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H C Wegener

Publications and source records attributed to H C Wegener.

54 records · Page 3Linked to original sources
PubMed1995

Evaluation of phenotypic and genotypic methods for epidemiological typing of Staphylococcus aureus isolates from bovine mastitis in Denmark.

The value of five different typing methods (antibiogram typing, biotyping, phage typing, plasmid profiling and restriction fragment length polymorphism of the gene encoding 16S and 23S ribosomal RNA (ribotyping)), in discriminating 105 Staphylococcus aureus strains from bovine milk samples obtained from 105 different Danish dairy herds was investigated. A total of 85 strains (81%) proved susceptible to all of the 11 antibiotics tested, and the remaining 20 strains could be divided into 5 different antibiogram patterns. The predominant resistance pattern, penicillin resistance, was observed in 15 (75%) of the 20 antibiotic resistant strains. Biotyping assigned the strains to 14 different types, with the most common type accounting for 25.7% of the strains. Ninety eight (93.3%) strains could be typed by phages, assigning them to 19 different phage types. The predominant phage type accounted for 31.4% of the strains. Eight different plasmid profiles was observed among 24 (23%) strains harbouring plasmids. Ribotyping yielded 30 different types, with the most common accounting for 29.5% of the strains. The single most discriminatory typing method was ribotyping (0.863) followed by biotyping (0.842) and phage typing (0.795). Plasmid profiling (0.395) and antibiogram typing (0.327) had low discriminatory indices. Correspondence among ribotypes and the presence or absence of plasmids were observed, as was some degree of correspondence between ribotype, phage type and biotype. In general the correspondence between phage type and ribotype were stronger than between biotype and ribotype and between biotype and phage type. All combinations of two or more methods led to an improved index of discrimination compared to the individual methods indicating, that some subdivision of types had taken place. The combination of phage, bio- or ribotyping or all three methods in combination are considered to be an efficient combination of typing methods for epidemiological investigation of S. aureus mastitis.

Animals↗
PubMed1995

Comparison of MICs of ceftiofur and other antimicrobial agents against bacterial pathogens of swine from the United States, Canada, and Denmark.

The MICs of ceftiofur and other antimicrobial agents, tested for comparison, for 515 bacterial isolates of pigs from the United States, Canada, and Denmark with various diseases were compared. The organisms tested included Actinobacillus pleuropneumoniae, Escherichia coli, Pasteurella multocida, Salmonella choleraesuis, Salmonella typhimurium, Streptococcus suis, Streptococcus dysgalactiae subsp. equisimilis, Streptococcus equi subsp. equi, and Streptococcus equi subsp. zooepidemicus. In addition to ceftiofur, the following antimicrobial agents or combinations were tested: enrofloxacin, ampicillin, sulfamethazine, trimethoprim-sulfadiazine (1:19), erythromycin, lincomycin, spectinomycin, lincomycin-spectinomycin (1:8), tilmicosin, and tetracycline. Tilmicosin was only tested against the U.S. isolates. Overall, ceftiofur and enrofloxacin were the most active antimicrobial agents tested against all isolates, with MICs inhibiting 90% of isolates tested (MIC90s) of < or = 2.0 and < or = 1.0 microgram/ml, respectively. Erythromycin, sulfamethazine, spectinomycin, and lincomycin demonstrated limited activity against all of the organisms tested, with MIC90s of > or = 8.0, > or = 256.0, > or = 32.0, and > or = 16.0 micrograms/ml, respectively. Trimethoprim-sulfadiazine was active against isolates of A. pleuropneumoniae, S. choleraesuis, S. typhimurium, P. multocida, S. equi, and S. suis (MIC90s, < or = 0.5 microgram/ml) but was less active against the E. coli strains tested (MIC90, > 16.0 micrograms/ml). Ampicillin was active against the P. multocida, S. suis, and S. equi isolates tested (MIC90s, 0.5, 0.06, and 0.06 micrograms/ml, respectively) and was moderately active against S. typhimurium (MIC90s, 2.0 micrograms/ml). However, this antimicrobial agent was much less active when it was tested against A. pleuropneumoniae, S. cholerae-suis, and E. coli (MIC90s, 16.0, > 32.0, and 32.0 micrograms/ml, respectively). Against the U.S. isolates of A. pleuropneumoniae and P. multocida, tilmicosin was moderately active (MIC90s, 4.0 and 8.0 micrograms/ml, respectively). However, this compound was not active against the remaining U.S. isolates (MIC90s, > 64.0 micrograms/ml). Differences in the MICs from one country to another were not detected with enrofloxacin, ceftiofur, or lincomycin for the strains tested, but variations in the MICs of the remaining antimicrobial agents were observed.

Animals↗
PubMed1995

A comparative study of Staphylococcus aureus strains isolated from bovine subclinical mastitis during 1952-1956 and 1992.

Fifty-two strains of S. aureus isolated from cases of bovine subclinical mastitis in 52 different dairy herds in Denmark, in the periods 1952 to 1956 and 1992, were compared with regard to their phage- and EcoRI ribotypes. Furthermore, susceptibility to penicillin and production of fibrinolysin were used as additional phenotypic markers. Forty-nine strains (94%) could be separated into 12 phage types. Ribotyping assigned the 52 strains to 21 different types. Both methods showed that 57% of the 1950's strains and between 38-45% of the 1992 strains belonged to 3 dominating types. The remaining strains were placed by ribotyping in 8 types occurring among the 1952-1956 strains and 10 types occurring among the 1992 strains. In 87% of the strains the results of the 2 typing methods were in accordance. However, 7 strains gave different results by the 2 methods including 2 strains with major differences. Penicillin resistance only occurred in a single genotype from the 1950's compared to 6 different genotypes among the 1992 strains.

Animals↗
PubMed1995

Antimicrobial susceptibility and rRNA gene restriction patterns among Staphylococcus intermedius from healthy dogs and from dogs suffering from pyoderma or otitis externa.

A total of 60 Staphylococcus intermedius strains from dogs were investigated by their sensitivity to various antibiotics (50 strains) and by their rRNA gene restriction patterns (ribotyping) (60 strains). Fifteen isolates were from healthy dogs, 9 with otitis externa, and 36 with pyoderma, including 10 strains from a previous study. Sixty per cent of the 50 strains tested for antibiotic susceptibility demonstrated resistance to penicillin, 24% to spiramycin, 20% to tetracycline, 16% to chloramphenicol, and 2% to fucidic acid. All isolates were susceptible to amoxycillin with clavulanic acid, enrofloxacin, and sulphonamides with trimethoprim. There were no significant differences in antimicrobial susceptibility patterns observed among isolates from pyoderma, otitis externa or healthy dogs. Among the 60 strains studied by ribotyping, 10 different ribotypes were identified: 6 different ribotypes among isolates from otitis externa, 8 among isolates from pyoderma, and 5 among isolates from healthy dogs. One ribotype (profile C) was dominant among the isolates from healthy dogs while another ribotype (profile A) was dominant among strains from dogs suffering from pyoderma. This profile was not demonstrated in any of the strains from healthy dogs. From 5 different dogs suffering from pyoderma, 2 different clones were demonstrated based on their plasmid profile and antibiogram. In these dogs 1 of the clones always belonged to ribotype A. The results concerning strains of S. intermedius isolated from furunculosis suggest the existence of distinct subpopulations with different pathogenicity to dogs.

Animals↗
PubMed1995

Staphylococcal and other bacterial species associated with intramammary infections in Danish dairy herds.

Four thousand six hundred forty-five quarter milk samples from 1179 cows from 20 commercial dairy herds were examined in order to determine the prevalence of bacterial species. A total of 859 isolates from 839 (18.1%) culture positive samples could be assigned to 34 different species and subspecies. Diagnostics of staphylococcal species was based on conventional procedures able to differentiate between all 36 species and subspecies presently acknowledged. Staphylococcus aureus was found in 10.2% of the samples and was the most common species isolated. Streptococcus dysgalactiae (1.6%) and Streptococcus uberis (1.4%) were the second and third most common species isolated. Seventeen different coagulase negative staphylococcal species (CNS) were found in 4.1% of the samples. The most frequently isolated CNS were S. epidermidis (1.3%), S. chromogenes (1.0%) and S. simulans (0.7%). Isolates of S. aureus were phage typed, and isolates of S. epidermidis were investigated by phage typing, antibiogram typing, and biotyping. A total of 378 (79.9%) isolates of S. aureus could be typed by phages, assigning them to 18 different phage types. However, 6 phage types accounted for 92.1% of the typable isolates. One to 2 phage types predominated within each herd. Eleven (18%) isolates of S. epidermidis could be typed by phages, assigning the isolates to 3 different types. Biotyping of S. epidermidis produced a total of 8 different types, the most common accounting for 29.5% of the isolates. A total of 6 different antibiogram types were observed among all isolates of S. epidermidis. Resistance towards penicillin (36.1%), tetracycline (9.8%) and streptomycin (9.8%), were recorded in the isolates of S. epidermidis. However, 35 (57.4%) of the isolates were susceptible to all 12 antibiotics tested.

Animals↗
PubMed1994

Salmonella typhimurium phage types from human salmonellosis in Denmark 1988-1993.

A total of 989 isolates of Salmonella enterica ssp. enterica serovar Typhimurium from cases of human salmonellosis were investigated by phage typing. The isolates comprised all isolates recovered during the month of August in each of the years from 1988 to 1993. Phage typing assigned 82.6% of the strains to 36 different definitive types, 11.9% of the strains belonged to types of unknown lysis pattern (RDNC), and 5.5% could not be typed by the phages used (NT). Three phage types (12, 66 and 110) made up approximately 50% of the isolates in each of the years investigated. During the period in question these types showed major changes in prevalence: phage type 12 increased from 4.0% in 1988 to a maximum of 55.2% in 1992, and phage type 66 and phage type 110 were reduced from 40.1% and 27.8% to a minimum of 3.9% and 4.8% in 1993 and 1992, respectively. The increasing prevalence of phage type 12 among isolates from human salmonellosis most likely reflects the increasing significance of pork as a source of human salmonellosis. The reduction in phage types 66 and 110 is paralleled by a reduction in S. Typhimurium in Danish poultry. Some phage types were associated with travel, namely 17, 193 and 194. It is concluded that phage typing, although here performed retrospectively, produces valuable epidemiological information regarding changes in the relative importance of different sources of infection in humans. It is suggested that phage typing be performed prospectively on both human and animal S. Typhimurium isolates in Denmark.

Bacteriophage Typing↗
PubMed1994

Antimicrobial susceptibility of Staphylococcus hyicus isolated from exudative epidermitis in pigs.

Exudative epidermitis or greasy pig syndrome is caused by the coagulase-variable staphylococcal species Staphylococcus hyicus. Treatment of this disease is problematic because of the limited number of antimicrobial agents available for this purpose. Thirteen antimicrobial agents were evaluated for their activities against 100 S. hyicus strains isolated from pigs with exudative epidermitis. Novobiocin was the most active compound tested, with an MIC for 90% of the strains tested (MIC90) of < or = 0.06 microgram/ml. Enrofloxacin, ampicillin, and ceftiofur were the next most active compounds, with MIC90s of 0.25, 0.5, and 1.0 microgram/ml, respectively. However, 41.4% of the 99 strains tested were positive for beta-lactamase production. The MIC90s of erythromycin, tetracycline, and streptomycin were > 32.0 micrograms/ml. Initial testing with sulfadiazine-trimethoprim yielded an MIC90 of > 64.0 micrograms/ml, but subsequent testing with thymidine phosphorylase-supplemented medium yielded an MIC90 of 0.06 microgram/ml. Both lincomycin and spectinomycin were relatively inactive against the S. hyicus strains tested, with MIC90s of > 64.0 and > 128.0 micrograms/ml, respectively. However, the combination of the two compounds at ratios of 1:2 (lincomycin to spectinomycin) and 1:8 were more active, with MIC90s of 16.0 and 4.0 micrograms/ml, respectively. These results indicate that novobiocin and sulfadiazine-trimethoprim were the most active compounds tested against the S. hyicus strains isolated from pigs with exudative epidermitis. Furthermore, the combination of lincomycin and spectinomycin was more active than the individual compounds against the strains tested.

Animals↗
PubMed1994

Phage types of Salmonella enterica ssp. enterica serovar typhimurium isolated from production animals and humans in Denmark.

S. Typhimurium is one of the 2 most common salmonella serotypes causing human salmonellosis in Denmark. In order to illustrate the significance of different production animals as a source of infection, 1461 isolates were characterized by phage typing. The isolates originated from human patients and from cattle, pigs and poultry. By phage typing the isolates could be separated in 35 different phage types. Five types (10, 12, 66, 110 and 135) predominated and comprised 78.8% of the isolates. In humans, 57.3% of the isolates were phage type 12. This phage type was also predominant in pig herds and, to a lesser degree, in cattle. Phage types 110, 120, 135 and 193 constituted 86.5% of the poultry isolates while these phage types only made up 12.9% of the human isolates. The investigation showed that pigs are probably a major source of S. Typhimurium infection in humans in Denmark today.

Animals↗
PubMed1993

Staphylococcus hyicus-skin reactions in piglets caused by crude extracellular products and by partially purified exfoliative toxin.

Staphylococcus hyicus may cause a spontaneous generalized exudative epidermitis in piglets. The progression and regression of macroscopical and histopathological lesions in piglet skin after subcutaneous injection of sterile concentrated culture supernatant (CCS) from one virulent and one avirulent strain of S. hyicus was studied every 24 h until 144 h post-injection. CCS from the virulent strain caused local alterations of the epidermis comparable to those of spontaneous exudative epidermitis: exfoliation, crust formation, exocytosis, formation of vesicles, and pustules and acanthosis. CCS from the avirulent strain only caused a transient erythema of the skin and no histopathological alterations of the epidermis. Additionally, proteins in CCS from the virulent strain were fractionated by column chromatography. Skin reactions similar to those caused by CCS from the virulent strain were induced by one fraction of proteins that contained eight protein bands in SDS-PAGE analysis. Two of these protein bands, with molecular weights of approximately 27 kDa and 30 kDa, were unique to the virulent strain compared to the avirulent strain. The results of this study indicate that one of these two proteins or both is a heat-labile exfoliative toxin, and that the toxin is a significant factor in the pathogenesis of exudative epidermitis in piglets.

Animals↗
PubMed1993

Antibiotic-resistance and plasmids in Staphylococcus hyicus isolated from pigs with exudative epidermitis and from healthy pigs.

A total of 100 S. hyicus strains isolated from healthy piglets and piglets with exudative epidermitis originating from 100 different herds was examined for drug-resistance and prevalence of plasmids. Resistance to macrolide/linosamide antibiotics could be related to plasmids in 55 (93%) of the 59 resistant strains: A plasmid of 2.4 kb mediating resistance to macrolides and lincosamides was observed in 25 strains, and a plasmid of 11.5 kb mediating resistance to both macrolides/lincosamides and tetracycline was observed in 30 strains. A plasmid with a molecular weight of 4.5 kb was shown by curing experiments to be associated with resistance to tetracycline in 12 strains. All together, 47 strains were resistant to tetracycline. In 42 (89%) of these strains tetracycline-resistance was found to be encoded by plasmids. Fifty six strains were resistant to streptomycin, and resistance was associated with the presence of a 4.4 kb plasmid in 17 strains studied. Resistance to penicillin, observed in 44 strains, and resistance to kanamycin, observed in 15 strains, could not be related to plasmids in any of these strains. The 11.5 kb plasmid was observed in 39% of the strains isolated from piglets with EE, and in 7% of the strains isolated from healthy piglets. Despite its higher prevalence in strains from piglets with EE, the 11.5 kb plasmid could not be shown to encode production of capsule or exfoliative substances: factors which might play a role in the development of exudative epidermitis in piglets.

Animals↗
PubMed1993

Characterization of bovine Haemophilus somnus by biotyping, plasmid profiling, REA-patterns and ribotyping.

A total of 105 strains of H. somnus isolated from cattle in Denmark and other countries during 1982-1991 were compared with regard to biotypes (fermentation of 8 different sugars), plasmid profiles, Taq1 restriction endonuclease analysis of chromosomal DNA (REA-typing) and EcoRI-generated DNA restriction fragment length polymorphisms of rRNA genes (ribotyping). Eighty-four strains originating from cases of pneumonia, and 21 originating from the genitals of bulls were included in this study. Biotyping yielded 21 different types. Twenty-two of the isolates contained plasmids, and these were divided into 12 distinct plasmid profiles. Analysis of chromosomal DNA restriction patterns, resulted in 33 different REA patterns and 16 different ribopatterns in the investigated strains. Biotypes, REA-types, and ribotypes generally showed good correlation, whereas plasmid profiles did not correlate with any other typing method. Seventy-eight percent of all Danish isolates from pneumonia belonged to the same REA-, and ribotype, indicating a single clone. Furthermore, a single strain from semen belonged to this type, but generally strains isolated from the genital tract showed little homology to strains isolated from cases of pneumonia with regard to REA-, and ribotypes. The typing methods applied in the present investigation appeared to be useful indicators of epidemiological relatedness between H. somnus strains from cattle, and might be used for epidemiological investigations as well as for taxonomic studies of this species.

Animals↗
PubMed1993

Diagnostic value of phage typing, antibiogram typing, and plasmid profiling of Staphylococcus hyicus from piglets with exudative epidermitis.

A total of 989 isolates of S. hyicus were recovered from the skin of 103 piglets (9.6 isolates per piglet) with exudative epidermitis (EE), and phage typed. Phage patterns of 806 typable isolates (81%) could be divided into 44 distinct phage types. From 1 to 6 different phage types were found on individual piglets, with an average of 1.9 phage type per piglet. Antibiogram patterns of 384 isolates from 40 randomly selected piglets with EE showed a mean of 2.3 different antibiograms per investigated piglet, ranging from 1 to 6 antibiograms per piglet. Plasmid profiles of 248 S. hyicus isolates from 25 randomly selected piglets showed an average of 2.8 different plasmid profiles per piglet. Seven EE outbreaks in pig herds vaccinated with autogenous vaccine were investigated. In all these herds, strains recovered from the present outbreak differed by two or more type markers to the strains from the previous outbreak used for production of the autogenous vaccine. This finding suggest, that lack of protection might be due to the presence of other virulent types in the investigated herd than those used for production of autogenous vaccine.

Animals↗
PubMed1993

Staphylococcus hyicus virulence in relation to exudative epidermitis in pigs.

Staphylococcus hyicus strains with different phage types, plasmid profiles, and antibiotic resistance patterns were isolated from piglets with exudative epidermitis. The strains could be divided into virulent strains, producing exudative epidermitis, and avirulent strains, producing no dermal changes when injected in experimental piglets. The results showed that both virulent and avirulent strains were present simultaneously on diseased piglets. This constitutes a diagnostic problem. Concentrated culture supernatants from nine virulent strains injected in the skin of healthy piglets produced a crusting reaction in all piglets. Acanthosis was observed in the histopathological examination of the crustaceous skin. Concentrated culture supernatants from nine avirulent strains produced no macroscopic or microscopic skin changes. Protein profiles from all virulent strains and seven out of nine avirulent strains showed a high degree of protein band homology. An approximately 30 kDa protein present in all concentrated culture supernatants capable of producing skin changes, could not be detected in samples that did not produce skin changes. No other protein showed a similar association. It is concluded that crusting reaction of piglet skin is a suitable indicator of virulence in S. hyicus in relation to exudative epidermitis, and that virulent strains produce a 30 kDa protein, absent in concentrated culture supernatants from avirulent strains. This 30 kDa protein might be an exfoliative toxin.

Animals↗
PubMed1992

A longitudinal study of Staphylococcus hyicus colonization of vagina of gilts and transmission to piglets.

High Staphylococcus hyicus colonization rates were found in vaginal samples of healthy breeding sows and in skin samples of their offspring. Twenty-two different phage types were identified among the 720 isolates of S. hyicus examined. Two to 13 different phage types were isolated per herd. Phage typing, as well as characterization of about 10% of the isolates by plasmid profiles and antibiogram patterns, showed that, several different clones of S. hyicus could be present simultaneously in vagina of gilts and also on skin of piglets. Generally isolates from the vagina of one animal were identical as regards to phage types, plasmid profiles, and antibiogram patterns during the entire investigation period. Isolates from the skin of piglets were of the same type as their mothers, indicating that vertical transmission had taken place. S. hyicus strains isolated from the skin of piglets within 24 h after birth were identical to strains isolated 3 weeks after birth from the same litter, indicating that the vaginal strains became part of a stable skin flora.

Animals↗
PubMed1992

Nucleotide sequence and phylogeny of the tet(L) tetracycline resistance determinant encoded by plasmid pSTE1 from Staphylococcus hyicus.

The nucleotide sequence of the tetracycline resistance (tet) gene and its regulatory region, encoded by the plasmid pSTE1 from Staphylococcus hyicus, was determined. The tet gene was inducible by tetracycline and encoded a hydrophobic protein of 458 amino acids. Comparisons between the predicted amino acid sequences of the pSTE1-encoded Tet from S. hyicus and the previously sequenced Tet K variants from Staphylococcus aureus, Tet L variants from Bacillus cereus, Bacillus stearothermophilus, and Bacillus subtilis, Tet M variants from Streptococcus faecalis and Staphylococcus aureus as well as Tet O from Streptococcus mutans were performed. An alignment of Tet amino acid sequences revealed the presence of 30 conserved amino acids among these Tet variants. On the basis of the alignment, a phylogenetic tree was constructed. It demonstrated large evolutionary distances between the Tet M and Tet O variants on one hand and the Tet K and Tet L variants on the other hand. The pSTE1-encoded Tet proved to be closely related to the Tet L proteins originally found on small Bacillus plasmids. The observed extensive similarities in the nucleotide sequences of the tet genes and in the deduced Tet amino acid sequences allowed the assignment of the pSTE1-encoded Tet to the Tet proteins of class L.

Amino Acid Sequence↗
PubMedDate not supplied

Development of a phage typing system for Staphylococcus hyicus.

Bacteriophages were released by 98% of 100 Staphylococcus hyicus strains studied after treatment with mitomycin C. Twenty-three phages with different lytic spectra were included in a phage typing system and used for typing S. hyicus. On a test-set of 100 epidemiologically unrelated S. hyicus strains isolated from Danish pig herds, the phages were able to type 92% of the strains, producing 16 different phage types. Reproducibility of the phage typing system after subculture of the strains and using fresh phage stock was 96%. Typability ranged from 52 to 80% when typing porcine strains originating from other countries. Although phages were isolated from porcine skin strains exclusively, the system produced phage types in S. hyicus strains of bovine origin. Ten strains of S. aureus and S. chromogens were not typable by these phages. Strains belonging to one phage type (A/B/C/W) were isolated significantly more often from piglets with exudative epidermidis than from healthy piglets. The phage typing system described appears to be a valuable tool in diagnosis of exudative epidermidis in pigs, and furthermore, might be of value in epidemiological studies of S. hyicus.

Animals↗
PubMedDate not supplied

Use of antimicrobial growth promoters in food animals and Enterococcus faecium resistance to therapeutic antimicrobial drugs in Europe.

Supplementing animal feed with antimicrobial agents to enhance growth has been common practice for more than 30 years and is estimated to constitute more than half the total antimicrobial use worldwide. The potential public health consequences of this use have been debated; however, until recently, clear evidence of a health risk was not available. Accumulating evidence now indicates that the use of the glycopeptide avoparcin as a growth promoter has created in food animals a major reservoir of Enterococcus faecium, which contains the high level glycopeptide resistance determinant vanA, located on the Tn1546 transposon. Furthermore, glycopeptide-resistant strains, as well as resistance determinants, can be transmitted from animals to humans. Two antimicrobial classes expected to provide the future therapeutic options for treatment of infections with vancomycin-resistant enterococci have analogues among the growth promoters, and a huge animal reservoir of resistant E. faecium has already been created, posing a new public health problem.

Animal Feed↗