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D A Caugant

Publications and source records attributed to D A Caugant.

At least 37 records · Page 2Linked to original sources
PubMed2002

[Molecular epidemiology of meningococci].

By using the techniques of molecular biology, such as multilocus enzyme electrophoresis and multilocus sequence typing, it has been possible to identify the clones of meningococci that have been responsible for major epidemics in the world and to elucidate the routes of spread of these bacteria. Although meningococci can rearrange very rapidly their genome through the process of transformation, some clones or some groups of closely related clones have been stable and have been associated with increases of incidence of disease during decades. A clone with an epidemic potential can be disseminated globally within a few years, but the reasons for the development of an epidemic in a particular population are still not fully understood.

Bacterial Typing Techniques↗
PubMed2001

Fit genotypes and escape variants of subgroup III Neisseria meningitidis during three pandemics of epidemic meningitis.

The genetic variability at six polymorphic loci was examined within a global collection of 502 isolates of subgroup III, serogroup A Neisseria meningitidis. Nine "genoclouds" were identified, consisting of genotypes that were isolated repeatedly plus 48 descendent genotypes that were isolated rarely. These genoclouds have caused three pandemic waves of disease since the mid-1960s, the most recent of which was imported from East Asia to Europe and Africa in the mid-1990s. Many of the genotypes are escape variants, resulting from positive selection that we attribute to herd immunity. Despite positive selection, most escape variants are less fit than their parents and are lost because of competition and bottlenecks during spread from country to country. Competition between fit genotypes results in dramatic changes in population composition over short time periods.

Alleles↗
PubMed2001

Antibiotic sensitivity still prevails in Norwegian blood culture isolates.

We describe the antimicrobial susceptibility of bacteraemia isolates from Norway. From March 1998 to February 1999, four university hospitals covering all parts of Norway collected their first 10 isolates each month. Minimal inhibitory concentrations were determined for: Enterobacteriaceae (n=192), staphylococci (n=89) and Streptococcus pneumoniae (n=69) using the Etest. NCCLS breakpoints were used. About 20% of all blood culture isolates in Norway in this period were investigated. Compared with countries outside Scandinavia antibiotic sensitivity still prevails. Only minor differences in resistance were found between participating hospitals, between hospital departments and between hospital- and community-acquired pathogens. The prudent use of antibiotics in Norway may contribute to the fact that antibiotic resistance still remains low in the most common bacterial pathogens causing bloodstream infections.

Anti-Bacterial Agents↗
PubMed2001

Interpreting the rising incidence of meningococcal disease in Belgium: the contribution of molecular typing.

During a period of increasing meningococcal disease incidence in Belgium, all 538 serogroup B and all 87 serogroup C strains isolated between 1996 and 1998 were investigated by PCR with the arbitrary primer D8635, which is able to identify lineage III strains. In all, 399 strains (64%) were attributed to lineage III on the basis of PCR-based typing. Since their introduction in the Belgian population in the early 1990s, lineage III strains have become increasingly variable in phenotype. Currently, they are represented by strains belonging to 38 different phenotypes, of which 25 were not found in the period 1990-1995. The 87 serogroup C strains were further investigated by pulsed-field gel electrophoresis (PFGE), and a subset of 30 strains was also investigated by multilocus sequence typing (MLST). Strains of phenotype C:2b:P1.5,2, which currently constitute the majority of the serogroup C strains, were demonstrated to belong to cluster A4. Comparison of the discriminatory ability of D8635-primed PCR, PFGE and MLST revealed that D8635-primed PCR was the least discriminatory method and PFGE the most discriminatory method. However, the MLST data were more readily interpreted than the PFGE fingerprint patterns and can be compared easily with data obtained in other studies. In conclusion, the ongoing increase of meningococcal disease in Belgium could be attributed not only to the further expansion of lineage III, but also to the introduction of C:2b:P1.5,2 strains of cluster A4 in to the Belgian population.

Bacterial Typing Techniques↗
PubMed2001

Molecular epidemiology of Mycobacterium tuberculosis in Norway.

The incidence of tuberculosis in Norway is one of the lowest in the world, and approximately half of the cases occur in first- and second-generation immigrants. In the present study, the genetic diversity of 92% of all strains of Mycobacterium tuberculosis isolated in Norway in 1994 to 1998 was assessed using restriction fragment length polymorphism (RFLP) analysis, with the insertion sequence IS6110 and the repetitive element DR as probes, to determine the degree of active transmission between patients. The DR probe was used as a secondary molecular marker to support or rule out clustering of strains with fewer than five copies of IS6110. After exclusion of 20 cultures representing laboratory contamination, 573 different IS6110 patterns were found among the 698 strains analyzed. Of these 573 patterns, 542 were observed only once and 31 were shared by 2 to 14 isolates. Among 81 strains (11.5%) carrying fewer than five copies of IS6110, 56 RFLP patterns were found when the results of both the IS6110 and DR methods were combined. Among the 698 strains, 570 were considered to be independent cases. A total of 14.5% of the native Norwegians and 19.7% of the foreign patients were part of a cluster. Thus, the degree of recent transmission of tuberculosis in Norway is low and the great majority of the cases are due to reactivation of previous disease. Transmission between immigrants and native Norwegians is uncommon. Two outbreaks, one among native Norwegians and one mainly among immigrants, have been ongoing for several years, indicating that, even in a low-incidence country such as Norway, with a good national program for tuberculosis surveillance, certain transmission chains are difficult to break.

Adolescent↗
PubMed2001

Disseminated Mycobacterium celatum (type 3) infection in a domestic ferret (Mustela putorius furo).

A 4-year-old male ferret (Mustela putoriusfuro) had a 6-month history of weight loss and gradual development of depression and coughing. Necropsy findings included pale gray tissue around the distal trachea, multiple nodules in the lungs, a single nodule in the stomach wall, gray foci in the liver, and enlarged lymph nodes. Histologic examination revealed multifocal to coalescing granulomatous inflammation in the trachea, lungs, stomach, liver, and lymph nodes, with acid-fast bacteria in epithelioid cells and macrophages. The acid-fast bacteria were identified as Mycobacterium celatum (type 3) using DNA sequence analysis of the 16S ribosomal DNA gene. M. celatum is a recently described mycobacterium isolated mainly from immunocompromised humans. This is the first report of M. celatum infection in an animal.

Animals↗
PubMed2001

The panmictic nature of Neisseria meningitidis serogroup B during a period of endemic disease in Canada.

Three hundred and one (301) strains of Neisseria meningitidis serogroup B, isolated from patients with meningococcal disease during the years 1994-1996, were subjected to multilocus enzyme electrophoresis, serotyping, and serosubtyping. Based on the analyses of 14 enzyme loci, 177 electrophoretic types (ETs) were identified. Of these, 136 were represented by single isolates and 41 were represented by multiple isolates (range 2-31). The mean genetic diversity for isolates was 0.444 and for ETs was 0.440. The index of association (I(A)) between loci was 0.530 +/- 0.08 for isolates and 0.256 +/- 0.10 for ETs. Cluster analysis revealed the presence of 39 lineages each represented by a single ET or clusters of ETs. The most common serotypes were 4, 15, and 14 and accounted for 84 (28.0%), 53 (17.6%), and 32 (10.6%) of the isolates, respectively, and were dispersed amongst 46 ETs (1-122), 35 ETs (3-165), and 26 ETs (18-76), respectively. The 109 (36.6%) nontypable (NT) isolates were amongst 74 ETs (6-177). The mean genetic diversity for serotypes 4, 15, and 14 and NT isolates was 0.368, 0.371, 0.343, and 0.442, respectively, and for ETs was 0.363, 0.354, 0.397, and 0.440, respectively. Combinations of serotypes and serosubtypes (number of isolates) that occurred most frequently were 4:P1.14 (17), 14:P1.16 (16), NT:P1.16 (16), 15:P1.16 (13), and NT:P1.13 (13). The majority of group B disease in Canada during 1994-1996 was caused by meningococci of considerable genetic diversity, and reflects a situation of endemic disease. However, the results also indicate that organisms belonging to the ET-5 complex, which has been responsible for outbreaks of group B disease globally for several decades, have been introduced into the country.

Alleles↗
PubMed2001

Epidemiology of invasive meningococcal infections of children in Slovenia during 1993-1999.

Invasive strains of Neisseria meningitidis isolated from sterile body fluids of children aged 0-14 years were intentionally collected in nine Slovenian laboratories, and sent to the laboratory of the National Institute of Public Health, Ljubljana for final evaluation. From 1993-1999 we collected 53 invasive strains from children presented in this study. The incidence rate of invasive diseases in children shows that there is a rapid fall from 4.74/100,000 in 1993 to 0.90/100,000 in 1999. Invasive diseases predominated in children in the age group 0-1 year (19.6 cases per 100,000 children); followed by the age groups 2-4 years, 5-9 years and 10-14 years. The results of serogrouping indicate that the largest proportion of meningococci isolated (90%) were group B, while 8% of isolates were group C and only 2% group Y. The serotype/serosubtype distribution shows that the most frequent serotype (excluding 19 non-typable NT strains) was serotype 22, which was expressed in 9 strains and the most frequent serosubtype (excluding 11 NST strains) was P1.5,2 found in 7 strains. The most frequently isolated strains (excluding NT/NST strains) were B:22:P1.14; B:NT:P1.5 and B:NT:P1.16. Thirty-one strains collected during 1993-1995 were analysed by multilocus enzyme electrophoresis (MEE). There were 25 electrophoretic types (ETs) among 31 strains; the strains were very heterogeneous with only four ETs being represented by more than one strain. Study shows that meningococcal disease is still endemic in Slovenia.

Adolescent↗
PubMed2000

Injectional anthrax in a heroin skin-popper.

Anthrax is rare in western Europe but may arise sporadically in people exposed to animal products from endemic areas. A heroin-injecting drug user presented with a severe soft-tissue infection at the injection site, septic shock, and meningitis. A gram-positive endospore-forming aerobic rod was isolated from the soft tissue and cerebrospinal fluid; confirmation of Bacillus anthracis was made by PCR. Since contaminated heroin was the probable source of infection, this case is of concern and warrants surveillance.

Anthrax↗
PubMed2000

[Meningococcal disease in Africa--epidemiology and prevention].

Neisseria meningitidis is one of the most common causes of purulent meningitis all over the world. Large epidemics caused by meningococci have spread during the last decade throughout vast areas of Africa, also outside the region referred to as the classic "Meningitis Belt". Globally, this organism each year causes about 300,000 cases and 30,000 deaths; most of these are children. Meningococci of serogroup A cause a major part of these epidemics, and a remarkable feature of the epidemical situation is that the bacteria differ very little in antigenic properties as they belong to the same clonal group of meningococci. Immunization with safe and effective vaccines is the most efficient way of combatting these epidemics. The currently available polysaccharide vaccines against serogroup. A meningococcal disease do not induce long-term immunological memory and do not provide adequate protection of children below two years of age. There is an urgent need for a vaccine that induces long-term immunological memory in all age groups, so it can be included in the routine vaccination program. In contrast to serogroup C, the development of conjugate vaccines against serogroup A meningococcal disease has not yielded the positive results hoped for. The development of alternative protein-based vaccines therefore needs to be intensified.

Adolescent↗
PubMed2000

Genomic rearrangements in neisseria meningitidis strains of the ET-5 complex.

A physical map of the chromosome of Neisseria meningitidis strain 44/76, which belongs to the epidemic clone ET-5, was constructed. DNA fragments obtained after SfiI and NheI digestion were resolved by pulsed field gel electrophoresis (PFGE). The overall arrangement of 26 genetic markers localized on the 2.3-Mb chromosome was conserved in comparison with that in meningococcal strains B1940 and Z2491. Simplified physical maps of 29 additional strains belonging to the ET-5 complex isolated from various parts of the world were compared with that of strain 44/76. Ten distinct patterns of hybridization were identified. While two of the seven probes hybridized to fragments of the same size in all strains, the remaining probes hybridized to different fragments, in some cases to fragments not adjacent on the chromosome of 44/76. These results indicated the occurrence of genetic rearrangements in the genome of the ET-5 meningococcal clone in the course of its epidemic spread. </HEA

DNA, Bacterial↗
PubMed2000

Genome stability of Bacillus thuringiensis subsp. israelensis isolates.

Swedish soil isolates biochemically classified as Bacillus thuringiensis subsp. israelensis were further examined for genetic diversity by multilocus enzyme electrophoresis (MLEE), random amplified polymorphic DNA analysis (RAPD), pulse field gel electrophoresis (PFGE), and Southern blotting, and were compared with reference strains. All the tested strains belonging to the Bt. israelensis serotype H14 were found to be identical, as judged from the RAPD analysis. MLEE analysis gave a similar result; only one H14 strain was found to differ from the remaining H14 strains by one null allele. PFGE analysis confirmed a very close relationship between the H14 strains but revealed an SfiI restriction fragment of variable size. Southern blot analyses were carried out with probes for the chromosomally encoded flagellin gene(s) and the plasmid-encoded mosquitocidal toxins. All probes gave similar hybridization patterns in the H14 strains. The mosquito toxin probes hybridized only to the H14 strains, except for one probe hybridizing to strain 6:3, which was originally isolated from the same soil sample as strains 6:11 and 6:12. Because the RAPD, MLEE, and PFGE analyses showed that strain 6:3 appears to be unrelated to strains 6:11 and 6:12, the presence of a mosquito toxin sequence in strain 6:3 may suggest that gene transfer has occurred.

Animals↗
PubMed2000

Distribution of the meningococcal insertion sequence IS1301 in clonal lineages of Neisseria meningitidis.

The distribution of the meningococcal insertion sequence IS1301 was analysed in 496 strains of different serogroups and clonal lineages of Neisseria meningitidis, and in 64 neisserial strains other than N. meningitidis. IS1301 was found in meningococci, but not in apathogenic Neisseria sp. and Neisseria gonorrhoeae. The copy numbers of IS1301 varied between 2 and 17 per genome. IS1301 positive strains were mostly found among the serogroups 29E, W135, X, and Y. Clonal lineages of serogroup A, B, and C meningococci associated with epidemic meningococcal disease were rarely positive for IS1301.

Blotting, Southern↗
PubMed2000

Genetic characterization of a new variant within the ET-37 complex of Neisseria meningitidis associated with outbreaks in various parts of the world.

A new variant within the electrophoretic type (ET)-37 complex of Neisseria meningitidis, ET-15, first detected in Canada in 1986, has been associated with severe clinical infections and high mortality rates in several European countries, Israel and Australia. To ascertain the genetic and epidemiological relationships of ET-15 strains from different geographical areas, 72 ET-15 isolates from 10 countries were compared to 13 isolates representing other clones of the ET-37 complex. The 85 strains were analysed by pulsed-field gel electrophoresis (PFGE) using 2 restriction endonucleases and Southern hybridization with 10 genetic markers. Four ET-15 strains and 4 other strains of the ET-37 complex were further examined using an additional restriction enzyme and a total of 18 genetic markers. PFGE fingerprints of the ET-15 strains were closely related. Strains within each country were even more closely related, suggesting single introductions of the clone. Physical mapping of genes in ET-15 and other strains of the ET-37 complex demonstrated that large genetic rearrangements of the genome have occurred in association with the appearance of the ET-15 variant.

DNA Primers↗
PubMed2000

Characterisation of isolates of Staphylococcus aureus from acute, chronic and subclinical mastitis in cows in Norway.

Eighty-six Staphylococcus aureus isolates from cases of bovine mastitis were characterised biochemically and with respect to serotype, multilocus enzyme electrophoresis genotypes, antibiotic sensitivity, and production of enterotoxins A through D (SEA-D) and toxic shock syndrome toxin-1 (TSST-1). The samples were obtained from 81 different cows from 79 Norwegian dairy herds in 10 different counties in southern Norway. There was an equal representation of isolates from cases of acute, chronic and subclinical mastitis. Multilocus enzyme electrophoresis using 13 genetic loci showed that 69 of 86 isolates had the same electrophoretic type. This common electrophoretic type comprised isolates that differed in the expression of other phenotypical characteristics studied. Fifty-eight percent of the isolates produced one or more enterotoxins, predominantly a combination of SEC and TSST-1. Capsular serotyping revealed that 95% of the isolates belonged to serotype 8. No correlation was found between the factors studied and the clinical classification of mastitis. It appears that the majority of S. aureus isolates recovered from cases of bovine mastitis in Norway are genetically closely related and express common phenotypical characteristics.

Acute Disease↗
PubMed2000

Molecular characteristics and susceptibility to antibiotics of serogroup A Neisseria meningitidis strains isolated in Senegal in 1999.

A total of 22 strains of Neisseria meningitidis isolated from cerebrospinal fluid samples of patients in Dakar, Senegal, in the course of an epidemic of meningococcal meningitis in 1999 were studied. All the strains were serogroup A, serotype 21:P1.9 and belonged to clonal subgroup III-1. The strains were resistant to sulphonamide, but were susceptible to ampicillin, ceftriaxone and chloramphenicol, which are used in the treatment of cerebrospinal meningitis in Senegal.

Alleles↗
PubMed2000

Molecular epidemiological survey of Listeria monocytogenes in seafoods and seafood-processing plants.

To evaluate the role of seafoods in the epidemiology of human listeriosis and the role of the processing environment as a source of Listeria monocytogenes in seafood products, 305 L. monocytogenes isolates were characterized by multilocus enzyme electrophoresis using 21 genetic loci and restriction enzyme analysis of total DNA. Forty-four isolates were recovered from patients in Norway; 93 were isolated from seafoods, seafood-processing environments, and seawater from 55 different producers; and the remaining 168 isolates originated from six seafood-processing plants and one transport terminal examined in detail for L. monocytogenes. The patient isolates fell into 11 electrophoretic types, with four of them being responsible for 77% of the listeriosis cases in 1992 to 1996. Isolates from Norwegian seafoods and processing environments showed great genetic diversity, indicating that seafoods and seafood-processing environments do not offer a niche for specific L. monocytogenes strains. On the other hand, isolates from individual processing plants were genetically more homogenous, showing that plants are likely to be colonized with specific subclones of L. monocytogenes. The isolation of identical subclones of L. monocytogenes from both human patients and seafoods, including ready-to-eat products, suggests that such products may have been possible sources for listeriosis cases in Norway.

Animals↗