Biomedical subjects

A Schroeter

Publications and source records attributed to A Schroeter.

At least 19 recordsLinked to original sources

PubMed2005

Pulsed-field gel electrophoresis, plasmid profiles and phage types for the human isolates of Salmonella enterica serovar Enteritidis obtained over 13 years in Taiwan.

AIMS: Plasmid profile, phage typing, and pulsed-field gel electrophoresis (PFGE) patterns of 124 Salmonella Enteritidis strains isolated in 1998-2002 in Taiwan were analysed and the results were compared with those of the 63 strains obtained in 1991-1997, so that molecular subtypes and epidemic strains for Salmonella Enteritidis over a 13-year period (1991-2002) could be elucidated. METHODS AND RESULTS: A total of 124 strains of Salmonella Enteritidis isolated from human in Taiwan between 1998 and 2002 were analysed by PFGE, plasmid analysis and phage typing. The results obtained were compared with those of the 63 strains obtained in 1991-1997, so that the clonal relationships for a total of 187 strains obtained over 13 years could be elucidated. For PFGE, restriction enzymes XbaI, SpeI and NotI were used for chromosomal DNA digestion. Results showed 28 PFGE pattern combinations for the 187 Salmonella strains. Of them, pattern X3S3N3 was the major subtype as 130 strains isolated from different locations during 1991-2002 showed this PFGE pattern. For all these 187 strains, the genetic similarity was higher than 80%. Plasmid analysis showed 17 distinct types, which consist of one to four plasmids and the predominant phage type of those strains was PT4 (71.6%) and PT6a (13.4%). The three methods identified different degrees of polymorphism in the following order: plasmid profile (18 types, D = 0.659) > PFGE (28 types, D = 0.512) > phage typing (13 types, D = 0.438). As PFGE patterns, phage type and plasmid profile were combined for subtyping, the 187 strains could be grouped into 46 subtypes and the discriminatory index was raised to 0.795. For these 46 subtypes, the predominant one was X3S3N3/P1/PT4, which contained 77 (41%) isolates. CONCLUSIONS: Most of the Salmonella Enteritidis strains from sporadic cases were with pattern X3S3N3. They were the prevalent and may be the epidemic strains found in Taiwan during 1991-2002. The present study suggested that the several variants were derived from a single clonal line and the genome for strains of Salmonella Enteritidis are highly conserved over a 13-year period (1991-2002). SIGNIFICANCE AND IMPACT OF THE STUDY: The results obtained here are useful for epidemiolgical study of salmonellosis caused by Salmonella Enteritidis in Taiwan. Comparing the data of the present study with those obtained for strains from other countries, the major subtypes for Salmonella Enteritidis infection in the world can be elucidated.

Bacteriophage Typing↗

PubMed2004

Internationalization of healthcare applications: a generic approach for PACS workstations.

OBJECTIVES: Along with the revolution of information technology and the increasing use of computers world-wide, software providers recognize the emerging need for internationalized, or global, software applications. The importance of internationalization comes from its benefits such as addressing a broader audience, making the software applications more accessible, easier to use, more flexible to support and providing users with more consistent information. In addition, some governmental agencies, e.g., in Spain, accept only fully localized software. Although the healthcare communication standards, namely, Digital Imaging and Communication in Medicine (DICOM) and Health Level Seven (HL7) support wide areas of internationalization, most of the implementers are still protective about supporting the complex languages. This paper describes a generic internationalization approach for Picture Archiving and Communication System (PACS) workstations. METHODS: The Unicode standard is used to internationalize the application user interface. An encoding converter was developed to encode and decode the data between the rendering module (in Unicode encoding) and the DICOM data (in ISO 8859 encoding). An integration gateway was required to integrate the internationalized PACS components with the different PACS installations. To introduce a pragmatic example, the described approach was applied to the CHILI PACS workstation. RESULTS: The approach has enabled the application to handle the different internationalization aspects transparently, such as supporting complex languages, switching between different languages at runtime, and supporting multilingual clinical reports. CONCLUSIONS: In the healthcare enterprises, internationalized applications play an essential role in supporting a seamless flow of information between the heterogeneous multivendor information systems.

Germany↗

PubMed2003

Incidence of quinolone resistance in strains of Salmonella isolated from poultry, cattle and pigs in Germany between 1998 and 2001.

This paper reports the susceptibility to the quinolone nalidixic acid and the fluoroquinolone ciprofloxacin of 14,514 strains of Salmonella isolated in Germany from poultry, cattle and pigs between 1998 and 2001. Quinolone-resistant salmonellae were most frequently isolated from poultry, with a prevalence of 10.2 to 16.8 per cent. Poultry-associated serotypes, such as Salmonella Paratyphi B (d-tartrate positive), Salmonella Hadar and Salmonella Virchow, had the highest prevalence of quinolone resistance, ranging between 35 and 74 per cent. All the nalidixic acid-resistant strains also had a reduced susceptibility to ciprofloxacin, with minimum inhibitory concentrations (MICS) of 0.125 to 2 microg/ml. A comparison of the MICS for ciprofloxacin of the strains of these poultry-associated serotypes and Salmonella Enteritidis phage type 4 isolated in 1998/99 and 2000/01 indicated that there had been a shift towards higher MIC values of up to 2 microg/ml. The quinolone resistance-determining region (QRDR) of the gyrA gene and the homologue region of the parC gene of 31 selected strains were sequenced. Several different amino acid changes were observed in gyrA of the quinolone-resistant isolates at positions 83 and 87, but no substitutions were observed in parC.

Amino Acid Sequence↗

PubMed2000

Clinical and differential diagnosis of Creutzfeldt-Jakob disease.

Until recently, the clinical diagnosis of CJD relied mainly on three criteria. These include patient history (rapidly progressive dementia), neurological findings (ataxia, pyramidal/extrapyramidal signs, myoclonus, akinetic mutism) and typical electroencephalographic (EEG) findings. These criteria are fulfilled in typical cases. The occurrence or increase of certain proteins in cerebrospinal fluid (CSF; 14-3-3, neuron-specific enolase) now provide important adjuncts in recognizing variant forms. Although these proteins can be detected in other neurological diseases accompanied with substantial brain damage such as encephalitis, they are also characterized by their high sensitivity and specificity with regard to other dementing processes (Alzheimer and vascular dementia). The increase in the number of positive cases during the last years in Germany reflects an improved case ascertainment rather than the appearance of the variant CJD (vCJD). Although several recent cases with a long duration of the disease were actually recognized, they did not reveal the typical florid plaques at autopsy. They were revealed as a rare variant of sporadic CJD, which is characterized by homocygosity for valine at codon 129 and PrP(Sc) type 1. This variant is positive for the 14-3-3 protein in CSF. Further subtypes described by Parchi et al. can also be characterized by a certain pattern of clinical symptomatology, EEG- and 14-3-3-findings. In addition, differential diagnosis revealed some treatable dementias among the most common diseases (Alzheimer and vascular dementia) such as herpes encephalitis, multiple sclerosis and Hashimoto encephalitis, particularly in the younger age group.

Cerebrospinal Fluid↗

PubMed1999

How to improve the clinical diagnosis of Creutzfeldt-Jakob disease.

This paper describes a prospective follow-up of 364 patients initially notified as suspected Creutzfeldt-Jakob disease to a Surveillance Unit in Göttingen, Germany. Six patients were diagnosed as having genetic prion disease by blood analysis and were excluded from the study. After examination and review of the remaining 358, 193 were classified as probable Creutzfeldt-Jakob disease. However, autopsy revealed that five of the 193 did not have Creutzfeldt-Jakob disease (four cases, Alzheimer's disease; one case, cerebral lymphoma). Of the 54 patients classified as possible Creutzfeldt-Jakob disease, 10 had another diagnosis made at autopsy. Two of the 111 cases originally classified as having other diseases were found to have Creutzfeldt-Jakob disease on autopsy. Autopsy evidence, together with follow-up of the patients still living and those who died without autopsy, revealed a broad range of other diagnoses. In the younger age groups, the commonest were chronic inflammatory diseases including Hashimoto encephalitis, whilst rapidly progressive Alzheimer's disease was most common in the older age groups. The presence of 14-3-3 protein in the CSF discriminated better between Creutzfeldt-Jakob disease and other rapidly progressive dementias than did the EEG pattern or the MRI. The inclusion of this CSF protein in the criteria of Masters and colleagues (Ann Neurol 1979; 5: 177-88) improves the accuracy and confidence in the clinical diagnosis of Creutzfeldt-Jakob disease.

14-3-3 Proteins↗

PubMed1999

Incidence of quinolone resistance over the period 1986 to 1998 in veterinary Salmonella isolates from Germany.

A total of 24,591 nonhuman salmonella strains isolated in Germany between 1986 and 1998 were examined for their resistance to nalidixic acid by an agar diffusion method. The rate of resistance (inhibition zone, </=13 mm) ranged from 0.2% in 1986 to a peak of 14. 8% in 1990. Between 1991 and 1998 the MICs for nalidixic acid-resistant strains ranged from more than 256 microg/ml for nalidixic acid to between 0.25 and 128 microg/ml for enrofloxacin. In the early 1990s a particularly high incidence of fluoroquinolone resistance (49.5%) was seen among isolates of Salmonella enterica serotype Typhimurium (Salmonella Typhimurium) definitive phage type 204c that mainly originated from cattle. Among isolates from poultry an increase in the incidence of nalidixic acid resistance to a peak of 14.4% was observed in 1994. This peak was due to the presence of specific resistant serotypes, mainly serotypes Hadar, Saintpaul, Paratyphi B (D-tartrate positive; formerly serotype Java) and Newport. Such strains exhibited a decreased susceptibility to enrofloxacin (MIC, 1 microg/ml). Among isolates from pigs the peak incidence of resistance was reached in 1993, with 7.5% of isolates resistant to nalidixic acid and enrofloxacin. The study demonstrates an increase in the incidence of strains that are resistant to nalidixic acid and that have decreased susceptibility to enrofloxacin after the licensing of enrofloxacin. In addition, the number of other serotypes that exhibited nalidixic acid resistance or reduced enrofloxacin susceptibility increased among the total number of isolates investigated between 1992 and 1998.

Animals↗

PubMed1999

[Investigation of foodborne outbreak due to Salmonella infantis using epidemiological and microbiological methods].

In foodborne outbreaks, direct microbiological diagnosis is often not possible due to lack of remaining food samples. Therefore, in this investigation of an outbreak of Salmonella infantis at a fair, we chose an epidemiological approach in addition to microbiological testing. In a case control study, fair participants with symptoms of acute gastroenteritis as well as participants showing no signs of disease were interviewed by telephone. Questions concerning what food had been eaten at the fair and the course of disease had priority. Data analysis showed a significantly elevated odds ratio of 144 (p < 0.00001) for the consumption of potato salad. Salmonella infantis was cultured in faeces of symptomatic individuals as well as from left-over potato salad in high concentration. In conclusion, our data show that the cause of a foodborne outbreak can be detected through the application of epidemiologic methods with a high degree of certainty. In order to eliminate memory bias, a structured interview should be carried out as soon as possible after the initial outbreak.

Antibodies, Bacterial↗

PubMed1996

[Prevalence of motile salmonellae in egg-laying hens at the end of the laying period].

A total of 3504 hens of the layer-type from 122 flocks (belonging to 89 farms), each with more than 10,000 animals, were culturally examined at the time of slaughter. Of these hens, 2112 (60.3%) from 74 flocks (60.7%) were obtained from 21.3% of the laying-hen farms in a selected region of Lower Saxony in Germany. The other hens came from the remaining part of Lower Saxony and seven other German states (Brandenburg, Mecklenburg Vorpommern, North Rhine Westphalia, Schleswig Holstein, Saxony, Saxony Anhalt, and Thuringia). After arrival at the slaughter house, a random sample of 29 layers was collected from each of the flocks, and liver and spleen, as well as cecal samples, were separately cultured for each bird. Motile salmonellae could be proved in 365 (10.4%) layers from 67 flocks (54.9%). In the selected region, 48 out of 74 flocks (64.9%) and 289 out of 2112 layers (13.7%) were Salmonella-positive. However, the isolation frequency of salmonellae did not differ significantly between flocks of brown and white layers. These Salmonella (S.) isolates could be serologically assigned to 6 different serovars, namely S. enteritidis (SE), S. infantis (SI), S. livingstone (SL), S. typhimurium (ST), S. indiana (SID) and S. cerro; only one isolate of serogroup D1 was incompletely serotyped. SE was detected in 5.8% of the hens from 47.5% of the tested flocks, of which 4.6% of the animals and 32.8% of the flocks came from the selected region in Lower Saxony. The SE isolates were classified into 12 different lysotypes. In 41 out of 58 SE-positive flocks (70.7%), the isolates belonged to lysotype (lt) 4, in 12 flocks (20.7%) to lt 8, in 5 flocks (8.6%) to lt 7, and in 3 flocks (5.2%) to lt 11. A total of 190 (93.1%) out of 204 isolates of the serovar SE carried plasmids. All the plasmid-positive SE-strains harboured the serovar-specific 37 MD virulence-plasmid, nine of them (4.4%) in conjunction with a second and eight strains (3.9%) with a second and a third smaller plasmid.

Animals↗

PubMed1996

[Immunization with potential Salmonella enteritidis mutants--1. Production and in vitro characterization].

Production and in vitro characterization of potential vaccine strains are the first steps leading to an efficient Salmonella Enteritidis oral live vaccine for homologous immunization of poultry. The paper presents the results of the production of adenine-amino acid auxotrophic mutants using N-methyl-N'-nitro-N-nitrosoguanidine mutagenesis. The mutant strains were characterized using the following properties: auxotrophy, stability of mutation, reversion rate, generation time, metabolic properties, serotype, motility, plasmid content, phage type, SDS-PAGE patterns, as well as cell culture adhesion and invasion. Ten S. Enteritidis double auxotrophic mutants were obtained which are stable auxotrophically and where the risk of reversion was minimal. All strains were found to be plasmid-free. 5 mutants were selected for further investigations concerning their attenuation and immunological value.

Animals↗

PubMed1994

Salmonella enteritidis phage types in Germany.

In order to monitor the epidemiological situation of S. enteritidis in Germany, in 1990-91 1138 isolates from more than 180 locations in West Germany were phage typed. 1124 strains (98.8%) from all sources were typeable, belonging to 21 different phage types (PT). PT4 strains were isolated most frequently (70.8%). In addition, PT7, 25, 34 and 8 were of epidemiological relevance with incidences of 7.2 to 4.5%. The comparison of data shows that in Germany, like in other parts of Europe, PT4 predominates. This phage type is, however, infrequent in North America, where PT8 has the highest incidence.

Animals↗

PubMed1994

Molecular typing methods for S. enteritidis.

The predominance of certain phage types of Salmonella enteritidis in various countries makes further epidemiological subgrouping necessary. Today this is achieved by using molecular typing methods. For various bacterial species, plasmid profiling, the pattern of outer membrane proteins and lipopolysaccharides, the fingerprinting of total genomic DNA including ribotyping, and multilocus enzyme electrophoretic typing, have proven very useful. When such methods have been applied to S. enteritidis, they revealed a homogeneous, clonal structure in contemporary PT4 isolates. Furthermore they indicate that the clone observed today emerged from a heterogeneous population before the onset of the epidemic.

Animals↗

PubMed1993

[Plasmid profiles of different Salmonella serovars from poultry flocks in Germany].

151 salmonella isolates belonging to 6 serotypes and originating from diverse material collected in broiler chicken farms, hatcheries and poultry slaughteries in Northern Germany during 1984 and 1990 were investigated for their plasmid DNA content. This is the first report describing plasmids of S. saint-paul, isolated from poultry lines. The different plasmids of 22 Md, 3.1 Md, 2.4 Md and 1.1 Md molecular weight can be used for further epidemiological studies of salmonellosis in poultry. The 62 Md plasmid of S. typhimurium and the 36 Md plasmid of S. enteritidis have been found to be serovar specific. The smaller plasmids (m. w. less than 5.0 Md), found in S. virchow and S. blockley can be used for further epidemiological studies.

Animals↗

PubMed1989

RelA mutation and pBR322 plasmid amplification in amino acid-starved cells of Escherichia coli.

Plasmid pBR322 is amplified following amino-acid limitation in Escherichia coli relA hosts. In relA+ hosts there was no significant amplification or a much smaller one. Plasmid amplification is due to the relA mutation; when the relA+ allele is transferred into the relA mutant CP79 this strain no longer amplifies plasmid DNA during amino acid starvation. It is concluded that ppGpp is a negative effector of plasmid replication. Amplification is temperature dependent, being maximal at 32 degrees C and negligible at 37 degrees C.

Amino Acids↗

PubMed1989

Cutaneous T cell lymphoma with suppressor phenotype and function.

Cutaneous T cell lymphomas (CTCL) are typically malignancies of postthymic helper T cells which retain helper function when assayed in vitro. We have described a case clinically and morphologically consistent with CTCL, but in which the tumor cells unequivocally had a suppressor T cell phenotype and suppressor function. This case could be differentiated from other varieties of peripheral T cell lymphomas by multiple clinical and laboratory parameters. The increasingly routine use of immune phenotyping in the evaluation of malignant lymphomas will likely result in the identification of additional cases of this entity, which should be studied to assess its clinical and prognostic relationship to the more common helper cell CTCL.

Humans↗

PubMed1988

Amplification of different ColE1 plasmids in an Escherichia coli relA strain.

Amino acid starved cells of an E. coli relA strain accumulate a large amount of pBR322 plasmid DNA. In this study ColE1 related plasmids of different copy number and size including a high copy number plasmid mutant of pBR322 were amplified in a relA strain of E. coli K-12 under amino acid limitation in order to determine the upper plasmid level in amino acid starved cells. In all cases we measured a 4 to 6 fold increase of the plasmid copy number in comparison to log-phase cells independent of the size, the number of origins per plasmid molecule or the copy number in log-phase cells. The plasmid copy number in amino acid starved cells varies from about 200 (pBR322-dimer) to about 2000 (high copy number plasmid pERIII-BPL4, see Boros et al. 1986). Rop+ and rop- plasmids show the same amplification rate under the used conditions.

Amino Acids↗

PubMed1988

Expression of a cloned beta-glucanase gene from Bacillus amyloliquefaciens in an Escherichia coli relA strain after plasmid amplification.

Amino acid starvation of cells of the Escherichia coli relA strain, CP79, which cannot accumulate guanosine tetraphosphate (ppGpp) in response to amino acid limitation, increased the pEG1 plasmid content about 5- to 7-fold in comparison with exponentially growing cells (pEG1:pBR322 with an insertion of Bacillus amyloliquefaciens DNA coding for beta-glucanase). In contrast, no pEG1 amplification occurred in E. coli CP78, the stringently controlled counterpart, after amino acid starvation. In order to verify these results, the plasmid DNA content was monitored by measuring the expression of pEG1-encoded beta-glucanase from B. amyloliquefaciens both before and after plasmid amplification. When amino acid starved CP79 cells were given an additional dose of amino acids, a more than 10-fold increase in pEG1-encoded beta-glucanase activity (per cell mass) was measured. This increase in enzyme activity correlates with pEG1 amplification during amino acid limitation. Under comparable conditions the activity of beta-glucanase was not increased in strain CP78, which did not amplify the plasmid. We suggest that the replication of pEG1 in amino acid starved E. coli cells is somehow under negative control by ppGpp. Moreover, we found the Bacillus beta-glucanase in E. coli relA cells to be excreted into the growth medium after starvation and overexpression.

Amino Acids↗

PubMed1987

Formation of extracellular neutral proteinase and the stringent response in Bacillus subtilis.

The kinetics of extracellular neutral proteinase synthesis by an isogenic stringent (IS58) and a relaxed (IS56) strain of B. subtilis were compared. The specific enzyme formation rate by the stringent strain was higher than that of the relaxed one. Norvaline addition (1 mg/mL) induced the formation of pppGpp and ppGpp, respectively, as well as the appearance of extracellular neutral proteinase activities in cultures of the stringent strain IS58 and a strain with high proteinase production (ZF-178) only. These correlations support the suggestion that (p)ppGpp are involved in the regulation processes responsible for production of extracellular neutral proteinases by B. subtilis.

Bacillus subtilis↗

PubMed1986

Physiological studies on pBR 322 DNA amplification in an Escherichia coli relA strain.

Amino acid limitation leads in E. coli relA cells which cannot synthesize guanosine tetraphosphate (ppGpp) under these conditions to an amplification of pBR 322 DNA. We previously proposed that ppGpp produced in E. coli relA+ cells subjected to amino acid limitation inhibits pBR 322 DNA replication (Hecker et al. 1983). In further experiments it was established that an E. coli relA strain shows plasmid amplification during amino acid limitation (arginine, threonine, leucine or histidine) only in the presence of sufficient concentrations of phosphate, ammonia and glucose. Plasmid amplification does not occur if ammonia or phosphate is depleted. We suggest that glucose, ammonia and phosphate are needed for nucleotide and deoxynucleotide synthesis as the essential prerequisite for plasmid amplification. The activity of beta-lactamase was determined as an indicator for the expression of plasmid-encoded genes. The enzyme activity remains on a low level during plasmid amplification because of arginine exhaustion. A remarkable increase in the activity of beta-lactamase was observed after resumption of growth of relA cells containing amplified plasmid DNA. The plasmid content decreased as the cells continued to grow. We found that plasmid amplification and expression of plasmid-localized genes are opposite reactions which do not occur at the same time.

Amino Acids↗