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- Lindqvist, Maria, 1983-
(författare)
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Epidemiological and molecular biological studies of multi-resistant methicillin-susceptible Staphylococcus aureus
- 2014
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Antibiotic resistance is increasingly recognised as a major problem and threat. During the last decades Gram-positive bacteria in general, and methicillin-resistant Staphylococcus aureus (MRSA) in particular, have been in focus both concerning matters of antibiotic resistance and as pathogens causing health care-associated (nosocomial) infections. In contrast to MRSA, studies on clonal distribution of methicillin-susceptible S. aureus (MSSA) are scarce. However, interest in MSSA has increased since it was shown that MRSA emerges from susceptible backgrounds by acquisition of a staphylococcal cassette chromosome element, carrying the mecA gene encoding methicillin-resistance (SCCmec).In an outbreak investigation of MRSA in Östergötland County, Sweden, in 2005, a high incidence of MSSA isolates with concomitant resistance to erythromycin, clindamycin and tobramycin (ECT-R) was detected. Analysis showed that 91 % of the investigated isolates were genetically related (clonal). The ECT-R clone was divided into four different but closely related patterns with pulsed-field gel electrophoresis (PFGE), and was designated spa type t002. Whole genome sequencing revealed that the ECT-R clone carried a pseudo-SCC element estimated to be 12 kb in size, showing a resemblance of more than 99 % with the SCCmec type II element of MRSA strain N315 (New York/Japan clone). This suggested a probable derivation from a highly successful MRSA strain, which had partially excised its SCCmec. The clonal outbreak was concentrated in eight hospital departments and two primary care centres, all located in the city of Linköping. Despite a high exchange of patients with the hospitals in the neighbouring counties in southeast Sweden (Jönköping- and Kalmar County), the ECT-R clone seemed to be limited to Östergötland County. However, a tobramycin-resistant clone predominated by isolates of spa type t084 was found in all three counties in southeast Sweden, and in particular among newborns, suggesting inter-hospital transmission.The ECT-R clone has survived as an abundant MSSA clone for a decade in Östergötland County, which indicates an insufficiency in the maintenance of basic hygiene guidelines, and that the clone probably possesses mechanisms of virulence and transmission that are yet to be discovered.
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| 3. |
- Lisi, Matteo, 1982-, et al.
(författare)
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Reduced myocardial strain is the best predictor of left atrial fibrosis and symptoms in patients undergoing heart transplantation
- 2016
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Annan publikation (övrigt vetenskapligt/konstnärligt)abstract
- Background: Left ventricular systolic dysfunction and raised diastolic pressures contribute to progressive left atrial (LA). We aimed to assess LA peak atrial longitudinal strain (PALS), in predicting the extent of LA fibrosis in patients with end-stage heart failure (HF) undergoing heart transplantation (HTx).Methods: We studied 48 patients with severe systolic HF (EF≤25% and NYHA class III-IV) before HTx. PALS, LA volume and LA stiffness were all measured. From the LA myocardial histological analysis, the ratio of fibrotic to total sample area determined the extent of fibrosis (%). Right heart catheterization and cardiopulmonary exercise testing were also assessed. Results: LA fibrosis correlated strongly with PALS (R=-0.76; p<0.0001) and NYHA class (R=0.73; p<0.0001) and to a lesser extent with VO2 max (R=-0.65; p=0.001), LA stiffness (R=0.58; p=0.001), PAoP (R=0.51; p=0.03), E/e′ (R=0.55; p=0.01) and E/A (R=0.46; p=0.01). Global PALS correlated modestly with VO2 max (R=0.53; p=0.001) and LA volume (R=-0.48; p=0.01) and weakly with E/e′ (R=-0.36; p=0.03). Multivariate regression analysis identified global PALS as the main determinant of LA myocardial fibrosis (β =-0.62, p<0.001). A cut off value of 7.6% gave an AUC of 0.79 on the ROC curve with a sensitivity of 87% and specificity of 84% in predicting >50% myocardial fibrosis.Conclusions:LA PALS is the most accurate LA function parameter that correlates with the extent of myocardial fibrosis in patients with advanced systolic HF requiring HTx.PALS of 7.6% could be used as a cut off value for identifying patients with severe LA fibrosis.
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