PubMed Health⌕ Search

Biomedical subjects

L O Frøholm

Publications and source records attributed to L O Frøholm.

At least 19 recordsLinked to original sources
PubMed2006

Carriage of Streptococcus pneumoniae in healthy Norwegian children attending day-care centres.

An observational study to examine Streptococcus pneumoniae carriage in Norwegian children was initiated after two cases of pneumococcal meningitis, caused by the England(14)-9 clone, occurred in one day-care centre in Oslo. All children recruited from the day-care centre where the cases occurred were vaccinated with a seven-valent pneumococcal conjugate vaccine; the other participants who attended three other day-care centres nearby were not. The children were followed for 9 months, and three samplings took place. At the first visit, 45.7% of the children were colonised by pneumococci in the nasopharynx. The children harboured a variety of serotypes, with serotypes 6A, 23F, 6B and 19F being the most frequent. The numbers of children carrying vaccine serotypes decreased in both the vaccinated and the non-vaccinated groups. Thus, no significant effect of vaccine on carriage was detected in this relatively small study.

Carrier State↗
PubMed2004

Systemic pneumococcal disease in Norway 1995-2001: capsular serotypes and antimicrobial resistance.

A total of 4624 pneumococcal isolates from episodes of systemic pneumococcal disease were received at the Norwegian Institute of Public Health during the period 1995-2001. All isolates were serotyped and tested for susceptibility to benzylpenicillin, lincomycin, erythromycin, tetracycline and trimethroprim sulphamethoxazole. The proportion of strains resistant to these antimicrobial agents remained stable at a low level, ranging from 0.1% for benzylpenicillin to 2.5% for erythromycin. The distribution of serotypes was also stable over the 7 years: serotypes 1, 4, 9, 14, 7, 6 and 23 were the most frequent, representing 70.5% of isolates. Overall, 95.8% of the isolates were of serotypes/groups included in the current 23-valent polysaccharide vaccine, 52.2% were of serotypes/groups included in the 7-valent conjugated vaccine and 85.5% were of serotypes/groups included in the 11-valent conjugated vaccine.

Adolescent↗
PubMed2002

Do HIV-seropositive patients become colonised with drug-resistant microorganisms?

The aim of the present study was to investigate whether HIV-infected patients, a group that is supposedly at risk for infection with antibiotic-resistant microbes, really does so, and to assess possible risk factors for acquiring these organisms. During the period from January 1998 to July 1999, samples of normal flora were obtained from 107 HIV-infected patients attending an outpatient clinic in Oslo, Norway. The samples were cultured for Streptococcus pneumoniae, Haemophilus influenzae, Escherichia coli, coagulase-negative staphylococci and Candida spp., and the resulting isolates were tested for antimicrobial susceptibility. The patients studied represented all stages of HIV infection, from recently infected to severely immunocompromised. Samples were taken at one, two or three time-points to determine whether antimicrobial resistance in colonising microorganisms increases over time. Antimicrobial resistance was linked primarily to antimicrobial prophylaxis, but it did not increase during the observation period. The level of a patient's immunodeficiency and the consequently intensified medical care was also of some importance. Even though about 50% of the patients were receiving antimicrobial agents at the time of sampling, the level of resistance found in these patients was very similar to that found in other patient groups in Norway; except for Candida albicans isolates, which were less susceptible to fluconazole. Overall, antimicrobial resistance was uncommon in the HIV-seropositive patients studied, a finding that is probably related to the overall low prevalence of antimicrobial resistance in the general population in Norway.

Adult↗
PubMed2002

Molecular characteristics of Neisseria meningitidis strains isolated in Burkina Faso in 2001.

In the course of an epidemic of meningitis in Burkina Faso in 2001, 27 cerebrospinal fluid samples from patients in 7 districts were forwarded to Norway for isolation and characterization of the causative agents. Neisseria meningitidis was isolated from 13 (48%) samples. The isolates were analysed using serological and genetic methods. Of the 13 strains, 4 were serogroup A, serotype 21:P1.9, sequence type (ST)-5 and belonged to clonal subgroup III, while the remaining 9 strains were serogroup W135, serotype 2a:P1.5,2, ST-11 and belonged to the electrophoretic type-37 complex. PCR analyses revealed meningococcal DNA in 13/14 culture-negative samples. Sequence analysis of the PCR products demonstrated that at least 3 different meningococcal strains were responsible for these 13 cases. Our results show that the W135 strain associated with the 2000 hajj (Muslim pilgrimage) outbreak was a significant cause of disease in Burkina Faso in 2001. Further studies are warranted to determine whether W135 is about to replace serogroup A in sub-Saharan Africa.

Adolescent↗
PubMed2000

Emerging antibiotic resistance in Salmonella typhimurium in Norway.

The antimicrobial resistance of 809 Salmonella Typhimurium isolates collected from humans in Norway between 1975 and 1998 was studied. The material was subdivided into domestic and foreign isolates according to whether the patient had recently travelled abroad or not. In imported isolates the largest increase in resistance was in 1996 when 35% of the isolates were multi-resistant. The first multi-resistant isolate acquired in Norway appeared in 1994, but already in 1998 23% of the isolates domestically acquired were multi-resistant, and a majority were S. Typhimurium DT104. We found no ciprofloxacin resistance in domestically acquired isolates. Amplified fragment length polymorphism analysis was performed on selected multi-resistant isolates. The method discriminated well between different multi-resistant isolates, but not between DT104 isolates. Resistant and multi-resistant S. Typhimurium were until 1998 essentially recovered from patients who had travelled abroad, but multi-resistant isolates, mainly DT104, are now also being transmitted within the country.

Disease Outbreaks↗
PubMed2000

A nasal whole-cell pertussis vaccine induces specific systemic and cross-reactive mucosal antibody responses in human volunteers.

A whole-cell pertussis vaccine, each dose consisting of 250 microg of protein, was given intranasally four times at weekly intervals to six adult volunteers. All vaccinees responded with increases in nasal fluid IgA antibodies to Bordetella pertussis whole-cell antigen. Three vaccinees with high nasal antibody responses also developed increased serum IgA and IgG antibodies to this antigen. Salivary antibody responses to the whole-cell antigen, as well as antibodies in serum and secretions to pertussis toxin (PT) and filamentous haemagglutinin (FHA) were negligible, except for a moderate increase in nasal fluid antibodies to FHA. Unexpectedly, the same vaccinees developed significant rises in nasal and salivary IgA antibodies to meningococcal outer-membrane antigens, whereas corresponding serum IgA and IgG antibodies were unchanged. Thus it appears that mucosal immunisation may induce secretory antibodies with broader specificities than can be found in serum.

Adhesins, Bacterial↗
PubMed1999

Outbreak of meningococcal disease in western Norway due to a new serogroup C variant of the ET-5 clone: effect of vaccination and selective carriage eradication.

A new sulphonamide resistant (SR) C: 15:P1.7,16 meningococcal strain, a variant of the ET-5 clone, dominated in an outbreak of 22 cases in western Norway commencing in 1995. The first eight patients were 15-21 years old from the Nordhordland area, initiating a carrier study in the local high schools. Carriage of SR serogroup C meningococci was detected by routine methods and treated with a single dose of ofloxacin 400 mg. Of 20 treated carriers, 14 harboured the outbreak strain C: 15:P1.7,16. Vaccination of 4000 children, adolescents and close contacts of patients was also performed. After the intervention, 14 additional cases of meningococcal disease occurred, 8 due to the outbreak strain. However, incidence rates dropped from 180 to 30 per 100000 per year in the student population, but increased from 0 to 13 in the rest of the population in Nordhordland. Carriage eradication is not generally recommended in Norway. However, tracing and treating meningococcal carriage may have reduced transmission and disease in this outbreak situation.

Adolescent↗
PubMed1999

Low occurrence of antibiotic resistance in Escherichia coli and staphylococci isolated from blood cultures in two Norwegian hospitals in 1991-92 and 1995-96.

The aim of this study was to investigate the antibiotic resistance rates of major bacterial pathogens causing bloodstream infections in two very different types of hospital in Norway. We examined all Escherichia coli and staphylococci (330 isolates) causing bloodstream infections from one general county hospital and one specialist national cancer hospital during the periods 1991-92 and 1995-96. Minimal inhibitory concentrations (MICs) were determined using the E-test. E. coli and staphylococci constituted 46.7% of all isolates from bloodstream infections in the two hospitals. Overall, E. coli isolates were resistant to amoxicillin (21%), trimethoprim (21%), doxycycline (20%) and trimethoprim-sulphamethoxazole (17%), while Staphylococcus aureus strains were resistant to benzylpenicillin (66%). No methicillin-resistant S. aureus was detected. Coagulase-negative staphylococci were often multiresistant, but remained fully sensitive to vancomycin. For a few antibiotics, significantly more resistance was found in the specialist hospital. In our material we found no significant increase in resistance between 1991-92 and 1995-96. In conclusion, antimicrobial resistance still remains low in important bacterial pathogens causing bloodstream infections in Norway.

Bacteremia↗
PubMed1998

Identification of nasopharyngeal carriage of an outbreak strain of Neisseria meningitidis by pulsed-field gel electrophoresis versus phenotypic methods.

The clustering of four cases of meningococcal disease during a 3-month period in a small community with 2233 inhabitants prompted an interventional carrier survey in persons < 19 years old and in family members of the patients. The aims of the survey were to identify the nasopharyngeal carriers and the carriage rate of the outbreak strain, to offer chemoprophylaxis to those carrying the outbreak strain, and to study the discriminatory power of phenotypic methods versus pulsed-field gel electrophoresis (PFGE) on carrier isolates during an outbreak. A high percentage of the population in the age group 0-19 years (73.7%) participated in the study. Among the 469 samples collected in this age group, meningococci were grown from 43 (9.2%). The highest carriage rates were in the age group 18-19 years (36.4%). With a provisional definition of the outbreak strain (group B or non-groupable Neisseria meningitidis with reduced sulphonamide sensitivity), six carriers were identified. All were treated with a single dose of ofloxacin. Four of these persons (0.76% of all tested) were later shown to have harboured the outbreak strain when analysed by PFGE. Three of them were epidemiologically closely related to one of the index cases. Serogrouping alone is not sufficient for the identification of an epidemic strain of N. meningitidis. Complete concordance of type and subtype antigens correctly identified the outbreak strain in this study. PFGE is well suited for the identification of an outbreak strain of N. meningitidis versus non-epidemic strains in tonsillo-pharyngeal specimens.

Adolescent↗
PubMed1998

Effect of aluminium hydroxide and meningococcal serogroup C capsular polysaccharide on the immunogenicity and reactogenicity of a group B Neisseria meningitidis outer membrane vesicle vaccine.

Three different formulations of an outer membrane vesicle (OMV) vaccine against group B meningococcal disease have been prepared and tested for immunogenicity and reactogenicity in adult volunteers. The vaccines were prepared with or without aluminium hydroxide and serogroup C-polysaccharide (C-ps). Doses from 12.5 to 100 micrograms protein were given twice at a six weeks' interval. All three formulations were well tolerated and highly immunogenic, inducing bactericidal and opsonizing antibodies in humans. Adsorption of OMVs to aluminium hydroxide reduced the pyrogenicity in rabbits. The differences in immunogenicity between the formulations were relatively small, but after the second dose a stronger booster response was observed when the vaccines were adsorbed. Thus, a formulation with OMVs and C-ps represents a safe and highly immunogenic vaccine, even without aluminium hydroxide.

Adjuvants, Immunologic↗
PubMed1996

Polymerase chain reaction for case ascertainment of meningococcal meningitis: application to the cerebrospinal fluids collected in the course of the Norwegian meningococcal serogroup B protection trial.

To improve the diagnosis of systemic meningococcal disease we used a nested polymerase chain reaction (nPCR) test to detect meningococcal DNA in cerebrospinal fluid (CSF) samples from patients. The nPCR test was based on the gene coding for the PorA outer membrane protein, a major antigen of Neisseria meningitidis, which is the basis for determining the subtype of the strains. The method was tested on CSF samples from 87 patients with various disease aetiology, including 37 patients with systemic meningococcal disease. It was also applied to all 67 CSF samples from culture-negative patients with suspected meningococcal disease which were collected in the course of the Norwegian serogroup B vaccination trials, between 1987 and 1993. Of the 67 culture-negative CSF samples, 10 were nPCR positive. Two of the 67 CSF were positive with the antigen test, and both of these were nPCR positive. Serum pairs from 46 of the 67 culture-negative patients were analysed for serological serogroup response in an enzyme-linked immunosorbent assay (ELISA) against meningococcal capsular polysaccharides. Nine of the 10 nPCR-positive CSF samples belonged to patients with serological response judged as either typical of, or compatible with systemic meningococcal disease. Sequence analysis of the nPCR products was performed to determine the subtype of the infecting meningococcal strains. Four of the 10 positive CSF samples were infected with a strain of subtype P1.7,16, which is similar to the epidemic strain used to produce the vaccine. Inclusion of nPCR for diagnosis of meningococcal meningitis did not significantly alter the results of the vaccination trial, but added important information about the strain causing disease in 5 of 13 serogroup B cases without preserved isolates.

Base Sequence↗
PubMed1995

Serotypes and subtypes of Neisseria meningitidis: results of an international study comparing sensitivities and specificities of monoclonal antibodies.

An international study supported by the World Health Organization comparing monoclonal antibodies for serotyping and serosubtyping of Neisseria meningitidis strains was performed and the results were assessed in 1992. A collection of 6 serotype-specific (1, 2a, 2b, 4, 14, and 15) and 12 serosubtype-specific (P1.1, P1.2, P1.4, P1.5, P1.6, P1.7, P1.9, P1.10, P1.12, P1.14, P1.15, and P1.16) monoclonal antibodies was provided to 11 participating laboratories throughout the world. Monoclonal antibodies were tested on 85 Neisseria meningitidis strains with known reference results. Whole-cell enzyme-linked immunosorbent assay was used for analysis in 10 of 11 laboratories. The sensitivities and specificities of individual serotype- and subtype-specific monoclonal antibodies were evaluated. Differences in individual laboratories and with individual monoclonal antibodies were assessed. Relatively large differences in sensitivities were achieved in individual laboratories. On the contrary, the specificities remained at high levels in all laboratories. The sensitivities of serotype-specific monoclonal antibodies ranged from 72.0 to 100%. Individual serosubtype-specific monoclonal antibodies showed sensitivities ranging from 64.1 to 98.1%. The most frequent reason for the incorrect results obtained with the monoclonal antibodies were false-negative results. The collaborative study demonstrated that some monoclonal antibodies are not very sensitive. Another study to define the most suitable monoclonal antibodies is planned.

Antibodies, Bacterial↗
PubMed1994

[High incidence and mortality of systemic pneumococcal disease among persons without spleen].

We surveyed 472 cases of culture-confirmed systemic pneumococcal disease that were reported to the Norwegian Notification System for Infectious Diseases during a 12-month period in 1992-93. The clinicians in charge of the patients filled in a questionnaire providing information on underlying disease and outcome for 461 (98%) of the patients. Eight of these patients were splenectomized; all of them more than ten years before. Four died, two survived but had serious sequelae, and two survived without obvious sequelae upon discharge from hospital. Using a rough estimate of the prevalence of unvaccinated splenectomized persons in Norway, we estimate that this group, compared to the normal population, has a relative risk of 25 of developing systemic pneumococcal disease and a relative risk of 75 of dying from pneumococcal disease. The serotype of the pneumococcal strain that caused the disease was determined for seven of the eight patients. All serotypes were represented in the 23-valent pneumococcal polysaccharide vaccine. We strongly recommend that doctors trace and vaccinate splenectomized individuals.

Adult↗
PubMed1994

[All persons without spleen should be given pneumococcal vaccine].

Splenectomized individuals run increased risk of developing overwhelming septicemia from encapsulated bacteria, especially Streptococcus pneumoniae. Polyvalent pneumococcal polysaccharide vaccine should be given to all splenectomized individuals above two years of age. Antipneumococcal antibody levels should be measured three to five years after the first vaccination, and persons with low antibody levels should be revaccinated. Splenectomized persons may be given a supply of penicillin V to enable them to start therapy while avaiting medical attention.

Bacterial Vaccines↗
PubMed1994

Asymptomatic carriage of Neisseria meningitidis in a randomly sampled population.

To estimate the extent of meningococcal carriage in the Norwegian population and to investigate the relationship of several characteristics of the population to the carrier state, 1,500 individuals living in rural and small-town areas near Oslo were selected at random from the Norwegian National Population Registry. These persons were asked to complete a questionnaire and to volunteer for a bacteriological tonsillopharyngeal swab sampling. Sixty-three percent of the selected persons participated in the survey. Ninety-one (9.6%) of the volunteers harbored Neisseria meningitidis. The isolates were serogrouped, serotyped, tested for antibiotic resistance, and analyzed by multilocus enzyme electrophoresis. Eight (8.8%) of the 91 isolates represented clones of the two clone complexes that have been responsible for most of the systemic meningococal disease in Norway in the 1980s. Age between 15 and 24, male sex, and active and passive smoking were found to be independently associated with meningococcal carriage in logistic regression analyses. Working outside the home and having an occupation in transportation or industry also increased the risk for meningococcal carriage in individuals older than 17, when corrections for gender and smoking were made. Assuming that our sample is representative of the Norwegian population, we estimated that about 40,000 individuals in Norway are asymptomatic carriers of isolates with epidemic potential. Thus, carriage eradication among close contacts of persons with systemic disease is unlikely to have a significant impact on the overall epidemiological situation.

Adolescent↗
PubMed1993

A new variant of serosubtype P1.16 in Neisseria meningitidis from Norway, associated with increased resistance to bactericidal antibodies induced by a serogroup B outer membrane protein vaccine.

Based on differences in reaction pattern with monoclonal antibodies against the P1.16 epitope, a new variant of the class 1 protein in Neisseria meningitidis serogroup B was identified in Norway. A single amino acid deletion was revealed when the part of the gene region encoding the second variable region of the protein was sequenced. This new variant was designated P1.16c. About 5% of the B:15:P1.7,16 strains in Norway from the time period 1987-1991 were P1.16c. In a localized area in Southern Norway, 5/8 (62%) of the P1.7,16 strains were P1.16c. The P1.16b mutant, recently described in England, was not found among the Norwegian meningococcal isolates. Strains carrying the P1.16c mutation showed increased resistance to bactericidal killing, not only by P1.16-specific monoclonal antibodies, but also by the sera from individuals immunized with a vaccine based on outer membranes from a B:15:P1.7,16 strain.

Amino Acid Sequence↗