| 1. |
- Berglund, Torsten, et al.
(författare)
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One year of Neisseria gonorrhoeae isolates in Sweden : the prevalence study of antibiotic susceptibility shows relation to the geographic area of exposure
- 2002
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Ingår i: International Journal of STD and AIDS (London). - : SAGE Publications. - 0956-4624 .- 1758-1052. ; 13:2, s. 109-114
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Tidskriftsartikel (refereegranskat)abstract
- The aim of this study was to compare epidemiological data with antibiotic susceptibility patterns, so as to characterize the risk of infection with a highly resistant Neisseria gonorrhoeae strain. N. gonorrhoeae strains isolated in Sweden from February 1998 through January 1999 were tested for antibiotic susceptibility. Epidemiological data were received from each clinician reporting a case of gonorrhoea and these data were linked to the N. gonorrhoeae strains. A total of 348 N. gonorrhoeae isolates, representing 89% of all Swedish cases diagnosed during the 12-month period, were tested for antibiotic susceptibility. Of all isolates, 24% were β-lactamase-producing, and 18% had decreased susceptibility to ciprofloxacin (MIC>0.064 mg/l). All isolates were fully susceptible to ceftriaxone and spectinomycin. More than 99% of the isolates were fully susceptible to azithromycin. The antibiotic susceptibility varied with the places where patients were exposed to infection. When exposed in Asia, 63% of the isolates showed reduced susceptibility to ciprofloxacin, compared with 0-8.5% of the isolates from patients exposed in other places (RR=8.5, P<0.001). Ciprofloxacin cannot be recommended as the first choice of treatment if the place of exposure was in Asia.
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| 2. |
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| 3. |
- Clarke, S. C., et al.
(författare)
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Analysis of PorA variable region 3 in meningococci : implications for vaccine policy?
- 2003
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Ingår i: Vaccine. - 0264-410X .- 1873-2518. ; 21:19-20, s. 2468-2473
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Tidskriftsartikel (refereegranskat)abstract
- Outer membrane protein (OMP) vaccines are being developed against Neisseria meningitidis serogroup B which may provide protection against common circulating serotypes and serosubtypes in some countries. However, limited data is available in Europe from genosubtyping meningococci. We therefore undertook a retrospective analysis of the three main variable regions, VR1, VR2 as well as VR3, of the porA gene from N. meningitidis isolated from different countries, mainly from Scotland and Sweden. Analysis of this gene showed that, amongst 226 strains studied, there were a total of 78 different strains. No new VR1 or VR2 alleles were found but five new VR3 alleles are described. Our data indicates the importance of analysing the VR3 region of PorA in addition to VR1 and VR2 and also highlights, in general terms, the need for genosubtyping meningococci. Such analyses have major implications for the design of new meningococcal vaccines.
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| 4. |
- Issa, Mohamed, et al.
(författare)
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Neisseria meningitidis serogroup W-135 isolated from healthy carriers and patients in Sudan after the Hajj in 2000
- 2003
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Ingår i: Scandinavian Journal of Infectious Diseases. - 0036-5548 .- 1651-1980. ; 35:4, s. 230-233
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Tidskriftsartikel (refereegranskat)abstract
- The first epidemic in the world of meningococcal disease due to serogroup W-135 was reported during the Hajj in 2000, with subsequent spread. The aims of the present study were to investigate whether the Hajj 2000 Neisseria meningitidis serogroup W-135 had also been carried to Sudan in the eastern part of the African meningitis belt, by examining healthy Sudanese pilgrims (Hajj 2000) and members of their families, and whether the strain was causing meningitis. The phenotypic character of W-135 meningococci from Sudanese carriers (n = 5) and patients (n = 2) 1 y later was similar to W-135 strains associated with Hajj 2000. The present study, using the combination of the 2 molecular techniques; sequencing of the porA gene for variable regions (VR1, VR2 and VR3) and pulsed-field gel electrophoresis of the entire genome (using SpeI and NheI), shows that the Hajj 2000 serogroup W-135 clone (P1.5,2,36-2 of the ET-37 complex) most probably was introduced into Sudan, by pilgrims returning from the Hajj 2000. This strain has not been diagnosed before in Sudan. Close epidemiological surveillance is required to identify a possible new emerging meningitis epidemic.
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| 5. |
- Issa, Mohamed, et al.
(författare)
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PCR of Cerebrospinal Fluid for Diagnosis of Bacterial Meningitis During Meningococcal Epidemics : an Example from Sudan
- 2003
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Ingår i: Scandinavian Journal of Infectious Diseases. - : Informa UK Limited. - 0036-5548 .- 1651-1980. ; 35:10, s. 719-723
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Tidskriftsartikel (refereegranskat)abstract
- Meningococcal disease is feared due to its rapid progression and high case fatality rate, especially in the African meningitis belt, where epidemics of meningococcal meningitis appear cyclically. Culture, direct microscopy and antigen detection are the basic methods for diagnosis and species identification of bacterial meningitis. These methods are known to have limitations, especially in developing countries. The aim of the present study was to document the application of PCR technology for the diagnosis of bacterial meningitis in cerebrospinal fluid (CSF) samples (n = 52) collected during epidemics in Sudan. In the application of PCR for detection of the causative agent of bacterial meningitis (based on the 16S rRNA gene), bacterial DNA was identified in 49 samples. Common bacterial species causing bacterial meningitis could be detected in 31 of the CSF samples (27 meningococci), while 18 contained DNA, mainly from normally contaminating bacteria. A specific PCR for group A meningococci (based on the sacC gene) was positive in 27 of the CSF samples. The results show that PCR technology is a sharpedged tool for confirmation of a diagnosis of meningococcal meningitis and for obtaining a direct genogrouping of group A meningococci in CSF. It is important to stress the use of direct and specific PCRs to avoid interference by contaminating bacteria, a great problem in samples from areas in the meningitis belt.
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| 6. |
- Jacobsson, Susanne, et al.
(författare)
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Molecular characterisation of group A Neisseria meningitidis isolated in Sudan 1985–2001
- 2003
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Ingår i: Acta Pathologica, Microbiologica et Immunologica Scandinavica (APMIS). - : Wiley. - 0903-4641 .- 1600-0463. ; 111:11, s. 1060-1066
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Tidskriftsartikel (refereegranskat)abstract
- A total of 33 group A Neisseria meningitidis (Mc) isolates, collected in Sudan between 1985 and 2001, were studied in order to describe the changes over time in a country within the meningitis belt of Africa. The isolates were characterised by traditional phenotypic methods (serogrouping, serotyping, serosubtyping and antibiogram) and molecular techniques (genosubtyping, pulsed-field gel electrophoresis [PFGE] with restriction endonucleases SpeI and NheI, and multilocus sequence typing [MLST]). Three clones of group A Mc were identified: one before 1988 (sulphadiazine sensitive, serotype 4, genosubtype P1.7,13-1,35-1, sequence type 4 [ST-4]); another during and after the 1988 epidemic (sulphadiazine resistant, serotype 4, genosubtype P1.20,9,35-1, ST-5); and a third causing the 1999 epidemic (sulphadiazine resistant, serotype 4, genosubtype P1.20,9,35-1, ST-7). The first clone showed major differences compared to the other two. The second and third clones had many similarities with differences in only a single gene (pgm) in the MLST (47 of the 450 bp) but significant other differences according to the PFGE patterns. Within the clones, genosubtyping and MLST gave identical information (except one base substitution in the aroE gene in one isolate). However, the PFGE patterns showed changes over time within the clones, where SpeI revealed somewhat more diversity than NheI.
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| 7. |
- Unemo, Magnus, 1970-, et al.
(författare)
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Comparison of serologic and genetic porB-based typing of Neisseria gonorrhoeae : consequences for future characterization
- 2003
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Ingår i: Journal of Clinical Microbiology. - 0095-1137 .- 1098-660X. ; 41:9, s. 4141-4147
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Tidskriftsartikel (refereegranskat)abstract
- Due to temporal changes in the epidemiology of gonorrhea, a precise characterization of Neisseria gonorrhoeae is essential. In the present study genetic heterogeneity in the porB genes of N. gonorrhoeae was examined, and serovar determination was compared to porB gene sequencing. Among 108 N. gonorrhoeae isolates, phylogenetic analysis of the entire porB alleles (924 to 993 bp) identified 87 unique sequences. By analyzing only the four to six most heterogeneous porB gene regions (174 to 363 bp), 86 out of these 87 genetic variants were identified. Consequently, analysis of shorter highly variable regions of the porB gene generates high-level discriminatory ability as well as fast, objective, reproducible, and portable data for epidemiological characterization of N. gonorrhoeae. Regarding putative antigenic epitopes of PorB for Genetic Systems monoclonal antibodies (MAbs), some of the previous findings were confirmed, but new findings were also observed. For several of the MAbs, however, the precise amino acid residues of PorB critical for single-MAb reactivity were difficult to identify. In addition, repeated serovar determination of 108 N. gonorrhoeae isolates revealed discrepancies for 34 isolates, mostly due to nonreproducible reactivity with single MAbs. Thus, the prospects of a genetic typing system with congruent translation of the serovar determination seem to be limited. In conclusion, analysis of short highly variable regions of the porB gene could form the basis for a fast molecular epidemiological tool for the examination of emergence and transmission of N. gonorrhoeae strains within the community.
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| 8. |
- Unemo, Magnus, 1970-
(författare)
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Genotypic and phenotypic characterisation of Neisseria gonorrhoeae
- 2003
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- The bacterium Neisseria gonorrhoeae (the gonococcus) is the aetiological agent of gonorrhoea, which remains a major sexually transmitted infection/disease (STI/STD) worldwide. The incidence of gonorrhoea was previously high in many countries, Sweden included. The incidence in Sweden culminated in 1970 with 487 cases per 100,000 inhabitants. After that, the incidence declined almost every year until an all-time low of 2.4 was observed in 1996. ln 1997 the incidence of gonorrhoea began to significantly increase in Sweden, due mainly to a larger number of domestic cases of young heterosexuals of both sexes and homosexual men. This observation, in combination with the widespread use of suboptimal methods for characterisation and, in some countries, for diagnosis of the bacterium, as well as the rapid increase of resistance to several antibiotics, has intensified the research in the field of N. gonorrhoeae.In the present thesis (paper 1), a high prevalence of decreased susceptibility or resistance to several of the traditionally used gonorrhoea antibiotics was identified and correlated to the geographic area of exposure, especially Asia. Nevertheless, effective antibiotics for treating gonorrhoea are at hand. A substantial genetic heterogeneity within identical serological variants (serovars), i.e. intraserovar, as well as interserovar of N. gonorrhoeae strains circulating within the community was revealed, emphasising the importance of using highly discriminative (DNA-based) epidemiological characterisation methods for the bacteria (papers II-V). Effective DNA-based characterisation methods, i.e. pulsed-field gel electrophmesis (PFGE) of genomic DNA digested with rarely cutting restriction endonucleases and porB gene sequencing, were adapted, optimised and evaluated against conventional phenotypic methods, as epidemiological tools on Swedish N. gonorrhoeae isolates. These molecular techniques showed a significantly higher discriminatory ability, reproducibility, and objectivity than the serovar determinations using the Genetic Systems (OS) or the Pharmacia panel (Ph) ofmonoclonal antibodies (MAbs) (papers II & III). According to a comparison of serologic and genetic parB-based typing of N. gonorrhoeae, the precise amino acid residues of porB, critical for the reactivity of several of the GS MAbs, were difficult to identity (paper IV). In papers IV & V, a determination of genetic group (genogroup) and genetic variant (genovar) was developed based on real-time PCR of the entire porB gene with subsequent sequence analysis in real-time by synthesis, i.e. pyrosequencing technology, of short, highly polymorphic porB gene segments. This method provides a rapid, high-throughput, objective, highly discriminative, typeable, portable for interlaboratory comparisons, and reproducible molecular characterisation for N. gonorrhoeae. Genogroup and genovar determination can complement or even replace the internationally established serovar determination in routine use for following the transmission of individual strains in the community and confirming presumed epidemiological connections or discriminating isolates of suspected clusters of gonorrhoea cases.
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| 9. |
- Unemo, Magnus, 1970-, et al.
(författare)
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Molecular epidemiology of Neisseria gonorrhoeae : sequence analysis of the porB gene confirms presence of two circulating strains
- 2002
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Ingår i: Journal of Clinical Microbiology. - 0095-1137 .- 1098-660X. ; 40:10, s. 3741-3749
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Tidskriftsartikel (refereegranskat)abstract
- The phenotypic and genotypic characteristics of Neisseria gonorrhoeae strains fluctuate over time both locally and globally, and highly discriminative and precise characterization of the strains is essential. Conventional characterization of N. gonorrhoeae strains for epidemiological purposes is mostly based on phenotypic methods, which have some inherent limitations. In the present study sequence analysis of porB1b gene sequences was used for examination of the genetic relationships among N. gonorrhoeae strains. Substantial genetic heterogeneity was identified in the porB genes of serovar IB-2 isolates (8.1% of the nucleotide sites were polymorphic) and serovar IB-3 isolates (5.2% of the nucleotide sites were polymorphic) as well as between isolates of different serovars. The highest degree of diversity was identified in the gene segments encoding the surface-exposed loops of the mature PorB protein. Phylogenetic analysis of the porB1b gene sequences confirmed previous findings that have indicated the circulation of one N. gonorrhoeae strain each of serovar IB-2 and serovar IB-3 in the Swedish community. These strains caused the majority of the cases in two domestic core groups comprising homosexual men and young heterosexuals, respectively, and were also detected in other patients. The phylogenetic analyses of porB gene sequences in the present study showed congruence, but not complete identity, with previous results obtained by pulsed-field gel electrophoresis of the same isolates. In conclusion, porB gene sequencing can be used as a molecular epidemiological tool for examination of genetic relationships among emerging and circulating N. gonorrhoeae strains, as well as for confirmation or discrimination of clusters of gonorrhea cases.
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| 10. |
- Unemo, Magnus, 1970-, et al.
(författare)
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Molecular typing of Neisseria gonorrhoeae isolates by pyrosequencing of highly polymorphic segments of the porB gene
- 2004
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Ingår i: Journal of Clinical Microbiology. - 0095-1137 .- 1098-660X. ; 42:7, s. 2926-2934
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Tidskriftsartikel (refereegranskat)abstract
- For prevention and control of gonorrhea, an objective, highly discriminating, and reproducible molecular epidemiological characterization of Neisseria gonorrhoeae is essential. In the present study, in pursuance of providing such qualities, pyrosequencing technology, a fast real-time DNA sequence analysis, was applied to six short, highly polymorphic porB gene segments, with subsequent genetic variant (genovar) determination of the bacterial isolates. The sequencing templates were obtained by real-time PCR amplification, which also included fluorescence melting curve analysis of the entire porB gene in order to determine the genogroup (porB1a or porB1b allele) prior to pyrosequencing analysis. The PSQ 96 MA system used allowed rapid (in approximately 1.5 h) determination of 96 sequences of 20 to 65 correct nucleotides each. The results were reproducible and mostly in concordance with the results of conventional Sanger dideoxy sequencing, with the exception of shorter read lengths and some uncertainty in determining the correct number of identical nucleotides in homopolymeric segments. The number of sequence variants identified in each of the six highly polymorphic segments of the porB1a and porB1b alleles (encoding surface-exposed amino acid loops of the mature PorB protein) ranged from 5 to 11 and from 8 to 39, respectively. Among porB1a isolates (n = 22) and porB1b isolates (n = 65), 22 and 64 unique genovars, respectively, were identified. All isolates were typeable. The present results provide evidence of a high discriminatory ability, practically the same as that for sequencing of the entire porB gene. In conclusion, the fast and high-throughput pyrosequencing technology can be used for molecular epidemiological characterization of N. gonorrhoeae.
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