Biomedical subjects

K Schopfer

Publications and source records attributed to K Schopfer.

At least 19 recordsLinked to original sources

PubMed2005

Development of real-time PCR for the differential detection and quantification of Ureaplasma urealyticum and Ureaplasma parvum.

Ureaplasma parvum and Ureaplasma urealyticum are recently recognized species of the genus Ureaplasma. In humans, Ureaplasma spp. can be found on mucosal surfaces, primarily in the respiratory and urogenital tracts. They have been implicated in various human diseases such as nongonococcal urethritis, intrauterine infections in association with adverse pregnancy outcome and fetal morbidity, and pneumonitis in immunocompromised hosts. We have developed two quantitative real-time PCR assays to differentially detect U. parvum and U. urealyticum. Based upon the sequence information of the urease gene (ureB), we designed two TaqMan primer and probe combinations specific for U. parvum and U. urealyticum, respectively. The assays did not react with nucleic acid preparations from 16 bacterial species commonly encountered in relevant clinical specimens, including seven urease-producing species. Each assay had a detection limit of approximately five copies per reaction of the respective gene target. The results suggest that these assays are both sensitive and specific for U. parvum and U. urealyticum. Further investigation of both assays using clinical specimens is appropriate.

DNA, Bacterial↗

PubMed1998

Paediatric, invasive pneumococcal disease in Switzerland, 1985-1994. Swiss Pneumococcal Study Group.

BACKGROUND: Cost effective use of new vaccines against pneumococcal disease in children requires detailed information about the local epidemiology of pneumococcal infections. METHODS: Data on 393 culture-confirmed cases of invasive pneumococcal infection in children (<17 years) hospitalized in Swiss paediatric clinics were collected retrospectively for the years 1985-1994. RESULTS: Meningitis (42%) was most frequent, followed by pneumonia (28%) and bacteraemia (26%). The overall annual incidence was 2.7 cases per 100000 children <17 years old and 11 cases per 100000 children <2 years old. Annual incidence rates were stable over the study period. Lethality was high for meningitis (8.6%) and bacteraemia (8.9%). A history of basal skull fracture was reported in 3.3% of children with pneumococcal meningitis. Residence in a rural region was associated with an increased risk of pneumococcal infection (relative risk = 1.45, 95% confidence interval: 1.01-2.00). CONCLUSIONS: Paediatric, invasive pneumococcal disease seems to be less frequent in Switzerland than in other European and non-European countries. This may be due to differences in diagnostic strategies and lower frequency of risk factors such as the use of day care. Children with a history of basal skull fracture are at increased risk for pneumococcal meningitis. Further investigation of the association of invasive pneumococcal infection with rural residence and the use of antibiotics for upper respiratory tract infections might give new insight into the dynamics of Streptococcus pneumoniae infection and the development of antibiotic resistance.

Adolescent↗

PubMed1997

Age-stratified seroprevalence of measles, mumps and rubella (MMR) virus infections in Switzerland after the introduction of MMR mass vaccination.

We have performed age-stratified seroprevalence studies for MMR to evaluate these vaccinations. Serum samples submitted for diagnostic testing were randomly selected for unlinked anonymous panels. IgG antibodies were tested by ELISA and indirect immunofluorescence. In the vaccination cohort (age 1.5 to 6.5 years), seroprevalence attained 80%. For measles and mumps it continued to increase to 95%, while for rubella it declined transiently to 60% between 7 and 12 years of age. We observed no differences according to gender in any age group in 1991-1992. (Semi)quantitative values of the IgG antibodies against all three viruses increased during adolescence, suggesting wild virus circulation. In 1992, MMR vaccination has reached < 80% of the children during their second year of age. Due to previous monovalent measles and mumps vaccinations in pre-school children and due to endemic and epidemic activity, particularly of mumps virus, a trough of the seroprevalence in adolescents was evident only for rubella. MMR vaccination campaigns performed at school since 1987 have increase seroprevalence in this population segment and have probably over-compensated for the expected shift to the right of the seroprevalence curves. A more compulsive implementation of the recommended childhood vaccination schedule and continued efforts at catchup vaccinations during school age especially for rubella are necessary to avoid the accumulation of susceptible young adults during the forthcoming decades.

Adolescent↗

PubMed1996

Risk factors for invasive Haemophilus influenzae disease among children 2-16 years of age in the vaccine era, Switzerland 1991-1993. The Swiss H. Influenzae Study Group.

BACKGROUND: Continued surveillance, and detailed investigation of direct and indirect effects of conjugated vaccines and risk factors for invasive H.influenzae serotype B (Hib) disease in the vaccine era are important. METHODS: 143 cases with invasive disease between 1991 and 1993 aged 2-16 years were selected retrospectively from a large incidence trend study. Controls (n = 336) were recruited from local vital registries and matched to cases for age, gender, and residence. Hib vaccination histories among study subjects and their siblings and other sociodemographic variables were obtained by questionnaires completed by the parents of these children. Adjusted odds ratio (OR) estimates were calculated by conditional logistic regression analysis. RESULTS: Most vaccinated subjects had received the Polysaccharide-Diphtheria Toxoid vaccine and estimated vaccine efficacy was high (95%; 95% confidence interval [CI] 60-99%). Also, the results suggested that protection afforded by vaccination against Hib extended to the family members of vaccinated children. School attendance was found to be protective against invasive Hib disease (OR:0.33; CI:1.2-14.4). Cases more often than controls reported suffering from asthma and allergies (OR:4.8; CI:1.2-19.4). CONCLUSIONS: Post-licensure vaccine efficacy is high among children > or = 2 years of age. The observed association between asthma and epiglottitis is novel and deserves further investigation.

Adolescent↗

PubMed1996

Molecular characteristics of Haemophilus influenzae causing invasive disease during the period of vaccination in Switzerland: analysis of strains isolated between 1986 and 1993.

The broad use of conjugated vaccines against Haemophilus influenzae type b may select for strains to which the polysaccharide vaccine does not provide immunity. We analyzed 392 consecutive H. influenzae isolates from Swiss children 0 to 16 years of age with invasive disease during the years 1986 to 1993. Bacterial strains were characterized by serotyping, capsular genotyping, outer membrane protein (OMP) subtyping, and ribotyping. Of 392 strains, 372 were serotype b, 1 was serotype a, 3 were serotype f, and 16 were nontypeable H. influenzae. After the introduction of Haemophilus conjugate vaccines in 1990, there was a relative increase of nontypeable strains from 3 to 6.6% (P = 0.27). Of the type b strains, 281 (75.5%) had the same OMP subtype and ribotype pattern. This clone predominated in the pre- and postvaccine periods. After the year 1990, the proportions of OMP subtype 1c and OMP subtype 3 tended to increase. Isolates from previously vaccinated (n = 10) and nonvaccinated patients did not differ in their subtype distributions. We conclude that the administration of conjugated vaccines decreased invasive disease caused by the most prevalent H. influenzae type b clone. However, further surveillance of circulating H. influenzae strains during the period of vaccination is indicated.

Adolescent↗

PubMed1996

Invasive Haemophilus influenzae disease and epiglottitis among Swiss children from 1980 to 1993: evidence for herd immunity among older age groups. The Swiss Haemophilus Influenzae Study Group.

We analysed time trends in the incidence of invasive Haemophilus influenzae disease in Switzerland between 1980 and 1993 to investigate whether conjugated H. influenzae type b vaccines, licensed in Switzerland in May 1990, confer indirect protection to children in older, non-vaccinated age groups. Data were obtained from the records of 39 Swiss paediatric clinics for 2,857 children 0-16 years old with invasive H. influenzae disease. Incidence time trends were analysed by Poisson regression. The diseases incidence decreased by 80% among 0-4-year-old children (i.e. those eligible for vaccination) between 1990 and 1993. Among children aged 5-16 years, there also was an abrupt 50% fall in the incidence of H. influenzae meningitis after 1990. However, the incidence of epiglottitis in this age group had started to decline before conjugated vaccines became available, with no additional decline thereafter. While our results suggest some indirect protection conferred to older, non-vaccinated children through the administration of conjugated vaccines to younger children, they also argue that underlying time trends of invasive H. influenzae disease need not be considered when interpreting incidence rates in the vaccine era.

Adolescent↗

PubMed1995

[Tuberculosis: quo vadis? Spotlight on history and current aspects].

In short review some milestones of the history of tuberculosis research are outlined. Perspectives on the past, present and the future of tuberculosis research are linked to these historical facts. Within this context the contribution of members of the Medical Faculty at the University of Berne such as L. Lichtheim, Th. Langhans and E. A. E. Klebs receive particular consideration in connection with the 125th anniversary issue of the "Schweizerische Medizinische Wochenschrift" which was founded in 1871 by Klebs.

Europe↗

PubMed1995

[Ludwig Lichtheim and Robert Koch. How the discovery of the tubercle bacillus in Switzerland was made known (1882/1883)].

The discovery of the tubercle bacillus by Robert Koch in March 1882 was immediately reported by the medical press, including that of Switzerland. Among the clinicians most active in introducing the new views and techniques to Swiss medical practitioners was Ludwig Lichtheim (1845-1928), professor of internal medicine in Berne (1879-1888), who had been acquainted with Koch since their time in Breslau. Lichtheim's successful efforts are illustrated by quotations from his (unpublished) memoirs.

Bacteriology↗

PubMed1995

[Current developments in Mycobacteria diagnosis].

The reemergence of tuberculosis in the industrialized countries has hastened the development of new laboratory techniques. Hence, well-known shortcomings of traditional techniques such as the lack of a rapid and specific detection system, the delayed availability of species identification and drug susceptibility results, and the lack of a reliable method for determining strain identity for epidemiological purposes, have become immediate targets for implementing molecular biology techniques. In particular, nucleic acid amplification techniques, restriction fragment-length polymorphism and single-strand conformation polymorphism analyses have dramatically improved diagnostic timeliness and accuracy of mycobacteriology laboratory results. Our paper reviews recent developments and comments on the diagnostic applications of the new tools as compared to traditional techniques.

Amino Acid Sequence↗

PubMed1995

The incidence of rubella virus infections in Switzerland after the introduction of the MMR mass vaccination programme.

We have collected data on the incidence of rubella in Switzerland from 1987 to 1992 to help evaluating the impact of the measles, mumps and rubella (MMR) mass vaccination programme which started in 1985 in this country. We used detailed informations on samples submitted for diagnostic testing in conjunction with anonymous laboratory notifications to the Swiss Federal Office for Public Health, and data from the Swiss sentinel network of general practitioners to find trends in the incidence of rubella after the introduction of mass vaccination. We observed an unabated seasonal oscillation without decreasing trend during the observation period and were unable to detect a shift in the age distribution of cases. An important proportion of laboratory-confirmed rubella occurred in women of childbearing age. Immigrants from regions with low endemicity of rubella were at increased risk of contracting rubella and transmitting it to their offspring. We conclude, that MMR mass vaccination has not interrupted the circulation of rubella virus in Switzerland, and that improvements in the implementation and surveillance of the MMR vaccination campaign are necessary in order to avoid untoward effects of it.

Adolescent↗

PubMed1995

Isolation of Coxiella burnetii from heart valves of patients treated for Q fever endocarditis.

Coxiella burnetii was isolated from the valve material of two patients who underwent valvectomy because of progressive congestive heart failure due to endocarditis. In each case antibiotic therapy was administered for several months prior to valvectomy. Classical histopathological examination of the valves did not reveal an etiology. However, coxiella-like organisms were demonstrated in valvular material with Köster, Stamp, and Giemsa stains, and the organisms were grown in cell culture. Antibody titers were consistent with the diagnosis of chronic C. burnetii infection. This report illustrates the advantage of simple and fast staining techniques and cell culture for the demonstration and isolation of C. burnetii in the heart valve tissue of patients with Q fever endocarditis.

Antibodies, Bacterial↗

PubMed1994

Screening of respiratory tract specimens for the presence of Mycobacterium tuberculosis by using the Gen-Probe Amplified Mycobacterium Tuberculosis Direct Test.

A prospective 2-month trial involving 617 respiratory tract specimens was conducted to compare sensitivity, specificity, and predictive values of the newly developed Gen-Probe Amplified Mycobacterium Tuberculosis Direct Test kit (AMTDT; Gen-Probe, Inc., San Diego, Calif.) for the rapid detection of Mycobacterium tuberculosis and of fluorescent acid-fast staining versus combined BACTEC 12B and solid-medium cultures as the "gold standard." A total of 590 specimens were culture and AMTDT negative. Twenty-one (3.4%) cultures yielded M. tuberculosis. Of these, 15 (71.4%) were detected by AMTDT, whereas 6 (28.6%) were missed. M. tuberculosis did not grow in six (28.6%) of AMTDT-positive specimens derived from three patients under treatment for tuberculosis. AMTDT exhibited a sensitivity, a specificity, a negative predictive value, and a positive predictive value of 71.4, 99, 99, and 71.4%, respectively. In comparison, the same values for fluorescent microscopy were 66.7, 98.3, 98.8, and 58.3%, respectively. AMTDT was easy to perform and highly specific. However, a screening test would require an improved sensitivity and, when feasible, the implementation of an internal amplification control.

Bacteriological Techniques↗

PubMed1993

Molecular approach to identifying route of transmission of tuberculosis in the community.

There is growing concern that tuberculosis is spread in Europe in the way that it is in the USA. We have used DNA "fingerprinting" in a systematic evaluation of tuberculosis cases notified in our community to uncover foci of transmission. An IS6110 probe was used to test all isolates from culture-confirmed tuberculosis cases (163 patients) notified in 1991-92 in the Canton of Berne. In total, 45 patients (27.6%), potentially linked on the basis of restriction fragment length polymorphism, were investigated epidemiologically. The largest group (n = 22) included members of a defined social group (drug addicts, homeless persons, alcoholics), from whom tuberculosis spread to the general population. A key patient developed multidrug-resistant tuberculosis during the surveillance period. This population study showed that (i) extensive transmission of Mycobacterium tuberculosis is now taking place in Europe in the same social setting as in the USA; (ii) there is definite "spillover" to the general population; (iii) the dimensions of the problem cannot be recognised easily by routine public health service activities because of the complexity of the transmission network; and (iv) multidrug-resistant tuberculosis develops in this setting.

Adult↗

PubMed1993

Detection of rifampicin-resistance mutations in Mycobacterium tuberculosis.

Control of tuberculosis is threatened by widespread emergence of drug resistance in Mycobacterium tuberculosis. Understanding the molecular basis of resistance might lead to development of novel rapid methods for diagnosing drug resistance. We set out to determine the molecular basis of resistance to rifampicin, a major component of multidrug regimens used for treating tuberculosis. Resistance to rifampicin involves alterations of RNA polymerase. The gene that encodes the RNA polymerase subunit beta (rpoB) was cloned. Sequence information from this gene was used to design primers for direct amplification and sequencing of a 411 bp rpoB fragment from 122 isolates of M tuberculosis. Mutations involving 8 conserved aminoacids were identified in 64 of 66 rifampicin-resistant isolates of diverse geographical origin, but in none of 56 sensitive isolates. All mutations were clustered within a region of 23 aminoacids. Thus, substitution of a limited number of highly conserved aminoacids encoded by the rpoB gene appears to be the molecular mechanism responsible for "single step" high-level resistance to rifampicin in M tuberculosis. This information was used to develop a strategy (polymerase chain reaction-single-strand conformation polymorphism) that allowed efficient detection of all known rifampicin-resistant mutants. These findings provide the basis for rapid detection of rifampicin resistance, a marker of multidrug-resistant tuberculosis.

Base Sequence↗

PubMed1993

Simultaneous detection of DNA and RNA by differential polymerase chain reaction (DIFF-PCR).

A new technique, the differential polymerase chain reaction (DIFF-PCR), allows the simultaneous amplification of DNA and homologous RNA in a single assay by the combination of DNA-PCR and RNA-PCR on the same target. DNA-PCR amplifies a selected segment of dsDNA, whereas RNA-PCR amplifies a complementary DNA (cDNA), produced by reverse transcription of RNA. In a mixture of target DNA and RNA, DNA is amplified using a combination of sense and antisense primers under high-stringency conditions giving a D-amplicon. RNA is first reverse-transcribed with a primer carrying a nontarget 5' end into a tagged cDNA at low stringency. Tagged cDNA is subsequently amplified, providing an R-amplicon smaller in size than the D-amplicon. By quantifying the relative amounts of amplified RNA and homologous DNA, a sensitive measure for the transcription rate of a defined DNA segment is obtained. Thus, DIFF-PCR may serve as a useful tool for monitoring gene expression as well as for studying gene regulation and gene function.

Base Sequence↗

PubMed1992

[Rubella epidemiology in military recruit schools].

In 1986, at the start of their training, 6877 male recruits were screened for the presence of anti-rubella IgG antibodies. 595 (9%) were seronegative. Of the latter group, 475 (80%) were retested in the week prior to discharge. During their four months of training, 113 (24%) exhibited seroconversion which proved acquisition of a rubella virus infection during the period of service. A clinical diagnosis of rubella was established in 15 (13%) of the persons with seroconversion. Catarrhal symptoms were present in half of those infected, whereas 41 (36%) did not report sick, suggesting a subclinical course of infection. Rubella is hardly a problem for the military in Switzerland. However, outbreaks such as the ones reported may have implications for the epidemiology of rubella in the general population, and hence should be taken into account in the planning of programs attempting to eliminate rubella virus infections.

Adult↗

PubMed1991

Variant of hyper-IgE syndrome: the differentiation from atopic dermatitis is important because of treatment and prognosis.

The hyper-IgE syndrome is characterized clinically by recurrent staphylococcal abscesses of the skin, lungs and other sites from infancy. Affected patients also have a pruritic dermatitis that differs in character and distribution from lesions of atopic dermatitis. Most lack other signs of atopic disease, develop persistent pneumatoceles and have osteopenia. Laboratory abnormalities include the consistent presence of marked hyperimmunoglobulinemia E and eosinophilia of blood, sputum and tissues. They may have other inconsistent abnormalities of humoral and cellular immune responses and sometimes of phagocytic cell chemotactic responsiveness. Other clinical problems reported in such patients have included lymphomas, cryptococcal meningitis and cutaneous fungal disease. An 18-year-old male patient with a variant of the hyper-IgE syndrome, which he had acquired after a measles attack at the age of 5 years, suffered from recurrent ulcerative dermatitis and lymph node abscesses. Immunological investigation revealed an excessively elevated total serum IgE level (46,850 IU/ml), the presence of specific IgE to staphylococci, and quantitative and functional deficiency of IgG2. Skin and serological (radioallergosorbent) tests to inhalant and nutritive allergens were negative. Differentiation from atopic dermatitis should be made, because a long-term antistaphylococcal regime not only improves skin lesions but hinders the occurrence of lung abscesses and pneumatoceles.

Abscess↗

PubMed1989

[Epidemiologic study of 2 S. typhimurium outbreaks using plasmid fingerprints].

An outbreak of salmonellosis in an old people's home is reported. The infectious agent, S. typhi-murium, was isolated not only from several inmates but also from sick cows of the farm belonging to the home, in animal feed, from employees of the local butcher's shop, and finally in sludge from the local sewage plant. Plasmid analysis provided evidence of a common origin for the isolated S. typhi-murium strains. The incriminated strains harboured, together with two low-molecular-weight plasmids, a plasmid of approximately 50 Mdal, which was also demonstrated in some other S. typhi-murium strains isolated from clinical cases in the area around St. Gallen.

Adult↗