1.
Rasmussen, Gunlög, 1973-, et al.
(författare)
Long term molecular epidemiology of methicillin-susceptible staphylococcus aureus bacteremia isolates in Sweden
2014
Ingår i: PLOS ONE. - San Francisco, USA : Public Library Science. - 1932-6203. ; 9:12
Tidskriftsartikel (refereegranskat) abstract
Staphylococcus aureus is one of the major pathogens that causes bacteremia; therefore, it is important to understand the long-term molecular epidemiology of S. aureus bacteremia infections. In particular, little is known about the population structure of methicillin-sensitive S. aureus (MSSA) compared to that of methicillin-resistant S. aureus. We investigated potential changes in the MSSA molecular epidemiology in Örebro County, Sweden, from 1980 through 2010. 400 MSSA bacteremia isolates, the first 100 isolated each decade from 1980 through 2010, were retrospectively identified and analyzed regarding assignment to clonal complexes (CCs), presence of virulence genes and antibiotic resistant determinants with DNA microarray-based genotyping. 24 different CCs were identified. Most isolates (80%) belonged to 6 predominant lineages. Of those, the number of isolates assigned to CC5 and CC15 increased, and those assigned to CC8, CC25, and CC30 decreased. The most prevalent clone, CC45, did not show a significant change in prevalence during the study period. A change in prevalence was observed for some of the virulence genes, mainly attributed with their association to certain CCs. With the exception of the common blaZ gene (encoding penicillinase), antibiotic resistance genes were only sporadically detected. In conclusion, the MSSA population structure was genetically diverse. We observed decadal changes in assignments to five predominant clones, and corresponding changes in the prevalence of some virulence genes linked to CC affiliation. In light of the restrictive antibiotics prescriptions and extensive infection control procedures in Sweden, antibiotic resistance genes were rarely detected and their prevalence unaffected during the study period.
2.
Monecke, Stefan, et al.
(författare)
Rapid detection of Panton-Valentine leukocidin in Staphylococcus aureus cultures by use of a lateral flow assay based on monoclonal antibodies
2013
Ingår i: Journal of Clinical Microbiology. - Washington, USA : American society of microbiology. - 0095-1137 .- 1098-660X. ; 51:2, s. 487-95
Tidskriftsartikel (refereegranskat) abstract
Panton-Valentine leukocidin (PVL) is a virulence factor of Staphylococcus aureus, which is associated with skin and soft-tissue infections and necrotizing pneumonia. To develop a rapid phenotypic assay, recombinant PVL F component was used to generate monoclonal antibodies by phage display. These antibodies were spotted on protein microarrays and screened using different lukF-PV preparations and detection antibodies. This led to the identification of the optimal antibody combination that was then used to establish a lateral flow assay. This test was used to detect PVL in S. aureus cultures. The detection limit of the assay with purified native and recombinant antigens was determined to be around 1 ng/ml. Overnight cultures from various solid and liquid media proved suitable for PVL detection. Six hundred strains and clinical isolates from patients from America, Europe, Australia, Africa, and the Middle East were tested. Isolates were genotyped in parallel by DNA microarray hybridization for confirmation of PVL status and assignment to clonal complexes. The sensitivity, specificity, and positive and negative predictive values of the assay in this trial were 99.7, 98.3, 98.4, and 99.7%, respectively. A total of 302 clinical isolates and reference strains were PVL positive and were assigned to 21 different clonal complexes. In summary, the lateral flow test allows rapid and economical detection of PVL in a routine bacteriology laboratory. As the test utilizes cultures from standard media and does not require sophisticated equipment, it can be easily integrated into a laboratory's workflow and might contribute to timely therapy of PVL-associated infections.
3.
Asfaw Idosa, Berhane, 1977-, et al.
(författare)
C10X polymorphism in the CARD8 gene is associated with bacteraemia
2014
Ingår i: Immunity, inflammation and disease. - West Sussex, UK : John Wiley & Sons. - 2050-4527. ; 2:1, s. 13-20
Tidskriftsartikel (refereegranskat) abstract
The NLRP3 inflammasome is an intracellular multi-protein complex that triggers caspase-1 mediated maturation of interleukin-1β (IL-1β); one of the most potent mediators of inflammation and a major cytokine produced during severe infections, like sepsis. However, the excessive cytokine levels seem to stage for tissue injury and organ failure, and high levels of IL-1β correlates with severity and mortality of sepsis. Instead, recent data suggest caspase-1 to function as a guardian against severe infections. CARD8 has been implied to regulate the synthesis of IL-1β via interaction to caspase-1. In recent years, polymorphism of CARD8 (C10X) per se or in combination with NLRP3 (Q705K) has been implicated with increased risk of inflammation. The aim was to investigate the correlation of these polymorphisms with severe blood stream infection. Human DNA was extracted from blood culture bottles that were found to be positive for microbial growth (i.e. patients with bacteraemia). Polymorphisms Q705K in the NLRP3 gene and C10X in the CARD8 gene were genotyped using TaqMan genotyping assay. The results were compared to healthy controls and to samples from patients with negative cultures. The polymorphism C10X was significantly over-represented among patients with bacteraemia as compared to healthy controls, whereas patients with negative blood culture were not associated with a higher prevalence. No association was observed with polymorphism Q705K of NLRP3 in either group of patients. Patients carrying polymorphism C10X in the CARD8 gene are at increased risk of developing bacteraemia and severe inflammation.
4.
Cajander, Sara, 1980-, et al.
(författare)
Preliminary results in quantitation of HLA-DRA by real-time PCR : a promising approach to identify immunosuppression in sepsis
2013
Ingår i: Critical Care. - London, United Kingdom : BioMed Central. - 1364-8535 .- 1466-609X. ; 17:5
Tidskriftsartikel (refereegranskat) abstract
Introduction: Reduced monocyte human leukocyte antigen (mHLA)-DR surface expression in the late phase of sepsis is postulated as a general biomarker of sepsis-induced immunosuppression and an independent predictor of nosocomial infections. However, traditional monitoring of mHLA-DR by flow cytometry has disadvantages due to specific laboratory requirements. An mRNA-based HLA-DR monitoring by polymerase chain reaction (PCR) would improve the clinical usage and facilitate conduction of large multicenter studies. In this study, we evaluated an mRNA-based HLA-DR monitoring by quantitative real-time PCR (qRT-PCR) as an alternative method to traditional flow cytometry.Methods: Fifty-nine patients with sepsis and blood culture growing pathogenic bacteria were studied. Blood samples were collected at day 1 or 2 after admission, for measurement of mHLA-DR by flow cytometry and mRNA expression of HLA-DRA and class II transactivator (CIITA) by qRT-PCR. Blood samples from blood donors were used as controls (n = 30).Results: A significant reduced expression of mHLA-DR, HLA-DRA, and CIITA was seen in septic patients compared with controls. HLA-DRA mRNA level in whole blood was highly correlated with surface expression of mHLA-DR.Conclusions: Patients with sepsis display a diminished expression of HLA-DR at the monocyte surface as well as in the gene expression at the mRNA level. The mRNA expression level of HLA-DRA monitored by qRT-PCR correlates highly with surface expression of HLA-DR and appears to be a possible future biomarker for evaluation of immunosuppression in sepsis.
