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Biomedical subjects

A Kaufhold

Publications and source records attributed to A Kaufhold.

At least 37 records · Page 2Linked to original sources
PubMed1995

Antimicrobial resistance and type distribution of Streptococcus pneumoniae isolates causing systemic infections in Germany, 1992-1994.

A prospective study of pneumococcal infections was performed in cooperation with 40 clinical microbiology laboratories in Germany. Minimal inhibitory concentration (MIC) values for 844 strains of Streptococcus pneumoniae, isolated from patients with systemic infections, were determined in tests with penicillin, tetracycline, erythromycin, chloramphenicol, cefotaxime, and clindamycin by a standard broth microdilution method; 1.8% of pneumococcal isolates exhibited reduced susceptibility to penicillin (MIC, > or = 0.1 micrograms/mL). The Etest, which was used to confirm the level of resistance to penicillin, proved to be a reliable and easily performed method for determination of MICs. The rates of resistance to clindamycin, erythromycin, tetracycline, and chloramphenicol were 1.4%, 3.2%, 11.0%, and 1.9%, respectively. Resistance to cefotaxime was not observed. Typing of a randomly selected subgroup of all strains (n = 115) showed types 1 (9.6%), 14 (8.7%), 3 (7.8%), and 23F (7.8%) to be the most prevalent types in Germany. At least 86.1% of these pneumococcal strains belonged to capsular types included in the 23-valent vaccine.

Adult↗
PubMed1995

M or M-like protein gene polymorphisms in human group G streptococci.

Many group G streptococci (GGS) isolated from infected humans (but not from animal sources) express M or M-like proteins with biological, immunochemical, and genetic features similar to those of group A streptococci (GAS). To further elucidate the recently proposed M-like protein gene (emmL gene) polymorphisms in GGS, Southern blots of genomic DNAs from 38 epidemiologically unrelated GGS strains isolated from human specimens and 12 GGS strains recovered from animal sources were hybridized with oligonucleotide probes designed to specifically detect GAS M class I and M class II M protein (emm) genes. All human-associated GGS strains showed DNA homology to the GAS M class I emm gene probe, whereas no hybridization was found with DNA from any of the animal-associated strains. The emmL genes from all human isolates were amplified by PCR, and the complete sequence of the emmL gene of the Rebecca Lancefield grouping strain D166B was determined. Again, this gene exhibited the structural features typical for emm genes of M class I GAS. The 5' regions of the PCR-amplified emmL genes of the remaining 37 human GGS strains were sequenced. This region showed a sequence diversity similar to that known for GAS emm genes. When strains whose N-terminal emmL gene sequences showed a homology of > 95% were defined as belonging to one genetic type, 30 strains were segregated into six distinct genetic types, whereas the remaining 8 strains each exhibited a unique emmL gene sequence. A high degree of homology between the N-terminal emmL gene segments of six GGS strains and the corresponding regions of either the emm12 or the emm57 gene of GAS was found, suggesting a horizontal gene transfer between strains of these species of beta-hemolytic streptococci. Besides a further understanding of the evolution of GGS emmL genes, the observed emmL gene polymorphisms in GGS could provide the basis for a molecular subspecies delineation of strains and offers the potential of typing GGS for epidemiological purposes.

Amino Acid Sequence↗
PubMed1994

Genetic variability of the emm-related gene of the large vir regulon of group A streptococci: potential intra- and intergenomic recombination events.

One of the most prevalent genetic lineages of group A streptococci (GAS) harbors a genomic locus termed the large vir regulon, which contains an emm gene encoding the antiphagocytic M protein, and structurally related fcrA and enn (emm-related) genes encoding immunoglobulin-binding proteins. In the present study more than 100 large vir regulons from 42 different GAS serotypes were analyzed by PCR and partial DNA sequencing. On comparing these data to published sequences, sites of mutational and putative recombinational events were identified and ordered with respect to their intra/intergenic or intra/intergenomic nature. The emm-related genes were found to display small intragenic deletions or insertions, were completely deleted from, or newly inserted into the genome, or were fused to adjacent genes. Intergenomic exchanges of complete emm-related genes, or segments thereof, between different vir regulons were detected. Most of these processes seem to involve short flanking direct repeats. Occasionally, the structural changes could be correlated with changes in the functions of the encoded proteins.

Amino Acid Sequence↗
PubMed1994

Rapid typing of group A streptococci by the use of DNA amplification and non-radioactive allele-specific oligonucleotide probes.

Because of the allelic variations within the M protein gene (emm gene) of group A streptococci, reliable typing of this important human pathogen can be accomplished by the use of emm gene-specific oligonucleotide probes. Two technical modifications (a reverse dot blot and a reverse line blot hybridization assay) of a novel approach for the type-specific identification of emm genes have been developed. Both procedures involved amplification of an emm gene by polymerase chain reaction. The non-radioactively labeled amplicon was subsequently hybridized to a membrane carrying an array of immobilized emm gene-specific oligonucleotide probes, thus allowing the simultaneous analysis of the gene polymorphism in a single hybridization reaction. The feasibility of these rapid and easy to perform methods was shown for the unequivocal identification of reference strains and clinical isolates belonging to 16 different M serotypes.

Alleles↗
PubMed1994

The fibronectin binding domain of the Sfb protein adhesin of Streptococcus pyogenes occurs in many group A streptococci and does not cross-react with heart myosin.

Sfb protein, a fibronectin binding adhesin of Streptococcus pyogenes (Lancefield group A streptococcus), mediates streptococcal adherence to human epithelial cells via its fibronectin binding domain coded by a repetitive gene region named fnbr. In the present study, Southern blot analysis using the fnbr gene region as a probe to screen genomic DNA from 51 epidemiologically unrelated clinical isolates of S. pyogenes revealed that 70% carried a sequence homologous to the fnbr probe. Among ten other streptococcal strains belonging to serological groups B, C, and G, DNA from only two human S. equisimilis (group C) strains reacted with the probe. Further analysis by PCR-mediated amplification of the binding repeat coding sequences revealed that repeats of different S. pyogenes isolates were identical in size but varied in number, ranging from one to five. Most of the isolates were shown to carry multiple repeats. Presence of the probe-positive sequence correlated strongly with streptococcal binding to purified fibronectin and adherence to HEp2 human epithelial cells; of the 36 probe-positive isolates, 95% bound fibronectin and 89% adhered strongly to epithelial cells, whereas among the 15 probe-negative isolates only 27% had binding activities for fibronectin and 27% showed strong adherence to HEp2 cells. Antibodies raised against the fibronectin binding domain of Sfb protein recognized streptococcal fibronectin binding surface proteins in most of the clinical isolates but did not react with heart or skeletal muscle myosin in an enzyme immunoassay, as is the case with antibodies directed to M protein, another major surface protein of group A streptococci. The results of the present study suggest that Sfb protein could be a potential candidate for a streptococcal vaccine.

Adhesins, Bacterial↗
PubMed1994

Recurrent systemic pneumococcal infection in an immunocompromised patient.

A case is reported of a splenectomized patient who experienced four episodes of systemic pneumococcal infection after receiving appropriate therapy in every instance. Serogrouping showed at least two different strains to be responsible for these infections. Immunological investigations showed a reduction in immunoglobulins, a decrease in in vitro immunoglobulin synthesis and a disorder of immunoregulatory T-cells, but immunological changes could not be readily explained by splenectomy alone.

Adult↗
PubMed1994

Serum antibody responses to vaccination with 23-valent pneumococcal vaccine in splenectomized patients.

Sixty-three patients that have been splenectomized for various disorders were vaccinated with Pneumovax 23, the currently available pneumococcal vaccine. Before and one month after splenectomy, IgG antibodies against 8 pneumococcal polysaccharide antigens (types 3, 4, 6B, 7F, 10A, 14, 19F, and 20) were determined by a highly reproducible and type-specific enzyme-linked immunosorbent assay (ELISA). In order to increase the specificity of the assay, this method involved the use of a capture antibody (F(ab')2-fragments of a type-specific rabbit antipneumococcal hyperimmune serum) to bind the pneumococcal antigens to the plastic surface of microtiter plates and the absorption of these sera with the cross-reacting C polysaccharide. Rates of patients showing a two-fold antibody increase were dependent on pneumococcal type, ranging from 12.7% to 33.3%. Antibody responses of single patients were not uniform for all pneumococcal serotypes investigated. Only one patient responded to all of the eight antigens tested. In spite of relatively low response rates, splenectomized patients should be routinely vaccinated with the pneumococcal vaccine, especially when the low rate of adverse reactions is taken into consideration. It is emphasised that the results of the present study and those reported in the literature have to be compared and interpreted with caution, because the available data on the antibody response to pneumococcal vaccination are based on assays that differ substantially in methodology.

Adult↗
PubMed1993

[Toxic shock syndrome caused by Streptococcus pyogenes].

Four days after being bitten by an insect a 35-year-old woman without any serious underlying disease developed an extensive phlegmonous inflammation of the left eyelid which soon spread to the entire left half of her face. Streptococcus pyogenes serotype M1, which produced the erythrogenic toxin A in vitro, was isolated from two blood cultures. The course of the illness was characterized by high fever, diarrhoea, vomiting, circulatory failure, consumption coagulopathy, abnormal renal functions and a generalized exanthem with desquamation of the skin, exhibiting the full-blown picture of a toxic shock syndrome caused by S. pyogenes. She eventually recovered completely under intensive care involving administration of catecholamines, fresh frozen plasma and antithrombin III substitution, as well as antibiotic treatment with clindamycin (600 mg three times daily), ampicillin/sulbactam (4 g three times daily)--after 3 days replaced by imipenem (0.5 g four times daily)--and gentamycin (80 mg three times daily) for two weeks. Extensive necroses later required plastic surgery to the left eyelid, cheek and temporal region.

Adult↗
PubMed1993

[Current data on the antibiotic sensitivity of Streptococcus pneumoniae (Pneumococcus). The significance of penicillin resistant isolates].

Antibiotic-resistant pneumococci, including strains resistant to penicillin, are being isolated with increasing frequency also in Europe. Therefore, we studied the antibiotic sensitivity to penicillin, erythromycin, chloramphenicol, tetracycline, ofloxacin, and ciprofloxacin in 131 strains of Streptococcus pneumoniae; most of them were isolated from patients with systemic infections. A reduced susceptibility to penicillin was found in 7.6% (n = 10) of the Streptococcus pneumoniae strains. For the first time in Germany, in the present investigation two pneumococcal strains highly resistant to penicillin were isolated (minimal inhibitory concentration [MIC] values > or = 2 mg/l). These strains exhibited high MIC values against various cephalosporins as well. 10.7% of all pneumococci were resistant to tetracycline, resistance to erythromycin was found in 3.8% of the isolates. The emergence of pneumococci in Germany with reduced susceptibility to penicillin underscores the importance to include alternative drugs in sensitivity testing of pneumococci involved in systemic infections. Depending on the localization of the infection, parenteral third generation cephalosporins, glycopeptides and quinolone derivatives are primarily adequate in the treatment of infections caused by penicillin-resistant pneumococci.

Anti-Bacterial Agents↗
PubMed1993

T cell activation and cytokine release in streptococcal toxic shock-like syndrome.

A 5-year-old girl with streptococcal toxic shock-like syndrome during varicella infection had high levels of tumor necrosis factor alpha and interleukin-6 but no interleukin-1 or interleukin-2 in the serum. Intravenous administration of gamma-globulin coincided with clinical improvement and with reduction of the levels of tumor necrosis factor alpha and interleukin-6. The data suggest that streptococcal pyrogenic exotoxins trigger synthesis of tumor necrosis factor alpha and interleukin-6 in vivo; intravenously administered gamma-globulin may down-regulate the cytokine response.

Arthritis, Infectious↗
PubMed1993

Molecular investigation of clinical Enterococcus faecium isolates highly resistant to gentamicin.

Over a 10-month period, 22 beta-lactamase negative E. faecium strains resistant to ampicillin were isolated from severely compromised hospitalized patients. Most isolates were clinically significant. Twenty of these strains were also resistant to extraordinarily high levels of gentamicin, a finding described rarely in E. faecium. By whole-cell DNA restriction endonuclease digestion, the 20 strains with both ampicillin and high-level gentamicin resistance segregated into only 3 different groups, suggesting introduction of limited clones into this population of patients. Plasmid DNA profiles and plasmid DNA restriction enzyme analysis supported this grouping for 18 of these 20 strains, the two remaining isolates had slightly different profiles. Both strains lacking high-level gentamicin resistance had clearly different molecular profiles. The results of hybridization experiments strongly suggested the presence of a similar genetic determinant of high-level gentamicin resistance in E. faecalis and E. faecium. High-level gentamicin resistance in E. faecium was shown to be transferable on conjugative plasmids, so that further dissemination of this resistance trait may be anticipated. Our data indicate that the use of a nucleic acid probe is a promising diagnostic tool for screening both E. faecium and E. faecalis for high-level gentamicin resistance.

Adult↗
PubMed1993

Chromosomally mediated high-level gentamicin resistance in Streptococcus mitis.

Four blood culture isolates of Streptococcus mitis were found to be resistant to penicillin (MIC, 16 to 32 micrograms/ml) and gentamicin (MIC, 128 or 1,000 micrograms/ml), and the two antibiotics demonstrated a lack of in vitro synergy. As shown by polymerase chain reaction assays, the structural gene known to encode high-level gentamicin resistance in Enterococcus faecalis, Enterococcus faecium, and Streptococcus agalactiae was also present in all four S. mitis strains. Attempts to isolate plasmids were unsuccessful, but an oligonucleotide probe derived from the gentamicin resistance gene hybridized to distinct restriction fragments of genomic DNA, suggesting that the resistance genes in these strains are integrated into the bacterial chromosome.

Chromosomes, Bacterial↗
PubMed1993

The microbiologic aspects, including diagnosis, of beta-hemolytic streptococcal and enterococcal infections.

Basic principles concerning the collection, transport, and processing of clinical specimens for the detection of Streptococcaceae are given. Identification of beta-hemolytic streptococci (S. pyogenes, S. agalactiae, Lancefield group C and G streptococci, S. anginosus) and enterococci is based on the careful observation of colony morphology and hemolytic pattern on sheep blood agar plates; subsequent genus or species confirmation is achieved by rather simple biochemical or enzymatic tests and by detection of streptococcal cell wall carbohydrate antigens (Lancefield grouping). Rapid antigen tests for the detection of group A and B streptococci directly from pharyngeal and vaginal swabs, respectively, are highly specific, thus allowing an immediate antibiotic therapy in patients with a positive test result. The reported sensitivities of these nonculture tests are too low to exclude streptococcal colonization or infection, however. The elucidation of the genetics of some major virulence factors of group A and B streptococci has contributed to knowledge of their association with disease, and molecular techniques have supplemented the traditional (mostly culture and serologic) methods for an improved understanding of the epidemiology and pathogenesis of streptococcal infections. Recently employed examples include the M protein gene typing of group A streptococci by oligonucleotide probes and the use of PCR assays for the detection of the genes encoding for the pyrogenic exotoxins. Restriction enzyme endonuclease digestions of bacterial DNA in association with DNA fragment separation by conventional or PFGE have been applied successfully to several species of Streptococcaceae (e.g., S. pyogenes, S. agalactiae). Enterococci are important pathogens in the hospital setting, exhibiting high morbidity and mortality rates in bacteremic patients with severe underlying disease. Molecular typing methods have clearly confirmed their potential to be nosocomially transmitted. E. faecalis and E. faecium still account for the majority of human infections, but some of the newer enterococcal species (at present 19 species are recognized) have been encountered as well. The definitive species identification of enterococci requires the performance of an array of biochemical tests. The increasing antimicrobial resistance of enterococci, including high-level resistance to penicillins and aminoglycosides and occasionally also to glycopeptides, has hampered standard therapeutic regimens. All enterococci isolated from serious infections should be tested for high-level gentamicin and streptomycin resistance by one of several methods evaluated; beta-lactamase production (primarily found in E. faecalis) is reliably detected by the nitrocefin test.(ABSTRACT TRUNCATED AT 400 WORDS)

Enterococcus↗
PubMed1992

The group A streptococcal M-type 3 protein gene exhibits a C terminus typical for class I M proteins.

The M protein gene (emm gene) from a reference group A streptococcal strain of serotype M3 was amplified by the polymerase chain reaction and partially sequenced. Hybridization assays using an oligonucleotide probe derived from the N-terminal sequence revealed that this gene segment is highly homologous among M-type 3 isolates. Of note, analysis of the nucleotide sequence data from the C terminus of the gene confirmed that the emm 3 gene exhibited all the features characteristic for group A streptococcal M-class I molecules. Recently published sequence data that were assigned to emm 3 resulted from a strain confusion and were shown to be the first one derived from an emm gene of an M-untypable isolate.

Amino Acid Sequence↗
PubMed1992

Characterization of methicillin-susceptible and methicillin-resistant Staphylococcus aureus isolates by molecular typing methods.

Two groups of clinical Staphylococcus aureus isolates were examined by molecular typing methods. Detailed protocols for the technical procedures are described. By means of plasmid DNA profiles, plasmid DNA restriction enzyme digestion, as well as whole-cell DNA endonuclease digestions subjected to conventional agarose gel electrophoresis and pulsed-field gel electrophoresis, eight methicillin-susceptible S. aureus strains from three patients segregated into three different groups. Consecutive isolates from the same patient revealed identical fingerprints. Generally, good agreement between different molecular typing methods also was achieved in the investigation of 28 methicillin-resistant isolates. However, compared to whole-cell DNA restriction endonuclease analysis, plasmid DNA profiling (all but one strain had detectable plasmid DNA) showed a somewhat greater discriminatory ability. The techniques evaluated were reproducible and relatively easy to perform and provided valuable tools for studying the epidemiology of S. aureus in hospitals.

Bacterial Typing Techniques↗
PubMed1992

Identical genes confer high-level resistance to gentamicin upon Enterococcus faecalis, Enterococcus faecium, and Streptococcus agalactiae.

The structural gene coding for the bifunctional aminoglycoside-modifying 6'-acetyltransferase-2''-phosphotransferase (6'AAC-2''APH) enzyme was specifically amplified by the polymerase chain reaction using template DNA of clinical isolates of enterococci (both Enterococcus faecalis and Enterococcus faecium) and the single high-level gentamicin-resistant Streptococcus agalactiae strain identified thus far. The results of the present study demonstrated that the genes encoding this antibiotic resistance trait are highly homologous in these species. In dot blot hybridization assays using nonradioactively labeled oligonucleotide probes, strains with and without high-level gentamicin resistance could be discerned unequivocally. The gene segment encoding 6'-acetylating activity and the gene segment encoding 2''-phosphorylating activity were simultaneously present in all isolates exhibiting high-level gentamicin resistance.

Acetyltransferases↗