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1.
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2.
The aim of this study was to determine the intramammary dose of benzylpenicillin required to maintain a concentration in the milk above the MIC for the Gram‐positive bacteria that cause mastitis. The product used in this study was a commercially available procaine benzylpenicillin in an oily suspension with micronized particles. Three dose levels were used: 200,000, 300,000, and 600,000 IU. Concentrations of benzylpenicillin in cow milk and plasma were determined after a single intramammary dose was administered into one quarter of each of the five cows in each treatment group. Samples were analyzed using an HPLC‐MS/MS method, which was validated during the study. Concentrations in the milk were well above the MIC for the target pathogens for all doses tested. There was a linear dose‐dependent increase in the mean AUCs of benzylpenicillin concentrations in plasma and milk. At the first milking, 12 hr after dosing, there was a significant difference between the mean milk benzylpenicillin concentrations in cows treated with a dose of 600,000 IU, and those treated with 200,000 or 300,000 IU. Although this study shows a linear relationship between the dose of procaine benzylpenicillin administered and the concentration in the milk in the healthy udder, it would be useful to conduct studies on cows with mastitis to define the optimum dose and duration of intramammary treatment with benzylpenicillin.  相似文献   

3.
杀菌/通透性增加蛋白(bactericidal permeability increasing protein, BPI)是一种主要存在于中性粒细胞内的阳离子抗菌蛋白,具有杀菌及中和内毒素作用,在革兰氏阴性菌感染的治疗方面有很好的应用前景。作者主要对BPI分子结构、生物学功能、作用机制及应用前景等方面进行综述。  相似文献   

4.
By investigating the prevalence and resistance characteristics of Gram-negative bacteria from organic and conventional kept laying hens against 31 (Campylobacter: 29) different antibiotics using the microdilution method, we determined to what extent different keeping systems influence bacterial resistance patterns. For this purpose, samples from 10 organic and 10 conventional flocks in Bavaria (Germany) were investigated four times between January 2004 and April 2005. Altogether, 799 cloacal swabs and 800 eggs (contents and shells) were examined. The bacterial investigation performed with standardized cultural methods showed prevalence for all bacteria groups in about the same order of magnitude in the two different keeping systems: Salmonella spp. 3.5% (organic ([org])) versus 1.8% (conventional ([con])); Campylobacter spp. 34.8%(org) versus 29.0%(con) and E. coli 64.4%(org) versus 69.0%(con). Coliforms (Citrobacter, Enterobacter, Pantoea) were only isolated in single cases. In eggs, generally less bacteria were detected, predominantly Escherichia; Salmonella and Campylobacter were only scarcely isolated. Salmonella enterica ssp. enterica serovar Typhimurium (n=10) were resistant to up to nine, S. of the serogroup B (n=4) up to six antibiotics. All tested Salmonella (n=23) proved to be resistant to spectinomycin. Escherichia coli (n=257(org) and 276(con)) from organic layers showed significant lower resistance rates and higher rates of susceptible isolates to nine agents, namely amoxicillin/clavulanic acid, ampicillin, cefaclor, cefoxitin, cefuroxime, doxycycline, mezlocillin, neomycin and piperacillin. In contrast, only two antibiotics turned out to be more effective in conventional isolates (gentamicin and tobramycin). In the case of Campylobacter jejuni (n=118(org) and 99(con)), statistically significantly better rates were observed for isolates from organic flocks concerning imipenem and amoxicillin/clavulanic acid, whereas fosfomycin was more potent in strains from conventional flocks. Results of this study indicate that both resistance rates and mean minimum inhibitory concentrations of bacteria isolated from organic keeping systems have lower values than those from conventional ones, particularly recognizable for E. coli. Thus, organic livestock farming with its restrictions and additional requirements contributes to further effectiveness of antibiotics.  相似文献   

5.
By investigating the prevalence and antimicrobial resistance characteristics of Gram‐positive bacteria from organic and conventional keeping systems of laying hens, it was to be determined to what extent these properties are influenced by the different systems. For this purpose, a total of 799 cloacal swabs and 800 egg samples were examined. Prevalences for all selected bacteria from cloacal swabs were much the same for both organic and caged birds: Listeria spp. 1.3%[org] versus 1.6%[con]; Enterococcus spp. 95.5%[org] versus 97.5%[con]. Egg contents and eggshells were generally contaminated to a lesser extent, primarily with Enterococcus spp. Listeria isolates were susceptible to almost all tested antibiotics, only three Listeria innocua from conventional keepings were resistant to clindamycin; one isolate additionally to imipenem. High percentages of Enterococcus faecalis were resistant to doxycycline and macrolides. Enterococcus faecium proved to have high resistance rates to clindamycin, fosfomycin and erythromycin; 9.1% were even resistant to the reserve antibiotic synercid. Further, Enterococcus spp. showed higher resistance rates to doxycycline, erythromycin, fosfomycin and rifampicin. No glycopeptide resistant enterococci were detected. A correlation between keeping system and resistance/susceptibility rates could be demonstrated. In detail, E. faecalis from organic laying hen husbandries showed significant lower resistance prevalences to tylosin, streptomycin and doxycycline; susceptibility rates were higher for enrofloxacin and ciprofloxacin. Rifampicin and imipenem were more effective in isolates from conventional keepings (P < 0.05). The amounts of resistant isolates of the Enterococcus raffinosus from organic farms were significantly lower, the amounts of sensitive isolates were significantly higher than from conventional farms concerning eight antibiotics (P < 0.05). When comparing the susceptibility/resistance rates, as well as the mean minimum inhibitory concentrations values, the consistent tendency is that bacteria from organic layer flocks are more susceptible to antimicrobials. These results show that organic livestock farming plays a part in contributing to reduced antibiotic resistance.  相似文献   

6.
Increasing reports of multidrug‐resistant bacterial infections in animals has created a need for novel antimicrobial agents that do not promote cross‐resistance to critically important antimicrobial classes used in human medicine. In response to the recent emergence of antimicrobial resistance in several bovine mastitis pathogens, in vitro antimicrobial susceptibility was determined for four polyether ionophores (lasalocid, monensin, narasin and salinomycin) against Staphylococcus spp. and Streptococcus spp. isolated from clinical cases. In addition, erythrocyte haemolysis and WST ‐1 cell proliferation assays were used to assess in vitro mammalian cell cytotoxicity and biofilm susceptibility testing was performed using the minimum biofilm eradication concentration (MBEC ?) biofilm assay. Lasalocid, monensin, narasin and salinomycin exhibited bacteriostatic antimicrobial activity against all pathogens tested, including methicillin‐resistant staphylococci, with MIC 90 values <16 μg/ml. Narasin and monensin displayed the least toxicity against mammalian cell lines and all compounds significantly reduced viable cell numbers in a Staphylococcus aureus biofilm. Based on in vitro characterization, all four ionophores offer potentially novel treatments against bovine mastitis but in vivo studies will be essential to determine whether acceptable safety and efficacy is present following intramammary administration.  相似文献   

7.
采用平板细菌计数法对四个牛场奶牛乳头药浴前、后的细菌总数进行统计分析。结果显示A、B、C三个牛场乳头药浴前与药浴后的细菌总数差异极显著(P<0.05),D牛场乳头药浴前与药浴后的细菌总数无统计学差异(P>0.05)。表明A~C场奶牛乳头药浴剂效果较好,D场效果欠佳。此外,对培养的细菌进行革兰氏染色和镜检,结果显示主要有沙门氏菌、大肠杆菌、葡萄球菌和枯草芽孢杆菌,与文献报道相符。  相似文献   

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9.
Rumen fermentation can produce hydrogen sulfide (H2S), and H2S can be rapidly absorbed by the intestinal wall in nature. If excessive H2S was produced in rumen, it might be toxic to ruminants. This article reviews the research progress of toxicity of H2S, rumen H2S production pathway and its influential factors to lay a foundation for further research and application of rumen H2S‐producing regulation in ruminant.  相似文献   

10.
The objective of this study was to investigate the effect of sundried pistachio by‐products (PBP) as a replacement of alfalfa hay (AH) on blood metabolites, rumen fermentation and populations of rumen bacteria involved in biohydrogenation (BH) in Baluchi sheep. Four adult male Baluchi sheep (41 ± 1.3 kg, BW) fitted with ruminal cannulae were randomly assigned to four experimental diets in a 4 × 4 Latin square design. The dietary treatments were as follows: (i) control, (ii) 12% PBP (0.33 of AH in basal diet replaced by PBP), (iii) 24% PBP (0.66 of AH in basal diet replaced by PBP) and (iv) 36% PBP (all of AH in basal diet replaced by PBP). The basal diet was 360 g/kg dry matter (DM) alfalfa hay, 160 g/kg DM wheat straw and 480 g/kg DM concentrate. The trial consisted of four periods, each composed of 16 days adaptation and 4 days data collection including measurement of blood metabolites, rumen fermentation and population of bacteria. No differences were observed in rumen pH among the treatments, while rumen ammonia‐N concentrations were decreased (p< 0.05) with increasing PBP by up to 36% DM of the diets. Using of 36% PBP in the diet reduced (p < 0.05) total volatile fatty acids (VFA) concentrations and the molar proportion of acetate, while the concentration of propionate, butyrate and acetate to propionate ratio were similar to all other treatments. The concentration of blood urea nitrogen (BUN) decreased (p < 0.01) with increasing PBP by up to 36% DM in the diets of sheep. However, other blood metabolites were not affected by the experimental diets. It was concluded that PBP in replacement of AH had no effects on the relative abundance of Butyrivibrio fibrisolvens and Butyrivibrio proteoclasticus in relation to the control diet.  相似文献   

11.
通过对参加兽用生物制品检验中级工职业技能鉴定的63名考生细菌革兰氏染色结果进行分析,了解我国兽用生物制品生产企业细菌革兰氏染色及显微镜操作能力的整体水平。63名考生对随机选取大肠杆菌或金黄色葡萄球菌进行革兰氏染色显微镜检查,要求考生在规定时间内完成细菌革兰氏染色并提交显微镜观察结果。92%考生检验结果满意(58/63);8%检验结果不满意(5/63);最高分50分(满分),最低分14分。体现出我国兽用生物制品生产企业检验人员的细菌染色显微镜观察水平参差不齐,尽管大部分检验人员掌握了细菌革兰氏染色及普通光学显微镜操作技能,但仍有小部分检验人员细菌染色及操作显微镜能力有待进一步提高。  相似文献   

12.
An in vitro study was conducted to quantitatively investigate the metabolism of pipecolic acid (Pip), a neuromodulator, by mixed rumen bacteria (B), mixed rumen protozoa (P), a combination of B and P (BP), species‐enriched rumen protozoal suspension (Polyplastron sp., Diploplastron sp., entodinia and Entodinium caudatum) and pure cultures of several isolates of rumen bacteria (Prevetolla bryantii, Prevetolla albensis, Streptococcus bovis, Veillonella parvula, Megasphaera elsdenii and Ruminococcus albus). Only P produced Pip from L‐lysine (1.0 mmol/L L‐Lys) at a rate of 83.5 ± 1.6 µmol/L/h and even in BP, Pip was produced from L‐Lys by P and increased at a rate of 31.2 ± 3.8 µmol/L/h. Pip production by P was highest when the substrate (L‐Lys) concentration was 6 mmol/L and then the rate was 580 ± 36 µmol/L/h. Pipecolic acid production by P suspension enriched with different species of protozoa showed that Polyplastron sp. had the highest Pip production rate of 0.907 ± 0.092 µmol/L/mg protozoal protein per h, and Diploplastron sp. had the lowest rate of 0.55 ± 0.13 µmol/L/mg protozoal protein per h. The addition of D‐Lys (1.0 mmol/L) as a substrate to the P suspension revealed that P were also able to produce Pip from D‐Lys, though at a lower rate (1/3) compared with L‐Lys (1.0 mmol/L), suggesting the presence of epimerases in P. It was confirmed that B were unable to produce Pip from L‐ or D‐Lys. Only B degraded Pip (1.0 mmol/L) after a lag phase at a rate of 56.0 ± 1.5 µmol/L/h. The B suspension was able to degrade D‐Lys, though the products were not identified. Pip degradation by pure culture of some species of rumen bacteria showed that P. bryantii and R. albus had the highest rate followed by P. albensis, S. bovis and M. elsdenii with a low rate of Pip degradation. Veillonella parvula showed no ability to degrade Pip. The results suggest that a fairly large proportion of rumen‐produced Pip is likely to be absorbed by the host animal before degradation by rumen bacteria.  相似文献   

13.
Methane production from co‐digestion of dairy manure and waste milk, milk from cows treated with antibiotics for mastitis, was tested in a 2 × 4 factorial design. Four different waste milk percentages (w/w): 0% (SM), 10% (SMWM10), 20% (SMWM20) and 30% (SMWM30), were tested with two slurry percentages (w/w): 50% (A) and 25% (B) and the rest being manure at 55°C for 12 days in batch digesters. The results analyzed using a Gompertz model showed SMWM10 produced the highest methane production potential (Pm)/g volatile solids added followed by SM in both A and B. This Pm of SMWM10 in A and B was statistically non‐significant (P > 0.05). More than 96% of cefazolin‐resistant bacteria and 100% of multi‐drug‐resistant bacteria reductions were observed in all the treatments. Inclusion of waste milk at 10% in single stage digester enhances the methane production from dairy manure and could offer added benefit of waste milk treatment and disposal.  相似文献   

14.
The paper deals with the hygienic advantages of sanitation to treat dairy manure in full‐scale biogas plants. The slurry samples were collected from two thermophilic biogas plants (55°C) and two mesophilic biogas plants (38°C) in Hokkaido Japan. A detectable number of Coli‐aerogenes group and Enterococcus in the slurries after anaerobic digestion (AD) could not be found in either thermophilic biogas plants. However, in both mesophilic biogas plants the viable numbers of Coli‐aerogenes group and Enterococcus were detected in the slurries even after anaerobic digestion. The mean decimation reduction time (T90) values of the Coli‐aerogenes group and Enterococcus in the slurries during mesophilic digestion were 13.3 days and 16.7 days, respectively.  相似文献   

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16.
The objective of this study was to determine the effects of incremental replacement of dietary linoleic acid by >20-carbon polyunsaturated fatty acids (PUFA) on changes in population of ruminal micro-organisms associated with fibre digestion and biohydrogenation using real-time PCR of bacterial 16S rRNA sequences. Four beef steers with ruminal cannulas were randomly assigned to control (CK, 65:35 forage to concentrate), CK with 3% sunflower oil plus 1% fish oil (S3F1), 2.5% sunflower oil plus 1.5% fish oil (S2.5F1.5) or 2% sunflower oil plus 2% fish oil (S2F2) in a 4 × 4 Latin square design with 21-day periods. Ruminal fluid was collected on day 15 of each period. Compared with CK, oil addition led to lower ruminal acetate and butyrate but greater propionate concentration. DNA copy number of Anaerovibrio lipolytica in ruminal fluid was greater with oil (average 5.38 vs. 3.62 × 10(5) DNA copy number), particularly with S2F2 relative to CK. Fibrobacter succinogenes and Butyrivibrio fibrisolvens DNA copy number decreased by 74% (1.06 vs. 4.01 × 10(5)) and 39% (5.16 vs. 8.42 × 10(7)) in response to S2F2 compared with CK. DNA copy numbers of Ruminococcus flavefaciens and Ruminococcus albus were not affected by incremental fish oil. Results suggest that greater availability of PUFA with >20 carbons (i.e. eicosapentaenoic acid and docosahexaenoic acid) promoted changes in bacterial populations that are relevant for fibre digestion and biohydrogenation.  相似文献   

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18.
A bovine myeloid antimicrobial peptide (BMAP‐28) is a member of the cathelicidin family which is included in the innate immune system of mammals. Recently, there have been many studies about antimicrobial peptides. This study aims to clarify whether BMAP‐28 has bactericidal activity against methicillin‐resistant Staphylococcus aureus (MRSA) and compares its activity against methicillin‐susceptible S. aureus (MSSA) and MRSA. We found that the peptide was effective in killing MRSA (minimal inhibitory concentration (MIC) range; 5–20 µg/mL). It was also revealed that MSSA (MIC range; 1.25–20 µg/mL) had two levels of susceptibility to BMAP‐28. We also examined the effect of BMAP‐28 on bacterial shape to visually show its activity. After exposure to the peptide, both MSSA and MRSA cells showed the morphological changes on their surfaces. Our results indicate that BMAP‐28 is a promising candidate for medicine against drug‐resistant bacteria.  相似文献   

19.
This study evaluated the effects of dietary concentrate levels and 2‐methylbutyrate (2MB ) supplementation on performance, ruminal fermentation, bacteria abundance, microbial enzyme activity and urinary excretion of purine derivatives (PD ) in steers. Eight ruminally cannulated Simmental steers (12 months of age; 389 ± 3.7 kg of body weight) were used in a replicated 4 × 4 Latin square design with a 2 × 2 factorial arrangement. Moderate‐concentrate (400 g/kg diet [MC ]) or high‐concentrate (600 g/kg diet [HC ]) diets were fed with or without 2MB (0 g/day [2MB ?] or 15.0 g/day [2MB +]). Dry matter intake and average daily gain increased, but feed conversion ratio decreased with the HC diet or 2MB supplementation. Ruminal pH decreased, but total volatile fatty acid increased with the HC diet or 2MB supplementation. Molar proportion of acetate and acetate‐to‐propionate ratio decreased with the HC diet, but increased with 2MB supplementation. Propionate molar proportion and ruminal NH 3‐N content increased with the HC diet, but decreased with 2MB supplementation. Neutral detergent fibre degradability decreased with the HC diet, but increased with 2MB supplementation. Crude protein degradability increased with the HC diet or 2MB supplementation. Abundance of Ruminococcus albus , Ruminococcus flavefaciens , Fibrobacter succinogenes and Bufyrivibrio fibrisolvens as well as activities of carboxymethyl cellulase, cellobiase, xylanase and pectinase decreased with the HC diet, but increased with 2MB supplementation. However, abundance of Prevotella ruminicola and Ruminobacter amylophilus as well as activities of α‐amylase and protease increased with the HC diet or 2MB supplementation. Total PD excretion also increased with the HC diet or 2MB supplementation. The results suggested that growth performance, ruminal fermentation, CP degradability and total PD excretion increased with increasing dietary concentrate level from 40% to 60% or 2MB supplementation. The observed diet × 2MB interaction indicated that supplementation of 2MB was more efficacious for improving growth performance, ruminal fermentation and total PD excretion with promoted ruminal bacteria abundance and enzyme activity in the MC diet than in the HC diet.  相似文献   

20.
In the lactic acid bacteria (LAB) strains screened from our LAB collection, Lactobacillus (L.) sakei strain no. 23 and L. curvatus strain no. 28 degraded meat protein and tolerated salt and nitrite in vitro. Fermented sausages inoculated strains no. 23 and no. 28 showed not only favorable increases in viable LAB counts and reduced pH, but also the degradation of meat protein. The sausages fermented with these strains showed significantly higher antioxidant activity than those without LAB or fermented by each LAB type strain. Angiotensin‐I‐converting‐enzyme (ACE) inhibitory activity was also significantly higher in the sausages fermented with strain no. 23 than in those fermented with the type strain. Higher ACE inhibitory activity was also observed in the sausages fermented with strain no. 28, but did not differ significantly from those with the type strain. An analysis of the proteolysis and degradation products formed by each LAB in sausages suggested that those bioactivities yielded fermentation products such as peptides. Therefore, LAB starters that can adequately ferment meat, such as strains no. 23 and no. 28, should contribute to the production of bioactive compounds in meat products.  相似文献   

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