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1.
Adherence of Streptococcus dysgalactiae isolates from cattle and S equi isolates from horses to their respective host epithelial cells was compared with the adherence of S pyogenes to human epithelial cells. The adherence was quantitatively determined by use of fluorescein-labeled streptococci. All 3 streptococcal species adhered selectively to their respective host cells. The mechanism of adherence was evaluated by binding studies with adhesive plasma protein, fibronectin. Although all 3 streptococcal species bound fibronectin, S dysgalactiae and S equi interacted preferentially with a 210-kilodalton (kD) C-terminal fragment of fibronectin, whereas S pyogenes bound only a 29-kD N-terminal fragment. A synthetic peptide Gly-Arg-Gly-Asp-Ser, representing the host cell attachment site of fibronectin, partially inhibited the binding of fibronectin and of its 210 kD fragment to S dysgalactiae, but not to S equi. The binding of fibronectin and its 29-kD fragment to S pyogenes was not inhibited by Gly-Arg-Gly-Asp-Ser. These differences in binding activities corresponded to the ability of fibronectin to mediate the adherence of the streptococci to the epithelial cells: fibronectin strongly inhibited the adherence of S pyogenes and S equi to the epithelial cells, but only weakly inhibited that of S dysgalactiae.  相似文献   

2.
The binding of bovine complement S protein (vitronectin) to Streptococcus dysgalactiae isolates from cattle with mastitis and the S protein's role in streptococcal adherence to bovine epithelial cells were investigated. All 25 clinical isolates of S dysgalactiae interacted with bovine S protein. None of the other streptococcal species tested bound to bovine S protein. The S protein-binding sites were saturable and highly sensitive to trypsin. The binding of bovine S protein to S dysgalactiae isolates was specific and could not be inhibited by other plasma proteins, such as fibronectin, albumin, fibrinogen, alpha 2-macroglobulin, or IgG. Similarly, streptococcal binding of bovine S protein was not influenced by the synthetic peptide Gly-Arg-Gly-Asp-Ser, which constituted the host cell attachment sequence of S protein. In adherence experiments, prior binding of bovine S protein to S dysgalactiae enhanced streptococcal adherence to bovine epithelial cells. The enhancing effects by bovine S protein were abolished when the respective binding sites on the streptococci were digested by trypsin. Thus, bovine S protein could be an important mediator of adherence of S dysgalactiae to bovine epithelial cells.  相似文献   

3.
Five hundred and seventy-nine milk samples were collected from dairy cows on seven farms in Khartoum North area and one farm in Omdurman and examined by bacteriological cultures for the presence of streptococci. One hundred and ninety-three (33.33%) isolates were recovered and identified on the basis of bacteriological characteristics and biochemical reactions as: S. pyogenes, S. agalactiae, S. dysgalactiae, S. faecalis, S. faecium, S. bovis, S. equi, S. lactis and S. uberis. Fifty-seven isolates representing the preliminary identification were tested by the latex-agglutination test to determine the serological groups. It was found that 39 strains belonged to group B, 3 strains to group C. Four strains gave a weak reaction with group D sera and were identified by biochemical tests as S. uberis. Two isolates could not be identified by the available sera. The isolation of S. uberis, S. bovis, S. equi, S. lactis, S. faecalis, S. faecium and S. pyogenes from cows in the Sudan was reported for the first time.  相似文献   

4.
Mannitol agar for microbiologic diagnosis of bovine mastitis   总被引：1，自引：0，他引：1  
A medium containing mannitol (mannitol agar) was developed and evaluated as a tool for the microbiologic diagnosis of bovine mastitis. Mannitol agar supported growth of all important bacterial mastitis pathogens (staphylococci, streptococci, coliforms, and pseudomonads) except Corynebacterium pyogenes. Color change around colonies in the agar permitted the differentiation of pathogenic from nonpathogenic staphylococci. Most Staphylococcus aureus strains and some Staphylococcus epidermidis strains produced yellow zones. These yellow zone-producing strains (mannitol fermenters) of staphylococci were obtained from quarters with significantly elevated (P less than 0.05) somatic cell counts (SCC) in the milk, as compared with uninfected quarters and, therefore, would be considered pathogens. Mannitol-negative strains of S epidermidis (those with red zones) were obtained from quarters with SCC similar to those of uninfected quarters. The streptococci could be divided into 2 groups on the basis of color change around the colonies: Streptococcus agalactiae, Str dysgalactiae, and group G streptococci produced red zones; Str uberis, Str bovis, and enterococci produced yellow zones. Pathogenic streptococci (Str agalactiae, Str dysgalactiae, Str uberis, and group G streptococci) were obtained from quarters with SCC significantly higher (P less than 0.01) than those of uninfected quarters. Streptococcus bovis and enterococci were obtained from quarters with SCC similar to those of uninfected quarters and were considered nonpathogenic. Pathogenic streptococci were found in much higher concentration than nonpathogenic streptococci and could be differentiated on that basis.  相似文献   

5.
Accurate identification of mastitis pathogens is often compromised when using conventional culture-based methods. Here, we report a novel, rapid assay tested for speciation of bacterial mastitis pathogens using high-resolution melt analysis (HRMA) of 16S rDNA sequences. Real-time PCR amplification of 16S rRNA gene fragment, spanning the variable region V5 and V6 was performed with a resulting amplicon of 290bp. First, a library was generated of melt curves of 9 common pathogens that are implicated in bovine mastitis. Six of the isolates, Escherichia coli, Streptococcus agalactiae, Klebsiella pneumoniae, Streptococcus uberis, Staphylococcus aureus and Mycoplasma bovis, were type strains while the other 3, Arcanobacterium pyogenes, Corynebacterium bovis and Streptococcus dysgalactiae, were bovine mastitis field isolates. Four of the type strains, E. coli, S. agalactiae, K. pneumoniae and S. aureus, were found to be of human origin, while the other 3 type strains were isolated from bovine infections. Secondly, the melt curves and corresponding amplicon sequences of A. pyogenes, E. coli, S. agalactiae, S. dysgalactiae, K. pneumoniae, S. uberis and S. aureus were compared with 10 bovine mastitis field isolates of each pathogen. Based on the distinct differences in melt curves and sequences between human and bovine isolates of E. coli and K. pneumoniae, it was deemed necessary to select a set of bovine strains for these pathogens to be used as reference strains in the HRMA. Next, the HRMA was validated by three interpreters analyzing the differential clustering pattern of melt curves of 60 bacterial cultures obtained from mastitis milk samples. The three test interpreters were blinded to the culture and sequencing results of the isolates. Overall accuracy of the validation assay was 95% as there was difficulty in identifying the streptococci due to heterogeneity observed in the PCR amplicons of S. uberis. The present study revealed that broad-range real-time PCR with HRMA can be used as a powerful, fast and low-cost tool for the differentiation of clinically important bacterial mastitis pathogens.  相似文献   

6.
Liposomes containing aminoglycosides have been shown to enhance the killing of Brucella abortus and Staphylococcus aureus inside bovine phagocytic cells. This study examined the mechanism by which liposomes containing aminoglycoside enhance the intracellular killing of bacteria. Liposomes with entrapped aminoglycoside were found to significantly enhance the intraphagocytic killing of bacteria in bovine phagocytic cells (in vitro) when compared to free drug. Liposomes with entrapped aminoglycoside were also found to deliver significantly higher levels of aminoglycoside into phagocytic cells when compared to free drug (gentamicin) or free drug and liposomes without entrapped antibiotic. Antibiotic delivered to adherent phagocytic cells could be detected 3 days after treatment of the cells with liposomes containing aminoglycoside. No antibiotic could be detected in the supernatants of phagocytic cell cultures 3 days after treatment with liposomes containing antibiotic was only observed when the intraphagocytic bacteria were sensitive to the antibiotic entrapped in the liposomes. The rate of phagocytosis of S. aureus by cells treated with cationic liposomes (no entrapped antibiotic) did not differ from the rate of phagocytosis of control cells not treated with cationic liposomes. This study shows that the enhanced intraphagocytic killing of bacteria in bovine phagocytic cells occurs by direct delivery of entrapped antibiotic into the phagocytic cell by the liposome delivery vehicle and not by nonspecific enhancement of phagocytic cell function. Liposomes containing aminoglycoside appear to have no toxic effects on phagocytic cell function or viability in vitro.  相似文献   

7.
A total of 166 samples of secretions collected from Danish heifers suffering from clinically diagnosed summer mastitis were examined bacteriologically. One hundred and sixty three samples yielded positive findings whereas no growth was obtained from 3 specimens. The majority of samples revealed a mixed flora in which the predominant components were Actinomyces pyogenes, Peptostreptococcus indolicus, a microaerophilic coccus (Stuart-Schwan coccus), Fusobacterium necrophorum, Bacteriodes melaninogenicus and Streptococcus dysgalactiae. Pure cultures were recovered in only 7% of cases. P. indolicus was isolated from 875 of the cases, a microaerophilic coccus from 84%, A. pyogenes from 72%, Fusobacterium necrophorum from 52%, Str. dysgalactiae from 37%, B. melaninogenicus from 33% and various unidentified obligate anaerobic Gram-negative rods from 31%. The results confirm the complex bacterial aetiology of summer mastitis.  相似文献   

8.
Streptococci belonging to serological groups A, B, C, G, L and U were studied for their interaction with 125I-labelled fibronectin and its fragments. Fibronectin purified from humans plasma by affinity chromatography on gelatin-agarose and heparin-agarose was cleaved by thrombin into a 29,000 Dalton and a 210,000 Dalton fragments. Terminal analysis of purified fragments indicated that 29,000 fragment was from amino-terminal and 210,000 fragment from carboxyl-terminal domain of fibronectin. Binding of fibronectin was observed in all streptococci except those of group B. Streptococci of groups A, G, L, U and S. equisimilis reacted only with 29,000 Dalton fragment whereas S. dysgalactiae, S. zooepidermicus and S. equi reacted only with 210,000 Dalton fragment. The streptococcal binding sites for these two fragments were distinct from each other. Fibrinogen blocked the binding of 210,000 Dalton fragment but not of 29,000 Dalton fragment. Trypsinization of streptococci did not affect their binding sites for 210,000 Dalton fragment but destroyed those for 29,000 Dalton fragment. The results indicate that the streptococci of group A and G as well as S. equisimilis which are mainly pathogenic in humans bind amino-terminal fragment of fibronectin. This may facilitate the adherence of these pathogens. On the other hand, the streptococci isolated from animal infections had different binding sites recognized only by carboxyl-terminal part of fibronectin.  相似文献   

9.
The antibacterial properties of bacteriophage lytic enzymes may be of importance in future mastitis control programs. A prophage was isolated from a strain of Streptococcus uberis (ATCC 700407) following exposure to mitomycin C. Partial sequencing of the phage DNA revealed a putative lysin based on sequence similarity to other streptococcal phage lysins. The putative lysin (Ply700) was recombinantly expressed in Escherichia coli, and chromatographically purified. Addition of the purified Ply700 to bacterial suspensions of S. uberis, Streptococcus pyogenes, and Streptococcus dysgalactiae caused a rapid, calcium-dependent lysis while there was little activity against Streptococcus agalactiae, Staphylococcus aureus, or E. coli. Killing of S. uberis in milk by Ply700 (50 microg/ml) was confirmed by plate count assay. Activity was related to the initial concentration of bacteria in that 31% killing (P<0.05) was observed with an inoculating dose of approximately 4500 cfu/ml, while 81% killing (P<0.01) was observed when the inoculum was reduced to approximately 600 cfu/ml. In contrast, complete sterilization was observed in parallel cultures suspended in assay buffer indicating that factors in milk are able to neutralize the lysin. Functional characterization of the C-terminal domain, as a component of a GFP fusion protein, revealed its calcium-dependent ability to bind to S. uberis. The C-terminal domain may have utility in targeting S. uberis while it remains to be determined if the lysin by itself has sufficient potency in milk for effective use in the control of S. uberis mastitis.  相似文献   

10.
为探明贵州省某猪场引起猪体表脓肿的原因,本研究对该猪场脓肿部位的脓汁进行细菌分离培养,并对分离所得的细菌进行革兰氏染色镜检、生化试验、药敏试验、16S rDNA序列分子分析及动物感染试验。结果显示,从脓汁中成功分离到了3株菌落形态不一的菌株,分别为金黄色葡萄球菌、化脓隐秘杆菌、停乳链球菌类马亚种,根据分离地点和时间将其分别命名为GZGP2018-1、GZGP2018-2和GZGP2018-3;GZGP2018-1菌株与NCBI上金黄色葡萄球菌的同源性高达99.9%,GZGP2018-2菌株与NCBI上化脓隐秘杆菌的同源性高达99.9%,GZGP2018-3菌株与NCBI上停乳链球菌类马亚种的同源性高达100%;3株分离菌株对头孢拉定、环丙沙星、磺胺间甲氧嘧啶和氟苯尼考较敏感,对青霉素类药物和红霉素耐药;3株分离菌株对试验小鼠均具有致死性。本研究为该猪场猪体表脓肿的发病原因、实验室诊断方法及日常防控提供了理论参考。  相似文献   

11.
Streptococcus pyogenes, S. agalactiae, S. dysgalactiae, S. equi, S. equisimilis, S. zooepidemicus, Streptococcus group G and L were found to produce deoxyribonucleases (DNases) which were demonstrated using the Toluidine Blue DNA Agar (TDA) described for staphylococcal DNases. The activity of streptococcal DNases increased in the presence of Mg++ and Ca++ ions, the pH optimum was about 7.5 and native DNA was the best enzyme substrate. It is consequently recommended to modify the TDA according to these results for the demonstration of streptococcal DNases. All streptococcal DNases, except the DNase of S. zooepidemicus, were found to be heat-stable. Isoelectric focusing was a convenient technique for separation of streptococcal DNases and for estimation of the pI values of the DNases. S. agalactiae and S. dysgalactiae generally exhibited distinct species specific patterns in the isoelectric focusing experiments. The DNases produced by S. pyogenes were serologically related to the DNases of S. dysgalactiae and Streptococcus group G. A similar relationship was demonstrated between the DNases produced by S. equisimilis and Streptococcus group L.  相似文献   

12.
Bèta-hemolytic streptococci from pigs: bacteriological diagnosis   总被引：1，自引：0，他引：1  
Bèta-hemolytic streptococci from lesions in pigs were identified as S. dysgalactiae biotype "equisimilis" and S. dysgalactiae serovar L, S. porcinus, S. agalactiae, E. faecalis and CO2 dependent and broad bèta-hemolytic S. suis. Data are provided which can be used in the interpretation of commercial identification systems. Tests results and physiological characteristics which complete identification procedures using coagglutination tests are proposed and discussed.  相似文献   

13.
An outbreak of strangle-like disease involving 26 horses farmed in central Italy was investigated by clinic examination, endoscopy, cytology, bacteriology and polymerase chain reaction (PCR). At weekly interval, a total of three nasal swabs and one guttural pouches lavage fluid (GPLF) were collected, and no Streptococcus equi subsp. equi carrier was found. Some horses showed upper airways disease and endoscopic signs of pharyngeal lymphoid hyperplasia of different grade and/or abnormal endoscopic appearance of guttural pouches. Streptococcus dysgalactiae subsp. equisimilis was isolated from 14 horses while S. equi subsp. zooepidemicus was isolated from six horses. PCR confirmed the biochemical and serological identification of all isolates and was positive in 10 bacteriological negative samples. The absence of S. equi and the frequent detection of S. equisimilis and S. zooepidemicus suggest that beta-haemolytic streptococci other than S. equi could be the causative agent of strangle-like disease.  相似文献   

14.
肝素可剂量依赖性地抑制化脓隐秘杆菌(Trueperella pyogenes)黏附宿主细胞.本研究旨在认识化脓隐秘杆菌肝素结合蛋白及其黏附特性,采用肝素琼脂糖凝胶从化脓隐秘杆菌裂解物中提取蛋白,运用蛋白质质谱和免疫印迹对所提取的蛋白质进行鉴定.采用免疫印迹检测所提取蛋白质与自然感染化脓隐秘杆菌山羊血清的反应原性.制备重...  相似文献   

15.
A total of 855 pig lungs were collected at slaughter and evaluated macroscopically. Bacteriological examinations were carried out on tissue samples from chronic pleuropneumonic lesions (n = 196) and from chronic bronchopneumonic lesions with suppuration (n = 14). Samples from normal lung tissue (n = 22) were also included. Pasteurella multocida was isolated from 54%, Actinobacillus (Haemophilus) pleuropneumoniae from 11%, and Streptococcus spp. from 14% of the pneumonic lesions, respectively. From normal lung tissue P. multocida was isolated from 3 (14%) of the samples, A. pleuropneumoniae was not recovered and streptococci were isolated from only 1 (5%) of these samples. The above mentioned bacterial species were recovered either in pure cultures or mixed with various other microbes. A total of 109 P. multocida strains were further characterized by capsular serotyping and testing for production of dermonecrotic toxin. Ninety-nine (91%) of the strains were capsular type A 10 (9%) were type D. Out of the type A and the type D strains 94% and 90% were toxigenic, respectively. Most of the A. pleuropneumoniae strains were serotype 2. Strains of serotypes 1 and 7 were also identified. The majority of the streptococci were identified as either Streptococcus suis or Streptococcus dysgalactiae. Actinomyces pyogenes was isolated from 14% of the lesions and anaerobic bacteria from 18%, respectively. The significance of the various bacterial species in relation to the development of chronic pneumonic lesions is discussed. Special attention is paid to P. multocida, and it is concluded that this bacterial species is probably of importance for the development of both types of chronic pneumonias.  相似文献   

16.
Streptococcus dysgalactiae serogroup C, G and L strains were investigated by polymerase chain reaction (PCR) using oligonucleotide primers designed according to species-specific parts of the 16S-23S rDNA intergenic spacer region. The oligonucleotide primers with specificity for the 16S-23S rDNA intergenic spacer region allowed a correct identification of all S. dysgalactiae serogroups C, G and L strains investigated. No cross-reactivities could be observed with any of the control strains indicating the usefulness of PCR-technology to identify the serologically heterogeneous species S. dysgalactiae.  相似文献   

17.
Penethamate hydriodide was highly effective in killing Streptococcus uberis, Streptococcus dysgalactiae subsp. dysgalactiae and Staphylococcus aureus that internalized mammary epithelial cells. At higher concentrations (32 microg/mL to 32 mg/mL), killing rates ranged from 85% to 100%. At lower concentrations (0.032 microg/mL to 3.2 microg/mL), killing rates ranged from 0 to 80%. Results of this proof-of-concept study demonstrated that: (1) penethamate hydriodide is capable of entering mammary epithelial cells and killing intracellular mastitis pathogens without affecting mammary epithelial cell viability, (2) the in vitro model used is capable of quantifying the fate of mastitis pathogens internalized into mammary epithelial cells, and (3) this in vitro model can be used to determine the effectiveness of antibiotics at killing bacteria within the cytoplasm of mammary epithelial cells.  相似文献   

18.
We previously showed that Staphylococcus aureus cells adhered mainly to an elongated cell type, present in cultures of bovine mammary gland cells. Moreover, we showed that this adhesion was mediated by binding to fibronectin. The same in vitro model was used here, to study adhesion of other important mastitis pathogens. Like the S. aureus strains, the Streptococcus dysgalactiae strains adhered mainly to elongated cells, which seemed to be mediated by fibronectin binding. In contrast, Streptococcus uberis strains adhered mainly to cubic cells. Since the cubic cells did not express fibronectin and S. uberis cells bound fibronectin less efficiently, the adhesion of S. uberis cells was independent of fibronectin binding. Streptococcus agalactiae strains adhered poorly to both cell types. The specificity and efficiency of adhesion of Escherichia coli strains was strongly strain dependent. None of the S. agalactiae and E. coli strains tested was able to bind fibronectin efficiently. The results suggest that the different mastitis pathogens have different target cell specificities and use different mechanisms to adhere to cells of the bovine mammary gland.  相似文献   

19.
To examine the effect of parity on polymorphonuclear neutrophils (PMN) function, phagocytic and bactericidal activity of the PMN isolated from blood and milk against Staphylococcus aureus was compared between groups of 6 primiparous and 6 multiparous healthy dairy cows during early lactation using bacteriological and PMN-pathogen interaction assays. Latex-stimulated luminol-amplified chemiluminescence (CL) and viability of these PMN were also investigated. The phagocytosis and killing of S. aureus by blood were remarkably higher than those of milk PMN. Similarly, the CL and viability in blood PMN were markedly higher than in milk PMN. Both in blood and in milk the phagocytosis of S. aureus by PMN in primiparous cows was substantially higher than in multiparous cows. The killing activity of blood PMN against S. aureus was 42.3+/-3.4% and 23.2+/-1.7% in primiparous and multiparous, respectively. Milk PMN killed only 20.7+/-2% S. aureus in primiparous and 10.2+/-1.3% in multiparous cows. Blood and milk PMN CL and milk PMN viability were significantly higher in primiparous cows. The pronounced reduction in phagocytic and bactericidal activity in blood and milk-resident PMN from multiparous cows, in part, resulted from the pronounced decrease of PMN viability and free radicals production capacity; this suggests that heifers' udders could be more protected against S. aureus, which remains to be tested in the field.  相似文献   

20.
The growth and the toxin (i.e. hemolysin) producing capacity of Corynebacterium pyogenes were studied in monocultures and in co-cultures with 1 or more of the organisms frequently accompanying it in summer mastitis in cattle (Peptococcus indolicus, Stuart-Schwan cocci, Bacteroides melaninogenicus subsp. levii, Fusobacterium necrophorum and Streptococcus dysgalactiae) or with organisms seldom associated with summer mastitis (Streptococcus uberis, Streptococcus agalactiae, non-toxic staphylococci and Escherichia coli).Pc. indolicus, and to some extent also Stuart-Schwan cocci, stimulated the growth as well as the hemolysin producing capacity of Gb. pyogenes (Table 1) while Str. dysgalactiae, Str. uberis, Str. agalactiae, E. coli and the majority of the staphylococci reduced these activities. Most F. necrophorum strains stimulated the growth, but not the hemolytic activity. With B. melaninogenicus the results were inconclusive.The effect of Pc. indolicus appeared to be associated with the production of a filterable factor (Tables 2 and 3).Mouse toxicity and hemolytic activity of culture filtrates were closely correlated (Table 4).  相似文献   

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