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U Vecht

Publications and source records attributed to U Vecht.

36 records · Page 2Linked to original sources
PubMed1993

Discrimination between virulent and nonvirulent Streptococcus suis type 2 strains by enzyme-linked immunosorbent assay.

Discrimination between virulent and nonvirulent strains of Streptococcus suis type 2 will allow proper diagnosis of diseased pigs and the identification of carrier pigs. To discriminate between virulent and nonvirulent strains, we developed two double antibody sandwich (DAS) enzyme-linked immunosorbent assays (ELISA) using specific monoclonal antibodies directed against two virulence markers of S. suis type 2. One mAb was directed against the 136-kilodalton (kDa) cell-wall-associated protein, designated muramidase-released-protein (MRP). The other mAb was directed against a 110-kDa extracellular protein, provisionally called extracellular factor (EF). We examined 179 strains of S. suis serotype 2, 22 strains of S. suis serotypes 1 to 22, 22 other streptococci, 20 other bacterial strains, and one yeast. The ELISA results were almost identical with western blot analysis of these strains. Visual readings of the two DAS-ELISAs were enough to discriminate accurately between the three phenotypes of S. suis type 2. We concluded that the two DAS-ELISAs are reliable, rapid, and simple assays to identify virulent strains of S. suis type 2.

Animals↗
PubMed1993

Repeats in an extracellular protein of weakly pathogenic strains of Streptococcus suis type 2 are absent in pathogenic strains.

Streptococcus suis type 2 strains that are pathogenic for pigs produce a 110-kDa extracellular protein factor (EF). Nonpathogenic and weakly pathogenic strains do not produce EF or produce a protein (EF*) that is immunologically related to EF. To study the pathogenesis of S. suis type 2 in pigs and to develop tools and methods for the control of S. suis type 2 infections, we cloned and characterized the genes encoding EF and various EF* proteins. Analysis of the deduced amino acid sequences showed that the first 833 amino acids at the N terminus of the EF and EF* proteins were nearly identical. The proteins differed, however, at their C termini. Unlike the 110-kDa EF protein, the EF* proteins contained several repeated units of 76 amino acids. The number and arrangement of the repeats in the EF* proteins varied. The data suggest that the gene encoding EF could have evolved from an epf* gene by a specific deletion event. The lack of repeated amino acid units in the EF protein may be related to virulence.

Amino Acid Sequence↗
PubMed1992

Virulence of Streptococcus suis type 2 strains in newborn germfree pigs depends on phenotype.

To determine whether the virulence of Streptococcus suis type 2 is associated with the phenotype of the strain, we infected newborn germfree pigs with 10 strains of S. suis type 2 categorized by three phenotypes. In an earlier study, the phenotypes were distinguished by the presence or absence of the muramidase-released protein (MRP) and an extracellular factor (EF) and were designated MRP+ EF+, MRP+ EF- and MRP- EF-. Pigs were first inoculated with Bordetella bronchiseptica to predispose them to infection and were then intranasally inoculated with the streptococci. Strains of the MRP+ EF+ phenotype induced fever and increased the number of polymorphonuclear leukocytes in blood. Specific clinical signs of disease such as nervous disorders and lameness were also observed. At necropsy bacteriologic and pathologic examination disclosed meningoencephalitis, polyserositis, and polyarthritis. Strains of the MRP+ EF- phenotype induced only nonspecific clinical signs of disease such as recumbency, lack of appetite, and fever; only slight pathologic changes were detected in the serosae. The four strains of the MRP- EF- phenotype induced no signs of disease. These findings indicate that the 110-kDa EF and, to a lesser degree, the 136-kDa MRP may be associated with the virulence of the bacterium. The results demonstrated that S. suis type 2 strains producing both MRP and EF are pathogenic for pigs.

Animals↗
PubMed1992

Cloning and nucleotide sequence of the gene encoding the 136-kilodalton surface protein (muramidase-released protein) of Streptococcus suis type 2.

We cloned and sequenced the gene encoding the muramidase-released protein (MRP) of a pathogenic Streptococcus suis type 2 strain to determine whether its amino acid sequence resembles that of proteins with known functions and to determine its function in virulence. The complete nucleotide sequence composing the gene and the regions flanking it was determined. The deduced amino acid sequence revealed the presence of a signal peptide at the N terminus and a cell envelope anchor at the C terminus, both of which resembled similar regions in several other surface proteins from gram-positive bacteria. The processed form of MRP has a length of 1,209 amino acids and a calculated molecular weight of 131,094. A highly repetitive region preceded the envelope anchor. The repeated units were preceded by a proline-rich stretch of amino acids (26 of 86). No overall homologies were observed between the amino acid sequence of MRP and protein sequences in the EMBL data bank. A particular region within the amino acid sequence, however, showed some similarity with the fibronectin-binding protein of Staphylococcus aureus. Binding of MRP to human fibronectin, however, could not be confirmed.

Amino Acid Sequence↗
PubMed1991

Effect of damage to the teat end on the experimental induction of mastitis in dry cows with Corynebacterium pyogenes.

The teat ends of 12 dry cows were contaminated with Corynebacterium pyogenes. To determine whether a pre-existing (an)aerobic bacterial infection of the udder was a predisposing factor for a C pyogenes mastitis they included infected and uninfected quarters. Anaerobic bacteria could not be found and mastitis was not induced. When the teats were contaminated with C pyogenes after the teat ends had been injured 30 of the quarters became infected, and anaerobic bacteria were demonstrated in many quarters.

Animals↗
PubMed1991

Identification of two proteins associated with virulence of Streptococcus suis type 2.

The protein profiles of various cell fractions of 180 strains of Streptococcus suis type 2, which were isolated from diseased pigs, from healthy pigs when they were slaughtered, and from human patients, were analyzed by sodium dodecyl sulfate-polyacrylamide gel electrophoresis and immunoblotting. The isolates from diseased pigs contained two proteins that were absent in most of the isolates from healthy pigs. One of these proteins was a 136-kDa protein that was previously identified as the muramidase-released protein (MRP). This protein was predominantly detected in protoplast supernatants and culture supernatants. The second protein was a 110-kDa protein that was detected only in culture supernatants and therefore was provisionally called extracellular factor (EF). Three phenotypes of S. suis type 2 strains were recognized. Isolates from organs of diseased pigs mainly belonged to the MRP+ EF+ phenotype (77%), while isolates from tonsils of healthy pigs mainly had the MRP- EF- phenotype (86%). Most of the isolates from human patients contained MRP (89%); 74% had the MRP+ EF- phenotype. These findings confirm the results of previous investigations which demonstrated that S. suis type 2 strains differ in virulence. Monoclonal antibodies raised against the 110-kDa EF recognized proteins with higher molecular weights in culture supernatants of all of the strains with the MRP+ EF- phenotype. However, none of the strains with the MRP+ EF+ phenotype produced these high-molecular-weight proteins. Our results demonstrate that MRP and EF are associated with virulence. This suggests that one or both of these proteins are virulence factors that play a role in the pathogenesis of S. suis type 2 infections in pigs and human patients.

Animals↗
PubMed1989

[Sensitivity pattern of Staphylococcus aureus isolated from quarter milk from cattle].

Strains of Staphylococcus aureus (n = 319) from bovine quarter milk were tested for susceptibility to antimicrobial drugs. The minimum inhibitory concentration (MIC), was determined by agar dilution methods, and the diameter of the inhibition area was determined by agar diffusion methods. In addition beta-lactamase production was tested. The strains tested showed resistance to penicillin, (38.4%), oxytetracyclin (21.2%), and streptomycin (11.5%). Little or no resistance was found to the other antimicrobials in this study. A strong correlation between dilution and diffusion methods was calculated for oxytetracyclin: r = 0.88, and for streptomycin: r = -0.90; correlation for penicillin was weaker: r = -0.66. Since 17% of the strains with an MIC for penicillin less than 0.16 mg/L are still able to produce beta-lactamase, we recommend that when antibiotic susceptibility of staphylococci is examined, beta-lactamase production should also be tested. Dapsone, a sulfone compound, formerly not considered a chemotherapeutical drug under Dutch law, had an MIC less than or equal to 0.64 mg/L for 85% of the strains. Therefore, we recommend that sulfone compounds should be registered under the new Veterinary Medicines Act. Since the resistance patterns of S. aureus strains to most antimicrobial drugs were the same as those seen in earlier studies, we find no reason to resort to new generations of broad-spectrum antibiotics in routine prevention and treatment of mastitis.

Animals↗
PubMed1989

Differences in virulence between two strains of Streptococcus suis type II after experimentally induced infection of newborn germ-free pigs.

Fifteen newborn germ-free pigs were inoculated with 2 strains, D-282 and T-15, of Streptococcus suis type II. Some pigs also were preinoculated with Bordetella bronchiseptica, which successfully predisposed them to S suis infection. The 2 streptococcal strains were differentiated by muramidase treatment, which released certain high molecular-weight proteins, termed muramidase-released proteins (MRP), from the cell wall of strain D-282, but not from the cell wall of strain T-15. Only strain D-282 (MRP-positive) induced clinical signs of disease and markedly increased neutrophil numbers in pigs. Streptococci were more frequently isolated from fecal swab specimens obtained from pigs inoculated with strain D-282 (MRP-positive) than from specimens obtained from pigs inoculated with strain T-15 (MRP-negative). Both strains were isolated from nasal swab specimens obtained from all infected pigs. Postmortem examination revealed fibrinopurulent meningitis, polyserositis, and polyarthritis in pigs inoculated with strain D-282; this strain was isolated from the CNS, serosae, visceral organs, heart, and joints. Whereas strains D-282 caused several pathologic changes, strain T-15, isolated from the lungs, caused only pneumonia. Both strains were isolated from the tonsils of all pigs. Virulence differed distinctly between the MRP-positive and the MRP-negative strains.

Animals↗
PubMed1987

[Klebsiella pneumoniae mastitis as a dairying problem].

Quarter samples were taken from lactating and dry cows of a dairy herd in the Netherlands. Klebsiella pneumoniae was isolated from milk and dry udder secretum of cattle, and from the bedding of the cubicles. The animals concerned did not show any clinical symptoms. For some years Klebsiella mastitis caused severe problems on this farm. A strict hygienic program resulted in complete control of the disease. Diagnostics, therapy and prevention of Klebsiella mastitis are discussed.

Animals↗
PubMed1987

[Streptococcus suis type 2 in swine. An imported problem?].

Investigations were carried out on eighteen farms in the Province of Gelderland to determine whether it was possible to use biopsy specimens of the tonsils to differentiate between farms with clinical problems caused by Streptococcus suis type 2 and farms without these problems. The proportion of carriers of this organism on the farms was 14 per cent and 2 per cent respectively, so that this differentiation is feasible. It was also studied whether this proportion differed on farms which imported pigs from Great Britain and farms which did not do so; the proportion of carriers on farms having animals imported from Great Britain was found to be higher than that on farms not using these importations, viz., 17 per cent and one per cent respectively.

Animals↗
PubMed1987

[Milk cell count as a selection criterion in breeding dairy cattle with improved resistance to mastitis].

The cell counts in the milk of female progeny of thirty-one bulls of the Meuse-Rhine-IJssel breed were determined in three breeding areas in the Netherlands, viz., in the provinces of Overijssel, Gelderland and North Brabant. The individual cell counts of the milk of 1,741 females in their first lactations were determined in study I. Eleven bulls, the female progeny of which showed high or low average cell counts in the milk, were selected on the basis of these results. The quarter milk of older females sired by these eleven bulls was studied (bacteriological examination and determination of cell counts). Females in their first and second lactations were examined in study II. This was done in 1,071 females sired by ten of the initially selected eleven bulls. The heritability of the cell counts in the milk of the females sired by thirty-one bulls, which cows were in their first lactations, was 0.081. On the basis of geometric means of the cell counts in the milk of the females in their first lactations, the rank order of the bulls which had sired them corresponded inadequately with that of half-sibs in their third and fourth lactations. In study II, the similarity in rank order of these two age groups was much better: groups of female progeny averaging low cell counts and percentages in their first lactations corresponded with low cell count averages and percentages of quarters of older half-sib progeny in their third and fourth lactations, which quarters were found to be positive on bacteriological examination. There were some differences in rank order.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1987

The detection of obligate anaerobic bacteria in udder secretions of dry cattle with mastitis during summer: a comparison between gas-liquid chromatography and bacteriological culturing methods.

Udder secretions sampled during the summer in 1984 and 1985 from mastitic quarters of 51 non-lactating cattle, mainly heifers less than 2 years of age, were examined bacteriologically for the presence of (facultative) aerobic and obligate anaerobic bacteria (OAB) and by gas-liquid chromatography (GLC) in order to detect volatile fatty acids (VFA), metabolic end-products of OAB. Forty-nine samples yielded positive cultures and in 20 cases these were mixtures of (facultative) aerobes and OAB. Only two specimens appeared to be sterile and from one specimen only were OAB cultured. Corynebacterium pyogenes was isolated from 35% of the cases and Peptococcus indolicus and Fusobacterium necrophorum from 31 and 22%, respectively. In most specimens (19/21) which yielded OAB after culturing, VFA (C3-C6) could be detected by GLC. Detection of VFA in summer mastitis secretions appeared to be a useful technique to evaluate the importance and association of OAB with summer mastitis. Because samples can be easily collected and stored at -20 degrees C, this is especially advantageous in situations where adequate facilities for the isolation of OAB are not readily available.

Acute Disease↗
PubMed1987

Streptococcus suis type 2 infections in pigs in the Netherlands (Part two).

Since 1983 some pig breeding and fattening farms in the Netherlands have been faced with a considerable mortality in pigs due to Streptococcus suis type 2 infections. The most predominant clinical feature of S. suis type 2 infection is meningitis, although sudden deaths often occur. It was noted that some affected farms had imported breeding stock from the United Kingdom. Tonsils of slaughter pigs were collected from herds with and without a history of S. suis type 2 infections. Bacteriological examination was done by using an elective-selective medium. No significant difference was found in carrier rates of S. suis type 2 between clinically healthy and affected herds (38% vs. 45%). A cohort study was carried out by regular bacteriological examination of tonsil biopsies on a farm with a high incidence of streptococcal meningitis. Twenty-seven percent of the pigs were carriers of S. suis type 2 at nine weeks of age. Possible methods for disease control are discussed.

Animals↗
PubMed1985

A chronic indurative mastitis in sheep, associated with maedi/visna virus infection.

A possible association of a chronic indurative mastitis with mvv (maedi visna virus) infection in sheep was investigated. Sheep of four flocks (group A), in which insufficient lamb growth apparently associated with insufficient milk production and probably related to udder induration, was a serious problem, were clinically examined in mid-lactation. The results were compared with four mvv-free flocks (group B) without such complaints. The incidence of udder induration in group A (n = 263) was about eight times higher than in group B (n = 206): 63.1 versus 8.0%. The clinical picture differed essentially between the groups. In group A the udder abnormalities were of a diffuse and indurative nature, involving both udder halves, while in group B the udder lesions were mainly nodular and often limited to one udder half. Bacteriological examination revealed a difference in infection rate of the udders (6.8% in group A versus 14.1% in group B). A substantial difference was observed in a comparison of the bacteriological infection rate of the clinically abnormal udders (5.4% in group A, versus 47.0% in group B). Serological examination with an indirect ELISA revealed 81% seropositive sheep in group A, versus 0% in group B. Twelve sheep of group A and five of group B, called for reason of mastitis, were selected for pathological examination. The gross and microscopic lesions showed a pronounced difference between both groups. In group A a diffuse interstitial mastitis with slight to moderate fibrosis and a pronounced lymphoid hyperplasia was observed. In group B the mastitis had a nodular character, with a chronic galactophoritis, extensive fibrosis, and in some cases chronic abscesses.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1985

Streptococcus suis infections in pigs in the Netherlands (Part I).

Data are presented on the incidence of various streptococcal infections in pigs in the Netherlands. 314 Strains isolated in the course of routine post-mortem diagnosis were examined. The most frequently occurring streptococcus was S. subacidus (bio) type II which was isolated in 31.2% of the cases. S. suis type 2 (Serogroup R) and S. equisimilis (Serogroup C) constituted 16.2% and 13.7% of the isolates respectively. Besides meningitis, endocarditis and polyserositis S. suis type 2 infections may frequently be associated with pneumonia (42%). The biochemical profiles of the various S. suis and S. subacidus (bio) types are presented. The profile of both species is almost identical. It seems justified to use the name S. suis for strains with this characteristic profile and to abandon the name S. subacidus. Haemolysis does not appear to be a suitable characteristic to screen for S. subacidus/S. suis types. In comparing three serological methods for typing S. suis type 2, gel precipitation using Fuller's extract and slide agglutination give an almost 100% correlation. These two methods are recommended for serotyping.

Animals↗
PubMed1985

Effect of bull selection for somatic cell count in first lactation on cell counts and pathogens in later lactations.

Somatic cell counts were measured one time on Meuse-Rhine-Ijssel cattle in The Netherlands. Experiment 1 involved 1,741 first lactation daughters of 31 bulls. Eleven bulls with daughters with either high or low average cell count were selected for further study of their daughters in third and fourth lactation. Cell counts and bacteriological tests were performed on 684 of the older daughters. A second experiment was conducted to measure daughters in second lactation and to obtain additional daughters in first lactation. This experiment recorded cell counts of 1,071 daughters of 10 of the bulls selected in Experiment 1. Heritability of the natural logarithm of cell count in first lactation was .081 based on daughters of 31 bulls in Experiment 1. Geometric daughter averages ranged from 206 to 700 X 10(3) cells/ml. Transmitting ability of bulls was estimated by the regressed least squares method. Ranking of bulls on first lactation cell count was different between the two experiments. Management factors and stage of lactation effects could be responsible for these differences. Within Experiment 2, the ranking of bulls on cell counts was nearly identical between first and second lactation. Daughter groups with low average cell count in first lactation in Experiment 2 had low averages in third and fourth lactation although some changes in ranking did occur. These results are consistent with a low to moderate genetic correlation between lactations for cell count. In general, daughter groups with higher average cell count had higher percentage of quarters with mastitis pathogens.

Animals↗
PubMed1984

[Spiramycin and the antibacterial therapy of mastitis].

The Minimum Inhibitory Concentrations (MIC) for 18 strains of staphylococci isolated from the national randomized mastitis surveys were determined. The antibiotics used were penicillin-G, cloxacillin and spiramycin. On the basis of these findings in addition to literature data concerning clinical efficacy trials it is concluded, that spiramycin is indicated for the treatment of persistent chronic udder infections caused by peniciline-G resistant strains of Staphylococcus aureus.

Animals↗