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Biomedical subjects

W Witte

Publications and source records attributed to W Witte.

At least 91 records · Page 5Linked to original sources
PubMed1994

Susceptibility to desferrioxamines and other chelators of coagulase-negative staphylococci.

A total of 233 staphylococci and micrococci belonging to 17 species were tested for their susceptibility to desferrioxamines B, G and E, respectively. Using an agar diffusion method on iron poor media, all of the S. epidermidis, 12 out of 22 S. hominis and 5 out of 22 S. capitis strains were susceptible to desferrioxamines. Among the S. capitis strains tested, two of them were susceptible to desferrioxamine E and resistant to desferrioxamines B and G. All other staphylococci and micrococci tested were resistant to desferrioxamines B, G and E. Different susceptibility to 5 mM ethylenediaminedi-(o-phenylacetic acid) as an artificial chelator demonstrated the existence of additional iron-supplying systems in staphylococci and micrococci.

Chelating Agents↗
PubMed1994

Clonal dissemination of two MRSA strains in Germany.

Clonal dissemination of two different MRSA strains, both clumping factor negative, has been observed in Germany for more than a year. Both strains possess the mec-A determinant and each exhibits a characteristic genomic DNA fragment pattern. One strain has spread in the north, the other in the south-west of Germany. Intensive care units are mainly affected by MRSA-infections and probably play a special role in further intra- and inter-hospital spread.

Bacteriophage Typing↗
PubMed1994

Cell surface hydrophobicity and adherence to extra-cellular matrix proteins in two collections of methicillin-resistant Staphylococcus aureus.

Non-specific and specific mechanisms of adherence have been examined in two collections of methicillin-resistant Staphylococcus aureus (MRSA). Determination of hydrophobicity by salt aggregation, hydrophobicity indices and of adherence to the extra-cellular matrix proteins fibronectin, vitronectin, laminin and collagen type 1 have failed to reveal any correlation with phage-type, plasmid profile or antibiogram. Further, the strain collections, made over a period of years in two countries, differ markedly in their adherence characteristics; MRSA are heterogeneous in this respect. Such heterogeneity may explain the polarization of views on the epidemicity or 'virulence' of MRSA. With the exception of adherence to collagen a small group of methicillin sensitive S. aureus had characteristics intermediate between the two groups of MRSA.

Agglutination Tests↗
PubMed1994

Staphylococcus aureus strains of type 95. Spread of a single clone.

Staphylococcus aureus strains of type 95 in Denmark have increased to a frequency of 20% of the total S. aureus population. A clonal origin and possible subdivision of these strains have been discussed. In the present investigation 35 epidemiologically unrelated S. aureus strains of type 95 as well as reference strains of other types have been analysed by other typing techniques including lectin-typing, multilocus enzyme electrophoresis and pulsed-field gel electrophoresis of genomic restriction fragments. No subdivision could be achieved based on any of these methods and a clonal origin seems therefore possible.

Arsenates↗
PubMed1994

[Nosocomial infections with the detection of Staphylococcus aureus in an average hospital--an 11-year analysis].

Nosocomial infections over an 11 years period were monitored prospectively in a district hospital. A total of nosocomial infections among 162.197 patients discharged from 1980-1990 were analyzed. The incidence rate of nosocomial infections was 3.6%. The predominant isolates were Escherichia coli and Staphylococcus aureus (11%). The highest rates of S. aureus infections were established in wound infections and skin and mucosal infections at surgery, gynaecology and paediatrics departments. The number of multiply resistant S. aureus strains has decreased and those of sensitive isolates has increased. 72% of 652 S. aureus isolates have been typed by phage typing and biotyping. Statistical analysis could not establish a significant relationship between phage patterns and nosocomial infections. The spectrum of phage patterns of these nosocomial strains was the same as those of the endogenous colonization of men. Nosocomial outbreaks could not been realized.

Bacteriophage Typing↗
PubMed1993

Environmental strains of Enterococcus faecium with inducible high-level resistance to glycopeptides.

High-level resistance to glycopeptides in Enterococcus faecium is associated with an inducible 39-kDa cytoplasmic membrane protein. The present paper shows that such glycopeptide-resistant E. faecium strains can not only be isolated in a definite clinical setting but also from waste water of sewage treatment plants. Nearer characterization of these and of clinical isolates by resistance pattern, biotyping, and genotyping (DNA-fingerprinting with pulsed-field gel electrophoresis) has shown that different glycopeptide-resistant E. faecium strains have been isolated from clinical sources and from waste water.

DNA Fingerprinting↗
PubMed1993

Unrelatedness of multiply resistant Staphylococcus aureus with resistance to methicillin and to quinolones (QR-MRSA) as evident from SmaI-digestion patterns of genomic DNA.

Methicillin-resistant S. aureus with quinolone-resistance (QR-MRSA) isolated in Germany from three outbreaks of nosocomial infections and from sporadic nosocomial infections in five hospitals exhibited different SmaI-restriction patterns of their genomic DNA. Phage-typing and determination of plasmid profiles performed in parallel confirmed this differentiation, with one exception. These results indicate that there is obviously no overregional spread of one particular QR-MRSA clone and that quinolone resistance has developed independently in different MRSA.

Bacterial Typing Techniques↗
PubMed1993

Outbreak of nosocomial infections with two different MRSA-strains involved: significance of genomic DNA fragment patterns in strains otherwise difficult to type.

Methicillin-resistant Staphylococcus aureus isolates from an outbreak of 17 cases of wound infection in a municipal hospital were typed by conventional methods, phage typing by three sets of phages, reverse phage typing and plasmid profiles, as well as by genomic DNA fragment patterns obtained after Sma-I digestion and pulsed-field electrophoresis. These isolates were non-typable by phages, only some were typable by reverse phage typing and were not uniform in plasmid profile. Only the genomic DNA fragment patterns resulted in a clear discrimination of 2 strains (12 isolates for the first and 7 isolates for the second). Both strains were disseminated in different wards of the same hospital and one strain had obviously spread to another clinic in the same city.

Bacterial Typing Techniques↗
PubMed1993

Typing of Staphylococcus aureus by pulsed-field gel electrophoresis, zymotyping, capsular typing, and phage typing: resolution of clonal relationships.

Sixty-nine Staphylococcus aureus isolates from two epidemiologically unrelated sources were typed by pulsed-field gel electrophoresis after SmaI digestion of chromosomal DNA (genome typing), and the results were compared with those obtained by other typing methods: phage typing with the international set of phages, capsular serotyping with monoclonal antibodies against capsular polysaccharides type 5 and 8, and zymotyping by polyacrylamide agarose electrophoresis for esterase polymorphism. A good correlation of S. aureus types was found by these four typing methods. Differentiation increased in the order capsular typing < zymotyping < phage typing < genome typing, yielding 2, 10, 20, and 26 different S. aureus types, respectively. Five of the 26 genome types were further divided into several subtypes revealing clonal relationships. When 36 French S. aureus isolates were compared with 33 German S. aureus isolates, 3 strains representing clonal populations were identical in both groups. S. aureus isolates from patients with cystic fibrosis were also typed at the beginning and the end of a 4-week summer camp for these patients. The results suggested a possible strain transmission during the summer camp. We conclude that genome typing by pulsed-field gel electrophoresis is a powerful tool not only for strain identification but also for the resolution of the clonal relationships of S. aureus strains.

Bacterial Typing Techniques↗
PubMed1992

Pulsed-field gel electrophoresis of genomic restriction fragments as a tool for the epidemiological analysis of Staphylococcus aureus and coagulase-negative staphylococci.

Thirteen Staphylococcus aureus and S. epidermidis strains obtained from nose and hand of two employees and one patient of a medical ward as well as two S. hemolyticus strains were analysed according to their restriction fragment length patterns (RFLP) by pulsed-field gel electrophoresis (PFGE) using the restriction enzymes SmaI and SstII. Species identification of the isolates was performed by a system which includes 20 biochemical reactions. Furthermore, the antibiotic resistance patterns of the strains were determined. While several isolates exhibited identical antibiotic susceptibilities and biochemical profiles, differences in the RFLP were obtained. In three cases, S. epidermidis strains colonizing the skin showed an identical restriction profile as isolates from the mucous membranes of the same person. We concluded that the analysis of staphylococcal strains by PFGE is an important epidemiological tool with high discrimination power.

Bacterial Typing Techniques↗
PubMed1992

Occurrence of quinolone resistance in Staphylococcus aureus from nosocomial infection.

Among 63 Staphylococcus aureus isolates (one isolate per one patient) counted from infections (from August to November 1991) in hospital T., eight exhibited resistance to fluoroquinolones. Seven of these quinolone-resistant isolates were multiply- and methicillin-resistant S. aureus (QR-MRSA). The results of phage-, plasmid- and genotyping (pulsed field electrophoresis) revealed that six different strain-clones of these MRSA were spread in the hospital. In vitro spontaneous mutants resistant to fluoroquinolones are 10-100-fold more frequent in MRSA than in other S. aureus when selected on isosensitest-agar containing 1 microgram/ml of ciprofloxacin. However, the same mutant frequencies were found in strain 8325-4 with and without the mecA-determinant. The resistance phenotype was stable over 30 generations of subculture in nutrient broth as well in natural quinolone resistant MRSA as in mutants of other types of S. aureus selected in vitro. The phenotypic association of quinolone resistance and MRSA is rather likely due to a higher frequency of spontaneous resistant mutants which are present in natural populations of MRSA. Data of chemotherapy prior to the isolation of S. aureus show that three of seven patients from whom QR-MRSA were isolated were treated with a quinolone. In eight cases of infections with non-MRSA and quinolone treatment the isolated S. aureus strains were in vitro sensitive to quinolones.

Anti-Infective Agents↗
PubMed1992

Overproduction of a penicillin-binding protein is not the only mechanism of penicillin resistance in Enterococcus faecium.

In 1989 and 1990, a large number of ampicillin-resistant strains of Enterococcus faecium were isolated from infected patients treated at intensive care units in Berlin, Germany. Twenty-five clinical isolates, including five different biotypes as classified by acid production from various sugars and a wide range of susceptibilities to ampicillin (MICs between 0.5 and 128 micrograms/ml), were selected for a detailed analysis of penicillin-binding proteins (PBPs). All strains contained a slowly reacting PBP with low penicillin affinity known to be present in enterococci. Overproduction of this PBP relative to susceptible isolates was noted, especially in all strains for which the MIC of ampicillin was 8 micrograms/ml, to a lesser degree in the more resistant strains, but not at all in the three highly resistant isolates for which the MIC was 128 micrograms/ml. In these three strains, this PBP appears to have a reduced affinity for beta-lactams. The results suggest that overproduction of PBP 6 correlates only with intermediate resistance levels and that higher resistance is mediated by yet another, still unknown mechanism, probably including reduction of beta-lactam affinity in one or more PBPs.

Bacterial Proteins↗
PubMed1991

[Decreasing oxytetracycline resistance in Enterobacteriaceae in veterinary and health conditions after exchange of this substance in animal nutrition].

The national strategy for the use of chemotherapeutics under which there is a distinction between therapeutics and growth promoters for all uses (human medicine, veterinary medicine, animal nutrition) has resulted in a distinct reduction of the selection pressure and a decrease of the OTC resistance among Enterobacteriaceae in the eastern German Länder (formerly GDR) due to a reduction of OTC feeding after 1981 and the final prohibition in 1983. In the following years Enterobacteriaceae were investigated as infectious pathogens for humans and animals using antibiograms. On the one hand, the OTC resistance of porcine and bovine E. coli strains decreased only by 27% and 17%, respectively, during the 1980 to 1988 period, on the other, the OTC resistance of bovine S. typhimurium dropped by 65%, porcine S. typhimurium by 50%, bovine S. dublin by 50%, porcine S. choleraesuis by 30% to a resistance level of about 13% (1989) demonstrating a reduced pressure of resistance. At the same time, OTC resistance became diminished from 50% and 70%, respectively, to 30% also in Enterobacteriaceae (E. coli, Klebsiella) and enterococci isolated from urine and wound infections of patients in the non-agricultural population although therapeutic habits had remained unchanged. The results shown point to a spreading of resistance plasmids which has to be expected far beyond the field of OTC use, for example after the use of antibacterial growth promoters in livestock farming. Control measures should be introduced.

Animal Feed↗
PubMed1991

[Differentiation of methicillin-resistant strains of Staphylococcus aureus by prophage specificity].

By inducing with mitomycin C the following phages were isolated from all the tested 32 methicillin resistant strains of S. aureus: the serogroup B phage was isolated from 2 strains, the serogroup B and F phages were isolated from 5 strains and the serogroup F phage was isolated from 25 strains. The phages were divided into 5 groups by the antiphage immunity. In group 1 of the phages 4 additional phages were specified. By the specificity of the prophages in the cultures all the strains were divided into 5 groups. Group 1 of the cultures was divided into 5 subgroups (A, B, C, D and E).

Bacteriophage Typing↗
PubMed1991

[Effect of prophages on transfer frequency of conjugative plasmid G 873].

Transfer of the conjugative plasmid G873 on filters and mixed cultivation of the donor and recipient cells in liquid media is described. In the both systems the use of the lysogenic recipient cells (phages of serogroups B and F) in the crossings increased mor than 100-fold the frequency of plasmid transfer. The conjugative transfer of the plasmid in the mixed cultivation system was proved. The conjugative transfer required the presence (while not obligatory) of calcium chloride and was restricted by the serum factors.

Animals↗
PubMed1990

Instability of in vitro resistance to imipenem in Pseudomonas aeruginosa.

In 3 from 19 clinical isolates of Pseudomonas aeruginosa imipenem-resistant subpopulations could be detected in vitro. In comparison to their wild strains these imipenem-resistant cells were lacking an outer-membrane-protein of 50 kD. In the subpopulation derived from Pseudomonas aeruginosa 76 resistance to imipenem was found to be instable. It could be lost within a short period of time after subcultivation in the absence of imipenem. Cells with restored sensitivity to imipenem possess the outer membrane protein of 50 kD as the wild strain does.

Azlocillin↗