| 1. |
- Petersson, A C, et al.
(författare)
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Evaluating the usefulness of spa typing, in comparison with pulsed-field gel electrophoresis, for epidemiological typing of methicillin-resistant Staphylococcus aureus in a low-prevalence region in Sweden 2000-2004.
- 2010
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Ingår i: Clinical Microbiology and Infection. - : Elsevier BV. - 1469-0691 .- 1198-743X. ; 16, s. 456-462
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Tidskriftsartikel (refereegranskat)abstract
- Clin Microbiol InfectAbstract The usefulness of spa typing was evaluated in relation to pulsed-field gel electrophoresis (PFGE), as a tool for epidemiological typing of methicillin-resistant Staphylococcus aureus (MRSA) in a low-prevalence region in southern Sweden. Bacterial isolates from 216 MRSA cases, newly identified in 2000-2004, were studied. The isolates were obtained from infected patients (31%), and from colonized individuals found by screening (69%). In total, 49 spa types and 73 PFGE patterns were identified. The discriminatory power of spa typing was lower (94.9 +/- 1.8%) than that of PFGE (97.3 +/- 1.2%). For two spa types (t002 and t008) the Panton-Valentine leukocidin results added useful discriminatory information. The most common spa types were t044 (n = 31; four PFGE patterns), t002 (n = 24; 10 PFGE patterns), t067 (n = 12; four PFGE patterns), t050 (n = 12; one PFGE pattern), and t324 (n = 11; one PFGE pattern). Epidemiological investigations identified 91 single cases and 39 transmission chains, each involving two to 13 cases. All the transmission chains were held together both by spa and PFGE typing. Among the 91 single-case isolates, 33 spa types and 50 PFGE patterns were unique (matchless) at the time of identification. The low prevalence of MRSA, the low number of outbreaks, and the wide spectrum of strains due to frequent acquisitions abroad (49% of the cases), makes spa typing a useful complement to epidemiological investigations in our setting. However, we still recommend the continued use of PFGE for further discrimination of isolates with identical spa types when epidemiological data can not exclude possible transmission.
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| 2. |
- Törös, Bianca, 1987-
(författare)
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Genome-based characterization of Neisseria meningitidis with focus on the emergent serogroup Y disease
- 2014
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Neisseria meningitidis, also referred to as meningococcus, is one of the leading causes of epidemic meningitis and septicaemia worldwide. Despite modern treatment, meningococcal disease remains associated with a high mortality (about 10%). Meningococcal disease is mainly restricted to specific hypervirulent lineages and specific capsular groups (serogroups), which have a changing global distribution over time. At the end of the 2000s, the previously unusual serogroup Y emerged, corresponding to half of all of the invasive meningococcal disease (IMD) cases in Sweden by the beginning of the 2010s. The aim of this thesis is to describe the emergence of serogroup Y meningococci genetically in an effort to understand some of the factors involved in the successful spread of this group throughout Sweden. In addition, genetic typing schemes were evaluated for surveillance and outbreak investigation.Our results indicate that the currently recommended typing for surveillance of meningococci could be altered to include the factor H-binding protein (fHbp). A highly variable multilocus variable number tandem repeat analysis (HV-MLVA) was able to confirm connected cases in a suspected small outbreak. In addition, a strain type sharing the same porA, fetA, porB, fHbp, penA and multilocus sequence type was found to be the principal cause of the increase in serogroup Y disease. However, a deeper resolution obtained from the core genomes revealed a subtype of this strain, which was mainly responsible for the increase. Finally, when the Swedish serogroup Y genomes were compared internationally, different strains seemed to dominate in different regions. This indicates that the increase was probably not due to one or more point introductions of a strain previously known internationally but more probably multifactorial.
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| 3. |
- Winqvist, Niclas, et al.
(författare)
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Long-term course of Mycobacterium tuberculosis infection in Swedish birth cohorts during the twentieth century.
- 2011
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Ingår i: The International Journal of Tuberculosis and Lung Disease. - : International Union Against Tuberculosis and Lung Disease. - 1815-7920 .- 1027-3719. ; 15:6, s. 736-740
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Tidskriftsartikel (refereegranskat)abstract
- Abstract SETTING: Sweden under transition from high to low tuberculosis (TB) incidence from 1920 to 2009. OBJECTIVE: To correlate estimates of TB infection in birth cohorts with the longitudinal incidence of active TB to assess the long-term risk and time pattern of reactivated TB. DESIGN: Time trend analysis on TB incidence using age-cohort modelling. RESULTS: The overall TB incidence decreased from 700 per 100 000 population in 1920 to 1.4 in 2009 in the Sweden-born population. The estimated disease rate (number of cases divided by the estimated number of infected in 1967), for each birth cohort between 1920 and 1940, was stable on a level between 9.8% and 10.7%. The reactivation rate of latent TB infection (LTBI) was 2% after 1967, when indigenous transmission had disappeared. CONCLUSION: Although approximately 10% of persons with LTBI developed active TB, the majority of cases occurred shortly after infection, and the rates of reactivation declined over time. This indicates extensive spontaneous clearance of LTBI
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