numbers of bacteria which remained in the lungs of the experimental animals. Clinical symptoms attributable to NH3 action were not recordable.  相似文献   

8.
Ponies with recurrent airway obstruction (principal ponies) and their controls were given aerosolized Micropolyspora faeni antigen via endotracheal tube during a period when the principal ponies were in disease remission. In both groups of ponies, we performed bronchoalveolar lavage (BAL) and measured pulmonary function at base line, and 5 hours after aerosol administration of 30 ml of 0.9% NaCl solution or 30 ml of 1% w/v particulate M faeni antigen in 0.9% NaCl solution. In both groups of ponies, aerosolized M faeni antigen increased WBC count, neutrophil numbers, and albumin concentration in BAL fluid, but macrophage numbers decreased. In the principal ponies, BAL mast cell numbers were decreased 5 hours after administration of M faeni antigen. The M faeni antigen had no effect on the mechanical properties of the lungs or on gas exchange in the control ponies, but did increase respiratory frequency minute ventilation and pulmonary resistance, and decreased arterial oxygen tension in the principal ponies. Changes in pulmonary function were apparent only in the principal ponies, which suggests that neutrophils, per se, do not cause pulmonary dysfunction and that M faeni may be one of the etiologic agents involved in chronic obstructive pulmonary disease.  相似文献   

9.
Four control calves were aerosolized with parainfluenza-3 and one week later with Pasteurella haemolytica. Three calves were given Corynebacterium parvum at a dose of 15 mg/m2 body surface area, infected with parainfluenza-3 virus one week later, and aerosolized with P. haemolytica two weeks after C. parvum injection. All calves were killed four hours after P. haemolytica exposure and the bacterial retention in the lung was determined. Parainfluenza-3 viral infection did not exert any suppressive effect on pulmonary clearance of P. haemolytica in six out of seven calves used. However, the bacterial colony counts in the lungs of control calves were higher (P less than 0.05) than those in calves given C. parvum. Hence, C. parvum appeared to enhance bacterial clearance. Despite the marked influx of neutrophils into the lungs after the bacterial inoculation, the neutrophil:macrophage ratio in lavage samples was less in calves given C. parvum than in the control calves. The alveolar macrophages in C. parvum treated calves were generally larger but did not differ significantly (P less than 0.05) from those in the controls. There was no significant (P less than 0.05) correlation between the percentages of alveolar macrophages and the bacterial clearance. In calves given C. parvum, bacterial clearance was enhanced in those calves which had larger macrophages.  相似文献   

10.
To introduce antigen to the respiratory mucosa, killed Actinobacillus pleuropneumoniae with quil A as adjuvant was administered to pigs as an aerosol. Immunisation by this aerosol induced a marked IgA response in the bronchoalveolar and nasal fluids, and in the serum. Following challenge with live bacteria two weeks after the last exposure to the aerosol, the immunised pigs were protected from the severe pleuropneumonia which developed in non-immunised pigs. The immunised pigs had lower antibody titres in the mucosal fluids and serum after exposure to the challenge. The immune response after experimental infection of non-immunised animals was a weak IgA antibody response in the bronchoalveolar and nasal fluids, whereas the systemic immune response after challenge included both IgA and IgG antibodies.  相似文献   

11.
One group of six pigs and another group of three pigs were separately exposed in a polyethylene enclosed chamber for ten minutes, respectively, to Haemophilus pleuropneumoniae serotype 1 and Bacillus subtilis aerosols generated by an ultrasonic nebulizer. Haemophilus pleuropneumoniae and B. subtilis were deposited throughout the lungs immediately following aerosol exposure. The number of H. pleuropneumoniae and B. subtilis deposited varied within and between lungs in each group. The mean numbers of both organisms deposited in the posterior (caudal and accessory) lobes were significantly greater than those in the anterior (cranial and middle) lobes (P less than 0.001). The four principals that received H. pleuropneumoniae aerosols and the two contact controls developed fatal fibrinous pneumonia which simulated that seen in natural infections. Since this exposure system consistently resulted in clinical disease it has good potential as a model for the study of pathogenesis of the disease and more specifically for the evaluation of vaccines.  相似文献   

12.
Escherichia coli isolated from pigs fed on a medicated diet containing 120 p.p.m. halquinol did not develop any resistance to this addition over a 6-week period.
Sensitivity patterns of the E. coli isolates to eight antimicrobial substances, although fluctuating slightly during the test period (but no more than a control group), did not significantly alter. However, the patterns did change significantly when for 17 days after the completion of the halquinol trial the pigs were fed a normal commercial ration medicated with a commonly used feed additive containing chlortetracycline hydrochloride, procaine penicillin and sulphadimidine.  相似文献   

13.
The purpose of this study was to evaluate the effects of dietary Chinese medicinal herbs (CMH) supplementation composed of Panax ginseng, Dioscoreaceae opposite, Atractylodes macrocephala, Glycyrrhiza uralensis, Ziziphus jujube and Platycodon grandiflorum, on the performance, intestinal tract morphology and immune activity in weanling pigs. Two hundred and forty weaned pigs were assigned randomly to four dietary groups including the negative control (basal diet), 0.1% CMH, 0.3% CMH and 0.114% antibiotic (Chlortetracycline calcium Complex, Sulfathiazole and Procaine Penicillin G) supplementation groups for a 28-day feeding trial. Results indicated that both CMH supplementation groups had a better gain and feed/gain than control group (CT) during the first 2 weeks of the experimental period. The 0.3% CMH had a significant decrease in the diarrhoea score in first 10 days of experimental period when compared with other groups. The CMH supplementation groups had a higher villous height, increased lactobacilli counts in digesta of ileum and decreased coliform counts in colon compared with CT. The immune activities of polymorphonuclear leucocytes (PMNs), including the respiratory burst and Salmonella-killing ability, were significantly enhanced in CMH supplementation groups at day 7 of experiment period. The CMH and antibiotic supplementations increased the nutrient digestibility such as dietary dry matter, crude protein and gross energy in weanling pigs. In conclusion, the dietary CMH supplementation improved intestinal morphology and immune activities of PMNs, thus giving rise to nutrient digestibility and reduce diarrhoea frequency in weanling pigs.  相似文献   

14.
非淀粉多糖酶对仔猪早期生产性能和消化性能的影响   总被引：10，自引：0，他引：10  
选用10头母猪生产的100多头仔猪 ,研究了玉米—豆粕型仔猪日粮中添加非淀粉多糖酶对仔猪早期生长性能和消化性能的影响。试验组在对照组日粮中添加120g/t非淀粉多糖酶。试验结果表明 ,添加非淀粉多糖酶使断奶仔猪蛋白质消化率提高9.67 %(P<0.05) ,有机物消化率提高15.40 %(P<0.05) ;添加非淀粉多糖酶对仔猪断奶前的生长无明显影响 ,但对断奶后0～14天的生长有显著的促进作用 ,可提高仔猪日增重10.40 %(P<0.05) ,提高窝重17.65 %(P<0.05)。试验结果同时提示断奶仔猪日粮中添加非淀粉多糖酶可有效地缓解仔猪断奶时的应激反应  相似文献   

15.
The aim of this investigation was to do a comparative study on the deposition and clearance of inhaled bacteria between the lungs and tracheae of mice exposed to aerosols of bacteria. Two hundred and eighty-eight mice were divided into four groups (n = 72) and exposed to aerosols of Pasteurella haemolytica or Staphylococcus aureus in four replicates. The numbers of bacteria were determined in the trachea and lungs of mice sacrificed 0, 2, 4, 8, 12, 24, 48 and 72 hours postexposure. Results indicated that bacterial deposition was greater in lungs than in tracheae. No significant (p greater than 0.05) difference was observed between P. haemolytica and S. aureus clearance rates. Although bacteria were rapidly eliminated from the whole respiratory tract, bacterial clearance was significantly (p less than 0.002) faster in tracheae than lungs. A significant (p less than 0.05) replicate effect was also observed.  相似文献   

16.
The methods of aerosol administration of kanamycin and IM injection of the antibiotic were compared for their protection of mice and squirrel monkeys against Klebsiella pneumoniae respiratory tract infection. Mice exposed to LD90 of K pneumoniae at 0.5, 4, 24, 48 and 72 hours after they were treated with aerosol of kanamycin (27 mg/kg of body weight) were significantly better protected at all exposure times than were mice given the antibiotic (450 mg/kg) by IM injection. Squirrel monkeys given the aerosol at dose level of 11.25 mg/kg were completely protected against K pneumoniae exposure at 6 and 24 hours, whereas only one of eight monkeys treated with the same dose given IM survived the exposure at 6 hours and none survived at 24 hours. Antibiotic clearance curves indicated that kanamycin remained in the lungs at higher concentrations and for longer periods after aerosol treatment than after IM treatment.  相似文献   

17.
To understand the role of non-secreted components of Actinobacillus pleuropneumoniae in virulence, we investigated in vitro cytotoxicity and in vivo pulmonary changes in pigs due to various A. pleuropneumoniae (serotype 1) fractions. Following 1.5 h incubation, lipopolysaccharide (LPS), 2 crude extracts and bacterial culture supernatant (BCS) at high concentrations were cytotoxic to porcine pulmonary alveolar macrophages (PAM), peripheral blood mononuclear leucocytes, neutrophils and a cultured porcine bone marrow cell line. Heat-killed bacteria were cytotoxic to PAM after 24 h incubation. The 2 crude extracts were prepared by shaking either intact bacteria after removing culture supernatants (crude surface extract, CSE), or whole bacterial culture (crude surface plus culture supernatant extract, CSSE) with glass beads in saline at 60 degrees C. Further experiments showed that proteins from the bacterial membrane were partially involved in cytotoxicities of these 2 extracts. Both BCS and CSSE caused multivocal hemorrhage and neutrophil infiltration when inoculated into porcine lungs, but CSE did not. The lung:whole body weight ratios of the pigs treated with CSSE were significantly higher (P < 0.05) than those of pigs treated with BCS, CSE, or control solution. It is concluded that beside the secreted proteins, bacterial surface components including LPS and non-secreted proteins were cytotoxic in vitro; and secreted and non-secreted components act synergistically to cause lung lesions.  相似文献   

18.
An aerosol generating system capable of producing inert, insoluble, non-toxic, respirable, submicronic particles suitable for deposition, retention and clearance studies in the lungs of calves was designed and tested. The machine generated high volume outputs of respirable aerosols by nebulization of an aqueous solution of metallic ions, drying the droplet aerosol, thermal degradation in the presence of oxygen to form insoluble oxides, and subsequent cooling of the aerosol. Aqueous solutions of ferric nitrate, ferric chloride, ferric citrate, ferric oxalate, zinc acetate, lead acetate, cobalt nitrate, cobalt chloride and cobalt acetate were examined, and the resultant aerosols characterized by particle size distribution, shape, aerosol mass concentration, and production of toxic by-products. Iron oxide and cobalt oxide aerosols were judged suitable for inhalation studies in calves, and cobalt oxide was selected for pulmonary clearance studies due to the low background content of cobalt in lung tissue. The cobalt oxide aerosol selected had a geometric mean diameter (GMD) of 0.54 to 0.65 micron with a dimensionless geometric standard deviation (GSD) of 1.41 to 1.71, a mass aerosol concentration of 124 to 335 mg/m3, and a NO2 contamination of 5 to 33 ppm. The cobalt oxide particles were measurably polydisperse, but virtually all particles were smaller than 2.0 microns making the aerosol totally respirable.  相似文献   

19.
In a field trial at a commercial piggery 22 pigs were vaccinated intraperitoneally, at 30 days and 60 days old, with formalin-killed Mycoplasma hyopneumoniae plus adjuvant. Two other groups of the same size, one receiving a ration containing antibiotics, were not vaccinated. The mean enzyme-linked immunosorbent assay (ELISA) ratio of the vaccinated group increased significantly (P less than 0.001) after 30 days, and continued to rise until day 156 of life. In the other two groups the ELISA ratio did not increase significantly until day 115. The vaccinated pigs in the 30-day period after the first vaccination grew significantly (P less than 0.01) more slowly than the controls but between days 60 and 144 they grew significantly faster (P less than 0.05) than the two other groups, thus compensating for their previous, relative loss. At slaughter (at 163 days old), the mean weight was similar in all groups. The mean score for pneumonia at slaughter for the vaccinated, medicated and control groups was 2.6 (+/- 4.3), 9.4 (+/- 14.0) and 10.5 (+/- 12.4), respectively. The proportion of M hyopneumoniae-affected lungs (4.8 per cent) in vaccinated pigs, as judged by immunofluorescence, was significantly less (P less than 0.001) than the control groups (40 per cent). Thus, intraperitoneal vaccination with killed M hyopneumoniae plus adjuvant might control mycoplasmal pneumonia in commercial piggeries.  相似文献   

20.
R K Myers  L H Arp 《Avian diseases》1987,31(3):622-628
Two groups of young turkeys, one passively immunized with homologous hyperimmune serum and the other unimmunized but receiving normal turkey serum, were aerosolized with Escherichia coli. Clearance of bacteria from lung and gross and microscopic lung and air-sac lesions were determined after necropsy at timed intervals. The group mean bacterial count in lungs of passively immunized turkeys was significantly less than the mean count in unimmunized turkeys. Lung lesions were generally similar in both groups and were focused in lymphoid nodules, at the junction of primary and secondary bronchi, and at the ostia to the air sacs. Unimmunized birds developed grossly evident purulent airsacculitis by 72 hours after aerosol exposure, whereas passively immunized birds did not.  相似文献   

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