| 1. |
- Dumke, Roger, et al.
(författare)
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Multi-center evaluation of one commercial and 12 in-house real-time PCR assays for detection of Mycoplasma pneumoniae
- 2017
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Ingår i: Diagnostic microbiology and infectious disease. - : ELSEVIER SCIENCE INC. - 0732-8893 .- 1879-0070. ; 88:2, s. 111-114
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Tidskriftsartikel (refereegranskat)abstract
- Detection of Mycoplasma pneumoniae by real-time PCR is not yet standardized across laboratories. We have implemented a standardization protocol to compare the performance of thirteen commercial and in-house approaches. Despite differences on threshold values of samples, all assays were able to detect at least 20 M. pneumoniae genomes per reaction.
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| 2. |
- Gullsby, Karolina
(författare)
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Molecular detection and epidemiological studies of atypical bacteria causing respiratory tract infections
- 2019
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Respiratory infections are common causes of morbidity and mortality. Chlamydia pneumoniae, Mycoplasma pneumoniae and Bordetella pertussis cause respiratory infection, often with similar symptoms. Molecular diagnostic methods are preferred since these bacteria are difficult to culture. The aim of this thesis was to evaluate and improve the diagnostics and knowledge of the epidemiology of these bacteria.A real-time polymerase chain reaction (PCR) method targeting the IS481 element present in the genome of B. pertussis was compared to culture and serology results, and a duplex real-time PCR method was constructed for detecting C. pneumoniae and M. pneumoniae, which was compared to two endpoint PCR methods. Both real-time PCR methods showed high sensitivity and specificity.Typing of 624 M. pneumoniae samples, collected from 1996 to 2017 from four counties, was performed by P1 typing and multiple-locus variable number tandem repeat analysis (MLVA). A polyclonal distribution of strains was seen over all epidemic periods, but strains of P1 type 2/variant 2 and MLVA types 3-5-6-2 and 4-5-7-2 predominated in 2010−2013. A shift from type 2 strains to different variant 2 strains was seen and a new variant, 2e, was detected in 2016−2017. An A2063G mutation associated with macrolide resistance was detected by a fluorescence resonance energy transfer (FRET) PCR method in one (0.16%) of 608 M. pneumoniae strains.Molecular characterisation using whole-genome sequencing of 93 B. pertussis isolates, collected between 1986 and 2016 from three counties showed that there were polyclonal strains in the county of Dalarna, Gävleborg and Uppsala in the years 2014−2016. Changes in virulence-related genes were detected: a shift from isolates harbouring the ptxP3 allele in favour of ptxP1 was seen, and almost all isolates had a disrupted prn gene. No detection of macrolide resistance in B. pertussis was detected.In conclusion, the validated real-time PCR methods for detection of B. pertussis, C. pneumoniae and M. pneumoniae have led to improved diagnostic methods for use in clinical laboratories. The molecular characterisation of M. pneumoniae and B. pertussis strains has contributed to the wider understanding of the genetic changes that has occurred over the epidemic periods, but further studies is needed.
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| 3. |
- Gullsby, Karolina, et al.
(författare)
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Molecular typing of Mycoplasma pneumoniae strains in Sweden, 1996–2017, and the emergence of a new P1 cytadhesin gene, Variant 2e
- 2019
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Ingår i: Journal of Clinical Microbiology. - : American Society for Microbiology. - 0095-1137 .- 1098-660X. ; 57:6
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Tidskriftsartikel (refereegranskat)abstract
- Mycoplasma pneumoniae causes respiratory infections, such as community-acquired pneumonia (CAP), with epidemics recurring every 3 to 7 years. In 2010 and 2011, many countries experienced an extraordinary epidemic peak. The cause of these recurring epidemics is not understood, but decreasing herd immunity and shifts in the strains' antigenic properties have been suggested as contributing factors. M. pneumoniae PCR-positive samples were collected between 1996 and 2017 from four neighboring counties inhabited by 12% of Sweden's population. A total of 578 isolates were characterized directly from 624 clinical samples using P1 typing by sequencing and multilocus variable number tandem repeat analysis (MLVA). A fluorescence resonance energy transfer (FRET)-PCR approach was also used to detect mutations associated with macrolide resistance in the 23S rRNA gene. Through P1 typing, the strains were classified into type 1 and type 2, as well as variants 2a, 2b, 2c, and a new variant found in nine of the strains, denoted variant 2e. Twelve MLVA types were distinguished, and 3-5-6-2 (42.4%), 4-5-7-2 (37.4%), and 3-6-6-2 (14.9%) predominated. Several P1 and MLVA types cocirculated each year, but type 2/variant 2 strains and MLVA types 3-5-6-2 and 4-5-7-2 predominated during the epidemic period comprising the peak of 2010 and 2011. In 2016 and 2017, type 1 became more common, and MLVA type 4-5-7-2 predominated. We also found that 0.2% (1/578) of the strains carried a macrolide resistance-associated mutation, indicating a very low prevalence of macrolide resistance in this region of Sweden.
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| 4. |
- Gullsby, Karolina, et al.
(författare)
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No detection of macrolide-resistant Mycoplasma pneumoniae from Swedish patients, 1996-2013.
- 2016
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Ingår i: Infection Ecology & Epidemiology. - : Informa UK Limited. - 2000-8686 .- 2000-8686. ; 6:1
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Tidskriftsartikel (refereegranskat)abstract
- BACKGROUND: Mycoplasma pneumoniae is a common cause of respiratory infections which can cause life-threatening pneumonia and serious extrapulmonary manifestations. Since the year 2000, the emergence of macrolide-resistant M. pneumoniae strains has increased with varying incidences across countries. In China more than 90% of the strains are resistant. M. pneumoniae diagnostics is mostly done with molecular methods, and in Sweden antibiotic resistance surveillance is not routinely performed. The prevalence of macrolide-resistant M. pneumoniae has not previously been studied in Sweden.MATERIAL AND METHODS: A total of 563 M. pneumoniae-positive respiratory samples, collected from four counties in Sweden between 1996 and 2013, were screened for mutations associated with macrolide resistance using a duplex FRET real-time PCR method. The real-time PCR targets the 23S rRNA gene, and differentiation between wild-type and resistant strains was achieved with a melting curve analysis.RESULTS: Of the 563 samples included, 548 were analyzed for mutations associated with macrolide resistance. No mutations were found. The detection rate of macrolide-resistant M. pneumoniae in this study was 0% [0.00-0.84%].CONCLUSION: No macrolide-resistant M. pneumoniae has been detected in Sweden. However, the emergence and spread of macrolide-resistant M. pneumoniae strains in many countries commands continuous epidemiological surveillance.
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| 5. |
- Herrmann, Björn, et al.
(författare)
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Chlamydia trachomatis testing : a national evaluation of internet based self-sampling in sweden
- 2019
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Ingår i: Sexually Transmitted Infections. - : BMJ Publishing Group Ltd. - 1368-4973 .- 1472-3263. ; 95, s. A72-A72
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Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)abstract
- Background Chlamydia trachomatis (CT) testing in Sweden is free of charge and now exceeds 600,000 annual tests in a population of 10 million. These tests include internet-based self-sampling tests, a service that gradually has been implemented as a part of routine diagnostics in all 21 counties. To our knowledge Sweden is the country with the highest coverage of internet based self-sampling for CT. This study evaluates the diagnostic outcome for self-sampling.Methods Requests for both self-sampling at home and clinic based sampling for CT-testing were sent to the laboratories in 18 of 21 counties. All 18 counties provided data on self-sampling in 2017 and 12 counties (representing 80% of the population) provided data on both self-collected samples at home and clinic based testing for the years 2013 to 2017.Results The proportion of self-sampling increased from 12.9% in 2013 to 17.8% in 2016 when compared to national chlamydia test figures. Between 23% and 26% of delivered test kits were never sent back for analysis during 2013–2017. In analysis of 12 counties self-sampling increased by 110% between 2013 (n=32,993) and 2017 (n=69,181) for women, compared to 67% for men (2013: n=21,008; 2017: n=35,091). Test volumes for clinic based sampling was fairly constant for both sexes (women 2013 n=245,274; 2017 n=243,338; men 2013 n=97,519; 2017 n=110,617). The proportion of men was 36% for self-sampling compared to 30% (p<0,00001) for clinic based sampling, and the positivity rate decreased for both groups from 2013 to 2017 (7,8% to 7,1% (p<0,01)) vs 9.1% to 7.0% (p<0,0001)). Corresponding figures for women went from 5.3% to 4.6% (p<0,0001)and from 4.9% to 4.1% (p<0,0001).Conclusion Self-sampling has increased significantly in recent years, especially among women.The positivity rate is similar in self-collected and clinic collected samples.Self-sampling reaches men more than clinic based testing, but not as much as expected.Disclosure No significant relationships.
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