| 1. |
- Ahlstrand, Erik, 1974-, et al.
(author)
-
Alteration of the colonization pattern of coagulase-negative staphylococci in patients undergoing treatment for hematological malignancy
- 2012
-
In: European Journal of Clinical Microbiology and Infectious Diseases. - New York, USA : Springer. - 0934-9723 .- 1435-4373. ; 31:7, s. 1679-1687
-
Journal article (peer-reviewed)abstract
- The aim was to prospectively describe the colonization pattern of coagulase-negative staphylococci (CoNS) and the relationship between colonizing and invasive CoNS isolates among patients undergoing treatment for hematological malignancy. Fourteen newly diagnosed patients were included with either multiple myeloma or acute leukemia. Patients were repeatedly sampled from nares, throat, axillae, and perineum, and the CoNS isolates obtained were phenotypically characterized together with blood isolates of CoNS using the PhenePlate system (PhP). During the treatment a gradual reduction in the heterogeneity of colonizing CoNS was observed as well as an inter-patient accumulation of phenotypically related and multi-drug-resistant CoNS. These clusters of CoNS persisted for 2–3 months after the end of therapy. Ten positive blood cultures of CoNS were obtained and in the majority of these cases CoNS of the same PhP type were found in superficial cultures collected prior to the blood culture sampling. In conclusion, the study shows that therapy for hematological malignancy is associated with a homogenization of colonizing CoNS isolates and that this acquired flora of CoNS is persistent several months after the end of therapy. Furthermore, the results suggest that the source of bloodstream infections of CoNS in hematological patients is colonizing CoNS of the skin and mucosa.
|
|
| 2. |
- Ahlstrand, Erik, 1974-
(author)
-
Coagulase-negative staphylococci in hematological malignancy
- 2013
-
Doctoral thesis (other academic/artistic)abstract
- Bacterial infections are common in hematological malignancy. Coagulase-negative staphylococci (CoNS) are among the most prevalent causes of bacteremia in patients with hematological malignancies.In this thesis, different aspects of CoNS in hematological malignancy have been studied in four papers:In paper 1, CoNS blood culture isolates from patients with hematological malignancies treated at the University Hospital of Örebro from 1980 to 2009 were revaluated for the presence of reduced sensitivity to glycopeptides. A high incidence of heterogeneous-intermediate glycopeptide resistance was observed and there was a trend towards increasing incidence of this phenotype over time.In paper 2, the colonization pattern of CoNS among patients undergoing intensive chemotherapy for hematological malignancy was investigated. A successive homogenization and an accumulation of CoNS phenotypes mutually present in a majority of included patients were demonstrated.In paper 3, a PCR method to determine the clinical significance of positive blood cultures of the CoNS species Staphylococcus epidermidis was evaluated. The test failed to discriminate bloodstream infection from blood culture contamination.Finally, in paper 4, the long-term molecular epidemiology of S. epidermidis blood culture isolates from patients with hematological malignancies was studied with multilocus sequence typing. A predominance of sequence type 2 was demonstrated during the entire 30 year study period.In conclusion, the results are consistent with that CoNS have established as important pathogens by its capacity to colonize the human skin, its ability to reside and spread in the hospital environment and its rapid adaptation to stressors such as antimicrobials.
|
|
| 3. |
- Ahlstrand, Erik, 1974-, et al.
(author)
-
Evaluation of a PCR method to determine the clinical significance of blood cultures with Staphylococcus epidermidis in patients with hematological malignancies
- 2014
-
In: Acta Pathologica, Microbiologica et Immunologica Scandinavica (APMIS). - : Wiley-Blackwell. - 0903-4641 .- 1600-0463. ; 122:6, s. 539-544
-
Journal article (peer-reviewed)abstract
- The aim was to investigate whether the detection and quantification of Staphylococcus epidermidis DNA in blood could distinguish S. epidermidis blood stream infections (BSIs) from blood culture contaminations in patients with hematological malignancies. The hld gene was chosen to identify S. epidermidis DNA and DNA in blood samples was detected by real-time PCR. Blood samples were obtained simultaneously with blood cultures positive for S. epidermidis (n = 30), during blood culture-negative episodes (n = 10) and episodes of bacteremia with other bacteria than S. epidermidis (n = 4) and from healthy blood donors (n = 10). In addition, DNA from S. epidermidis and a selection of other bacterial species were analyzed. Three different sets of criteria were used to classify episodes with positive blood cultures with S. epidermidis as BSIs or contaminations. All DNA preparations from S. epidermidis (n = 48) were hld-positive, but other bacterial species (n = 13) were negative. Sixteen (53%) of 30 blood samples from patients with blood cultures positive for S. epidermidis were hld-positive, but none of the controls. There was no clear association between a positive hld PCR and episodes interpreted as BSIs. In conclusion, hld PCR failed to distinguish S. epidermidis BSIs from blood culture contaminations in patients with hematological malignancies.
|
|
| 4. |
- Ahlstrand, Erik, 1974-, et al.
(author)
-
Long-term molecular epidemiology of staphylococcus epidermidis blood culture isolates from patients with hematological malignancies
- 2014
-
In: PLOS ONE. - San Francisco, USA : Public Library Science. - 1932-6203. ; 9:6
-
Journal article (peer-reviewed)abstract
- Staphylococcus epidermidis is an important cause of bloodstream infections in patients with hematological malignancies. Knowledge of the long-term epidemiology of these infections is limited. We surveyed all S. epidermidis blood culture isolates from patients treated for hematological malignancies at the University Hospital of Orebro, Sweden from 1980 to 2009. A total of 373 S. epidermidis isolates were identified and multilocus sequence typing, staphylococcal chromosome cassette mec (SCCmec) typing and standard antibiotic susceptibility testing were employed to characterize these isolates. The majority of the isolates 361/373 (97%) belonged to clonal complex 2, and the 373 isolates were divided into 45 sequence types (STs); Simpson's Diversity Index was 0.56. The most prevalent STs were ST2 (243/373, 65%) and ST215 (28/373, 8%). Ninety three percent (226/243) of the ST2 isolates displayed either SCCmec type III or IV. ST2 and 215 were isolated during the entire study period, and together these STs caused temporal peaks in the number of positive blood cultures of S. epidermidis. Methicillin resistance was detected in 213/273 (78%) of all isolates. In the two predominating STs, ST2 and ST215, methicillin resistance was detected in 256/271 isolates (95%), compared with 34/100 (34%) in other STs (p<0.001). In conclusion, in this long-term study of patients with hematological malignancies, we demonstrate a predominance of methicillin-resistant ST2 among S. epidermidis blood culture isolates.
|
|
| 5. |
- Andersen, Christen Lykkegaard, et al.
(author)
-
Circulating YKL-40 in patients with essential thrombocythemia and polycythemia vera treated with the novel histone deacetylase inhibitor vorinostat
- 2014
-
In: Leukemia Research. - : Elsevier. - 0145-2126 .- 1873-5835. ; 38:7, s. 816-821
-
Journal article (peer-reviewed)abstract
- YKL-40 regulates vascular endothelial growth factors and induces tumor proliferation. We investigated YKL-40 before and after treatment with vorinostat in 31 polycythemia vera (PV) and 16 essential thrombocythemia (ET) patients. Baseline PV patient levels were 2 times higher than in healthy controls (P<0.0001) and 1.7 times higher than in ET (P = 0.02). A significant correlation between YKL-40 at baseline and neutrophils, CRP, LDH, JAK2V617F and platelets in PV patients was observed, as well as a significantly greater reduction of YKL-40 levels in PV patients responding to therapy. YKL-40 might be a novel marker of disease burden and progression in myeloproliferative neoplasms.
|
|
